[PATCH v2 0/3] Introduce "efi_fake_mem_mirror" boot option

[PATCH v2 0/3] Introduce "efi_fake_mem_mirror" boot option

[Taku Izumi]

UEFI spec 2.5 introduces new Memory Attribute Definition named
EFI_MEMORY_MORE_RELIABLE which indicates which memory ranges are
mirrored. Now linux kernel can recognize which memory ranges are mirrored
by handling EFI_MEMORY_MORE_RELIABLE attributes.
However testing this feature necesitates boxes with UEFI spec 2.5 complied
firmware.

This patchset introduces new boot option named "efi_fake_mem_mirror".
By specifying this parameter, you can mark specific memory as
mirrored memory. This is useful for debugging of Memory Address Range
Mirroring feature.

v1 -> v2:
 - change abbreviation of EFI_MEMORY_MORE_RELIABLE from "RELY" to "MR"
 - add patch (2/3) for changing abbreviation of EFI_MEMORY_RUNTIME
 - migrate some code from arch/x86/platform/efi/quirks to
   drivers/firmware/efi/fake_mem.c and create config EFI_FAKE_MEMMAP

Taku Izumi (3):
  efi: Add EFI_MEMORY_MORE_RELIABLE support to efi_md_typeattr_format()
  efi: Change abbreviation of EFI_MEMORY_RUNTIME from "RUN" to "RT"
  x86, efi: Add "efi_fake_mem_mirror" boot option

 Documentation/kernel-parameters.txt |   8 ++
 arch/x86/include/asm/efi.h          |   1 +
 arch/x86/kernel/setup.c             |   4 +-
 arch/x86/platform/efi/efi.c         |   2 +-
 drivers/firmware/efi/Kconfig        |  12 +++
 drivers/firmware/efi/Makefile       |   1 +
 drivers/firmware/efi/efi.c          |   8 +-
 drivers/firmware/efi/fake_mem.c     | 204 ++++++++++++++++++++++++++++++++++++
 include/linux/efi.h                 |   6 ++
 9 files changed, 241 insertions(+), 5 deletions(-)
 create mode 100644 drivers/firmware/efi/fake_mem.c

-- 
1.8.3.1

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[PATCH v2 1/3] efi: Add EFI_MEMORY_MORE_RELIABLE support to efi_md_typeattr_format()

[Taku Izumi]

UEFI spec 2.5 introduces new Memory Attribute Definition named
EFI_MEMORY_MORE_RELIABLE. This patch adds this new attribute
support to efi_md_typeattr_format().

Signed-off-by: Taku Izumi <izumi.taku@jp.fujitsu.com>
---
 drivers/firmware/efi/efi.c | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
index d6144e3..8124078 100644
--- a/drivers/firmware/efi/efi.c
+++ b/drivers/firmware/efi/efi.c
@@ -589,12 +589,14 @@ char * __init efi_md_typeattr_format(char *buf, size_t size,
 	attr = md->attribute;
 	if (attr & ~(EFI_MEMORY_UC | EFI_MEMORY_WC | EFI_MEMORY_WT |
 		     EFI_MEMORY_WB | EFI_MEMORY_UCE | EFI_MEMORY_WP |
-		     EFI_MEMORY_RP | EFI_MEMORY_XP | EFI_MEMORY_RUNTIME))
+		     EFI_MEMORY_RP | EFI_MEMORY_XP | EFI_MEMORY_RUNTIME |
+		     EFI_MEMORY_MORE_RELIABLE))
 		snprintf(pos, size, "|attr=0x%016llx]",
 			 (unsigned long long)attr);
 	else
-		snprintf(pos, size, "|%3s|%2s|%2s|%2s|%3s|%2s|%2s|%2s|%2s]",
+		snprintf(pos, size, "|%3s|%2s|%2s|%2s|%2s|%3s|%2s|%2s|%2s|%2s]",
 			 attr & EFI_MEMORY_RUNTIME ? "RUN" : "",
+			 attr & EFI_MEMORY_MORE_RELIABLE ? "MR" : "",
 			 attr & EFI_MEMORY_XP      ? "XP"  : "",
 			 attr & EFI_MEMORY_RP      ? "RP"  : "",
 			 attr & EFI_MEMORY_WP      ? "WP"  : "",
-- 
1.8.3.1

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Re: [PATCH v2 1/3] efi: Add EFI_MEMORY_MORE_RELIABLE support to efi_md_typeattr_format()

[Matt Fleming]

On Thu, 27 Aug, at 02:11:19AM, Taku Izumi wrote:
> UEFI spec 2.5 introduces new Memory Attribute Definition named
> EFI_MEMORY_MORE_RELIABLE. This patch adds this new attribute
> support to efi_md_typeattr_format().
> 
> Signed-off-by: Taku Izumi <izumi.taku@jp.fujitsu.com>
> ---
>  drivers/firmware/efi/efi.c | 6 ++++--
>  1 file changed, 4 insertions(+), 2 deletions(-)

Thanks, applied!

-- 
Matt Fleming, Intel Open Source Technology Center

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[PATCH v2 2/3] efi: Change abbreviation of EFI_MEMORY_RUNTIME from "RUN" to "RT"

[Taku Izumi]

Now efi_md_typeattr_format() outputs "RUN" if passed EFI memory
descriptor has EFI_MEMORY_RUNTIME attribute. But "RT" is preferer
because it is shorter and clearer.

This patch changes abbreviation of EFI_MEMORY_RUNTIME from "RUN"
to "RT".

Suggested-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Taku Izumi <izumi.taku@jp.fujitsu.com>
---
 drivers/firmware/efi/efi.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
index 8124078..25b6477 100644
--- a/drivers/firmware/efi/efi.c
+++ b/drivers/firmware/efi/efi.c
@@ -594,8 +594,8 @@ char * __init efi_md_typeattr_format(char *buf, size_t size,
 		snprintf(pos, size, "|attr=0x%016llx]",
 			 (unsigned long long)attr);
 	else
-		snprintf(pos, size, "|%3s|%2s|%2s|%2s|%2s|%3s|%2s|%2s|%2s|%2s]",
-			 attr & EFI_MEMORY_RUNTIME ? "RUN" : "",
+		snprintf(pos, size, "|%2s|%2s|%2s|%2s|%2s|%3s|%2s|%2s|%2s|%2s]",
+			 attr & EFI_MEMORY_RUNTIME ? "RT" : "",
 			 attr & EFI_MEMORY_MORE_RELIABLE ? "MR" : "",
 			 attr & EFI_MEMORY_XP      ? "XP"  : "",
 			 attr & EFI_MEMORY_RP      ? "RP"  : "",
-- 
1.8.3.1

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Re: [PATCH v2 2/3] efi: Change abbreviation of EFI_MEMORY_RUNTIME from "RUN" to "RT"

[Matt Fleming]

On Thu, 27 Aug, at 02:11:29AM, Taku Izumi wrote:
> Now efi_md_typeattr_format() outputs "RUN" if passed EFI memory
> descriptor has EFI_MEMORY_RUNTIME attribute. But "RT" is preferer
> because it is shorter and clearer.
> 
> This patch changes abbreviation of EFI_MEMORY_RUNTIME from "RUN"
> to "RT".
> 
> Suggested-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
> Signed-off-by: Taku Izumi <izumi.taku@jp.fujitsu.com>
> ---
>  drivers/firmware/efi/efi.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
> index 8124078..25b6477 100644
> --- a/drivers/firmware/efi/efi.c
> +++ b/drivers/firmware/efi/efi.c
> @@ -594,8 +594,8 @@ char * __init efi_md_typeattr_format(char *buf, size_t size,
>  		snprintf(pos, size, "|attr=0x%016llx]",
>  			 (unsigned long long)attr);
>  	else
> -		snprintf(pos, size, "|%3s|%2s|%2s|%2s|%2s|%3s|%2s|%2s|%2s|%2s]",
> -			 attr & EFI_MEMORY_RUNTIME ? "RUN" : "",
> +		snprintf(pos, size, "|%2s|%2s|%2s|%2s|%2s|%3s|%2s|%2s|%2s|%2s]",
> +			 attr & EFI_MEMORY_RUNTIME ? "RT" : "",
>  			 attr & EFI_MEMORY_MORE_RELIABLE ? "MR" : "",
>  			 attr & EFI_MEMORY_XP      ? "XP"  : "",
>  			 attr & EFI_MEMORY_RP      ? "RP"  : "",

I know that Ard suggested this change but I don't think I should apply
this and the reason is that developers, particularly distro
developers, come to rely on the output we print for debugging
purposes.

They don't necessarily monitor all the patches getting merged upstream
closely enough to realise that it impacts their debugging strategy. So
when they notice that the output has gone from "RUN" to "RT" they're
naturally going to ask what the difference is... and the answer is "it
looks prettier". That's not a good enough reason.

Obviously if we're printing something that's completely incorrect, or
we can improve the message considerably, then yes, it makes sense to
change it - but that's not the case here.

Thanks for the patch, but sorry, I'm not going to apply this one.

-- 
Matt Fleming, Intel Open Source Technology Center

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Re: [PATCH v2 2/3] efi: Change abbreviation of EFI_MEMORY_RUNTIME from "RUN" to "RT"

[Ard Biesheuvel]

On 9 September 2015 at 15:27, Matt Fleming <matt@codeblueprint.co.uk> wrote:
> On Thu, 27 Aug, at 02:11:29AM, Taku Izumi wrote:
>> Now efi_md_typeattr_format() outputs "RUN" if passed EFI memory
>> descriptor has EFI_MEMORY_RUNTIME attribute. But "RT" is preferer
>> because it is shorter and clearer.
>>
>> This patch changes abbreviation of EFI_MEMORY_RUNTIME from "RUN"
>> to "RT".
>>
>> Suggested-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
>> Signed-off-by: Taku Izumi <izumi.taku@jp.fujitsu.com>
>> ---
>>  drivers/firmware/efi/efi.c | 4 ++--
>>  1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/firmware/efi/efi.c b/drivers/firmware/efi/efi.c
>> index 8124078..25b6477 100644
>> --- a/drivers/firmware/efi/efi.c
>> +++ b/drivers/firmware/efi/efi.c
>> @@ -594,8 +594,8 @@ char * __init efi_md_typeattr_format(char *buf, size_t size,
>>               snprintf(pos, size, "|attr=0x%016llx]",
>>                        (unsigned long long)attr);
>>       else
>> -             snprintf(pos, size, "|%3s|%2s|%2s|%2s|%2s|%3s|%2s|%2s|%2s|%2s]",
>> -                      attr & EFI_MEMORY_RUNTIME ? "RUN" : "",
>> +             snprintf(pos, size, "|%2s|%2s|%2s|%2s|%2s|%3s|%2s|%2s|%2s|%2s]",
>> +                      attr & EFI_MEMORY_RUNTIME ? "RT" : "",
>>                        attr & EFI_MEMORY_MORE_RELIABLE ? "MR" : "",
>>                        attr & EFI_MEMORY_XP      ? "XP"  : "",
>>                        attr & EFI_MEMORY_RP      ? "RP"  : "",
>
> I know that Ard suggested this change but I don't think I should apply
> this and the reason is that developers, particularly distro
> developers, come to rely on the output we print for debugging
> purposes.
>
> They don't necessarily monitor all the patches getting merged upstream
> closely enough to realise that it impacts their debugging strategy. So
> when they notice that the output has gone from "RUN" to "RT" they're
> naturally going to ask what the difference is... and the answer is "it
> looks prettier". That's not a good enough reason.
>
> Obviously if we're printing something that's completely incorrect, or
> we can improve the message considerably, then yes, it makes sense to
> change it - but that's not the case here.
>
> Thanks for the patch, but sorry, I'm not going to apply this one.
>

Ack. It was more an illustration of my argument for preferring MR over
REL[IY] than anything else,.

-- 
ard.

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[PATCH v2 3/3] x86, efi: Add "efi_fake_mem_mirror" boot option

[Taku Izumi]

This patch introduces new boot option named "efi_fake_mem_mirror".
By specifying this parameter, you can mark specific memory as
mirrored memory. This is useful for debugging of Address Range
Mirroring feature.

For example, if you specify "efi_fake_mem_mirror=2G@4G,2G@0x10a0000000",
the original (firmware provided) EFI memmap will be updated so that
the specified memory regions have EFI_MEMORY_MORE_RELIABLE attribute:

 <original EFI memmap>
   efi: mem00: [Boot Data          |  |  |  |  |  |   |WB|WT|WC|UC] range=[0x0000000000000000-0x0000000000001000) (0MB)
   efi: mem01: [Loader Data        |  |  |  |  |  |   |WB|WT|WC|UC] range=[0x0000000000001000-0x0000000000002000) (0MB)
   ...
   efi: mem35: [Boot Data          |  |  |  |  |  |   |WB|WT|WC|UC] range=[0x0000000047ee6000-0x0000000048014000) (1MB)
   efi: mem36: [Conventional Memory|  |  |  |  |  |   |WB|WT|WC|UC] range=[0x0000000100000000-0x00000020a0000000) (129536MB)
   efi: mem37: [Reserved           |RT|  |  |  |  |   |  |  |  |UC] range=[0x0000000060000000-0x0000000090000000) (768MB)

 <updated EFI memmap>
   efi: mem00: [Boot Data          |  |  |  |  |  |   |WB|WT|WC|UC] range=[0x0000000000000000-0x0000000000001000) (0MB)
   efi: mem01: [Loader Data        |  |  |  |  |  |   |WB|WT|WC|UC] range=[0x0000000000001000-0x0000000000002000) (0MB)
   ...
   efi: mem35: [Boot Data          |  |  |  |  |  |   |WB|WT|WC|UC] range=[0x0000000047ee6000-0x0000000048014000) (1MB)
   efi: mem36: [Conventional Memory|  |MR|  |  |  |   |WB|WT|WC|UC] range=[0x0000000100000000-0x0000000180000000) (2048MB)
   efi: mem37: [Conventional Memory|  |  |  |  |  |   |WB|WT|WC|UC] range=[0x0000000180000000-0x00000010a0000000) (61952MB)
   efi: mem38: [Conventional Memory|  |MR|  |  |  |   |WB|WT|WC|UC] range=[0x00000010a0000000-0x0000001120000000) (2048MB)
   efi: mem39: [Conventional Memory|  |  |  |  |  |   |WB|WT|WC|UC] range=[0x0000001120000000-0x00000020a0000000) (63488MB)
   efi: mem40: [Reserved           |RT|  |  |  |  |   |  |  |  |UC] range=[0x0000000060000000-0x0000000090000000) (768MB)

And you will find that the following message is output:

   efi: Memory: 4096M/131455M mirrored memory

Signed-off-by: Taku Izumi <izumi.taku@jp.fujitsu.com>
---
 Documentation/kernel-parameters.txt |   8 ++
 arch/x86/include/asm/efi.h          |   1 +
 arch/x86/kernel/setup.c             |   4 +-
 arch/x86/platform/efi/efi.c         |   2 +-
 drivers/firmware/efi/Kconfig        |  12 +++
 drivers/firmware/efi/Makefile       |   1 +
 drivers/firmware/efi/fake_mem.c     | 204 ++++++++++++++++++++++++++++++++++++
 include/linux/efi.h                 |   6 ++
 8 files changed, 236 insertions(+), 2 deletions(-)
 create mode 100644 drivers/firmware/efi/fake_mem.c

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 1d6f045..0efded6 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -1092,6 +1092,14 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
 			you are really sure that your UEFI does sane gc and
 			fulfills the spec otherwise your board may brick.
 
+	efi_fake_mem_mirror=nn[KMG]@ss[KMG][,nn[KMG]@ss[KMG],..] [EFI; X86]
+			Mark specific memory as mirrored memory and update
+			EFI memory map.
+			Region of memory to be marked is from ss to ss+nn.
+			Using this parameter you can do debugging of Address
+			Range Mirroring feature even if your box doesn't support
+			it.
+
 	eisa_irq_edge=	[PARISC,HW]
 			See header of drivers/parisc/eisa.c.
 
diff --git a/arch/x86/include/asm/efi.h b/arch/x86/include/asm/efi.h
index 155162e..479fd51 100644
--- a/arch/x86/include/asm/efi.h
+++ b/arch/x86/include/asm/efi.h
@@ -93,6 +93,7 @@ extern void __init efi_set_executable(efi_memory_desc_t *md, bool executable);
 extern int __init efi_memblock_x86_reserve_range(void);
 extern pgd_t * __init efi_call_phys_prolog(void);
 extern void __init efi_call_phys_epilog(pgd_t *save_pgd);
+extern void __init print_efi_memmap(void);
 extern void __init efi_unmap_memmap(void);
 extern void __init efi_memory_uc(u64 addr, unsigned long size);
 extern void __init efi_map_region(efi_memory_desc_t *md);
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 80f874b..e3ed628 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -1104,8 +1104,10 @@ void __init setup_arch(char **cmdline_p)
 	memblock_set_current_limit(ISA_END_ADDRESS);
 	memblock_x86_fill();
 
-	if (efi_enabled(EFI_BOOT))
+	if (efi_enabled(EFI_BOOT)) {
+		efi_fake_memmap();
 		efi_find_mirror();
+	}
 
 	/*
 	 * The EFI specification says that boot service code won't be called
diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c
index e4308fe..eee8068 100644
--- a/arch/x86/platform/efi/efi.c
+++ b/arch/x86/platform/efi/efi.c
@@ -222,7 +222,7 @@ int __init efi_memblock_x86_reserve_range(void)
 	return 0;
 }
 
-static void __init print_efi_memmap(void)
+void __init print_efi_memmap(void)
 {
 #ifdef EFI_DEBUG
 	efi_memory_desc_t *md;
diff --git a/drivers/firmware/efi/Kconfig b/drivers/firmware/efi/Kconfig
index 54071c1..4fafebe 100644
--- a/drivers/firmware/efi/Kconfig
+++ b/drivers/firmware/efi/Kconfig
@@ -52,6 +52,18 @@ config EFI_RUNTIME_MAP
 
 	  See also Documentation/ABI/testing/sysfs-firmware-efi-runtime-map.
 
+config EFI_FAKE_MEMMAP
+	bool "Enable EFI Fake memory mirror"
+	depends on EFI && X86
+	default n
+	help
+	  Saying Y here will enable "efi_fake_mem_miror" boot option.
+	  By specifying this parameter, you can mark specific memory as
+	  mirrored memory by updating original (firmware provided) EFI memmap.
+	  This is useful for debugging of Memory Address Range Mirroring
+	  feature.
+
+
 config EFI_PARAMS_FROM_FDT
 	bool
 	help
diff --git a/drivers/firmware/efi/Makefile b/drivers/firmware/efi/Makefile
index 6fd3da9..c24f005 100644
--- a/drivers/firmware/efi/Makefile
+++ b/drivers/firmware/efi/Makefile
@@ -9,3 +9,4 @@ obj-$(CONFIG_UEFI_CPER)			+= cper.o
 obj-$(CONFIG_EFI_RUNTIME_MAP)		+= runtime-map.o
 obj-$(CONFIG_EFI_RUNTIME_WRAPPERS)	+= runtime-wrappers.o
 obj-$(CONFIG_EFI_STUB)			+= libstub/
+obj-$(CONFIG_EFI_FAKE_MEMMAP)		+= fake_mem.o
diff --git a/drivers/firmware/efi/fake_mem.c b/drivers/firmware/efi/fake_mem.c
new file mode 100644
index 0000000..2645d4a
--- /dev/null
+++ b/drivers/firmware/efi/fake_mem.c
@@ -0,0 +1,204 @@
+/*
+ * fake_mem.c
+ *
+ * Copyright (C) 2015 FUJITSU LIMITED
+ * Author: Taku Izumi <izumi.taku@jp.fujitsu.com>
+ *
+ * This code introduces new boot option named "efi_fake_mem_mirror"
+ * By specifying this parameter, you can mark specific memory as
+ * mirrored memory by updating original (firmware provided) EFI
+ * memmap.
+ *
+ *  This program is free software; you can redistribute it and/or modify it
+ *  under the terms and conditions of the GNU General Public License,
+ *  version 2, as published by the Free Software Foundation.
+ *
+ *  This program is distributed in the hope it will be useful, but WITHOUT
+ *  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ *  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
+ *  more details.
+ *
+ *  You should have received a copy of the GNU General Public License along with
+ *  this program; if not, see <http://www.gnu.org/licenses/>.
+ *
+ *  The full GNU General Public License is included in this distribution in
+ *  the file called "COPYING".
+ */
+
+#include <linux/kernel.h>
+#include <linux/efi.h>
+#include <linux/init.h>
+#include <linux/memblock.h>
+#include <linux/types.h>
+#include <asm/efi.h>
+
+#define EFI_MAX_FAKE_MIRROR 8
+static struct range fake_mirrors[EFI_MAX_FAKE_MIRROR];
+static int num_fake_mirror;
+
+void __init efi_fake_memmap(void)
+{
+	u64 start, end, m_start, m_end;
+	int new_nr_map = memmap.nr_map;
+	efi_memory_desc_t *md;
+	u64 new_memmap_phy;
+	void *new_memmap;
+	void *old, *new;
+	int i;
+
+	if (!num_fake_mirror)
+		return;
+
+	/* count up the number of EFI memory descriptor */
+	for (old = memmap.map; old < memmap.map_end; old += memmap.desc_size) {
+		md = old;
+		start = md->phys_addr;
+		end = start + (md->num_pages << EFI_PAGE_SHIFT) - 1;
+
+		for (i = 0; i < num_fake_mirror; i++) {
+			/* mirroring range */
+			m_start = fake_mirrors[i].start;
+			m_end = fake_mirrors[i].end;
+
+			if (m_start <= start) {
+				/* split into 2 parts */
+				if (start < m_end && m_end < end)
+					new_nr_map++;
+			}
+			if (start < m_start && m_start < end) {
+				/* split into 3 parts */
+				if (m_end < end)
+					new_nr_map += 2;
+				/* split into 2 parts */
+				if (end <= m_end)
+					new_nr_map++;
+			}
+		}
+	}
+
+	/* allocate memory for new EFI memmap */
+	new_memmap_phy = memblock_alloc(memmap.desc_size * new_nr_map,
+					PAGE_SIZE);
+	if (!new_memmap_phy)
+		return;
+
+	/* create new EFI memmap */
+	new_memmap = early_memremap(new_memmap_phy,
+				    memmap.desc_size * new_nr_map);
+	for (old = memmap.map, new = new_memmap;
+	     old < memmap.map_end;
+	     old += memmap.desc_size, new += memmap.desc_size) {
+
+		/* copy original EFI memory descriptor */
+		memcpy(new, old, memmap.desc_size);
+		md = new;
+		start = md->phys_addr;
+		end = md->phys_addr + (md->num_pages << EFI_PAGE_SHIFT) - 1;
+
+		for (i = 0; i < num_fake_mirror; i++) {
+			/* mirroring range */
+			m_start = fake_mirrors[i].start;
+			m_end = fake_mirrors[i].end;
+
+			if (m_start <= start && end <= m_end)
+				md->attribute |= EFI_MEMORY_MORE_RELIABLE;
+
+			if (m_start <= start &&
+			    (start < m_end && m_end < end)) {
+				/* first part */
+				md->attribute |= EFI_MEMORY_MORE_RELIABLE;
+				md->num_pages = (m_end - md->phys_addr + 1) >>
+					EFI_PAGE_SHIFT;
+				/* latter part */
+				new += memmap.desc_size;
+				memcpy(new, old, memmap.desc_size);
+				md = new;
+				md->phys_addr = m_end + 1;
+				md->num_pages = (end - md->phys_addr + 1) >>
+					EFI_PAGE_SHIFT;
+			}
+
+			if ((start < m_start && m_start < end) && m_end < end) {
+				/* first part */
+				md->num_pages = (m_start - md->phys_addr) >>
+					EFI_PAGE_SHIFT;
+				/* middle part */
+				new += memmap.desc_size;
+				memcpy(new, old, memmap.desc_size);
+				md = new;
+				md->attribute |= EFI_MEMORY_MORE_RELIABLE;
+				md->phys_addr = m_start;
+				md->num_pages = (m_end - m_start + 1) >>
+					EFI_PAGE_SHIFT;
+				/* last part */
+				new += memmap.desc_size;
+				memcpy(new, old, memmap.desc_size);
+				md = new;
+				md->phys_addr = m_end + 1;
+				md->num_pages = (end - m_end) >>
+					EFI_PAGE_SHIFT;
+			}
+
+			if ((start < m_start && m_start < end) &&
+			    (end <= m_end)) {
+				/* first part */
+				md->num_pages = (m_start - md->phys_addr) >>
+					EFI_PAGE_SHIFT;
+				/* latter part */
+				new += memmap.desc_size;
+				memcpy(new, old, memmap.desc_size);
+				md = new;
+				md->phys_addr = m_start;
+				md->num_pages = (end - md->phys_addr + 1) >>
+					EFI_PAGE_SHIFT;
+				md->attribute |= EFI_MEMORY_MORE_RELIABLE;
+			}
+		}
+	}
+
+	/* swap into new EFI memmap */
+	efi_unmap_memmap();
+	memmap.map = new_memmap;
+	memmap.phys_map = (void *)new_memmap_phy;
+	memmap.nr_map = new_nr_map;
+	memmap.map_end = memmap.map + memmap.nr_map * memmap.desc_size;
+	set_bit(EFI_MEMMAP, &efi.flags);
+
+	/* print new EFI memmap */
+	print_efi_memmap();
+}
+
+static int __init setup_fake_mem_mirror(char *p)
+{
+	u64 start = 0, mem_size = 0;
+	int i;
+
+	if (!p)
+		return -EINVAL;
+
+	while (*p != '\0') {
+		mem_size = memparse(p, &p);
+		if (*p == '@')
+			start = memparse(p+1, &p);
+		else
+			break;
+
+		num_fake_mirror = add_range_with_merge(fake_mirrors,
+						       EFI_MAX_FAKE_MIRROR,
+						       num_fake_mirror,
+						       start,
+						       start + mem_size - 1);
+		if (*p == ',')
+			p++;
+	}
+
+	sort_range(fake_mirrors, num_fake_mirror);
+
+	for (i = 0; i < num_fake_mirror; i++)
+		pr_info("efi_fake_mem_mirror: [mem 0x%016llx-0x%016llx] marked as mirrored memory",
+			fake_mirrors[i].start, fake_mirrors[i].end);
+
+	return *p == '\0' ? 0 : -EINVAL;
+}
+
+early_param("efi_fake_mem_mirror", setup_fake_mem_mirror);
diff --git a/include/linux/efi.h b/include/linux/efi.h
index 85ef051..620baec 100644
--- a/include/linux/efi.h
+++ b/include/linux/efi.h
@@ -908,6 +908,12 @@ extern struct kobject *efi_kobj;
 extern int efi_reboot_quirk_mode;
 extern bool efi_poweroff_required(void);
 
+#ifdef CONFIG_EFI_FAKE_MEMMAP
+extern void __init efi_fake_memmap(void);
+#else
+static inline void efi_fake_memmap(void) { }
+#endif
+
 /* Iterate through an efi_memory_map */
 #define for_each_efi_memory_desc(m, md)					   \
 	for ((md) = (m)->map;						   \
-- 
1.8.3.1

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Re: [PATCH v2 3/3] x86, efi: Add "efi_fake_mem_mirror" boot option

[Matt Fleming]

On Thu, 27 Aug, at 02:11:37AM, Taku Izumi wrote:
> This patch introduces new boot option named "efi_fake_mem_mirror".
> By specifying this parameter, you can mark specific memory as
> mirrored memory. This is useful for debugging of Address Range
> Mirroring feature.
> 
> For example, if you specify "efi_fake_mem_mirror=2G@4G,2G@0x10a0000000",
> the original (firmware provided) EFI memmap will be updated so that
> the specified memory regions have EFI_MEMORY_MORE_RELIABLE attribute:
> 
>  <original EFI memmap>
>    efi: mem00: [Boot Data          |  |  |  |  |  |   |WB|WT|WC|UC] range=[0x0000000000000000-0x0000000000001000) (0MB)
>    efi: mem01: [Loader Data        |  |  |  |  |  |   |WB|WT|WC|UC] range=[0x0000000000001000-0x0000000000002000) (0MB)
>    ...
>    efi: mem35: [Boot Data          |  |  |  |  |  |   |WB|WT|WC|UC] range=[0x0000000047ee6000-0x0000000048014000) (1MB)
>    efi: mem36: [Conventional Memory|  |  |  |  |  |   |WB|WT|WC|UC] range=[0x0000000100000000-0x00000020a0000000) (129536MB)
>    efi: mem37: [Reserved           |RT|  |  |  |  |   |  |  |  |UC] range=[0x0000000060000000-0x0000000090000000) (768MB)
> 
>  <updated EFI memmap>
>    efi: mem00: [Boot Data          |  |  |  |  |  |   |WB|WT|WC|UC] range=[0x0000000000000000-0x0000000000001000) (0MB)
>    efi: mem01: [Loader Data        |  |  |  |  |  |   |WB|WT|WC|UC] range=[0x0000000000001000-0x0000000000002000) (0MB)
>    ...
>    efi: mem35: [Boot Data          |  |  |  |  |  |   |WB|WT|WC|UC] range=[0x0000000047ee6000-0x0000000048014000) (1MB)
>    efi: mem36: [Conventional Memory|  |MR|  |  |  |   |WB|WT|WC|UC] range=[0x0000000100000000-0x0000000180000000) (2048MB)
>    efi: mem37: [Conventional Memory|  |  |  |  |  |   |WB|WT|WC|UC] range=[0x0000000180000000-0x00000010a0000000) (61952MB)
>    efi: mem38: [Conventional Memory|  |MR|  |  |  |   |WB|WT|WC|UC] range=[0x00000010a0000000-0x0000001120000000) (2048MB)
>    efi: mem39: [Conventional Memory|  |  |  |  |  |   |WB|WT|WC|UC] range=[0x0000001120000000-0x00000020a0000000) (63488MB)
>    efi: mem40: [Reserved           |RT|  |  |  |  |   |  |  |  |UC] range=[0x0000000060000000-0x0000000090000000) (768MB)
> 
> And you will find that the following message is output:
> 
>    efi: Memory: 4096M/131455M mirrored memory
> 
> Signed-off-by: Taku Izumi <izumi.taku@jp.fujitsu.com>
> ---
>  Documentation/kernel-parameters.txt |   8 ++
>  arch/x86/include/asm/efi.h          |   1 +
>  arch/x86/kernel/setup.c             |   4 +-
>  arch/x86/platform/efi/efi.c         |   2 +-
>  drivers/firmware/efi/Kconfig        |  12 +++
>  drivers/firmware/efi/Makefile       |   1 +
>  drivers/firmware/efi/fake_mem.c     | 204 ++++++++++++++++++++++++++++++++++++
>  include/linux/efi.h                 |   6 ++
>  8 files changed, 236 insertions(+), 2 deletions(-)
>  create mode 100644 drivers/firmware/efi/fake_mem.c

[...]

> diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c
> index e4308fe..eee8068 100644
> --- a/arch/x86/platform/efi/efi.c
> +++ b/arch/x86/platform/efi/efi.c
> @@ -222,7 +222,7 @@ int __init efi_memblock_x86_reserve_range(void)
>  	return 0;
>  }
>  
> -static void __init print_efi_memmap(void)
> +void __init print_efi_memmap(void)
>  {
>  #ifdef EFI_DEBUG
>  	efi_memory_desc_t *md;

If we're going to make this function global we should stick to the
existing naming convention and rename it efi_print_memmap() in a
separate patch.

> diff --git a/drivers/firmware/efi/fake_mem.c b/drivers/firmware/efi/fake_mem.c
> new file mode 100644
> index 0000000..2645d4a
> --- /dev/null
> +++ b/drivers/firmware/efi/fake_mem.c
> @@ -0,0 +1,204 @@
> +/*
> + * fake_mem.c
> + *
> + * Copyright (C) 2015 FUJITSU LIMITED
> + * Author: Taku Izumi <izumi.taku@jp.fujitsu.com>
> + *
> + * This code introduces new boot option named "efi_fake_mem_mirror"
> + * By specifying this parameter, you can mark specific memory as
> + * mirrored memory by updating original (firmware provided) EFI
> + * memmap.
> + *
> + *  This program is free software; you can redistribute it and/or modify it
> + *  under the terms and conditions of the GNU General Public License,
> + *  version 2, as published by the Free Software Foundation.
> + *
> + *  This program is distributed in the hope it will be useful, but WITHOUT
> + *  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
> + *  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
> + *  more details.
> + *
> + *  You should have received a copy of the GNU General Public License along with
> + *  this program; if not, see <http://www.gnu.org/licenses/>.
> + *
> + *  The full GNU General Public License is included in this distribution in
> + *  the file called "COPYING".
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/efi.h>
> +#include <linux/init.h>
> +#include <linux/memblock.h>
> +#include <linux/types.h>
> +#include <asm/efi.h>
> +
> +#define EFI_MAX_FAKE_MIRROR 8
> +static struct range fake_mirrors[EFI_MAX_FAKE_MIRROR];

Should we make this a Kconfig option? Is there any reason that 8 has
to be the absolute maximum?

> +static int num_fake_mirror;
> +
> +void __init efi_fake_memmap(void)
> +{
> +	u64 start, end, m_start, m_end;
> +	int new_nr_map = memmap.nr_map;
> +	efi_memory_desc_t *md;
> +	u64 new_memmap_phy;
> +	void *new_memmap;
> +	void *old, *new;
> +	int i;
> +
> +	if (!num_fake_mirror)
> +		return;
> +

You probably also want to check that efi_enabled(EFI_MEMMAP) is true
here, if not, you shouldn't iterate over the EFI memory map.

> +	/* count up the number of EFI memory descriptor */
> +	for (old = memmap.map; old < memmap.map_end; old += memmap.desc_size) {
> +		md = old;
> +		start = md->phys_addr;
> +		end = start + (md->num_pages << EFI_PAGE_SHIFT) - 1;
> +
> +		for (i = 0; i < num_fake_mirror; i++) {
> +			/* mirroring range */
> +			m_start = fake_mirrors[i].start;
> +			m_end = fake_mirrors[i].end;
> +
> +			if (m_start <= start) {
> +				/* split into 2 parts */
> +				if (start < m_end && m_end < end)
> +					new_nr_map++;
> +			}
> +			if (start < m_start && m_start < end) {
> +				/* split into 3 parts */
> +				if (m_end < end)
> +					new_nr_map += 2;
> +				/* split into 2 parts */
> +				if (end <= m_end)
> +					new_nr_map++;
> +			}
> +		}
> +	}
> +
> +	/* allocate memory for new EFI memmap */
> +	new_memmap_phy = memblock_alloc(memmap.desc_size * new_nr_map,
> +					PAGE_SIZE);
> +	if (!new_memmap_phy)
> +		return;
> +
> +	/* create new EFI memmap */
> +	new_memmap = early_memremap(new_memmap_phy,
> +				    memmap.desc_size * new_nr_map);

early_memremap() can fail and return NULL, so you should check for
that.

The rest of the patch looks fine to me.

-- 
Matt Fleming, Intel Open Source Technology Center

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Re: [PATCH v2 3/3] x86, efi: Add "efi_fake_mem_mirror" boot option

[Ard Biesheuvel]

On 26 August 2015 at 19:11, Taku Izumi <izumi.taku@jp.fujitsu.com> wrote:
> This patch introduces new boot option named "efi_fake_mem_mirror".
> By specifying this parameter, you can mark specific memory as
> mirrored memory. This is useful for debugging of Address Range
> Mirroring feature.
>
> For example, if you specify "efi_fake_mem_mirror=2G@4G,2G@0x10a0000000",
> the original (firmware provided) EFI memmap will be updated so that
> the specified memory regions have EFI_MEMORY_MORE_RELIABLE attribute:
>
>  <original EFI memmap>
>    efi: mem00: [Boot Data          |  |  |  |  |  |   |WB|WT|WC|UC] range=[0x0000000000000000-0x0000000000001000) (0MB)
>    efi: mem01: [Loader Data        |  |  |  |  |  |   |WB|WT|WC|UC] range=[0x0000000000001000-0x0000000000002000) (0MB)
>    ...
>    efi: mem35: [Boot Data          |  |  |  |  |  |   |WB|WT|WC|UC] range=[0x0000000047ee6000-0x0000000048014000) (1MB)
>    efi: mem36: [Conventional Memory|  |  |  |  |  |   |WB|WT|WC|UC] range=[0x0000000100000000-0x00000020a0000000) (129536MB)
>    efi: mem37: [Reserved           |RT|  |  |  |  |   |  |  |  |UC] range=[0x0000000060000000-0x0000000090000000) (768MB)
>
>  <updated EFI memmap>
>    efi: mem00: [Boot Data          |  |  |  |  |  |   |WB|WT|WC|UC] range=[0x0000000000000000-0x0000000000001000) (0MB)
>    efi: mem01: [Loader Data        |  |  |  |  |  |   |WB|WT|WC|UC] range=[0x0000000000001000-0x0000000000002000) (0MB)
>    ...
>    efi: mem35: [Boot Data          |  |  |  |  |  |   |WB|WT|WC|UC] range=[0x0000000047ee6000-0x0000000048014000) (1MB)
>    efi: mem36: [Conventional Memory|  |MR|  |  |  |   |WB|WT|WC|UC] range=[0x0000000100000000-0x0000000180000000) (2048MB)
>    efi: mem37: [Conventional Memory|  |  |  |  |  |   |WB|WT|WC|UC] range=[0x0000000180000000-0x00000010a0000000) (61952MB)
>    efi: mem38: [Conventional Memory|  |MR|  |  |  |   |WB|WT|WC|UC] range=[0x00000010a0000000-0x0000001120000000) (2048MB)
>    efi: mem39: [Conventional Memory|  |  |  |  |  |   |WB|WT|WC|UC] range=[0x0000001120000000-0x00000020a0000000) (63488MB)
>    efi: mem40: [Reserved           |RT|  |  |  |  |   |  |  |  |UC] range=[0x0000000060000000-0x0000000090000000) (768MB)
>
> And you will find that the following message is output:
>
>    efi: Memory: 4096M/131455M mirrored memory
>
> Signed-off-by: Taku Izumi <izumi.taku@jp.fujitsu.com>

Hello Taku,

To be honest, I think that the naming of this feature is poorly
chosen. The UEFI spec gets it right by using 'MORE_RELIABLE'. Since
one way to implement more reliable memory ranges is mirroring, the
implementation detail of that has leaked into the generic naming,
which is confusing. Not your fault though, just something I wanted to
highlight.

So first of all, could you please update the example so that it only
shows a single more reliable region (or two but of different sizes)?
It took me a while to figure out that those 2 GB regions are not
mirrors of each other in any way, they are simply two separate regions
that are marked as more reliable than the remaining memory.

I do wonder if this functionality belongs in the kernel, though. I see
how it could be useful, and you can keep it as a local hack, but
generally, the firmware (OVMF?) is a better way to play around with
code like this, I think?

-- 
Ard.

> ---
>  Documentation/kernel-parameters.txt |   8 ++
>  arch/x86/include/asm/efi.h          |   1 +
>  arch/x86/kernel/setup.c             |   4 +-
>  arch/x86/platform/efi/efi.c         |   2 +-
>  drivers/firmware/efi/Kconfig        |  12 +++
>  drivers/firmware/efi/Makefile       |   1 +
>  drivers/firmware/efi/fake_mem.c     | 204 ++++++++++++++++++++++++++++++++++++
>  include/linux/efi.h                 |   6 ++
>  8 files changed, 236 insertions(+), 2 deletions(-)
>  create mode 100644 drivers/firmware/efi/fake_mem.c
>
> diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
> index 1d6f045..0efded6 100644
> --- a/Documentation/kernel-parameters.txt
> +++ b/Documentation/kernel-parameters.txt
> @@ -1092,6 +1092,14 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
>                         you are really sure that your UEFI does sane gc and
>                         fulfills the spec otherwise your board may brick.
>
> +       efi_fake_mem_mirror=nn[KMG]@ss[KMG][,nn[KMG]@ss[KMG],..] [EFI; X86]
> +                       Mark specific memory as mirrored memory and update
> +                       EFI memory map.
> +                       Region of memory to be marked is from ss to ss+nn.
> +                       Using this parameter you can do debugging of Address
> +                       Range Mirroring feature even if your box doesn't support
> +                       it.
> +
>         eisa_irq_edge=  [PARISC,HW]
>                         See header of drivers/parisc/eisa.c.
>
> diff --git a/arch/x86/include/asm/efi.h b/arch/x86/include/asm/efi.h
> index 155162e..479fd51 100644
> --- a/arch/x86/include/asm/efi.h
> +++ b/arch/x86/include/asm/efi.h
> @@ -93,6 +93,7 @@ extern void __init efi_set_executable(efi_memory_desc_t *md, bool executable);
>  extern int __init efi_memblock_x86_reserve_range(void);
>  extern pgd_t * __init efi_call_phys_prolog(void);
>  extern void __init efi_call_phys_epilog(pgd_t *save_pgd);
> +extern void __init print_efi_memmap(void);
>  extern void __init efi_unmap_memmap(void);
>  extern void __init efi_memory_uc(u64 addr, unsigned long size);
>  extern void __init efi_map_region(efi_memory_desc_t *md);
> diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
> index 80f874b..e3ed628 100644
> --- a/arch/x86/kernel/setup.c
> +++ b/arch/x86/kernel/setup.c
> @@ -1104,8 +1104,10 @@ void __init setup_arch(char **cmdline_p)
>         memblock_set_current_limit(ISA_END_ADDRESS);
>         memblock_x86_fill();
>
> -       if (efi_enabled(EFI_BOOT))
> +       if (efi_enabled(EFI_BOOT)) {
> +               efi_fake_memmap();
>                 efi_find_mirror();
> +       }
>
>         /*
>          * The EFI specification says that boot service code won't be called
> diff --git a/arch/x86/platform/efi/efi.c b/arch/x86/platform/efi/efi.c
> index e4308fe..eee8068 100644
> --- a/arch/x86/platform/efi/efi.c
> +++ b/arch/x86/platform/efi/efi.c
> @@ -222,7 +222,7 @@ int __init efi_memblock_x86_reserve_range(void)
>         return 0;
>  }
>
> -static void __init print_efi_memmap(void)
> +void __init print_efi_memmap(void)
>  {
>  #ifdef EFI_DEBUG
>         efi_memory_desc_t *md;
> diff --git a/drivers/firmware/efi/Kconfig b/drivers/firmware/efi/Kconfig
> index 54071c1..4fafebe 100644
> --- a/drivers/firmware/efi/Kconfig
> +++ b/drivers/firmware/efi/Kconfig
> @@ -52,6 +52,18 @@ config EFI_RUNTIME_MAP
>
>           See also Documentation/ABI/testing/sysfs-firmware-efi-runtime-map.
>
> +config EFI_FAKE_MEMMAP
> +       bool "Enable EFI Fake memory mirror"
> +       depends on EFI && X86
> +       default n
> +       help
> +         Saying Y here will enable "efi_fake_mem_miror" boot option.
> +         By specifying this parameter, you can mark specific memory as
> +         mirrored memory by updating original (firmware provided) EFI memmap.
> +         This is useful for debugging of Memory Address Range Mirroring
> +         feature.
> +
> +
>  config EFI_PARAMS_FROM_FDT
>         bool
>         help
> diff --git a/drivers/firmware/efi/Makefile b/drivers/firmware/efi/Makefile
> index 6fd3da9..c24f005 100644
> --- a/drivers/firmware/efi/Makefile
> +++ b/drivers/firmware/efi/Makefile
> @@ -9,3 +9,4 @@ obj-$(CONFIG_UEFI_CPER)                 += cper.o
>  obj-$(CONFIG_EFI_RUNTIME_MAP)          += runtime-map.o
>  obj-$(CONFIG_EFI_RUNTIME_WRAPPERS)     += runtime-wrappers.o
>  obj-$(CONFIG_EFI_STUB)                 += libstub/
> +obj-$(CONFIG_EFI_FAKE_MEMMAP)          += fake_mem.o
> diff --git a/drivers/firmware/efi/fake_mem.c b/drivers/firmware/efi/fake_mem.c
> new file mode 100644
> index 0000000..2645d4a
> --- /dev/null
> +++ b/drivers/firmware/efi/fake_mem.c
> @@ -0,0 +1,204 @@
> +/*
> + * fake_mem.c
> + *
> + * Copyright (C) 2015 FUJITSU LIMITED
> + * Author: Taku Izumi <izumi.taku@jp.fujitsu.com>
> + *
> + * This code introduces new boot option named "efi_fake_mem_mirror"
> + * By specifying this parameter, you can mark specific memory as
> + * mirrored memory by updating original (firmware provided) EFI
> + * memmap.
> + *
> + *  This program is free software; you can redistribute it and/or modify it
> + *  under the terms and conditions of the GNU General Public License,
> + *  version 2, as published by the Free Software Foundation.
> + *
> + *  This program is distributed in the hope it will be useful, but WITHOUT
> + *  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
> + *  FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
> + *  more details.
> + *
> + *  You should have received a copy of the GNU General Public License along with
> + *  this program; if not, see <http://www.gnu.org/licenses/>.
> + *
> + *  The full GNU General Public License is included in this distribution in
> + *  the file called "COPYING".
> + */
> +
> +#include <linux/kernel.h>
> +#include <linux/efi.h>
> +#include <linux/init.h>
> +#include <linux/memblock.h>
> +#include <linux/types.h>
> +#include <asm/efi.h>
> +
> +#define EFI_MAX_FAKE_MIRROR 8
> +static struct range fake_mirrors[EFI_MAX_FAKE_MIRROR];
> +static int num_fake_mirror;
> +
> +void __init efi_fake_memmap(void)
> +{
> +       u64 start, end, m_start, m_end;
> +       int new_nr_map = memmap.nr_map;
> +       efi_memory_desc_t *md;
> +       u64 new_memmap_phy;
> +       void *new_memmap;
> +       void *old, *new;
> +       int i;
> +
> +       if (!num_fake_mirror)
> +               return;
> +
> +       /* count up the number of EFI memory descriptor */
> +       for (old = memmap.map; old < memmap.map_end; old += memmap.desc_size) {
> +               md = old;
> +               start = md->phys_addr;
> +               end = start + (md->num_pages << EFI_PAGE_SHIFT) - 1;
> +
> +               for (i = 0; i < num_fake_mirror; i++) {
> +                       /* mirroring range */
> +                       m_start = fake_mirrors[i].start;
> +                       m_end = fake_mirrors[i].end;
> +
> +                       if (m_start <= start) {
> +                               /* split into 2 parts */
> +                               if (start < m_end && m_end < end)
> +                                       new_nr_map++;
> +                       }
> +                       if (start < m_start && m_start < end) {
> +                               /* split into 3 parts */
> +                               if (m_end < end)
> +                                       new_nr_map += 2;
> +                               /* split into 2 parts */
> +                               if (end <= m_end)
> +                                       new_nr_map++;
> +                       }
> +               }
> +       }
> +
> +       /* allocate memory for new EFI memmap */
> +       new_memmap_phy = memblock_alloc(memmap.desc_size * new_nr_map,
> +                                       PAGE_SIZE);
> +       if (!new_memmap_phy)
> +               return;
> +
> +       /* create new EFI memmap */
> +       new_memmap = early_memremap(new_memmap_phy,
> +                                   memmap.desc_size * new_nr_map);
> +       for (old = memmap.map, new = new_memmap;
> +            old < memmap.map_end;
> +            old += memmap.desc_size, new += memmap.desc_size) {
> +
> +               /* copy original EFI memory descriptor */
> +               memcpy(new, old, memmap.desc_size);
> +               md = new;
> +               start = md->phys_addr;
> +               end = md->phys_addr + (md->num_pages << EFI_PAGE_SHIFT) - 1;
> +
> +               for (i = 0; i < num_fake_mirror; i++) {
> +                       /* mirroring range */
> +                       m_start = fake_mirrors[i].start;
> +                       m_end = fake_mirrors[i].end;
> +
> +                       if (m_start <= start && end <= m_end)
> +                               md->attribute |= EFI_MEMORY_MORE_RELIABLE;
> +
> +                       if (m_start <= start &&
> +                           (start < m_end && m_end < end)) {
> +                               /* first part */
> +                               md->attribute |= EFI_MEMORY_MORE_RELIABLE;
> +                               md->num_pages = (m_end - md->phys_addr + 1) >>
> +                                       EFI_PAGE_SHIFT;
> +                               /* latter part */
> +                               new += memmap.desc_size;
> +                               memcpy(new, old, memmap.desc_size);
> +                               md = new;
> +                               md->phys_addr = m_end + 1;
> +                               md->num_pages = (end - md->phys_addr + 1) >>
> +                                       EFI_PAGE_SHIFT;
> +                       }
> +
> +                       if ((start < m_start && m_start < end) && m_end < end) {
> +                               /* first part */
> +                               md->num_pages = (m_start - md->phys_addr) >>
> +                                       EFI_PAGE_SHIFT;
> +                               /* middle part */
> +                               new += memmap.desc_size;
> +                               memcpy(new, old, memmap.desc_size);
> +                               md = new;
> +                               md->attribute |= EFI_MEMORY_MORE_RELIABLE;
> +                               md->phys_addr = m_start;
> +                               md->num_pages = (m_end - m_start + 1) >>
> +                                       EFI_PAGE_SHIFT;
> +                               /* last part */
> +                               new += memmap.desc_size;
> +                               memcpy(new, old, memmap.desc_size);
> +                               md = new;
> +                               md->phys_addr = m_end + 1;
> +                               md->num_pages = (end - m_end) >>
> +                                       EFI_PAGE_SHIFT;
> +                       }
> +
> +                       if ((start < m_start && m_start < end) &&
> +                           (end <= m_end)) {
> +                               /* first part */
> +                               md->num_pages = (m_start - md->phys_addr) >>
> +                                       EFI_PAGE_SHIFT;
> +                               /* latter part */
> +                               new += memmap.desc_size;
> +                               memcpy(new, old, memmap.desc_size);
> +                               md = new;
> +                               md->phys_addr = m_start;
> +                               md->num_pages = (end - md->phys_addr + 1) >>
> +                                       EFI_PAGE_SHIFT;
> +                               md->attribute |= EFI_MEMORY_MORE_RELIABLE;
> +                       }
> +               }
> +       }
> +
> +       /* swap into new EFI memmap */
> +       efi_unmap_memmap();
> +       memmap.map = new_memmap;
> +       memmap.phys_map = (void *)new_memmap_phy;
> +       memmap.nr_map = new_nr_map;
> +       memmap.map_end = memmap.map + memmap.nr_map * memmap.desc_size;
> +       set_bit(EFI_MEMMAP, &efi.flags);
> +
> +       /* print new EFI memmap */
> +       print_efi_memmap();
> +}
> +
> +static int __init setup_fake_mem_mirror(char *p)
> +{
> +       u64 start = 0, mem_size = 0;
> +       int i;
> +
> +       if (!p)
> +               return -EINVAL;
> +
> +       while (*p != '\0') {
> +               mem_size = memparse(p, &p);
> +               if (*p == '@')
> +                       start = memparse(p+1, &p);
> +               else
> +                       break;
> +
> +               num_fake_mirror = add_range_with_merge(fake_mirrors,
> +                                                      EFI_MAX_FAKE_MIRROR,
> +                                                      num_fake_mirror,
> +                                                      start,
> +                                                      start + mem_size - 1);
> +               if (*p == ',')
> +                       p++;
> +       }
> +
> +       sort_range(fake_mirrors, num_fake_mirror);
> +
> +       for (i = 0; i < num_fake_mirror; i++)
> +               pr_info("efi_fake_mem_mirror: [mem 0x%016llx-0x%016llx] marked as mirrored memory",
> +                       fake_mirrors[i].start, fake_mirrors[i].end);
> +
> +       return *p == '\0' ? 0 : -EINVAL;
> +}
> +
> +early_param("efi_fake_mem_mirror", setup_fake_mem_mirror);
> diff --git a/include/linux/efi.h b/include/linux/efi.h
> index 85ef051..620baec 100644
> --- a/include/linux/efi.h
> +++ b/include/linux/efi.h
> @@ -908,6 +908,12 @@ extern struct kobject *efi_kobj;
>  extern int efi_reboot_quirk_mode;
>  extern bool efi_poweroff_required(void);
>
> +#ifdef CONFIG_EFI_FAKE_MEMMAP
> +extern void __init efi_fake_memmap(void);
> +#else
> +static inline void efi_fake_memmap(void) { }
> +#endif
> +
>  /* Iterate through an efi_memory_map */
>  #define for_each_efi_memory_desc(m, md)                                           \
>         for ((md) = (m)->map;                                              \
> --
> 1.8.3.1
>

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Re: [PATCH v2 3/3] x86, efi: Add "efi_fake_mem_mirror" boot option

[Matt Fleming]

On Wed, 09 Sep, at 04:16:09PM, Ard Biesheuvel wrote:
> 
> Hello Taku,
> 
> To be honest, I think that the naming of this feature is poorly
> chosen. The UEFI spec gets it right by using 'MORE_RELIABLE'. Since
> one way to implement more reliable memory ranges is mirroring, the
> implementation detail of that has leaked into the generic naming,
> which is confusing. Not your fault though, just something I wanted to
> highlight.
 
Care to suggest an alternative option? efi_fake_mem_more_reliable ?

Maybe we should go further than this current design and generalise
things to allow an EFI_MEMORY_ATTRIBUTE value to be specified for
these memory ranges that supplements the ones actually provided by the
firmware?

Something like,

  efi_fake_mem=2G@4G:0x10000,2G@0x10a0000000:0x10000

Where 0x10000 is the EFI_MEMORY_MORE_RELIABLE attribute bit.

That would seem incredibly useful for testing the kernel side of the
EFI_PROPERTIES_TABLE changes, i.e. you wouldn't need support in the
firmware and could just "mock-up" an EFI memory map with EFI_MEMORY_XP
for the data regions (code regions and EFI_MEMORY_RO are a little
trickier as I understand it, because they may also contain data).

> So first of all, could you please update the example so that it only
> shows a single more reliable region (or two but of different sizes)?
> It took me a while to figure out that those 2 GB regions are not
> mirrors of each other in any way, they are simply two separate regions
> that are marked as more reliable than the remaining memory.
> 
> I do wonder if this functionality belongs in the kernel, though. I see
> how it could be useful, and you can keep it as a local hack, but
> generally, the firmware (OVMF?) is a better way to play around with
> code like this, I think?
 
I (partially) disagree. Using real life memory maps has its
advantages, since different layouts exercise the code in different
ways, and I'd really like to see this used on beefy machines with
multiple GB/TB or RAM. It also allows performance measurements to be
taken with bare metal accuracy. Plus there's precedent in the kernel
for creating fake memory/topology objects, e.g. see numa=fake.

Not everyone who touches the EFI memory mirror code is going to want
(or be able) to run firmware with EFI_MEMORY_MORE_RELIABLE support.

Having said that, I'd love to also see EFI_MEMORY_MORE_RELIABLE
support in OVMF! I think both options make sense for different
reasons.

-- 
Matt Fleming, Intel Open Source Technology Center

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Re: [PATCH v2 3/3] x86, efi: Add "efi_fake_mem_mirror" boot option

[Ard Biesheuvel]

On 12 September 2015 at 12:41, Matt Fleming <matt@codeblueprint.co.uk> wrote:
> On Wed, 09 Sep, at 04:16:09PM, Ard Biesheuvel wrote:
>>
>> Hello Taku,
>>
>> To be honest, I think that the naming of this feature is poorly
>> chosen. The UEFI spec gets it right by using 'MORE_RELIABLE'. Since
>> one way to implement more reliable memory ranges is mirroring, the
>> implementation detail of that has leaked into the generic naming,
>> which is confusing. Not your fault though, just something I wanted to
>> highlight.
>
> Care to suggest an alternative option? efi_fake_mem_more_reliable ?
>

No, that does not make sense either. I don't like the name that was
chosen when the feature was added to memblock, and now I suppose we
just have to live with it.

> Maybe we should go further than this current design and generalise
> things to allow an EFI_MEMORY_ATTRIBUTE value to be specified for
> these memory ranges that supplements the ones actually provided by the
> firmware?
>
> Something like,
>
>   efi_fake_mem=2G@4G:0x10000,2G@0x10a0000000:0x10000
>
> Where 0x10000 is the EFI_MEMORY_MORE_RELIABLE attribute bit.
>

Yes, I like that. Should we use a mask/xor pair for flexibility?

> That would seem incredibly useful for testing the kernel side of the
> EFI_PROPERTIES_TABLE changes, i.e. you wouldn't need support in the
> firmware and could just "mock-up" an EFI memory map with EFI_MEMORY_XP
> for the data regions (code regions and EFI_MEMORY_RO are a little
> trickier as I understand it, because they may also contain data).
>

... hence the need for the memprotect feature in the first place.
PE/COFF images are normally covered in their entirety (.text + .data)
by a single BScode/RTcode region.

But indeed, the ability to manipulate the memory map like that could
be useful, although it would need to be ported to the stub to be
useful on ARM, I think.

>> So first of all, could you please update the example so that it only
>> shows a single more reliable region (or two but of different sizes)?
>> It took me a while to figure out that those 2 GB regions are not
>> mirrors of each other in any way, they are simply two separate regions
>> that are marked as more reliable than the remaining memory.
>>
>> I do wonder if this functionality belongs in the kernel, though. I see
>> how it could be useful, and you can keep it as a local hack, but
>> generally, the firmware (OVMF?) is a better way to play around with
>> code like this, I think?
>
> I (partially) disagree. Using real life memory maps has its
> advantages, since different layouts exercise the code in different
> ways, and I'd really like to see this used on beefy machines with
> multiple GB/TB or RAM. It also allows performance measurements to be
> taken with bare metal accuracy. Plus there's precedent in the kernel
> for creating fake memory/topology objects, e.g. see numa=fake.
>

OK, perhaps I just don't understand the use case too well.

> Not everyone who touches the EFI memory mirror code is going to want
> (or be able) to run firmware with EFI_MEMORY_MORE_RELIABLE support.
>
> Having said that, I'd love to also see EFI_MEMORY_MORE_RELIABLE
> support in OVMF! I think both options make sense for different
> reasons.
>

Good point.

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