RE: [EXT] Re: [PATCH] cxl/mbox: Add Get Log Capabilities, Clear Log and Get Supported Logs Sub-List commands

[Srinivasulu Opensrc <sthanneeru.opensrc@micron.com>]

> -----Original Message-----
> From: Jonathan Cameron <Jonathan.Cameron@Huawei.com>
> Sent: Thursday, February 15, 2024 5:57 PM
> To: Srinivasulu Opensrc <sthanneeru.opensrc@micron.com>
> Cc: linux-cxl@vger.kernel.org; linux-mm@kvack.org;
> dan.j.williams@intel.com; john@jagalactic.com; Eishan Mirakhur
> <emirakhur@micron.com>; Ajay Joshi <ajayjoshi@micron.com>; Ravis
> OpenSrc <Ravis.OpenSrc@micron.com>; Srinivasulu Thanneeru
> <sthanneeru@micron.com>; shiju.jose@huawei.com
> Subject: Re: [EXT] Re: [PATCH] cxl/mbox: Add Get Log Capabilities, Clear Log
> and Get Supported Logs Sub-List commands
> 
> CAUTION: EXTERNAL EMAIL. Do not click links or open attachments unless
> you recognize the sender and were expecting this message.
> 
> 
> On Wed, 14 Feb 2024 16:09:01 +0000
> Srinivasulu Opensrc <sthanneeru.opensrc@micron.com> wrote:
> 
> > > -----Original Message-----
> > > From: Jonathan Cameron <Jonathan.Cameron@Huawei.com>
> > > Sent: Thursday, February 8, 2024 6:27 PM
> > > To: Srinivasulu Opensrc <sthanneeru.opensrc@micron.com>
> > > Cc: linux-cxl@vger.kernel.org; linux-mm@kvack.org;
> > > dan.j.williams@intel.com; john@jagalactic.com; Eishan Mirakhur
> > > <emirakhur@micron.com>; Ajay Joshi <ajayjoshi@micron.com>; Ravis
> > > OpenSrc <Ravis.OpenSrc@micron.com>; Srinivasulu Thanneeru
> > > <sthanneeru@micron.com>; shiju.jose@huawei.com
> > > Subject: [EXT] Re: [PATCH] cxl/mbox: Add Get Log Capabilities, Clear Log
> and
> > > Get Supported Logs Sub-List commands
> > >
> > > CAUTION: EXTERNAL EMAIL. Do not click links or open attachments unless
> > > you recognize the sender and were expecting this message.
> > >
> > >
> > > On Wed, 7 Feb 2024 16:06:34 +0530
> > > <sthanneeru.opensrc@micron.com> wrote:
> > >
> > > > From: Srinivasulu Thanneeru <sthanneeru.opensrc@micron.com>
> > > >
> > > > Adding UAPI support for
> > > > 1. CXL r3.1 8.2.9.5.3 Get Log Capabilities.
> > > > 2. CXL r3.1 8.2.9.5.4 Clear Log commands.
> > > > 3. CXL r3.1 8.2.9.5.6 Get Supported Logs Sub-List.
> > > >
> > > > Signed-off-by: Srinivasulu Thanneeru
> <sthanneeru.opensrc@micron.com>
> > >
> > > Hi Srinivasulu,
> > >
> > > Whilst I can conjecture some valid reasons to expose these to
> > > userspace, can you add some examples to this patch description?
> > >
> > > We might want to filter the clear in particular to avoid a clash
> > > with the driver log handling. That is only allow it for vendor
> > > logs.
> >
> > Are you suggesting that I should restrict the "Vendor Debug Log"
> functionality to
> > only apply to Vendor logs.? Why not include Component State Dumps logs
> that
> > support the clear log feature?
> >
> > I might be overlooking something; please enlighten me.
> 
> I had an old copy of the spec open. Indeed component state dumps
> should be safe to expose as well.

Thank you, Jonathan.
I'm considering adding the following snippet to the V2 patch for "clear log" filtering. 
Any initial feedback would be appreciated.

--------------
--- a/drivers/cxl/core/mbox.c
+++ b/drivers/cxl/core/mbox.c
enum {
        CEL_UUID,
        VENDOR_DEBUG_UUID,
+       COMPONENT_STATE_DUMP_UUID,
};

/* See CXL 2.0 Table 170. Get Log Input Payload */
static const uuid_t log_uuid[] = {
        [CEL_UUID] = DEFINE_CXL_CEL_UUID,
        [VENDOR_DEBUG_UUID] = DEFINE_CXL_VENDOR_DEBUG_UUID,
+       [COMPONENT_STATE_DUMP_UUID] = DEFINE_CXL_COMPONENT_STATE_DUMP_UUID,
 };

 /*
@@ -333,6 +346,12 @@ static bool cxl_payload_from_user_allowed(u16 opcode, void *payload_in)
                        return false;
                break;
        }
+
+       case CXL_MBOX_OP_CLEAR_LOG: {
+               const uuid_t *uuid = (uuid_t *)payload_in;
+               return (uuid_equal(uuid, &log_uuid[VENDOR_DEBUG_UUID])) ||
+                      (uuid_equal(uuid, &log_uuid[COMPONENT_STATE_DUMP_UUID]))
+               }
}

diff --git a/drivers/cxl/cxlmem.h b/drivers/cxl/cxlmem.h
--- a/drivers/cxl/cxlmem.h
+++ b/drivers/cxl/cxlmem.h
@@ -565,6 +565,9 @@ enum cxl_opcode {
 #define DEFINE_CXL_VENDOR_DEBUG_UUID                                           \
        UUID_INIT(0xe1819d9, 0x11a9, 0x400c, 0x81, 0x1f, 0xd6, 0x07, 0x19,     \
                  0x40, 0x3d, 0x86)
+#define DEFINE_CXL_COMPONENT_STATE_DUMP_UUID
+       UUID_INIT(0x3fab4cf, 0x01b6, 0x4332, 0x94, 0x3e, 0x5e, 0x99, 0x62,       \
+                 0xf2, 0x35, 0x67)
--------------
> >
> > For example, following both supports Clear log in our setups.
> > * 5e1819d9-11a9-400c-811f-d60719403d86 - Vendor Debug Log
> > * b3fab4cf-01b6-4332-943e-5e9962f23567 - Component State Dump Log
> >
> > >
> > > Perhaps split the patch into 2 parts. The less controversial
> > > GET_LOG_CAPS and GET_LOG_SUBLIST, followed by a patch for the
> > > destructive clear log.
> > >
> > > The memory scrub handling might well
> > > access the ECS log for example (I don't think the current proposal
> > > yet does this).
> > >
> > > Jonathan
> > >
> > >
> > > > ---
> > > >  drivers/cxl/core/mbox.c      | 3 +++
> > > >  drivers/cxl/cxlmem.h         | 3 +++
> > > >  include/uapi/linux/cxl_mem.h | 3 +++
> > > >  3 files changed, 9 insertions(+)
> > > >
> > > > diff --git a/drivers/cxl/core/mbox.c b/drivers/cxl/core/mbox.c
> > > > index 27166a411705..64a44e286488 100644
> > > > --- a/drivers/cxl/core/mbox.c
> > > > +++ b/drivers/cxl/core/mbox.c
> > > > @@ -64,6 +64,9 @@ static struct cxl_mem_command
> > > cxl_mem_commands[CXL_MEM_COMMAND_ID_MAX] = {
> > > >       CXL_CMD(SET_SHUTDOWN_STATE, 0x1, 0, 0),
> > > >       CXL_CMD(GET_SCAN_MEDIA_CAPS, 0x10, 0x4, 0),
> > > >       CXL_CMD(GET_TIMESTAMP, 0, 0x8, 0),
> > > > +     CXL_CMD(GET_LOG_CAPS, 0x10, 0x4, 0),
> > > > +     CXL_CMD(CLEAR_LOG, 0x10, 0, 0),
> > > > +     CXL_CMD(GET_LOG_SUBLIST, 0x2, CXL_VARIABLE_PAYLOAD, 0),
> > > >  };
> > > >
> > > >  /*
> > > > diff --git a/drivers/cxl/cxlmem.h b/drivers/cxl/cxlmem.h
> > > > index 5303d6942b88..4128c810051c 100644
> > > > --- a/drivers/cxl/cxlmem.h
> > > > +++ b/drivers/cxl/cxlmem.h
> > > > @@ -529,6 +529,9 @@ enum cxl_opcode {
> > > >       CXL_MBOX_OP_SET_TIMESTAMP       = 0x0301,
> > > >       CXL_MBOX_OP_GET_SUPPORTED_LOGS  = 0x0400,
> > > >       CXL_MBOX_OP_GET_LOG             = 0x0401,
> > > > +     CXL_MBOX_OP_GET_LOG_CAPS        = 0x0402,
> > > > +     CXL_MBOX_OP_CLEAR_LOG           = 0x0403,
> > > > +     CXL_MBOX_OP_GET_LOG_SUBLIST     = 0x0405,
> > >
> > > Name should include something to make it clear this is getting
> > > sublist of 'supported' logs.  Not the log.
> > >
> > > >       CXL_MBOX_OP_IDENTIFY            = 0x4000,
> > > >       CXL_MBOX_OP_GET_PARTITION_INFO  = 0x4100,
> > > >       CXL_MBOX_OP_SET_PARTITION_INFO  = 0x4101,
> > > > diff --git a/include/uapi/linux/cxl_mem.h
> b/include/uapi/linux/cxl_mem.h
> > > > index 42066f4eb890..d2df9782a5ef 100644
> > > > --- a/include/uapi/linux/cxl_mem.h
> > > > +++ b/include/uapi/linux/cxl_mem.h
> > > > @@ -47,6 +47,9 @@
> > > >       ___DEPRECATED(SCAN_MEDIA, "Scan Media"),                          \
> > > >       ___DEPRECATED(GET_SCAN_MEDIA, "Get Scan Media Results"),
> \
> > > >       ___C(GET_TIMESTAMP, "Get Timestamp"),                             \
> > > > +     ___C(GET_LOG_CAPS, "Get Log Capabilities"),                       \
> > > > +     ___C(CLEAR_LOG, "Clear Log"),                                     \
> > > > +     ___C(GET_LOG_SUBLIST, "Get Log Sublist"),                         \
> > >
> > > Likewise, mention it's list of supported logs.
> > >
> > > >       ___C(MAX, "invalid / last command")
> > > >
> > > >  #define ___C(a, b) CXL_MEM_COMMAND_ID_##a
> >