Re: [PATCH v9 04/12] x86/mm: get INVLPGB count max from CPUID

[Vern Hao <haoxing990@gmail.com>]

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*I do some test on my  Machine with AMD EPYC 7K83,  these patches work on
my host,  but failed on my guest with qemu.*

*in host, use lscpu cmd, you can see  invlpgb in flags,  but in guest no.*

*So are you plan to support it in guest?*


Best Regards!
Thanks


Rik van Riel <riel@surriel.com> 于2025年2月6日周四 12:45写道：

> The CPU advertises the maximum number of pages that can be shot down
> with one INVLPGB instruction in the CPUID data.
>
> Save that information for later use.
>
> Signed-off-by: Rik van Riel <riel@surriel.com>
> Tested-by: Manali Shukla <Manali.Shukla@amd.com>
> ---
>  arch/x86/Kconfig.cpu               | 5 +++++
>  arch/x86/include/asm/cpufeatures.h | 1 +
>  arch/x86/include/asm/tlbflush.h    | 7 +++++++
>  arch/x86/kernel/cpu/amd.c          | 8 ++++++++
>  4 files changed, 21 insertions(+)
>
> diff --git a/arch/x86/Kconfig.cpu b/arch/x86/Kconfig.cpu
> index 2a7279d80460..abe013a1b076 100644
> --- a/arch/x86/Kconfig.cpu
> +++ b/arch/x86/Kconfig.cpu
> @@ -395,6 +395,10 @@ config X86_VMX_FEATURE_NAMES
>         def_bool y
>         depends on IA32_FEAT_CTL
>
> +config X86_BROADCAST_TLB_FLUSH
> +       def_bool y
> +       depends on CPU_SUP_AMD && 64BIT
> +
>  menuconfig PROCESSOR_SELECT
>         bool "Supported processor vendors" if EXPERT
>         help
> @@ -431,6 +435,7 @@ config CPU_SUP_CYRIX_32
>  config CPU_SUP_AMD
>         default y
>         bool "Support AMD processors" if PROCESSOR_SELECT
> +       select X86_BROADCAST_TLB_FLUSH
>         help
>           This enables detection, tunings and quirks for AMD processors
>
> diff --git a/arch/x86/include/asm/cpufeatures.h
> b/arch/x86/include/asm/cpufeatures.h
> index 17b6590748c0..f9b832e971c5 100644
> --- a/arch/x86/include/asm/cpufeatures.h
> +++ b/arch/x86/include/asm/cpufeatures.h
> @@ -338,6 +338,7 @@
>  #define X86_FEATURE_CLZERO             (13*32+ 0) /* "clzero" CLZERO
> instruction */
>  #define X86_FEATURE_IRPERF             (13*32+ 1) /* "irperf"
> Instructions Retired Count */
>  #define X86_FEATURE_XSAVEERPTR         (13*32+ 2) /* "xsaveerptr" Always
> save/restore FP error pointers */
> +#define X86_FEATURE_INVLPGB            (13*32+ 3) /* INVLPGB and TLBSYNC
> instruction supported. */
>  #define X86_FEATURE_RDPRU              (13*32+ 4) /* "rdpru" Read
> processor register at user level */
>  #define X86_FEATURE_WBNOINVD           (13*32+ 9) /* "wbnoinvd" WBNOINVD
> instruction */
>  #define X86_FEATURE_AMD_IBPB           (13*32+12) /* Indirect Branch
> Prediction Barrier */
> diff --git a/arch/x86/include/asm/tlbflush.h
> b/arch/x86/include/asm/tlbflush.h
> index 02fc2aa06e9e..8fe3b2dda507 100644
> --- a/arch/x86/include/asm/tlbflush.h
> +++ b/arch/x86/include/asm/tlbflush.h
> @@ -183,6 +183,13 @@ static inline void cr4_init_shadow(void)
>  extern unsigned long mmu_cr4_features;
>  extern u32 *trampoline_cr4_features;
>
> +/* How many pages can we invalidate with one INVLPGB. */
> +#ifdef CONFIG_X86_BROADCAST_TLB_FLUSH
> +extern u16 invlpgb_count_max;
> +#else
> +#define invlpgb_count_max 1
> +#endif
> +
>  extern void initialize_tlbstate_and_flush(void);
>
>  /*
> diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
> index 79d2e17f6582..bcf73775b4f8 100644
> --- a/arch/x86/kernel/cpu/amd.c
> +++ b/arch/x86/kernel/cpu/amd.c
> @@ -29,6 +29,8 @@
>
>  #include "cpu.h"
>
> +u16 invlpgb_count_max __ro_after_init;
> +
>  static inline int rdmsrl_amd_safe(unsigned msr, unsigned long long *p)
>  {
>         u32 gprs[8] = { 0 };
> @@ -1135,6 +1137,12 @@ static void cpu_detect_tlb_amd(struct cpuinfo_x86
> *c)
>                 tlb_lli_2m[ENTRIES] = eax & mask;
>
>         tlb_lli_4m[ENTRIES] = tlb_lli_2m[ENTRIES] >> 1;
> +
> +       /* Max number of pages INVLPGB can invalidate in one shot */
> +       if (boot_cpu_has(X86_FEATURE_INVLPGB)) {
> +               cpuid(0x80000008, &eax, &ebx, &ecx, &edx);
> +               invlpgb_count_max = (edx & 0xffff) + 1;
> +       }
>  }
>
>  static const struct cpu_dev amd_cpu_dev = {
> --
> 2.47.1
>
>
>

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