On Wed, Mar 24, 2021 at 11:44:12AM -0500, Brijesh Singh wrote:
> Add CPU feature detection for Secure Encrypted Virtualization with
> Secure Nested Paging. This feature adds a strong memory integrity
> protection to help prevent malicious hypervisor-based attacks like
> data replay, memory re-mapping, and more.
> 
> Cc: Thomas Gleixner <t...@linutronix.de>
> Cc: Ingo Molnar <mi...@redhat.com>
> Cc: Borislav Petkov <b...@alien8.de>
> Cc: Joerg Roedel <jroe...@suse.de>
> Cc: "H. Peter Anvin" <h...@zytor.com>
> Cc: Tony Luck <tony.l...@intel.com>
> Cc: Dave Hansen <dave.han...@intel.com>
> Cc: "Peter Zijlstra (Intel)" <pet...@infradead.org>
> Cc: Paolo Bonzini <pbonz...@redhat.com>
> Cc: Tom Lendacky <thomas.lenda...@amd.com>
> Cc: David Rientjes <rient...@google.com>
> Cc: Sean Christopherson <sea...@google.com>
> Cc: x...@kernel.org
> Cc: k...@vger.kernel.org
> Signed-off-by: Brijesh Singh <brijesh.si...@amd.com>
> ---
>  arch/x86/include/asm/cpufeatures.h | 1 +
>  arch/x86/kernel/cpu/amd.c          | 3 ++-
>  arch/x86/kernel/cpu/scattered.c    | 1 +
>  3 files changed, 4 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/x86/include/asm/cpufeatures.h 
> b/arch/x86/include/asm/cpufeatures.h
> index 84b887825f12..a5b369f10bcd 100644
> --- a/arch/x86/include/asm/cpufeatures.h
> +++ b/arch/x86/include/asm/cpufeatures.h
> @@ -238,6 +238,7 @@
>  #define X86_FEATURE_VMW_VMMCALL              ( 8*32+19) /* "" VMware prefers 
> VMMCALL hypercall instruction */
>  #define X86_FEATURE_SEV_ES           ( 8*32+20) /* AMD Secure Encrypted 
> Virtualization - Encrypted State */
>  #define X86_FEATURE_VM_PAGE_FLUSH    ( 8*32+21) /* "" VM Page Flush MSR is 
> supported */
> +#define X86_FEATURE_SEV_SNP          ( 8*32+22) /* AMD Secure Encrypted 
> Virtualization - Secure Nested Paging */

That leaf got a separate word now: word 19.

For the future: pls redo your patches against tip/master because it has
the latest state of affairs in tip-land.

>  /* Intel-defined CPU features, CPUID level 0x00000007:0 (EBX), word 9 */
>  #define X86_FEATURE_FSGSBASE         ( 9*32+ 0) /* RDFSBASE, WRFSBASE, 
> RDGSBASE, WRGSBASE instructions*/
> diff --git a/arch/x86/kernel/cpu/amd.c b/arch/x86/kernel/cpu/amd.c
> index f8ca66f3d861..39f7a4b5b04c 100644
> --- a/arch/x86/kernel/cpu/amd.c
> +++ b/arch/x86/kernel/cpu/amd.c
> @@ -586,7 +586,7 @@ static void early_detect_mem_encrypt(struct cpuinfo_x86 
> *c)
>        *            If BIOS has not enabled SME then don't advertise the
>        *            SME feature (set in scattered.c).
>        *   For SEV: If BIOS has not enabled SEV then don't advertise the
> -      *            SEV and SEV_ES feature (set in scattered.c).
> +      *            SEV, SEV_ES and SEV_SNP feature (set in scattered.c).

So you can remove the "scattered.c" references in the comments here.

>        *
>        *   In all cases, since support for SME and SEV requires long mode,
>        *   don't advertise the feature under CONFIG_X86_32.
> @@ -618,6 +618,7 @@ static void early_detect_mem_encrypt(struct cpuinfo_x86 
> *c)
>  clear_sev:
>               setup_clear_cpu_cap(X86_FEATURE_SEV);
>               setup_clear_cpu_cap(X86_FEATURE_SEV_ES);
> +             setup_clear_cpu_cap(X86_FEATURE_SEV_SNP);
>       }
>  }
>  
> diff --git a/arch/x86/kernel/cpu/scattered.c b/arch/x86/kernel/cpu/scattered.c
> index 236924930bf0..eaec1278dc2e 100644
> --- a/arch/x86/kernel/cpu/scattered.c
> +++ b/arch/x86/kernel/cpu/scattered.c
> @@ -45,6 +45,7 @@ static const struct cpuid_bit cpuid_bits[] = {
>       { X86_FEATURE_SEV_ES,           CPUID_EAX,  3, 0x8000001f, 0 },
>       { X86_FEATURE_SME_COHERENT,     CPUID_EAX, 10, 0x8000001f, 0 },
>       { X86_FEATURE_VM_PAGE_FLUSH,    CPUID_EAX,  2, 0x8000001f, 0 },
> +     { X86_FEATURE_SEV_SNP,          CPUID_EAX,  4, 0x8000001f, 0 },
>       { 0, 0, 0, 0, 0 }
>  };

And this too.

Thx.

-- 
Regards/Gruss,
    Boris.

https://people.kernel.org/tglx/notes-about-netiquette

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