linux-kernel - Re: [PATCH, RESEND] x86/sev: Fix SEV check in sev_map_percpu

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Date: Fri, 26 Jan 2024 19:43:34 +0100
From: Paolo Bonzini <pbonzini@...hat.com>
To: "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>
Cc: Wanpeng Li <wanpengli@...cent.com>, Vitaly Kuznetsov <vkuznets@...hat.com>, 
	Sean Christopherson <seanjc@...gle.com>, Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>, 
	Borislav Petkov <bp@...en8.de>, Dave Hansen <dave.hansen@...ux.intel.com>, 
	Tom Lendacky <thomas.lendacky@....com>, x86@...nel.org, kvm@...r.kernel.org, 
	linux-kernel@...r.kernel.org, David Rientjes <rientjes@...gle.com>
Subject: Re: [PATCH, RESEND] x86/sev: Fix SEV check in sev_map_percpu_data()

On Wed, Jan 24, 2024 at 2:09 PM Kirill A. Shutemov
<kirill.shutemov@...ux.intel.com> wrote:
>
> The function sev_map_percpu_data() checks if it is running on an SEV
> platform by checking the CC_ATTR_GUEST_MEM_ENCRYPT attribute. However,
> this attribute is also defined for TDX.
>
> To avoid false positives, add a cc_vendor check.
>
> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@...ux.intel.com>
> Fixes: 4d96f9109109 ("x86/sev: Replace occurrences of sev_active() with cc_platform_has()")
> Suggested-by: Borislav Petkov (AMD) <bp@...en8.de>
> Acked-by: David Rientjes <rientjes@...gle.com>

Queued, with "x86/kvm in the subject".

Paolo

> ---

>  arch/x86/kernel/kvm.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
> index dfe9945b9bec..428ee74002e1 100644
> --- a/arch/x86/kernel/kvm.c
> +++ b/arch/x86/kernel/kvm.c
> @@ -434,7 +434,8 @@ static void __init sev_map_percpu_data(void)
>  {
>         int cpu;
>
> -       if (!cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT))
> +       if (cc_vendor != CC_VENDOR_AMD ||
> +           !cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT))
>                 return;
>
>         for_each_possible_cpu(cpu) {
> --
> 2.43.0
>