linux-kernel - Re: [PATCH v11 17/20] x86/sev: Allow Secure TSC feature for SNP guests

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Message-ID: <ddd3dfe3-986d-4433-13c4-c65c15673e9a@amd.com>
Date: Fri, 13 Sep 2024 11:53:05 -0500
From: Tom Lendacky <thomas.lendacky@....com>
To: Nikunj A Dadhania <nikunj@....com>, linux-kernel@...r.kernel.org,
 bp@...en8.de, x86@...nel.org, kvm@...r.kernel.org
Cc: mingo@...hat.com, tglx@...utronix.de, dave.hansen@...ux.intel.com,
 pgonda@...gle.com, seanjc@...gle.com, pbonzini@...hat.com
Subject: Re: [PATCH v11 17/20] x86/sev: Allow Secure TSC feature for SNP
 guests

On 7/31/24 10:08, Nikunj A Dadhania wrote:
> Now that all the required plumbing is done for enabling SNP Secure TSC
> feature, add Secure TSC to SNP features present list.

So I think this should be the last patch in the series after the TSC is
marked reliable, kvmclock is bypassed, etc. This way everything is in
place when the guest is allowed to run with Secure TSC.

> 
> Signed-off-by: Nikunj A Dadhania <nikunj@....com>
> Tested-by: Peter Gonda <pgonda@...gle.com>

Reviewed-by: Tom Lendacky <thomas.lendacky@....com>

> ---
>  arch/x86/boot/compressed/sev.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/arch/x86/boot/compressed/sev.c b/arch/x86/boot/compressed/sev.c
> index cd44e120fe53..bb55934c1cee 100644
> --- a/arch/x86/boot/compressed/sev.c
> +++ b/arch/x86/boot/compressed/sev.c
> @@ -401,7 +401,8 @@ void do_boot_stage2_vc(struct pt_regs *regs, unsigned long exit_code)
>   * by the guest kernel. As and when a new feature is implemented in the
>   * guest kernel, a corresponding bit should be added to the mask.
>   */
> -#define SNP_FEATURES_PRESENT	MSR_AMD64_SNP_DEBUG_SWAP
> +#define SNP_FEATURES_PRESENT	(MSR_AMD64_SNP_DEBUG_SWAP |	\
> +				 MSR_AMD64_SNP_SECURE_TSC)
>  
>  u64 snp_get_unsupported_features(u64 status)
>  {