Re: [PATCH kernel v5 6/6] x86/sev: Do not handle #VC for DR7 read/write

[Sean Christopherson <seanjc@google.com>]

On Tue, Apr 11, 2023, Alexey Kardashevskiy wrote:
> With MSR_AMD64_SEV_DEBUG_SWAP enabled, the guest is not expected to
> receive a #VC for reads or writes of DR7.
> 
> Update the SNP_FEATURES_PRESENT mask with MSR_AMD64_SNP_DEBUG_SWAP so
> an SNP guest doesn't gracefully terminate during SNP feature negotiation
> if MSR_AMD64_SEV_DEBUG_SWAP is enabled.
> 
> Since a guest is not expected to receive a #VC on DR7 accesses when
> MSR_AMD64_SEV_DEBUG_SWAP is enabled, return an error from the #VC
> handler in this situation.
> 
> Signed-off-by: Alexey Kardashevskiy <aik@amd.com>
> Reviewed-by: Carlos Bilbao <carlos.bilbao@amd.com>
> Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com>
> Reviewed-by: Pankaj Gupta <pankaj.gupta@amd.com>
> ---
> Changes:
> v4:
> * rebased on top of SNP feature negotiation
> 
> v2:
> * use new bit definition
> ---
>  arch/x86/boot/compressed/sev.c | 2 +-
>  arch/x86/kernel/sev.c          | 6 ++++++
>  2 files changed, 7 insertions(+), 1 deletion(-)

Can you post this separately (or bribe Boris to grab it)?  IIUC, this has no
dependency on the KVM enabling, i.e. can/should go through the tip tree without
waiting for the KVM patches to be applied.