On 10/21/2024 7:38 PM, Tom Lendacky wrote: > On 10/21/24 00:51, Nikunj A Dadhania wrote: >> The hypervisor should not be intercepting GUEST_TSC_FREQ MSR(0xcOO10134) >> when Secure TSC is enabled. A #VC exception will be generated if the >> GUEST_TSC_FREQ MSR is being intercepted. If this should occur and SecureTSC >> is enabled, terminate guest execution. >> >> Signed-off-by: Nikunj A Dadhania <nikunj@xxxxxxx> > > Reviewed-by: Tom Lendacky <thomas.lendacky@xxxxxxx> > > Just a minor comment/question below. > .. >> diff --git a/arch/x86/coco/sev/core.c b/arch/x86/coco/sev/core.c >> index 2ad7773458c0..4e9b1cc1f26b 100644 >> --- a/arch/x86/coco/sev/core.c >> +++ b/arch/x86/coco/sev/core.c >> @@ -1332,6 +1332,14 @@ static enum es_result vc_handle_msr(struct ghcb *ghcb, struct es_em_ctxt *ctxt) >> return ES_OK; >> } >> >> + /* >> + * GUEST_TSC_FREQ should not be intercepted when Secure TSC is >> + * enabled. Terminate the SNP guest when the interception is enabled. >> + */ >> + if (regs->cx == MSR_AMD64_GUEST_TSC_FREQ && cc_platform_has(CC_ATTR_GUEST_SNP_SECURE_TSC)) > > Should the cc_platform_has() check be changed into a check against > sev_status directly (similar to the DEBUG_SWAP support)? Just in case > this handler ends up getting used in early code where cc_platform_has() > can't be used. Sure, that makes sense. I will change it in my next version. Regards Nikunj
