| Message ID | 20231030063652.68675-12-nikunj@amd.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Add Secure TSC support for SNP guests | expand |
On 10/30/23 01:36, Nikunj A Dadhania wrote: > The hypervisor should not be intercepting RDTSC/RDTSCP when Secure TSC > is enabled. A #VC exception will be generated if the RDTSC/RDTSCP > instructions are being intercepted. If this should occur and Secure > TSC is enabled, terminate guest execution. > > Signed-off-by: Nikunj A Dadhania <nikunj@amd.com> > --- > arch/x86/kernel/sev-shared.c | 7 +++++++ > 1 file changed, 7 insertions(+) > > diff --git a/arch/x86/kernel/sev-shared.c b/arch/x86/kernel/sev-shared.c > index ccb0915e84e1..833b0ae38f0b 100644 > --- a/arch/x86/kernel/sev-shared.c > +++ b/arch/x86/kernel/sev-shared.c > @@ -991,6 +991,13 @@ static enum es_result vc_handle_rdtsc(struct ghcb *ghcb, > bool rdtscp = (exit_code == SVM_EXIT_RDTSCP); > enum es_result ret; > > + /* > + * RDTSC and RDTSCP should not be intercepted when Secure TSC is > + * enabled. Terminate the SNP guest when the interception is enabled. > + */ > + if (sev_status & MSR_AMD64_SNP_SECURE_TSC) If you have to use sev_status, then please document why cc_platform_has() can't be used in the comment above. Thanks, Tom > + return ES_VMM_ERROR; > + > ret = sev_es_ghcb_hv_call(ghcb, ctxt, exit_code, 0, 0); > if (ret != ES_OK) > return ret;
On 10/31/2023 2:02 AM, Tom Lendacky wrote: > On 10/30/23 01:36, Nikunj A Dadhania wrote: >> The hypervisor should not be intercepting RDTSC/RDTSCP when Secure TSC >> is enabled. A #VC exception will be generated if the RDTSC/RDTSCP >> instructions are being intercepted. If this should occur and Secure >> TSC is enabled, terminate guest execution. >> >> Signed-off-by: Nikunj A Dadhania <nikunj@amd.com> >> --- >> arch/x86/kernel/sev-shared.c | 7 +++++++ >> 1 file changed, 7 insertions(+) >> >> diff --git a/arch/x86/kernel/sev-shared.c b/arch/x86/kernel/sev-shared.c >> index ccb0915e84e1..833b0ae38f0b 100644 >> --- a/arch/x86/kernel/sev-shared.c >> +++ b/arch/x86/kernel/sev-shared.c >> @@ -991,6 +991,13 @@ static enum es_result vc_handle_rdtsc(struct ghcb *ghcb, >> bool rdtscp = (exit_code == SVM_EXIT_RDTSCP); >> enum es_result ret; >> + /* >> + * RDTSC and RDTSCP should not be intercepted when Secure TSC is >> + * enabled. Terminate the SNP guest when the interception is enabled. >> + */ >> + if (sev_status & MSR_AMD64_SNP_SECURE_TSC) > > If you have to use sev_status, then please document why cc_platform_has() can't be used in the comment above. Right, for sev-shared.c, cc_platform_has() is not available when compiling boot/compressed. Regards Nikunj
diff --git a/arch/x86/kernel/sev-shared.c b/arch/x86/kernel/sev-shared.c index ccb0915e84e1..833b0ae38f0b 100644 --- a/arch/x86/kernel/sev-shared.c +++ b/arch/x86/kernel/sev-shared.c @@ -991,6 +991,13 @@ static enum es_result vc_handle_rdtsc(struct ghcb *ghcb, bool rdtscp = (exit_code == SVM_EXIT_RDTSCP); enum es_result ret; + /* + * RDTSC and RDTSCP should not be intercepted when Secure TSC is + * enabled. Terminate the SNP guest when the interception is enabled. + */ + if (sev_status & MSR_AMD64_SNP_SECURE_TSC) + return ES_VMM_ERROR; + ret = sev_es_ghcb_hv_call(ghcb, ctxt, exit_code, 0, 0); if (ret != ES_OK) return ret;
The hypervisor should not be intercepting RDTSC/RDTSCP when Secure TSC is enabled. A #VC exception will be generated if the RDTSC/RDTSCP instructions are being intercepted. If this should occur and Secure TSC is enabled, terminate guest execution. Signed-off-by: Nikunj A Dadhania <nikunj@amd.com> --- arch/x86/kernel/sev-shared.c | 7 +++++++ 1 file changed, 7 insertions(+)