diff options
| author | Nikunj A Dadhania <nikunj@amd.com> | 2025-01-06 18:16:28 +0530 |
|---|---|---|
| committer | Borislav Petkov (AMD) <bp@alien8.de> | 2025-01-07 21:26:20 +0100 |
| commit | eef679a4b52e35be3b4a982a7f42bcc16054ec62 (patch) | |
| tree | 82aae4a35f53c7ba6712c19d8c11cf5e500042cb | |
| parent | 38cc6495cdec18a448b9e1de45fedce4118833a2 (diff) | |
x86/sev: Prevent RDTSC/RDTSCP interception for Secure TSC enabled guests
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,
guest execution should be terminated as the guest cannot rely on the TSC
value provided by the hypervisor.
Signed-off-by: Nikunj A Dadhania <nikunj@amd.com>
Signed-off-by: Borislav Petkov (AMD) <bp@alien8.de>
Reviewed-by: Tom Lendacky <thomas.lendacky@amd.com>
Tested-by: Peter Gonda <pgonda@google.com>
Link: https://lore.kernel.org/r/20250106124633.1418972-9-nikunj@amd.com
| -rw-r--r-- | arch/x86/coco/sev/shared.c | 10 |
1 files changed, 10 insertions, 0 deletions
diff --git a/arch/x86/coco/sev/shared.c b/arch/x86/coco/sev/shared.c index 71de53194089..4386f37bd31d 100644 --- a/arch/x86/coco/sev/shared.c +++ b/arch/x86/coco/sev/shared.c @@ -1140,6 +1140,16 @@ static enum es_result vc_handle_rdtsc(struct ghcb *ghcb, bool rdtscp = (exit_code == SVM_EXIT_RDTSCP); enum es_result 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, guest execution should be terminated as the guest + * cannot rely on the TSC value provided by the hypervisor. + */ + 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; |