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[v8,14/16] x86/sev: Mark Secure TSC as reliable

Message ID 20240215113128.275608-15-nikunj@amd.com (mailing list archive)
State New, archived
Headers show
Series Add Secure TSC support for SNP guests | expand

Commit Message

Nikunj A. Dadhania Feb. 15, 2024, 11:31 a.m. UTC
AMD SNP guests may have Secure TSC feature enabled. Use the Secure TSC
as the only reliable clock source in SEV-SNP guests when enabled,
bypassing unstable calibration.

Signed-off-by: Nikunj A Dadhania <nikunj@amd.com>
Tested-by: Peter Gonda <pgonda@google.com>
 arch/x86/mm/mem_encrypt_amd.c | 4 ++++
 1 file changed, 4 insertions(+)
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diff --git a/arch/x86/mm/mem_encrypt_amd.c b/arch/x86/mm/mem_encrypt_amd.c
index c81b57ca03b6..cc936999efc8 100644
--- a/arch/x86/mm/mem_encrypt_amd.c
+++ b/arch/x86/mm/mem_encrypt_amd.c
@@ -498,6 +498,10 @@  void __init sme_early_init(void)
 	if (sev_status & MSR_AMD64_SEV_ENABLED)
+	/* Mark the TSC as reliable when Secure TSC is enabled */
+	if (sev_status & MSR_AMD64_SNP_SECURE_TSC)
+		setup_force_cpu_cap(X86_FEATURE_TSC_RELIABLE);
 void __init mem_encrypt_free_decrypted_mem(void)