Thread (76 messages) 76 messages, 4 authors, 17d ago
COLD17d REVIEWED: 2 (0M)

[PATCH v5 05/51] x86/sev: Mark TSC as reliable when configuring Secure TSC

From: Sean Christopherson <seanjc@google.com>
Date: 2026-07-01 19:32:33
Also in: kvm, linux-coco, linux-doc, lkml, virtualization, xen-devel
Subsystem: the rest, x86 architecture (32-bit and 64-bit), x86 mm · Maintainers: Linus Torvalds, Thomas Gleixner, Ingo Molnar, Borislav Petkov, Dave Hansen, Andy Lutomirski, Peter Zijlstra

Move the code to mark the TSC as reliable from sme_early_init() to
snp_secure_tsc_init().  The only reader of TSC_RELIABLE is the aptly
named check_system_tsc_reliable(), which runs in tsc_init(), i.e.
after snp_secure_tsc_init().

This will allow consolidating the handling of TSC_KNOWN_FREQ and
TSC_RELIABLE when overriding the TSC calibration routine.

Cc: Tom Lendacky <thomas.lendacky@amd.com>
Reviewed-by: Nikunj A Dadhania <redacted>
Reviewed-by: David Woodhouse <redacted>
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
 arch/x86/coco/sev/core.c      | 2 ++
 arch/x86/mm/mem_encrypt_amd.c | 3 ---
 2 files changed, 2 insertions(+), 3 deletions(-)
diff --git a/arch/x86/coco/sev/core.c b/arch/x86/coco/sev/core.c
index ecd77d3217f3..ed0ac52a765e 100644
--- a/arch/x86/coco/sev/core.c
+++ b/arch/x86/coco/sev/core.c
@@ -2037,6 +2037,8 @@ void __init snp_secure_tsc_init(void)
 	secrets = (__force struct snp_secrets_page *)mem;
 
 	setup_force_cpu_cap(X86_FEATURE_TSC_KNOWN_FREQ);
+	setup_force_cpu_cap(X86_FEATURE_TSC_RELIABLE);
+
 	rdmsrq(MSR_AMD64_GUEST_TSC_FREQ, tsc_freq_mhz);
 
 	/* Extract the GUEST TSC MHZ from BIT[17:0], rest is reserved space */
diff --git a/arch/x86/mm/mem_encrypt_amd.c b/arch/x86/mm/mem_encrypt_amd.c
index 2f8c32173972..6c3af974c7c2 100644
--- a/arch/x86/mm/mem_encrypt_amd.c
+++ b/arch/x86/mm/mem_encrypt_amd.c
@@ -535,9 +535,6 @@ void __init sme_early_init(void)
 		 */
 		x86_init.resources.dmi_setup = snp_dmi_setup;
 	}
-
-	if (sev_status & MSR_AMD64_SNP_SECURE_TSC)
-		setup_force_cpu_cap(X86_FEATURE_TSC_RELIABLE);
 }
 
 void __init mem_encrypt_free_decrypted_mem(void)
-- 
2.55.0.rc0.799.gd6f94ed593-goog
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