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Message-ID: <20241021055156.2342564-6-nikunj@amd.com>
Date: Mon, 21 Oct 2024 11:21:48 +0530
From: Nikunj A Dadhania <nikunj@....com>
To: <linux-kernel@...r.kernel.org>, <thomas.lendacky@....com>, <bp@...en8.de>,
<x86@...nel.org>, <kvm@...r.kernel.org>
CC: <mingo@...hat.com>, <tglx@...utronix.de>, <dave.hansen@...ux.intel.com>,
<pgonda@...gle.com>, <seanjc@...gle.com>, <pbonzini@...hat.com>,
<nikunj@....com>
Subject: [PATCH v13 05/13] 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,
terminate guest execution.
Signed-off-by: Nikunj A Dadhania <nikunj@....com>
Tested-by: Peter Gonda <pgonda@...gle.com>
Reviewed-by: Tom Lendacky <thomas.lendacky@....com>
---
arch/x86/coco/sev/shared.c | 10 ++++++++++
1 file changed, 10 insertions(+)
diff --git a/arch/x86/coco/sev/shared.c b/arch/x86/coco/sev/shared.c
index 71de53194089..c2a9e2ada659 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;
+ /*
+ * RDTSC and RDTSCP should not be intercepted when Secure TSC is
+ * enabled. Terminate the SNP guest when the interception is enabled.
+ * This file is included from kernel/sev.c and boot/compressed/sev.c,
+ * use sev_status here as cc_platform_has() is not available when
+ * compiling boot/compressed/sev.c.
+ */
+ 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;
--
2.34.1
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