linux-kernel - [PATCH] KVM: SVM: Update dump_ghcb() to use the GHCB snapshot fields

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Message-ID: <8f03878443681496008b1b37b7c4bf77a342b459.1745866531.git.thomas.lendacky@amd.com>
Date: Mon, 28 Apr 2025 13:55:31 -0500
From: Tom Lendacky <thomas.lendacky@....com>
To: <kvm@...r.kernel.org>, <linux-kernel@...r.kernel.org>, <x86@...nel.org>
CC: Paolo Bonzini <pbonzini@...hat.com>, Sean Christopherson
	<seanjc@...gle.com>, Borislav Petkov <bp@...en8.de>, Dave Hansen
	<dave.hansen@...ux.intel.com>, Ingo Molnar <mingo@...hat.com>, "Thomas
 Gleixner" <tglx@...utronix.de>, Michael Roth <michael.roth@....com>
Subject: [PATCH] KVM: SVM: Update dump_ghcb() to use the GHCB snapshot fields

Commit 4e15a0ddc3ff ("KVM: SEV: snapshot the GHCB before accessing it")
updated the SEV code to take a snapshot of the GHCB before using it. But
the dump_ghcb() function wasn't updated to use the snapshot locations.
This results in incorrect output from dump_ghcb() for the "is_valid" and
"valid_bitmap" fields.

Update dump_ghcb() to use the proper locations.

Fixes: 4e15a0ddc3ff ("KVM: SEV: snapshot the GHCB before accessing it")
Signed-off-by: Tom Lendacky <thomas.lendacky@....com>
---
 arch/x86/kvm/svm/sev.c | 24 ++++++++++++------------
 1 file changed, 12 insertions(+), 12 deletions(-)

diff --git a/arch/x86/kvm/svm/sev.c b/arch/x86/kvm/svm/sev.c
index 0bc708ee2788..91e514d07f8a 100644
--- a/arch/x86/kvm/svm/sev.c
+++ b/arch/x86/kvm/svm/sev.c
@@ -3173,9 +3173,14 @@ void sev_free_vcpu(struct kvm_vcpu *vcpu)
 		kvfree(svm->sev_es.ghcb_sa);
 }
 
+static u64 kvm_ghcb_get_sw_exit_code(struct vmcb_control_area *control)
+{
+	return (((u64)control->exit_code_hi) << 32) | control->exit_code;
+}
+
 static void dump_ghcb(struct vcpu_svm *svm)
 {
-	struct ghcb *ghcb = svm->sev_es.ghcb;
+	struct vmcb_control_area *control = &svm->vmcb->control;
 	unsigned int nbits;
 
 	/* Re-use the dump_invalid_vmcb module parameter */
@@ -3184,18 +3189,18 @@ static void dump_ghcb(struct vcpu_svm *svm)
 		return;
 	}
 
-	nbits = sizeof(ghcb->save.valid_bitmap) * 8;
+	nbits = sizeof(svm->sev_es.valid_bitmap) * 8;
 
 	pr_err("GHCB (GPA=%016llx):\n", svm->vmcb->control.ghcb_gpa);
 	pr_err("%-20s%016llx is_valid: %u\n", "sw_exit_code",
-	       ghcb->save.sw_exit_code, ghcb_sw_exit_code_is_valid(ghcb));
+	       kvm_ghcb_get_sw_exit_code(control), kvm_ghcb_sw_exit_code_is_valid(svm));
 	pr_err("%-20s%016llx is_valid: %u\n", "sw_exit_info_1",
-	       ghcb->save.sw_exit_info_1, ghcb_sw_exit_info_1_is_valid(ghcb));
+	       control->exit_info_1, kvm_ghcb_sw_exit_info_1_is_valid(svm));
 	pr_err("%-20s%016llx is_valid: %u\n", "sw_exit_info_2",
-	       ghcb->save.sw_exit_info_2, ghcb_sw_exit_info_2_is_valid(ghcb));
+	       control->exit_info_2, kvm_ghcb_sw_exit_info_2_is_valid(svm));
 	pr_err("%-20s%016llx is_valid: %u\n", "sw_scratch",
-	       ghcb->save.sw_scratch, ghcb_sw_scratch_is_valid(ghcb));
-	pr_err("%-20s%*pb\n", "valid_bitmap", nbits, ghcb->save.valid_bitmap);
+	       svm->sev_es.sw_scratch, kvm_ghcb_sw_scratch_is_valid(svm));
+	pr_err("%-20s%*pb\n", "valid_bitmap", nbits, svm->sev_es.valid_bitmap);
 }
 
 static void sev_es_sync_to_ghcb(struct vcpu_svm *svm)
@@ -3266,11 +3271,6 @@ static void sev_es_sync_from_ghcb(struct vcpu_svm *svm)
 	memset(ghcb->save.valid_bitmap, 0, sizeof(ghcb->save.valid_bitmap));
 }
 
-static u64 kvm_ghcb_get_sw_exit_code(struct vmcb_control_area *control)
-{
-	return (((u64)control->exit_code_hi) << 32) | control->exit_code;
-}
-
 static int sev_es_validate_vmgexit(struct vcpu_svm *svm)
 {
 	struct vmcb_control_area *control = &svm->vmcb->control;

base-commit: 2d7124941a273c7233849a7a2bbfbeb7e28f1caa
-- 
2.46.2