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From: Sean Christopherson <seanjc@google.com>
To: Sean Christopherson <seanjc@google.com>,
	Paolo Bonzini <pbonzini@redhat.com>,
	 Vitaly Kuznetsov <vkuznets@redhat.com>,
	David Woodhouse <dwmw2@infradead.org>,
	Paul Durrant <paul@xen.org>
Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org,
	 Yosry Ahmed <yosry@kernel.org>
Subject: [PATCH 05/11] KVM: x86: Trace hypercall register *after* truncating values for 32-bit
Date: Thu,  9 Apr 2026 16:56:16 -0700	[thread overview]
Message-ID: <20260409235622.2052730-6-seanjc@google.com> (raw)
In-Reply-To: <20260409235622.2052730-1-seanjc@google.com>

When tracing hypercalls, invoke the tracepoint *after* truncating the
register values for 32-bit guests so as not to record unused garbage (in
the extremely unlikely scenario that the guest left garbage in a register
after transitioning from 64-bit mode to 32-bit mode).

Fixes: 229456fc34b1 ("KVM: convert custom marker based tracing to event traces")
Signed-off-by: Sean Christopherson <seanjc@google.com>
---
 arch/x86/kvm/x86.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 0a1b63c63d1a..34ee79c1cbf3 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -10438,8 +10438,6 @@ int ____kvm_emulate_hypercall(struct kvm_vcpu *vcpu, int cpl,
 
 	++vcpu->stat.hypercalls;
 
-	trace_kvm_hypercall(nr, a0, a1, a2, a3);
-
 	if (!op_64_bit) {
 		nr &= 0xFFFFFFFF;
 		a0 &= 0xFFFFFFFF;
@@ -10448,6 +10446,8 @@ int ____kvm_emulate_hypercall(struct kvm_vcpu *vcpu, int cpl,
 		a3 &= 0xFFFFFFFF;
 	}
 
+	trace_kvm_hypercall(nr, a0, a1, a2, a3);
+
 	if (cpl) {
 		ret = -KVM_EPERM;
 		goto out;
-- 
2.53.0.1213.gd9a14994de-goog


  parent reply	other threads:[~2026-04-09 23:56 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-04-09 23:56 [PATCH 00/11] KVM: x86: Clean up kvm_<reg>_{read,write}() mess Sean Christopherson
2026-04-09 23:56 ` [PATCH 01/11] KVM: SVM: Truncate INVLPGA address in compatibility mode Sean Christopherson
2026-04-09 23:56 ` [PATCH 02/11] KVM: x86/xen: Bug the VM if 32-bit KVM observes a 64-bit mode hypercall Sean Christopherson
2026-04-09 23:56 ` [PATCH 03/11] KVM: x86/xen: Don't truncate RAX when handling hypercall from protected guest Sean Christopherson
2026-04-09 23:56 ` [PATCH 04/11] KVM: VMX: Read 32-bit GPR values for ENCLS instructions outside of 64-bit mode Sean Christopherson
2026-04-09 23:56 ` Sean Christopherson [this message]
2026-04-09 23:56 ` [PATCH 06/11] KVM: x86: Move kvm_<reg>_{read,write}() definitions to x86.h Sean Christopherson
2026-04-09 23:56 ` [PATCH 07/11] KVM: x86: Add mode-aware versions of kvm_<reg>_{read,write}() helpers Sean Christopherson
2026-04-09 23:56 ` [PATCH 08/11] KVM: x86: Drop non-raw kvm_<reg>_write() helpers Sean Christopherson
2026-04-09 23:56 ` [PATCH 09/11] KVM: nSVM: Use kvm_rax_read() now that it's mode-aware Sean Christopherson
2026-04-09 23:56 ` [PATCH 10/11] Revert "KVM: VMX: Read 32-bit GPR values for ENCLS instructions outside of 64-bit mode" Sean Christopherson
2026-04-09 23:56 ` [PATCH 11/11] KVM: x86: Harden is_64_bit_hypercall() against bugs on 32-bit kernels Sean Christopherson

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