linux-kernel - [PATCH 28/29] KVM: TDX: Skip updating CPU dirty logging request for TDs

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Message-ID: <20250226195529.2314580-29-pbonzini@redhat.com>
Date: Wed, 26 Feb 2025 14:55:28 -0500
From: Paolo Bonzini <pbonzini@...hat.com>
To: linux-kernel@...r.kernel.org,
	kvm@...r.kernel.org
Cc: seanjc@...gle.com,
	Yan Zhao <yan.y.zhao@...el.com>,
	Rick Edgecombe <rick.p.edgecombe@...el.com>
Subject: [PATCH 28/29] KVM: TDX: Skip updating CPU dirty logging request for TDs

Wrap vmx_update_cpu_dirty_logging so as to ignore requests to update
CPU dirty logging for TDs, as basic TDX does not support the PML feature.
Invoking vmx_update_cpu_dirty_logging() for TDs would cause an incorrect
access to a kvm_vmx struct for a TDX VM, so block that before it happens.

Signed-off-by: Yan Zhao <yan.y.zhao@...el.com>
Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
---
 arch/x86/kvm/vmx/main.c | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/vmx/main.c b/arch/x86/kvm/vmx/main.c
index ba3a23747bb1..ec8223ee9d28 100644
--- a/arch/x86/kvm/vmx/main.c
+++ b/arch/x86/kvm/vmx/main.c
@@ -129,6 +129,18 @@ static void vt_vcpu_load(struct kvm_vcpu *vcpu, int cpu)
 	vmx_vcpu_load(vcpu, cpu);
 }
 
+static void vt_update_cpu_dirty_logging(struct kvm_vcpu *vcpu)
+{
+	/*
+	 * Basic TDX does not support feature PML. KVM does not enable PML in
+	 * TD's VMCS, nor does it allocate or flush PML buffer for TDX.
+	 */
+	if (WARN_ON_ONCE(is_td_vcpu(vcpu)))
+		return;
+
+	vmx_update_cpu_dirty_logging(vcpu);
+}
+
 static void vt_flush_tlb_all(struct kvm_vcpu *vcpu)
 {
 	if (is_td_vcpu(vcpu)) {
@@ -322,7 +334,7 @@ struct kvm_x86_ops vt_x86_ops __initdata = {
 	.check_intercept = vmx_check_intercept,
 	.handle_exit_irqoff = vmx_handle_exit_irqoff,
 
-	.update_cpu_dirty_logging = vmx_update_cpu_dirty_logging,
+	.update_cpu_dirty_logging = vt_update_cpu_dirty_logging,
 
 	.nested_ops = &vmx_nested_ops,
 
-- 
2.43.5