linux-kernel - [PATCH v3 3/5] KVM: nVMX: Precisely mark vAPIC and PID maps dirty when delivering nested PI

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Message-ID: <20251121223444.355422-4-seanjc@google.com>
Date: Fri, 21 Nov 2025 14:34:42 -0800
From: Sean Christopherson <seanjc@...gle.com>
To: Sean Christopherson <seanjc@...gle.com>, Paolo Bonzini <pbonzini@...hat.com>
Cc: kvm@...r.kernel.org, linux-kernel@...r.kernel.org, 
	Fred Griffoul <fgriffo@...zon.co.uk>
Subject: [PATCH v3 3/5] KVM: nVMX: Precisely mark vAPIC and PID maps dirty
 when delivering nested PI

Explicitly mark the vmcs12 vAPIC and PI descriptor pages as dirty when
delivering a nested posted interrupt instead of marking all vmcs12 pages
as dirty.  This will allow marking the APIC access page (and any future
 vmcs12 pages) as dirty in nested_mark_vmcs12_pages_dirty() without over-
dirtying in the nested PI case.  Manually marking the vAPIC and PID pages
as dirty also makes the flow a bit more self-documenting, e.g. it's not
obvious at first glance that vmx->nested.pi_desc is actually a host kernel
mapping of a vmcs12 page.

No functional change intended.

Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 arch/x86/kvm/vmx/nested.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/vmx/nested.c b/arch/x86/kvm/vmx/nested.c
index d4ef33578747..d0cf99903971 100644
--- a/arch/x86/kvm/vmx/nested.c
+++ b/arch/x86/kvm/vmx/nested.c
@@ -4027,7 +4027,8 @@ static int vmx_complete_nested_posted_interrupt(struct kvm_vcpu *vcpu)
 		}
 	}

-	nested_mark_vmcs12_pages_dirty(vcpu);
+	kvm_vcpu_map_mark_dirty(vcpu, &vmx->nested.virtual_apic_map);
+	kvm_vcpu_map_mark_dirty(vcpu, &vmx->nested.pi_desc_map);
 	return 0;

 mmio_needed:
-- 
2.52.0.rc2.455.g230fcf2819-goog