linux-kernel - [PATCH v3 10/10] KVM: x86: Update APICv ISR (a.k.a. SVI) as part of kvm_apic_update

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [day] [month] [year] [list]

Message-ID: <20251205231913.441872-11-seanjc@google.com>
Date: Fri,  5 Dec 2025 15:19:13 -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, 
	Dongli Zhang <dongli.zhang@...cle.com>, Chao Gao <chao.gao@...el.com>
Subject: [PATCH v3 10/10] KVM: x86: Update APICv ISR (a.k.a. SVI) as part of kvm_apic_update_apicv()

Fold the calls to .hwapic_isr_update() in kvm_apic_set_state() and
__kvm_vcpu_update_apicv() into kvm_apic_update_apicv(), as updating SVI is
directly related to updating KVM's own cache of ISR information, e.g.
SVI is more or less the APICv equivalent of highest_isr_cache.

Note, calling .hwapic_isr_update() during kvm_apic_update_apicv() has two
benign side effects.  First, it adds a call during kvm_lapic_reset(), but
that's a glorified nop as the ISR has already been zeroed.  Second, it
changes the order between .hwapic_isr_update() and
.apicv_post_state_restore() in kvm_apic_set_state(), but the former is
VMX-only and the latter is SVM-only, i.e. is also a glorified nop.

Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 arch/x86/kvm/lapic.c | 21 +++++----------------
 arch/x86/kvm/lapic.h |  1 -
 arch/x86/kvm/x86.c   |  2 --
 3 files changed, 5 insertions(+), 19 deletions(-)

diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index 1597dd0b0cc6..7be4d759884c 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -770,17 +770,6 @@ static inline void apic_clear_isr(int vec, struct kvm_lapic *apic)
 	}
 }
 
-void kvm_apic_update_hwapic_isr(struct kvm_vcpu *vcpu)
-{
-	struct kvm_lapic *apic = vcpu->arch.apic;
-
-	if (WARN_ON_ONCE(!lapic_in_kernel(vcpu)) || !apic->apicv_active)
-		return;
-
-	kvm_x86_call(hwapic_isr_update)(vcpu, apic_find_highest_isr(apic));
-}
-EXPORT_SYMBOL_FOR_KVM_INTERNAL(kvm_apic_update_hwapic_isr);
-
 int kvm_lapic_find_highest_irr(struct kvm_vcpu *vcpu)
 {
 	/* This may race with setting of irr in __apic_accept_irq() and
@@ -2785,10 +2774,12 @@ void kvm_apic_update_apicv(struct kvm_vcpu *vcpu)
 	 */
 	apic->irr_pending = true;
 
-	if (apic->apicv_active)
+	if (apic->apicv_active) {
 		apic->isr_count = 1;
-	else
+		kvm_x86_call(hwapic_isr_update)(vcpu, apic_find_highest_isr(apic));
+	} else {
 		apic->isr_count = count_vectors(apic->regs + APIC_ISR);
+	}
 
 	apic->highest_isr_cache = -1;
 }
@@ -3232,10 +3223,8 @@ int kvm_apic_set_state(struct kvm_vcpu *vcpu, struct kvm_lapic_state *s)
 	__start_apic_timer(apic, APIC_TMCCT);
 	kvm_lapic_set_reg(apic, APIC_TMCCT, 0);
 	kvm_apic_update_apicv(vcpu);
-	if (apic->apicv_active) {
+	if (apic->apicv_active)
 		kvm_x86_call(apicv_post_state_restore)(vcpu);
-		kvm_x86_call(hwapic_isr_update)(vcpu, apic_find_highest_isr(apic));
-	}
 	kvm_make_request(KVM_REQ_EVENT, vcpu);
 
 #ifdef CONFIG_KVM_IOAPIC
diff --git a/arch/x86/kvm/lapic.h b/arch/x86/kvm/lapic.h
index 282b9b7da98c..aa0a9b55dbb7 100644
--- a/arch/x86/kvm/lapic.h
+++ b/arch/x86/kvm/lapic.h
@@ -126,7 +126,6 @@ void kvm_apic_send_ipi(struct kvm_lapic *apic, u32 icr_low, u32 icr_high);
 int kvm_apic_set_base(struct kvm_vcpu *vcpu, u64 value, bool host_initiated);
 int kvm_apic_get_state(struct kvm_vcpu *vcpu, struct kvm_lapic_state *s);
 int kvm_apic_set_state(struct kvm_vcpu *vcpu, struct kvm_lapic_state *s);
-void kvm_apic_update_hwapic_isr(struct kvm_vcpu *vcpu);
 int kvm_lapic_find_highest_irr(struct kvm_vcpu *vcpu);
 
 u64 kvm_get_lapic_tscdeadline_msr(struct kvm_vcpu *vcpu);
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index ff8812f3a129..66c5edbbda2b 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -10894,8 +10894,6 @@ void __kvm_vcpu_update_apicv(struct kvm_vcpu *vcpu)
 	 */
 	if (!apic->apicv_active)
 		kvm_make_request(KVM_REQ_EVENT, vcpu);
-	else
-		kvm_apic_update_hwapic_isr(vcpu);
 
 out:
 	preempt_enable();
-- 
2.52.0.223.gf5cc29aaa4-goog