linux-kernel - Re: [PATCH 1/2] KVM: x86: Plumb in the vCPU to kvm_x86_ops.hwapic_isr

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Message-ID: <Zyh3wsWVvP2V2fNQ@intel.com>
Date: Mon, 4 Nov 2024 15:29:06 +0800
From: Chao Gao <chao.gao@...el.com>
To: Sean Christopherson <seanjc@...gle.com>
CC: Paolo Bonzini <pbonzini@...hat.com>, <kvm@...r.kernel.org>,
	<linux-kernel@...r.kernel.org>, Markku Ahvenjärvi
	<mankku@...il.com>, Janne Karhunen <janne.karhunen@...il.com>
Subject: Re: [PATCH 1/2] KVM: x86: Plumb in the vCPU to
 kvm_x86_ops.hwapic_isr_update()

On Fri, Nov 01, 2024 at 12:21:13PM -0700, Sean Christopherson wrote:
>Pass the target vCPU to the hwapic_isr_update() vendor hook so that VMX
>can defer the update until after nested VM-Exit if an EOI for L1's vAPIC
>occurs while L2 is active.
>
>No functional change intended.
>
>Cc: stable@...r.kernel.org
>Signed-off-by: Sean Christopherson <seanjc@...gle.com>

Reviewed-by: Chao Gao <chao.gao@...el.com>

>---
> arch/x86/include/asm/kvm_host.h |  2 +-
> arch/x86/kvm/lapic.c            | 11 +++++------
> arch/x86/kvm/vmx/vmx.c          |  2 +-
> arch/x86/kvm/vmx/x86_ops.h      |  2 +-
> 4 files changed, 8 insertions(+), 9 deletions(-)
>
>diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
>index 70c7ed0ef184..3f3de047cbfd 100644
>--- a/arch/x86/include/asm/kvm_host.h
>+++ b/arch/x86/include/asm/kvm_host.h
>@@ -1734,7 +1734,7 @@ struct kvm_x86_ops {
> 	bool allow_apicv_in_x2apic_without_x2apic_virtualization;
> 	void (*refresh_apicv_exec_ctrl)(struct kvm_vcpu *vcpu);
> 	void (*hwapic_irr_update)(struct kvm_vcpu *vcpu, int max_irr);
>-	void (*hwapic_isr_update)(int isr);
>+	void (*hwapic_isr_update)(struct kvm_vcpu *vcpu, int isr);
> 	void (*load_eoi_exitmap)(struct kvm_vcpu *vcpu, u64 *eoi_exit_bitmap);
> 	void (*set_virtual_apic_mode)(struct kvm_vcpu *vcpu);
> 	void (*set_apic_access_page_addr)(struct kvm_vcpu *vcpu);
>diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
>index 65412640cfc7..5be2be44a188 100644
>--- a/arch/x86/kvm/lapic.c
>+++ b/arch/x86/kvm/lapic.c
>@@ -763,7 +763,7 @@ static inline void apic_set_isr(int vec, struct kvm_lapic *apic)
> 	 * just set SVI.
> 	 */
> 	if (unlikely(apic->apicv_active))
>-		kvm_x86_call(hwapic_isr_update)(vec);
>+		kvm_x86_call(hwapic_isr_update)(apic->vcpu, vec);

Both branches need braces here. So, maybe take the opportunity to fix the coding style
issue.

> 	else {
> 		++apic->isr_count;
> 		BUG_ON(apic->isr_count > MAX_APIC_VECTOR);
>@@ -808,7 +808,7 @@ static inline void apic_clear_isr(int vec, struct kvm_lapic *apic)
> 	 * and must be left alone.
> 	 */
> 	if (unlikely(apic->apicv_active))
>-		kvm_x86_call(hwapic_isr_update)(apic_find_highest_isr(apic));
>+		kvm_x86_call(hwapic_isr_update)(apic->vcpu, apic_find_highest_isr(apic));

ditto

> 	else {
> 		--apic->isr_count;
> 		BUG_ON(apic->isr_count < 0);