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Message-ID: <20150730033909.GD15229@google.com>
Date: Wed, 29 Jul 2015 20:39:09 -0700
From: Steve Rutherford <srutherford@...gle.com>
To: Paolo Bonzini <pbonzini@...hat.com>
Cc: linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
alex.williamson@...hat.com, yang.z.zhang@...el.com,
srutherford@...el.com
Subject: Re: [PATCH 1/2] KVM: x86: set TMR when the interrupt is accepted
On Wed, Jul 29, 2015 at 03:37:34PM +0200, Paolo Bonzini wrote:
> Do not compute TMR in advance. Instead, set the TMR just before the interrupt
> is accepted into the IRR. This limits the coupling between IOAPIC and LAPIC.
>
> Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
> ---
> arch/x86/kvm/ioapic.c | 9 ++-------
> arch/x86/kvm/ioapic.h | 3 +--
> arch/x86/kvm/lapic.c | 19 ++++++++++---------
> arch/x86/kvm/lapic.h | 1 -
> arch/x86/kvm/x86.c | 5 +----
> 5 files changed, 14 insertions(+), 23 deletions(-)
>
> diff --git a/arch/x86/kvm/ioapic.c b/arch/x86/kvm/ioapic.c
> index 856f79105bb5..eaf4ec38d980 100644
> --- a/arch/x86/kvm/ioapic.c
> +++ b/arch/x86/kvm/ioapic.c
> @@ -246,8 +246,7 @@ static void update_handled_vectors(struct kvm_ioapic *ioapic)
> smp_wmb();
> }
>
> -void kvm_ioapic_scan_entry(struct kvm_vcpu *vcpu, u64 *eoi_exit_bitmap,
> - u32 *tmr)
> +void kvm_ioapic_scan_entry(struct kvm_vcpu *vcpu, u64 *eoi_exit_bitmap)
> {
> struct kvm_ioapic *ioapic = vcpu->kvm->arch.vioapic;
> union kvm_ioapic_redirect_entry *e;
> @@ -260,13 +259,9 @@ void kvm_ioapic_scan_entry(struct kvm_vcpu *vcpu, u64 *eoi_exit_bitmap,
> kvm_irq_has_notifier(ioapic->kvm, KVM_IRQCHIP_IOAPIC, index) ||
> index == RTC_GSI) {
> if (kvm_apic_match_dest(vcpu, NULL, 0,
> - e->fields.dest_id, e->fields.dest_mode)) {
> + e->fields.dest_id, e->fields.dest_mode))
> __set_bit(e->fields.vector,
> (unsigned long *)eoi_exit_bitmap);
> - if (e->fields.trig_mode == IOAPIC_LEVEL_TRIG)
> - __set_bit(e->fields.vector,
> - (unsigned long *)tmr);
> - }
> }
> }
> spin_unlock(&ioapic->lock);
> diff --git a/arch/x86/kvm/ioapic.h b/arch/x86/kvm/ioapic.h
> index ca0b0b4e6256..3dbd0e2aac4e 100644
> --- a/arch/x86/kvm/ioapic.h
> +++ b/arch/x86/kvm/ioapic.h
> @@ -120,7 +120,6 @@ int kvm_irq_delivery_to_apic(struct kvm *kvm, struct kvm_lapic *src,
> struct kvm_lapic_irq *irq, unsigned long *dest_map);
> int kvm_get_ioapic(struct kvm *kvm, struct kvm_ioapic_state *state);
> int kvm_set_ioapic(struct kvm *kvm, struct kvm_ioapic_state *state);
> -void kvm_ioapic_scan_entry(struct kvm_vcpu *vcpu, u64 *eoi_exit_bitmap,
> - u32 *tmr);
> +void kvm_ioapic_scan_entry(struct kvm_vcpu *vcpu, u64 *eoi_exit_bitmap);
>
> #endif
> diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
> index 2a5ca97c263b..9be64c77d6db 100644
> --- a/arch/x86/kvm/lapic.c
> +++ b/arch/x86/kvm/lapic.c
> @@ -551,15 +551,6 @@ static void pv_eoi_clr_pending(struct kvm_vcpu *vcpu)
> __clear_bit(KVM_APIC_PV_EOI_PENDING, &vcpu->arch.apic_attention);
> }
>
> -void kvm_apic_update_tmr(struct kvm_vcpu *vcpu, u32 *tmr)
> -{
> - struct kvm_lapic *apic = vcpu->arch.apic;
> - int i;
> -
> - for (i = 0; i < 8; i++)
> - apic_set_reg(apic, APIC_TMR + 0x10 * i, tmr[i]);
> -}
> -
> static void apic_update_ppr(struct kvm_lapic *apic)
> {
> u32 tpr, isrv, ppr, old_ppr;
> @@ -781,6 +772,9 @@ static int __apic_accept_irq(struct kvm_lapic *apic, int delivery_mode,
> case APIC_DM_LOWEST:
> vcpu->arch.apic_arb_prio++;
> case APIC_DM_FIXED:
> + if (unlikely(trig_mode && !level))
> + break;
> +
> /* FIXME add logic for vcpu on reset */
> if (unlikely(!apic_enabled(apic)))
> break;
> @@ -790,6 +784,13 @@ static int __apic_accept_irq(struct kvm_lapic *apic, int delivery_mode,
> if (dest_map)
> __set_bit(vcpu->vcpu_id, dest_map);
>
> + if (apic_test_vector(vector, apic->regs + APIC_TMR) != !!trig_mode) {
> + if (trig_mode)
> + apic_set_vector(vector, apic->regs + APIC_TMR);
> + else
> + apic_clear_vector(vector, apic->regs + APIC_TMR);
> + }
> +
> if (kvm_x86_ops->deliver_posted_interrupt)
> kvm_x86_ops->deliver_posted_interrupt(vcpu, vector);
> else {
> diff --git a/arch/x86/kvm/lapic.h b/arch/x86/kvm/lapic.h
> index 764037991d26..eb46d6bcaa75 100644
> --- a/arch/x86/kvm/lapic.h
> +++ b/arch/x86/kvm/lapic.h
> @@ -57,7 +57,6 @@ void kvm_lapic_set_base(struct kvm_vcpu *vcpu, u64 value);
> u64 kvm_lapic_get_base(struct kvm_vcpu *vcpu);
> void kvm_apic_set_version(struct kvm_vcpu *vcpu);
>
> -void kvm_apic_update_tmr(struct kvm_vcpu *vcpu, u32 *tmr);
> void __kvm_apic_update_irr(u32 *pir, void *regs);
> void kvm_apic_update_irr(struct kvm_vcpu *vcpu, u32 *pir);
> int kvm_apic_set_irq(struct kvm_vcpu *vcpu, struct kvm_lapic_irq *irq,
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 23e47a0b054b..48dc954542db 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -6149,17 +6149,14 @@ static void process_smi(struct kvm_vcpu *vcpu)
> static void vcpu_scan_ioapic(struct kvm_vcpu *vcpu)
> {
> u64 eoi_exit_bitmap[4];
> - u32 tmr[8];
>
> if (!kvm_apic_hw_enabled(vcpu->arch.apic))
> return;
>
> memset(eoi_exit_bitmap, 0, 32);
> - memset(tmr, 0, 32);
>
> - kvm_ioapic_scan_entry(vcpu, eoi_exit_bitmap, tmr);
> + kvm_ioapic_scan_entry(vcpu, eoi_exit_bitmap);
> kvm_x86_ops->load_eoi_exitmap(vcpu, eoi_exit_bitmap);
> - kvm_apic_update_tmr(vcpu, tmr);
> }
>
> static void kvm_vcpu_flush_tlb(struct kvm_vcpu *vcpu)
> --
> 1.8.3.1
>
>
> --
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Thanks for writing this. This makes TMR handling far cleaner.
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