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Date: Fri, 27 Nov 2020 13:52:58 +0100
From: Filippo Sironi <sironi@...zon.de>
To: Paolo Bonzini <pbonzini@...hat.com>,
<linux-kernel@...r.kernel.org>, <kvm@...r.kernel.org>
CC: <seanjc@...gle.com>, <stable@...r.kernel.org>
Subject: Re: [PATCH 1/2] KVM: x86: handle !lapic_in_kernel case in kvm_cpu_*_extint
On 11/27/20 12:21 PM, Paolo Bonzini wrote:
>
> Centralize handling of interrupts from the userspace APIC
> in kvm_cpu_has_extint and kvm_cpu_get_extint, since
> userspace APIC interrupts are handled more or less the
> same as ExtINTs are with split irqchip. This removes
> duplicated code from kvm_cpu_has_injectable_intr and
> kvm_cpu_has_interrupt, and makes the code more similar
> between kvm_cpu_has_{extint,interrupt} on one side
> and kvm_cpu_get_{extint,interrupt} on the other.
>
> Cc: stable@...r.kernel.org
> Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
> ---
> arch/x86/kvm/irq.c | 85 ++++++++++++++++++--------------------------
> arch/x86/kvm/lapic.c | 2 +-
> 2 files changed, 35 insertions(+), 52 deletions(-)
>
> diff --git a/arch/x86/kvm/irq.c b/arch/x86/kvm/irq.c
> index 99d118ffc67d..e2d49a506e7f 100644
> --- a/arch/x86/kvm/irq.c
> +++ b/arch/x86/kvm/irq.c
> @@ -42,15 +42,27 @@ static int pending_userspace_extint(struct kvm_vcpu *v)
> */
> static int kvm_cpu_has_extint(struct kvm_vcpu *v)
> {
> - u8 accept = kvm_apic_accept_pic_intr(v);
> + /*
> + * FIXME: interrupt.injected represents an interrupt that it's
> + * side-effects have already been applied (e.g. bit from IRR
> + * already moved to ISR). Therefore, it is incorrect to rely
> + * on interrupt.injected to know if there is a pending
> + * interrupt in the user-mode LAPIC.
> + * This leads to nVMX/nSVM not be able to distinguish
> + * if it should exit from L2 to L1 on EXTERNAL_INTERRUPT on
> + * pending interrupt or should re-inject an injected
> + * interrupt.
> + */
> + if (!lapic_in_kernel(v))
> + return v->arch.interrupt.injected;
>
> - if (accept) {
> - if (irqchip_split(v->kvm))
> - return pending_userspace_extint(v);
> - else
> - return v->kvm->arch.vpic->output;
> - } else
> + if (!kvm_apic_accept_pic_intr(v))
> return 0;
> +
> + if (irqchip_split(v->kvm))
> + return pending_userspace_extint(v);
> + else
> + return v->kvm->arch.vpic->output;
> }
>
> /*
> @@ -61,20 +73,6 @@ static int kvm_cpu_has_extint(struct kvm_vcpu *v)
> */
> int kvm_cpu_has_injectable_intr(struct kvm_vcpu *v)
> {
> - /*
> - * FIXME: interrupt.injected represents an interrupt that it's
> - * side-effects have already been applied (e.g. bit from IRR
> - * already moved to ISR). Therefore, it is incorrect to rely
> - * on interrupt.injected to know if there is a pending
> - * interrupt in the user-mode LAPIC.
> - * This leads to nVMX/nSVM not be able to distinguish
> - * if it should exit from L2 to L1 on EXTERNAL_INTERRUPT on
> - * pending interrupt or should re-inject an injected
> - * interrupt.
> - */
> - if (!lapic_in_kernel(v))
> - return v->arch.interrupt.injected;
> -
> if (kvm_cpu_has_extint(v))
> return 1;
>
> @@ -91,20 +89,6 @@ EXPORT_SYMBOL_GPL(kvm_cpu_has_injectable_intr);
> */
> int kvm_cpu_has_interrupt(struct kvm_vcpu *v)
> {
> - /*
> - * FIXME: interrupt.injected represents an interrupt that it's
> - * side-effects have already been applied (e.g. bit from IRR
> - * already moved to ISR). Therefore, it is incorrect to rely
> - * on interrupt.injected to know if there is a pending
> - * interrupt in the user-mode LAPIC.
> - * This leads to nVMX/nSVM not be able to distinguish
> - * if it should exit from L2 to L1 on EXTERNAL_INTERRUPT on
> - * pending interrupt or should re-inject an injected
> - * interrupt.
> - */
> - if (!lapic_in_kernel(v))
> - return v->arch.interrupt.injected;
> -
> if (kvm_cpu_has_extint(v))
> return 1;
>
> @@ -118,16 +102,21 @@ EXPORT_SYMBOL_GPL(kvm_cpu_has_interrupt);
> */
> static int kvm_cpu_get_extint(struct kvm_vcpu *v)
> {
> - if (kvm_cpu_has_extint(v)) {
> - if (irqchip_split(v->kvm)) {
> - int vector = v->arch.pending_external_vector;
> -
> - v->arch.pending_external_vector = -1;
> - return vector;
> - } else
> - return kvm_pic_read_irq(v->kvm); /* PIC */
> - } else
> + if (!kvm_cpu_has_extint(v)) {
> + WARN_ON(!lapic_in_kernel(v));
> return -1;
> + }
> +
> + if (!lapic_in_kernel(v))
> + return v->arch.interrupt.nr;
> +
> + if (irqchip_split(v->kvm)) {
> + int vector = v->arch.pending_external_vector;
> +
> + v->arch.pending_external_vector = -1;
> + return vector;
> + } else
> + return kvm_pic_read_irq(v->kvm); /* PIC */
> }
>
> /*
> @@ -135,13 +124,7 @@ static int kvm_cpu_get_extint(struct kvm_vcpu *v)
> */
> int kvm_cpu_get_interrupt(struct kvm_vcpu *v)
> {
> - int vector;
> -
> - if (!lapic_in_kernel(v))
> - return v->arch.interrupt.nr;
> -
> - vector = kvm_cpu_get_extint(v);
> -
> + int vector = kvm_cpu_get_extint(v);
> if (vector != -1)
> return vector; /* PIC */
>
> diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
> index 105e7859d1f2..bb5ff761d5e2 100644
> --- a/arch/x86/kvm/lapic.c
> +++ b/arch/x86/kvm/lapic.c
> @@ -2465,7 +2465,7 @@ int kvm_apic_has_interrupt(struct kvm_vcpu *vcpu)
> struct kvm_lapic *apic = vcpu->arch.apic;
> u32 ppr;
>
> - if (!kvm_apic_hw_enabled(apic))
> + if (!kvm_apic_present(vcpu))
> return -1;
>
> __apic_update_ppr(apic, &ppr);
> --
> 2.28.0
>
>
Reviewed-by: Filippo Sironi <sironi@...zon.de>
Amazon Development Center Germany GmbH
Krausenstr. 38
10117 Berlin
Geschaeftsfuehrung: Christian Schlaeger, Jonathan Weiss
Eingetragen am Amtsgericht Charlottenburg unter HRB 149173 B
Sitz: Berlin
Ust-ID: DE 289 237 879
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