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https://github.com/torvalds/linux
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1c1a9ce973
In order to enable userspace PIC support, the userspace PIC needs to be able to inject local interrupts even when the APICs are in the kernel. KVM_INTERRUPT now supports sending local interrupts to an APIC when APICs are in the kernel. The ready_for_interrupt_request flag is now only set when the CPU/APIC will immediately accept and inject an interrupt (i.e. APIC has not masked the PIC). When the PIC wishes to initiate an INTA cycle with, say, CPU0, it kicks CPU0 out of the guest, and renedezvous with CPU0 once it arrives in userspace. When the CPU/APIC unmasks the PIC, a KVM_EXIT_IRQ_WINDOW_OPEN is triggered, so that userspace has a chance to inject a PIC interrupt if it had been pending. Overall, this design can lead to a small number of spurious userspace renedezvous. In particular, whenever the PIC transistions from low to high while it is masked and whenever the PIC becomes unmasked while it is low. Note: this does not buffer more than one local interrupt in the kernel, so the VMM needs to enter the guest in order to complete interrupt injection before injecting an additional interrupt. Compiles for x86. Can pass the KVM Unit Tests. Signed-off-by: Steve Rutherford <srutherford@google.com> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
150 lines
3.4 KiB
C
150 lines
3.4 KiB
C
/*
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* irq.c: API for in kernel interrupt controller
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* Copyright (c) 2007, Intel Corporation.
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* Copyright 2009 Red Hat, Inc. and/or its affiliates.
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms and conditions of the GNU General Public License,
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* version 2, as published by the Free Software Foundation.
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*
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* This program is distributed in the hope it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
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* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
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* more details.
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*
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* You should have received a copy of the GNU General Public License along with
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* this program; if not, write to the Free Software Foundation, Inc., 59 Temple
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* Place - Suite 330, Boston, MA 02111-1307 USA.
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* Authors:
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* Yaozu (Eddie) Dong <Eddie.dong@intel.com>
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*
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*/
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#include <linux/module.h>
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#include <linux/kvm_host.h>
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#include "irq.h"
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#include "i8254.h"
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#include "x86.h"
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/*
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* check if there are pending timer events
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* to be processed.
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*/
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int kvm_cpu_has_pending_timer(struct kvm_vcpu *vcpu)
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{
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return apic_has_pending_timer(vcpu);
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}
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EXPORT_SYMBOL(kvm_cpu_has_pending_timer);
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/*
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* check if there is a pending userspace external interrupt
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*/
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static int pending_userspace_extint(struct kvm_vcpu *v)
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{
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return v->arch.pending_external_vector != -1;
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}
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/*
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* check if there is pending interrupt from
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* non-APIC source without intack.
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*/
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static int kvm_cpu_has_extint(struct kvm_vcpu *v)
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{
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u8 accept = kvm_apic_accept_pic_intr(v);
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if (accept) {
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if (irqchip_split(v->kvm))
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return pending_userspace_extint(v);
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else
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return pic_irqchip(v->kvm)->output;
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} else
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return 0;
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}
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/*
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* check if there is injectable interrupt:
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* when virtual interrupt delivery enabled,
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* interrupt from apic will handled by hardware,
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* we don't need to check it here.
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*/
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int kvm_cpu_has_injectable_intr(struct kvm_vcpu *v)
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{
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if (!lapic_in_kernel(v))
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return v->arch.interrupt.pending;
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if (kvm_cpu_has_extint(v))
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return 1;
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if (kvm_vcpu_apic_vid_enabled(v))
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return 0;
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return kvm_apic_has_interrupt(v) != -1; /* LAPIC */
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}
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/*
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* check if there is pending interrupt without
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* intack.
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*/
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int kvm_cpu_has_interrupt(struct kvm_vcpu *v)
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{
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if (!lapic_in_kernel(v))
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return v->arch.interrupt.pending;
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if (kvm_cpu_has_extint(v))
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return 1;
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return kvm_apic_has_interrupt(v) != -1; /* LAPIC */
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}
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EXPORT_SYMBOL_GPL(kvm_cpu_has_interrupt);
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/*
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* Read pending interrupt(from non-APIC source)
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* vector and intack.
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*/
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static int kvm_cpu_get_extint(struct kvm_vcpu *v)
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{
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if (kvm_cpu_has_extint(v)) {
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if (irqchip_split(v->kvm)) {
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int vector = v->arch.pending_external_vector;
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v->arch.pending_external_vector = -1;
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return vector;
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} else
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return kvm_pic_read_irq(v->kvm); /* PIC */
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} else
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return -1;
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}
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/*
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* Read pending interrupt vector and intack.
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*/
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int kvm_cpu_get_interrupt(struct kvm_vcpu *v)
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{
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int vector;
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if (!lapic_in_kernel(v))
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return v->arch.interrupt.nr;
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vector = kvm_cpu_get_extint(v);
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if (vector != -1)
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return vector; /* PIC */
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return kvm_get_apic_interrupt(v); /* APIC */
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}
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EXPORT_SYMBOL_GPL(kvm_cpu_get_interrupt);
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void kvm_inject_pending_timer_irqs(struct kvm_vcpu *vcpu)
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{
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kvm_inject_apic_timer_irqs(vcpu);
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/* TODO: PIT, RTC etc. */
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}
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EXPORT_SYMBOL_GPL(kvm_inject_pending_timer_irqs);
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void __kvm_migrate_timers(struct kvm_vcpu *vcpu)
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{
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__kvm_migrate_apic_timer(vcpu);
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__kvm_migrate_pit_timer(vcpu);
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}
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