mirror of
https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git
synced 2024-10-31 08:28:13 +00:00
40da8ccd72
It turns out that we can't handle event channels *entirely* in userspace by delivering them as ExtINT, because KVM is a bit picky about when it accepts ExtINT interrupts from a legacy PIC. The in-kernel local APIC has to have LVT0 configured in APIC_MODE_EXTINT and unmasked, which isn't necessarily the case for Xen guests especially on secondary CPUs. To cope with this, add kvm_xen_get_interrupt() which checks the evtchn_pending_upcall field in the Xen vcpu_info, and delivers the Xen upcall vector (configured by KVM_XEN_ATTR_TYPE_UPCALL_VECTOR) if it's set regardless of LAPIC LVT0 configuration. This gives us the minimum support we need for completely userspace-based implementation of event channels. This does mean that vcpu_enter_guest() needs to check for the evtchn_pending_upcall flag being set, because it can't rely on someone having set KVM_REQ_EVENT unless we were to add some way for userspace to do so manually. Signed-off-by: David Woodhouse <dwmw@amazon.co.uk>
161 lines
3.6 KiB
C
161 lines
3.6 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
|
|
/*
|
|
* irq.c: API for in kernel interrupt controller
|
|
* Copyright (c) 2007, Intel Corporation.
|
|
* Copyright 2009 Red Hat, Inc. and/or its affiliates.
|
|
*
|
|
* Authors:
|
|
* Yaozu (Eddie) Dong <Eddie.dong@intel.com>
|
|
*/
|
|
|
|
#include <linux/export.h>
|
|
#include <linux/kvm_host.h>
|
|
|
|
#include "irq.h"
|
|
#include "i8254.h"
|
|
#include "x86.h"
|
|
#include "xen.h"
|
|
|
|
/*
|
|
* check if there are pending timer events
|
|
* to be processed.
|
|
*/
|
|
int kvm_cpu_has_pending_timer(struct kvm_vcpu *vcpu)
|
|
{
|
|
if (lapic_in_kernel(vcpu))
|
|
return apic_has_pending_timer(vcpu);
|
|
|
|
return 0;
|
|
}
|
|
EXPORT_SYMBOL(kvm_cpu_has_pending_timer);
|
|
|
|
/*
|
|
* check if there is a pending userspace external interrupt
|
|
*/
|
|
static int pending_userspace_extint(struct kvm_vcpu *v)
|
|
{
|
|
return v->arch.pending_external_vector != -1;
|
|
}
|
|
|
|
/*
|
|
* check if there is pending interrupt from
|
|
* non-APIC source without intack.
|
|
*/
|
|
int kvm_cpu_has_extint(struct kvm_vcpu *v)
|
|
{
|
|
/*
|
|
* FIXME: interrupt.injected represents an interrupt whose
|
|
* 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_xen_has_interrupt(v))
|
|
return 1;
|
|
|
|
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;
|
|
}
|
|
|
|
/*
|
|
* check if there is injectable interrupt:
|
|
* when virtual interrupt delivery enabled,
|
|
* interrupt from apic will handled by hardware,
|
|
* we don't need to check it here.
|
|
*/
|
|
int kvm_cpu_has_injectable_intr(struct kvm_vcpu *v)
|
|
{
|
|
if (kvm_cpu_has_extint(v))
|
|
return 1;
|
|
|
|
if (!is_guest_mode(v) && kvm_vcpu_apicv_active(v))
|
|
return 0;
|
|
|
|
return kvm_apic_has_interrupt(v) != -1; /* LAPIC */
|
|
}
|
|
EXPORT_SYMBOL_GPL(kvm_cpu_has_injectable_intr);
|
|
|
|
/*
|
|
* check if there is pending interrupt without
|
|
* intack.
|
|
*/
|
|
int kvm_cpu_has_interrupt(struct kvm_vcpu *v)
|
|
{
|
|
if (kvm_cpu_has_extint(v))
|
|
return 1;
|
|
|
|
return kvm_apic_has_interrupt(v) != -1; /* LAPIC */
|
|
}
|
|
EXPORT_SYMBOL_GPL(kvm_cpu_has_interrupt);
|
|
|
|
/*
|
|
* Read pending interrupt(from non-APIC source)
|
|
* vector and intack.
|
|
*/
|
|
static int kvm_cpu_get_extint(struct kvm_vcpu *v)
|
|
{
|
|
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 (kvm_xen_has_interrupt(v))
|
|
return v->kvm->arch.xen.upcall_vector;
|
|
|
|
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 */
|
|
}
|
|
|
|
/*
|
|
* Read pending interrupt vector and intack.
|
|
*/
|
|
int kvm_cpu_get_interrupt(struct kvm_vcpu *v)
|
|
{
|
|
int vector = kvm_cpu_get_extint(v);
|
|
if (vector != -1)
|
|
return vector; /* PIC */
|
|
|
|
return kvm_get_apic_interrupt(v); /* APIC */
|
|
}
|
|
EXPORT_SYMBOL_GPL(kvm_cpu_get_interrupt);
|
|
|
|
void kvm_inject_pending_timer_irqs(struct kvm_vcpu *vcpu)
|
|
{
|
|
if (lapic_in_kernel(vcpu))
|
|
kvm_inject_apic_timer_irqs(vcpu);
|
|
}
|
|
EXPORT_SYMBOL_GPL(kvm_inject_pending_timer_irqs);
|
|
|
|
void __kvm_migrate_timers(struct kvm_vcpu *vcpu)
|
|
{
|
|
__kvm_migrate_apic_timer(vcpu);
|
|
__kvm_migrate_pit_timer(vcpu);
|
|
static_call_cond(kvm_x86_migrate_timers)(vcpu);
|
|
}
|
|
|
|
bool kvm_arch_irqfd_allowed(struct kvm *kvm, struct kvm_irqfd *args)
|
|
{
|
|
bool resample = args->flags & KVM_IRQFD_FLAG_RESAMPLE;
|
|
|
|
return resample ? irqchip_kernel(kvm) : irqchip_in_kernel(kvm);
|
|
}
|