[PATCH 1/1] KVM: ioapic: Record edge-triggered interrupts delivery status.

Wincy Van
2014-12-24T03:14:29Z

This patch fixes the bug discussed in
https://www.mail-archive.com/kvm@vger.kernel.org/msg109813.html

This patch uses a new field named irr_delivered to record the
delivery status of edge-triggered interrupts, and clears the
delivered interrupts in kvm_get_ioapic. So it has the same effect
of commit 0bc830b05c667218d703f2026ec866c49df974fc
("KVM: ioapic: clear IRR for edge-triggered interrupts at delivery")
while avoids the bug of Windows guests.

Signed-off-by: Wincy Van <fanwenyi0529@gmail.com>
---
arch/x86/kvm/ioapic.c | 7 ++++++-
arch/x86/kvm/ioapic.h | 1 +
2 files changed, 7 insertions(+), 1 deletions(-)

diff --git a/arch/x86/kvm/ioapic.c b/arch/x86/kvm/ioapic.c
index b1947e0..a2e9d96 100644
--- a/arch/x86/kvm/ioapic.c
+++ b/arch/x86/kvm/ioapic.c
@@ -206,6 +206,8 @@ static int ioapic_set_irq(struct kvm_ioapic *ioapic, unsigned int irq,

old_irr = ioapic->irr;
ioapic->irr |= mask;
+ if (edge)
+ ioapic->irr_delivered &= ~mask;
if ((edge && old_irr == ioapic->irr) ||
(!edge && entry.fields.remote_irr)) {
ret = 0;
@@ -349,7 +351,7 @@ static int ioapic_service(struct kvm_ioapic *ioapic, int irq, bool line_status)
irqe.shorthand = 0;

if (irqe.trig_mode == IOAPIC_EDGE_TRIG)
- ioapic->irr &= ~(1 << irq);
+ ioapic->irr_delivered |= 1 << irq;

if (irq == RTC_GSI && line_status) {
/*
@@ -597,6 +599,7 @@ static void kvm_ioapic_reset(struct kvm_ioapic *ioapic)
ioapic->base_address = IOAPIC_DEFAULT_BASE_ADDRESS;
ioapic->ioregsel = 0;
ioapic->irr = 0;
+ ioapic->irr_delivered = 0;
ioapic->id = 0;
memset(ioapic->irq_eoi, 0x00, IOAPIC_NUM_PINS);
rtc_irq_eoi_tracking_reset(ioapic);
@@ -654,6 +657,7 @@ int kvm_get_ioapic(struct kvm *kvm, struct kvm_ioapic_state *state)

spin_lock(&ioapic->lock);
memcpy(state, ioapic, sizeof(struct kvm_ioapic_state));
+ state->irr &= ~ioapic->irr_delivered;
spin_unlock(&ioapic->lock);
return 0;
}
@@ -667,6 +671,7 @@ int kvm_set_ioapic(struct kvm *kvm, struct kvm_ioapic_state *state)
spin_lock(&ioapic->lock);
memcpy(ioapic, state, sizeof(struct kvm_ioapic_state));
ioapic->irr = 0;
+ ioapic->irr_delivered = 0;
update_handled_vectors(ioapic);
kvm_vcpu_request_scan_ioapic(kvm);
kvm_ioapic_inject_all(ioapic, state->irr);
diff --git a/arch/x86/kvm/ioapic.h b/arch/x86/kvm/ioapic.h
index 3c91955..a5cdfc0 100644
--- a/arch/x86/kvm/ioapic.h
+++ b/arch/x86/kvm/ioapic.h
@@ -77,6 +77,7 @@ struct kvm_ioapic {
struct rtc_status rtc_status;
struct delayed_work eoi_inject;
u32 irq_eoi[IOAPIC_NUM_PINS];
+ u32 irr_delivered;
};

#ifdef DEBUG
--
1.7.1