diff options
| author | Gleb Natapov <gleb@redhat.com> | 2009-07-05 18:48:11 +0300 |
|---|---|---|
| committer | Avi Kivity <avi@redhat.com> | 2009-08-09 11:45:49 +0300 |
| commit | b4a2f5e723e4f7df46731106faf9e2405673c073 (patch) | |
| tree | 98766bcb94182957b27b9bdd371c742d927da951 /virt/kvm/ioapic.c | |
| parent | 53a27b39ff4d2492f84b1fdc2f0047175f0b0b93 (diff) | |
| download | lwn-b4a2f5e723e4f7df46731106faf9e2405673c073.tar.gz lwn-b4a2f5e723e4f7df46731106faf9e2405673c073.zip | |
KVM: Avoid redelivery of edge interrupt before next edge
The check for an edge is broken in current ioapic code. ioapic->irr is
cleared on each edge interrupt by ioapic_service() and this makes
old_irr != ioapic->irr condition in kvm_ioapic_set_irq() to be always
true. The patch fixes the code to properly recognise edge.
Some HW emulation calls set_irq() without level change. If each such
call is propagated to an OS it may confuse a device driver. This is the
case with keyboard device emulation and Windows XP x64 installer on SMP VM.
Each keystroke produce two interrupts (down/up) one interrupt is
submitted to CPU0 and another to CPU1. This confuses Windows somehow
and it ignores keystrokes.
Signed-off-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
Diffstat (limited to 'virt/kvm/ioapic.c')
| -rw-r--r-- | virt/kvm/ioapic.c | 10 |
1 files changed, 5 insertions, 5 deletions
diff --git a/virt/kvm/ioapic.c b/virt/kvm/ioapic.c index 1eddae94bab3..1150c6d5c7b8 100644 --- a/virt/kvm/ioapic.c +++ b/virt/kvm/ioapic.c @@ -95,8 +95,6 @@ static int ioapic_service(struct kvm_ioapic *ioapic, unsigned int idx) if (injected && pent->fields.trig_mode == IOAPIC_LEVEL_TRIG) pent->fields.remote_irr = 1; } - if (!pent->fields.trig_mode) - ioapic->irr &= ~(1 << idx); return injected; } @@ -136,7 +134,8 @@ static void ioapic_write_indirect(struct kvm_ioapic *ioapic, u32 val) mask_after = ioapic->redirtbl[index].fields.mask; if (mask_before != mask_after) kvm_fire_mask_notifiers(ioapic->kvm, index, mask_after); - if (ioapic->irr & (1 << index)) + if (ioapic->redirtbl[index].fields.trig_mode == IOAPIC_LEVEL_TRIG + && ioapic->irr & (1 << index)) ioapic_service(ioapic, index); break; } @@ -184,9 +183,10 @@ int kvm_ioapic_set_irq(struct kvm_ioapic *ioapic, int irq, int level) if (!level) ioapic->irr &= ~mask; else { + int edge = (entry.fields.trig_mode == IOAPIC_EDGE_TRIG); ioapic->irr |= mask; - if ((!entry.fields.trig_mode && old_irr != ioapic->irr) - || !entry.fields.remote_irr) + if ((edge && old_irr != ioapic->irr) || + (!edge && !entry.fields.remote_irr)) ret = ioapic_service(ioapic, irq); } } |