Avi Kivity wrote:
Xu, Anthony wrote:
In kvm-ia64, we use the same guest firmware (GFW)as in Xen, GFW uses
PRT to present PCI interrupt routing, all PCI devices'
interrupt pins
connect to IOAPIC, which doesn't match with kvm-ia64 Qemu PCI interrupt
routing.
This patch modify Qemu PCI interupt routing code to match with GFW,
Then PCI devices in qemu can work in kvm-ia64, for exmaple, NIC
Signed-off-by: Anthony Xu < anthony.xu@xxxxxxxxx >
diff --git a/virt/kvm/ioapic.c b/virt/kvm/ioapic.c
index 99a1736..80c116c 100644
--- a/virt/kvm/ioapic.c
+++ b/virt/kvm/ioapic.c
@@ -272,7 +272,11 @@ void kvm_ioapic_set_irq(struct kvm_ioapic *ioapic,
int irq, int level)
if (irq >= 0 && irq < IOAPIC_NUM_PINS) {
entry = ioapic->redirtbl[irq];
- level ^= entry.fields.polarity;
+// polarity of all devices in qemu is active high
+// regardless of ioapic setting
+
+// level ^= entry.fields.polarity;
+
There are two errors in this patch:
- kvm is not there just for qemu; it should be possible to use kvm
with some other userspace, which would assume that kvm correctly
emulates ioapic polarity
- you are modifying shared code and so affect x86 as well
Apparently this is broken on x86 too. I was just trying this patch with
Mac OS X as target and magically the in-kernel APIC starts working, so I
guess something is going wrong already here.
Btw, according to the ACPI tables, all PCI interrupts are currently
defined Active-Low.
Alex
I suggest modifying the firmware to report the interrupts as active
high. Since Xen does not emulate polarity, the change will not affect
it and the firmware can continue to be shared. I'd also recommend
fixing Xen to emulate the polarity correctly, if possible.
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