[Qemu-devel] [PATCH] Fix irq route entries exceed KVM_MAX_IRQ_ROUTES
Last month, we experienced several guests crash(6cores-8cores),qemu logs
display the following messages:
qemu-system-x86_64: /build/qemu-2.1.2/kvm-all.c:976:
kvm_irqchip_commit_routes: Assertion `ret == 0' failed.
After analysis and verification, we can confirm it's irq-balance
daemon(in guest) leads to the assertion failure.So start a 8 core guest
with two disks, execute the following scripts will reproduce the BUG quickly:
vda_irq_num=25
vdb_irq_num=27
while [ 1 ]
do
for irq in {1,2,4,8,10,20,40,80}
do
echo $irq > /proc/irq/$vda_irq_num/smp_affinity
echo $irq > /proc/irq/$vdb_irq_num/smp_affinity
dd if=/dev/vda of=/dev/zero bs=4K count=100 iflag=direct
dd if=/dev/vdb of=/dev/zero bs=4K count=100 iflag=direct
done
done
QEMU setup static irq route entries in kvm_pc_setup_irq_routing(),PIC and
IOAPIC share the first 15 GSI numbers,take up 23 GSI numbers,but take up 38
irq route entries.When change irq smp_affinity in guest,a dynamic route
entry may be setup,the current logic is:if allocate GSI number succeeds,
a new route entry can be added.The available dynamic GSI numbers is
1021(KVM_MAX_IRQ_ROUTES-23),but available irq route entries is only
986(KVM_MAX_IRQ_ROUTES-38),GSI numbers greater than route entries.
irq-balance's behavior will eventually leads to total irq route entries
exceed KVM_MAX_IRQ_ROUTES,ioctl(KVM_SET_GSI_ROUTING) fail and
kvm_irqchip_commit_routes() trigger assertion failure.
This patch fix the BUG.
Signed-off-by: Wenshuang Ma
---
kvm-all.c | 11 +++
1 files changed, 11 insertions(+), 0 deletions(-)
diff --git a/kvm-all.c b/kvm-all.c
index 18cc6b4..f47e1b1 100644
--- a/kvm-all.c
+++ b/kvm-all.c
@@ -1123,6 +1123,17 @@ static int kvm_irqchip_get_virq(KVMState *s)
int i, bit;
bool retry = true;
+/*
+ * PIC and IOAPIC share the first 15 GSI numbers,available GSI
+ * numbers greater than IRQ route entries. If allocate GSI number
+ * succeeds, a new route entry can be added, so total IRQ route
+ * enties can exceed gsi_count, flush dynamic MSI entries when
+ * IRQ route entries arrive gsi_count.
+ */
+if (!s->direct_msi && s->irq_routes->nr == s->gsi_count) {
+kvm_flush_dynamic_msi_routes(s);
+}
+
again:
/* Return the lowest unused GSI in the bitmap */
for (i = 0; i < max_words; i++) {
--
1.7.1
Re: [Qemu-devel] [PATCH] Fix irq route entries exceed KVM_MAX_IRQ_ROUTES
On Dec31 03:45, kevinnma(马文霜) wrote:
> diff --git a/kvm-all.c b/kvm-all.c
> index 18cc6b4..f47e1b1 100644
> --- a/kvm-all.c
> +++ b/kvm-all.c
> @@ -1123,6 +1123,17 @@ static int kvm_irqchip_get_virq(KVMState *s)
> int i, bit;
> bool retry = true;
>
> +/*
> + * PIC and IOAPIC share the first 15 GSI numbers,available GSI
> + * numbers greater than IRQ route entries. If allocate GSI number
> + * succeeds, a new route entry can be added, so total IRQ route
> + * enties can exceed gsi_count, flush dynamic MSI entries when
> + * IRQ route entries arrive gsi_count.
> + */
> +if (!s->direct_msi && s->irq_routes->nr == s->gsi_count) {
> +kvm_flush_dynamic_msi_routes(s);
> +}
> +
> again:
> /* Return the lowest unused GSI in the bitmap */
> for (i = 0; i < max_words; i++) {
Any comments on this patch?
--
William
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Re: [Qemu-devel] [PATCH] Fix irq route entries exceed KVM_MAX_IRQ_ROUTES
On 31/12/2014 04:45, kevinnma(马文霜) wrote:
> Last month, we experienced several guests crash(6cores-8cores),qemu logs
> display the following messages:
>
> qemu-system-x86_64: /build/qemu-2.1.2/kvm-all.c:976:
> kvm_irqchip_commit_routes: Assertion `ret == 0' failed.
>
> After analysis and verification, we can confirm it's irq-balance
> daemon(in guest) leads to the assertion failure.So start a 8 core guest
> with two disks, execute the following scripts will reproduce the BUG quickly:
>
> vda_irq_num=25
> vdb_irq_num=27
> while [ 1 ]
> do
> for irq in {1,2,4,8,10,20,40,80}
> do
> echo $irq > /proc/irq/$vda_irq_num/smp_affinity
> echo $irq > /proc/irq/$vdb_irq_num/smp_affinity
> dd if=/dev/vda of=/dev/zero bs=4K count=100 iflag=direct
> dd if=/dev/vdb of=/dev/zero bs=4K count=100 iflag=direct
> done
> done
>
> QEMU setup static irq route entries in kvm_pc_setup_irq_routing(),PIC and
> IOAPIC share the first 15 GSI numbers,take up 23 GSI numbers,but take up 38
> irq route entries.When change irq smp_affinity in guest,a dynamic route
> entry may be setup,the current logic is:if allocate GSI number succeeds,
> a new route entry can be added.The available dynamic GSI numbers is
> 1021(KVM_MAX_IRQ_ROUTES-23),but available irq route entries is only
> 986(KVM_MAX_IRQ_ROUTES-38),GSI numbers greater than route entries.
> irq-balance's behavior will eventually leads to total irq route entries
> exceed KVM_MAX_IRQ_ROUTES,ioctl(KVM_SET_GSI_ROUTING) fail and
> kvm_irqchip_commit_routes() trigger assertion failure.
I have two questions:
1) why isn't the existing check in kvm_irqchip_get_virq enough to fix
the bug?
if (!s->direct_msi && retry) {
retry = false;
kvm_flush_dynamic_msi_routes(s);
goto again;
}
2) If you introduce this extra call to kvm_flush_dynamic_msi_routes,
does the existing check become obsolete?
Thanks,
Paolo
