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[Qemu-devel] [PULL 08/19] Fix irq route entries exceeding KVM_MAX_IRQ_RO
From: |
Paolo Bonzini |
Subject: |
[Qemu-devel] [PULL 08/19] Fix irq route entries exceeding KVM_MAX_IRQ_ROUTES |
Date: |
Mon, 6 Jul 2015 14:34:57 +0200 |
From: 马文霜 <address@hidden>
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. Start a 8 core guest with
two disks, execute the following scripts will reproduce the BUG quickly:
irq_affinity.sh
========================================================================
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 <address@hidden>
Cc: address@hidden
Signed-off-by: Paolo Bonzini <address@hidden>
---
kvm-all.c | 17 ++++++++++-------
1 file changed, 10 insertions(+), 7 deletions(-)
diff --git a/kvm-all.c b/kvm-all.c
index 53e01d4..e98b08d 100644
--- a/kvm-all.c
+++ b/kvm-all.c
@@ -1099,9 +1099,17 @@ static int kvm_irqchip_get_virq(KVMState *s)
uint32_t *word = s->used_gsi_bitmap;
int max_words = ALIGN(s->gsi_count, 32) / 32;
int i, zeroes;
- bool retry = true;
-again:
+ /*
+ * PIC and IOAPIC share the first 16 GSI numbers, thus the available
+ * GSI numbers are more than the number of IRQ route. Allocating a GSI
+ * number can succeed even though a new route entry cannot be added.
+ * When this happens, flush dynamic MSI entries to free IRQ route entries.
+ */
+ if (!s->direct_msi && s->irq_routes->nr == s->gsi_count) {
+ kvm_flush_dynamic_msi_routes(s);
+ }
+
/* Return the lowest unused GSI in the bitmap */
for (i = 0; i < max_words; i++) {
zeroes = ctz32(~word[i]);
@@ -1111,11 +1119,6 @@ again:
return zeroes + i * 32;
}
- if (!s->direct_msi && retry) {
- retry = false;
- kvm_flush_dynamic_msi_routes(s);
- goto again;
- }
return -ENOSPC;
}
--
2.4.3
- [Qemu-devel] [PULL 00/19] Multithread, multiarch, multicompiler, multi^WKVM changes for 2015-07-06, Paolo Bonzini, 2015/07/06
- [Qemu-devel] [PULL 02/19] cutils: allow compilation with icc, Paolo Bonzini, 2015/07/06
- [Qemu-devel] [PULL 01/19] qemu-common: add VEC_OR macro, Paolo Bonzini, 2015/07/06
- [Qemu-devel] [PULL 04/19] cpu-defs: Move CPU_TEMP_BUF_NLONGS to tcg, Paolo Bonzini, 2015/07/06
- [Qemu-devel] [PULL 05/19] include/exec: Move standard exceptions to cpu-all.h, Paolo Bonzini, 2015/07/06
- [Qemu-devel] [PULL 07/19] cpu-defs: Move out TB_JMP defines, Paolo Bonzini, 2015/07/06
- [Qemu-devel] [PULL 03/19] memory_mapping: Rework cpu related includes, Paolo Bonzini, 2015/07/06
- [Qemu-devel] [PULL 06/19] include/exec: Move tb hash functions out, Paolo Bonzini, 2015/07/06
- [Qemu-devel] [PULL 08/19] Fix irq route entries exceeding KVM_MAX_IRQ_ROUTES,
Paolo Bonzini <=
- [Qemu-devel] [PULL 09/19] main-loop: use qemu_mutex_lock_iothread consistently, Paolo Bonzini, 2015/07/06
- [Qemu-devel] [PULL 11/19] memory: Add global-locking property to memory regions, Paolo Bonzini, 2015/07/06
- [Qemu-devel] [PULL 12/19] exec: pull qemu_flush_coalesced_mmio_buffer() into address_space_rw/ld*/st*, Paolo Bonzini, 2015/07/06
- [Qemu-devel] [PULL 13/19] memory: let address_space_rw/ld*/st* run outside the BQL, Paolo Bonzini, 2015/07/06
- [Qemu-devel] [PULL 10/19] main-loop: introduce qemu_mutex_iothread_locked, Paolo Bonzini, 2015/07/06
- [Qemu-devel] [PULL 15/19] kvm: Switch to unlocked PIO, Paolo Bonzini, 2015/07/06
- [Qemu-devel] [PULL 14/19] kvm: First step to push iothread lock out of inner run loop, Paolo Bonzini, 2015/07/06
- [Qemu-devel] [PULL 16/19] acpi: mark PMTIMER as unlocked, Paolo Bonzini, 2015/07/06
- [Qemu-devel] [PULL 19/19] exec: skip MMIO regions correctly in cpu_physical_memory_write_rom_internal, Paolo Bonzini, 2015/07/06
- [Qemu-devel] [PULL 18/19] Stop including qemu-common.h in memory.h, Paolo Bonzini, 2015/07/06