From 361ed00eefd4471d7aa709e0009c44581b8b6451 Mon Sep 17 00:00:00 2001 From: Xiubo Li Date: Wed, 15 Jun 2016 18:00:33 +0800 Subject: [PATCH] kvm: Fix irq route entries exceeding KVM_MAX_IRQ_ROUTES commit caf1ff26e1aa178133df68ac3d40815fed2187d9 upstream. These days, we experienced one guest crash with 8 cores and 3 disks, with qemu error logs as bellow: qemu-system-x86_64: /build/qemu-2.0.0/kvm-all.c:984: kvm_irqchip_commit_routes: Assertion `ret == 0' failed. And then we found one patch(bdf026317d) in qemu tree, which said could fix this bug. Execute the following script 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 ======================================================================== The following qemu log is added in the qemu code and is displayed when this bug reproduced: kvm_irqchip_commit_routes: max gsi: 1008, nr_allocated_irq_routes: 1024, irq_routes->nr: 1024, gsi_count: 1024. That's to say when irq_routes->nr == 1024, there are 1024 routing entries, but in the kernel code when routes->nr >= 1024, will just return -EINVAL; The nr is the number of the routing entries which is in of [1 ~ KVM_MAX_IRQ_ROUTES], not the index in [0 ~ KVM_MAX_IRQ_ROUTES - 1]. This patch fix the BUG above. Signed-off-by: Xiubo Li Signed-off-by: Wei Tang Signed-off-by: Zhang Zhuoyu Signed-off-by: Paolo Bonzini [bwh: Backported to 3.2: adjust filename] Signed-off-by: Ben Hutchings --- virt/kvm/assigned-dev.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/virt/kvm/assigned-dev.c b/virt/kvm/assigned-dev.c index 758e3b36d4cf..e9f3b3ab4803 100644 --- a/virt/kvm/assigned-dev.c +++ b/virt/kvm/assigned-dev.c @@ -826,7 +826,7 @@ long kvm_vm_ioctl_assigned_device(struct kvm *kvm, unsigned ioctl, if (copy_from_user(&routing, argp, sizeof(routing))) goto out; r = -EINVAL; - if (routing.nr >= KVM_MAX_IRQ_ROUTES) + if (routing.nr > KVM_MAX_IRQ_ROUTES) goto out; if (routing.flags) goto out; -- 2.39.2