qemu-kvm/SOURCES/kvm-kvm-error-out-of-kvm_irqchip_add_msi_route-in-case-o.patch

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2024-06-20 08:38:02 +00:00
From 8a8fa4ab4dc05502550ca207926cd0c93a3341ea Mon Sep 17 00:00:00 2001
From: Igor Mammedov <imammedo@redhat.com>
Date: Mon, 8 Apr 2024 12:43:49 +0200
Subject: [PATCH] kvm: error out of kvm_irqchip_add_msi_route() in case of full
route table
RH-Author: Igor Mammedov <imammedo@redhat.com>
RH-MergeRequest: 374: kvm: error out of kvm_irqchip_add_msi_route() in case of full route table
RH-Jira: RHEL-32990
RH-Acked-by: Ani Sinha <anisinha@redhat.com>
RH-Acked-by: Miroslav Rezanina <mrezanin@redhat.com>
RH-Commit: [1/1] df31f2d0cafe10a1ac22a2bebb85dc17c1e891e0
RH-Jira: RHEL-32990
subj is calling kvm_add_routing_entry() which simply extends
KVMState::irq_routes::entries[]
but doesn't check if number of routes goes beyond limit the kernel
is willing to accept. Which later leads toi the assert
qemu-kvm: ../accel/kvm/kvm-all.c:1833: kvm_irqchip_commit_routes: Assertion `ret == 0' failed
typically it happens during guest boot for large enough guest
Reproduced with:
./qemu --enable-kvm -m 8G -smp 64 -machine pc \
`for b in {1..2}; do echo -n "-device pci-bridge,id=pci$b,chassis_nr=$b ";
for i in {0..31}; do touch /tmp/vblk$b$i;
echo -n "-drive file=/tmp/vblk$b$i,if=none,id=drive$b$i,format=raw
-device virtio-blk-pci,drive=drive$b$i,bus=pci$b ";
done; done`
While crash at boot time is bad, the same might happen at hotplug time
which is unacceptable.
So instead calling kvm_add_routing_entry() unconditionally, check first
that number of routes won't exceed KVM_CAP_IRQ_ROUTING. This way virtio
device insteads killin qemu, will gracefully fail to initialize device
as expected with following warnings on console:
virtio-blk failed to set guest notifier (-28), ensure -accel kvm is set.
virtio_bus_start_ioeventfd: failed. Fallback to userspace (slower).
Signed-off-by: Igor Mammedov <imammedo@redhat.com>
---
accel/kvm/kvm-all.c | 15 ++++++++++-----
1 file changed, 10 insertions(+), 5 deletions(-)
diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c
index e39a810a4e..f1a4564cbd 100644
--- a/accel/kvm/kvm-all.c
+++ b/accel/kvm/kvm-all.c
@@ -2000,12 +2000,17 @@ int kvm_irqchip_add_msi_route(KVMRouteChange *c, int vector, PCIDevice *dev)
return -EINVAL;
}
- trace_kvm_irqchip_add_msi_route(dev ? dev->name : (char *)"N/A",
- vector, virq);
+ if (s->irq_routes->nr < s->gsi_count) {
+ trace_kvm_irqchip_add_msi_route(dev ? dev->name : (char *)"N/A",
+ vector, virq);
- kvm_add_routing_entry(s, &kroute);
- kvm_arch_add_msi_route_post(&kroute, vector, dev);
- c->changes++;
+ kvm_add_routing_entry(s, &kroute);
+ kvm_arch_add_msi_route_post(&kroute, vector, dev);
+ c->changes++;
+ } else {
+ kvm_irqchip_release_virq(s, virq);
+ return -ENOSPC;
+ }
return virq;
}
--
2.39.3