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Re: [PATCH v2 1/1] virtio-pci: Fix the crash that the vector was used af
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From: |
Jason Wang |
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Subject: |
Re: [PATCH v2 1/1] virtio-pci: Fix the crash that the vector was used after released. |
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Date: |
Wed, 10 Apr 2024 16:28:44 +0800 |
Offline:
On Wed, Apr 10, 2024 at 2:28 PM Cindy Lu <lulu@redhat.com> wrote:
>
> On Wed, Apr 10, 2024 at 1:36 PM Jason Wang <jasowang@redhat.com> wrote:
> >
> > On Wed, Apr 10, 2024 at 1:29 PM Cindy Lu <lulu@redhat.com> wrote:
> > >
> > > When the guest triggers vhost_stop and then virtio_reset, the vector will
> > > the
> > > IRQFD for this vector will be released and change to VIRTIO_NO_VECTOR.
> > > After that, the guest called vhost_net_start, (at this time, the
> > > configure
> > > vector is still VIRTIO_NO_VECTOR), vector 0 still was not "init".
> > > The guest system continued to boot, set the vector back to 0, and then
> > > met the crash.
> > >
> > > To fix this, we need to call the function
> > > "kvm_virtio_pci_vector_use_one()"
> > > when the vector changes back from VIRTIO_NO_VECTOR
> > >
> > > (gdb) bt
> > > 0 __pthread_kill_implementation (threadid=<optimized out>,
> > > signo=signo@entry=6, no_tid=no_tid@entry=0)
> > > at pthread_kill.c:44
> > > 1 0x00007fc87148ec53 in __pthread_kill_internal (signo=6,
> > > threadid=<optimized out>) at pthread_kill.c:78
> > > 2 0x00007fc87143e956 in __GI_raise (sig=sig@entry=6) at
> > > ../sysdeps/posix/raise.c:26
> > > 3 0x00007fc8714287f4 in __GI_abort () at abort.c:79
> > > 4 0x00007fc87142871b in __assert_fail_base
> > > (fmt=0x7fc8715bbde0 "%s%s%s:%u: %s%sAssertion `%s' failed.\n%n",
> > > assertion=0x5606413efd53 "ret == 0", file=0x5606413ef87d
> > > "../accel/kvm/kvm-all.c", line=1837, function=<optimized out>) at
> > > assert.c:92
> > > 5 0x00007fc871437536 in __GI___assert_fail
> > > (assertion=0x5606413efd53 "ret == 0", file=0x5606413ef87d
> > > "../accel/kvm/kvm-all.c", line=1837, function=0x5606413f06f0
> > > <__PRETTY_FUNCTION__.19> "kvm_irqchip_commit_routes") at assert.c:101
> > > 6 0x0000560640f884b5 in kvm_irqchip_commit_routes (s=0x560642cae1f0) at
> > > ../accel/kvm/kvm-all.c:1837
> > > 7 0x0000560640c98f8e in virtio_pci_one_vector_unmask
> > > (proxy=0x560643c65f00, queue_no=4294967295, vector=0, msg=...,
> > > n=0x560643c6e4c8)
> > > at ../hw/virtio/virtio-pci.c:1005
> > > 8 0x0000560640c99201 in virtio_pci_vector_unmask (dev=0x560643c65f00,
> > > vector=0, msg=...)
> > > at ../hw/virtio/virtio-pci.c:1070
> > > 9 0x0000560640bc402e in msix_fire_vector_notifier (dev=0x560643c65f00,
> > > vector=0, is_masked=false)
> > > at ../hw/pci/msix.c:120
> > > 10 0x0000560640bc40f1 in msix_handle_mask_update (dev=0x560643c65f00,
> > > vector=0, was_masked=true)
> > > at ../hw/pci/msix.c:140
> > > 11 0x0000560640bc4503 in msix_table_mmio_write (opaque=0x560643c65f00,
> > > addr=12, val=0, size=4)
> > > at ../hw/pci/msix.c:231
> > > 12 0x0000560640f26d83 in memory_region_write_accessor
> > > (mr=0x560643c66540, addr=12, value=0x7fc86b7bc628, size=4, shift=0,
> > > mask=4294967295, attrs=...)
> > > at ../system/memory.c:497
> > > 13 0x0000560640f270a6 in access_with_adjusted_size
> > >
> > > (addr=12, value=0x7fc86b7bc628, size=4, access_size_min=1,
> > > access_size_max=4, access_fn=0x560640f26c8d
> > > <memory_region_write_accessor>, mr=0x560643c66540, attrs=...) at
> > > ../system/memory.c:573
> > > 14 0x0000560640f2a2b5 in memory_region_dispatch_write (mr=0x560643c66540,
> > > addr=12, data=0, op=MO_32, attrs=...)
> > > at ../system/memory.c:1521
> > > 15 0x0000560640f37bac in flatview_write_continue
> > > (fv=0x7fc65805e0b0, addr=4273803276, attrs=..., ptr=0x7fc871e9c028,
> > > len=4, addr1=12, l=4, mr=0x560643c66540)
> > > at ../system/physmem.c:2714
> > > 16 0x0000560640f37d0f in flatview_write
> > > (fv=0x7fc65805e0b0, addr=4273803276, attrs=..., buf=0x7fc871e9c028,
> > > len=4) at ../system/physmem.c:2756
> > > 17 0x0000560640f380bf in address_space_write
> > > (as=0x560642161ae0 <address_space_memory>, addr=4273803276,
> > > attrs=..., buf=0x7fc871e9c028, len=4)
> > > at ../system/physmem.c:2863
> > > 18 0x0000560640f3812c in address_space_rw
> > > (as=0x560642161ae0 <address_space_memory>, addr=4273803276,
> > > attrs=..., buf=0x7fc871e9c028, len=4, is_write=true) at
> > > ../system/physmem.c:2873
> > > --Type <RET> for more, q to quit, c to continue without paging--
> > > 19 0x0000560640f8aa55 in kvm_cpu_exec (cpu=0x560642f205e0) at
> > > ../accel/kvm/kvm-all.c:2915
> > > 20 0x0000560640f8d731 in kvm_vcpu_thread_fn (arg=0x560642f205e0) at
> > > ../accel/kvm/kvm-accel-ops.c:51
> > > 21 0x00005606411949f4 in qemu_thread_start (args=0x560642f292b0) at
> > > ../util/qemu-thread-posix.c:541
> > > 22 0x00007fc87148cdcd in start_thread (arg=<optimized out>) at
> > > pthread_create.c:442
> > > 23 0x00007fc871512630 in clone3 () at
> > > ../sysdeps/unix/sysv/linux/x86_64/clone3.S:81
> > > (gdb)
> > > Signed-off-by: Cindy Lu <lulu@redhat.com>
> > > ---
> > > hw/virtio/virtio-pci.c | 35 +++++++++++++++++++++++++++++++++++
> > > 1 file changed, 35 insertions(+)
> > >
> > > diff --git a/hw/virtio/virtio-pci.c b/hw/virtio/virtio-pci.c
> > > index 1a7039fb0c..344f4fb844 100644
> > > --- a/hw/virtio/virtio-pci.c
> > > +++ b/hw/virtio/virtio-pci.c
> > > @@ -880,6 +880,7 @@ static int
> > > kvm_virtio_pci_vector_use_one(VirtIOPCIProxy *proxy, int queue_no)
> > > int ret;
> > > EventNotifier *n;
> > > PCIDevice *dev = &proxy->pci_dev;
> > > + VirtIOIRQFD *irqfd;
> > > VirtIODevice *vdev = virtio_bus_get_device(&proxy->bus);
> > > VirtioDeviceClass *k = VIRTIO_DEVICE_GET_CLASS(vdev);
> > >
> > > @@ -890,10 +891,19 @@ static int
> > > kvm_virtio_pci_vector_use_one(VirtIOPCIProxy *proxy, int queue_no)
> > > if (vector >= msix_nr_vectors_allocated(dev)) {
> > > return 0;
> > > }
> > > + /*
> > > + * if the irqfd still in use, means the irqfd was not
> > > + * release before and don't need to set up
> > > + */
> > > + irqfd = &proxy->vector_irqfd[vector];
> > > + if (irqfd->users != 0) {
> > > + return 0;
> > > + }
> >
> > kvm_virtio_pci_vq_vector_use() has a similar check and it looks to me
> > kvm_virtio_pci_irqfd_use() can work when users > 0.
> >
> > Any reason we need an extra check here?
> >
> > Thanks
> >
> in function kvm_virtio_pci_vq_vector_use(). this will not init the
> irqfd, but there will be an
> irqfd->users++;
This needs to be ref-counted correctly otherwise we may hit issues elsewhere.
More below.
> so the user number will be wrong in this irqfd, There will be check
> for this in other function
> sunch like kvm_virtio_pci_vq_vector_release()
> {
> VirtIOIRQFD *irqfd = &proxy->vector_irqfd[vector];
>
> if (--irqfd->users == 0) {
> kvm_irqchip_release_virq(kvm_state, irqfd->virq);
> }
> }
> this will cause problem
> thanks
> Cindy
>
>
> > > ret = kvm_virtio_pci_vq_vector_use(proxy, vector);
> > > if (ret < 0) {
> > > goto undo;
> > > }
> > > +
> > > /*
> > > * If guest supports masking, set up irqfd now.
> > > * Otherwise, delay until unmasked in the frontend.
> > > @@ -1570,7 +1580,19 @@ static void virtio_pci_common_write(void *opaque,
> > > hwaddr addr,
> > > } else {
> > > val = VIRTIO_NO_VECTOR;
> > > }
> > > + vector = vdev->config_vector;
> > > vdev->config_vector = val;
> > > + /*
> > > + *if the val was change from NO_VECTOR, this means the vector
> > > maybe
> > > + * release before, need to check if need to set up
> > > + */
> > > + if ((val != VIRTIO_NO_VECTOR) && (vector == VIRTIO_NO_VECTOR) &&
> > > + (vdev->status & VIRTIO_CONFIG_S_DRIVER_OK)) {
> > > + /* check if use irqfd*/
> > > + if (msix_enabled(&proxy->pci_dev) &&
> > > kvm_msi_via_irqfd_enabled()) {
> > > + kvm_virtio_pci_vector_use_one(proxy,
> > > VIRTIO_CONFIG_IRQ_IDX);
> > > + }
> > > + }
> > > break;
> > > case VIRTIO_PCI_COMMON_STATUS:
> > > if (!(val & VIRTIO_CONFIG_S_DRIVER_OK)) {
> > > @@ -1611,6 +1633,19 @@ static void virtio_pci_common_write(void *opaque,
> > > hwaddr addr,
> > > val = VIRTIO_NO_VECTOR;
> > > }
> > > virtio_queue_set_vector(vdev, vdev->queue_sel, val);
> > > +
> > > + /*
> > > + *if the val was change from NO_VECTOR, this means the vector
> > > maybe
> > > + * release before, need to check if need to set up
> > > + */
> > > +
> > > + if ((val != VIRTIO_NO_VECTOR) && (vector == VIRTIO_NO_VECTOR) &&
> > > + (vdev->status & VIRTIO_CONFIG_S_DRIVER_OK)) {
> > > + /* check if use irqfd*/
> > > + if (msix_enabled(&proxy->pci_dev) &&
> > > kvm_msi_via_irqfd_enabled()) {
> > > + kvm_virtio_pci_vector_use_one(proxy, vdev->queue_sel);
> > > + }
> > > + }
Need to deal with from X to Y, not only NO_VECTOR to x or x to NO_VECTOR.
So the logic might be
if (vdev->status &VIRTIO_CONFIG_S_DRIVER_OK) {
if (vector != NO_VECTOR)
vector_release_one()
if (val != NO_VECTOR)
vector_use_one()
}
?
Thanks
> > > break;
> > > case VIRTIO_PCI_COMMON_Q_ENABLE:
> > > if (val == 1) {
> > > --
> > > 2.43.0
> > >
> >
>