Runs into core dump on arm64 and the backtrace extracted from the
core dump is shown as below. It's caused by accessing uninitialized
@kvm_state in kvm_flush_coalesced_mmio_buffer() due to commit 176d073029
("hw/arm/virt: Use machine_memory_devices_init()"), where the machine's
memory region is added earlier than before.
main
qemu_init
configure_accelerators
qemu_opts_foreach
do_configure_accelerator
accel_init_machine
kvm_init
virt_kvm_type
virt_set_memmap
machine_memory_devices_init
memory_region_add_subregion
memory_region_add_subregion_common
memory_region_update_container_subregions
memory_region_transaction_begin
qemu_flush_coalesced_mmio_buffer
kvm_flush_coalesced_mmio_buffer
Fix it by bailing early in kvm_flush_coalesced_mmio_buffer() on the
uninitialized @kvm_state. With this applied, no crash is observed on
arm64.
Fixes: 176d073029 ("hw/arm/virt: Use machine_memory_devices_init()")
Signed-off-by: Gavin Shan <gshan@redhat.com>
---
v2: Bail early in kvm_flush_coalesced_mmio_buffer() on the uninitialized
@kvm_state and improved changelog (David/Peter)
---
accel/kvm/kvm-all.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c
index 373d876c05..7b3da8dc3a 100644
--- a/accel/kvm/kvm-all.c
+++ b/accel/kvm/kvm-all.c
@@ -2812,7 +2812,7 @@ void kvm_flush_coalesced_mmio_buffer(void)
{
KVMState *s = kvm_state;
- if (s->coalesced_flush_in_progress) {
+ if (!s || s->coalesced_flush_in_progress) {
return;
}
--
2.41.0
On 31/7/23 14:59, Gavin Shan wrote: > Runs into core dump on arm64 and the backtrace extracted from the > core dump is shown as below. It's caused by accessing uninitialized > @kvm_state in kvm_flush_coalesced_mmio_buffer() due to commit 176d073029 > ("hw/arm/virt: Use machine_memory_devices_init()"), where the machine's > memory region is added earlier than before. > > main > qemu_init > configure_accelerators > qemu_opts_foreach > do_configure_accelerator > accel_init_machine > kvm_init > virt_kvm_type > virt_set_memmap > machine_memory_devices_init > memory_region_add_subregion > memory_region_add_subregion_common > memory_region_update_container_subregions > memory_region_transaction_begin > qemu_flush_coalesced_mmio_buffer > kvm_flush_coalesced_mmio_buffer > > Fix it by bailing early in kvm_flush_coalesced_mmio_buffer() on the > uninitialized @kvm_state. With this applied, no crash is observed on > arm64. > > Fixes: 176d073029 ("hw/arm/virt: Use machine_memory_devices_init()") > Signed-off-by: Gavin Shan <gshan@redhat.com> > --- > v2: Bail early in kvm_flush_coalesced_mmio_buffer() on the uninitialized > @kvm_state and improved changelog (David/Peter) > --- > accel/kvm/kvm-all.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
On 31.07.23 14:59, Gavin Shan wrote: > Runs into core dump on arm64 and the backtrace extracted from the > core dump is shown as below. It's caused by accessing uninitialized > @kvm_state in kvm_flush_coalesced_mmio_buffer() due to commit 176d073029 > ("hw/arm/virt: Use machine_memory_devices_init()"), where the machine's > memory region is added earlier than before. > > main > qemu_init > configure_accelerators > qemu_opts_foreach > do_configure_accelerator > accel_init_machine > kvm_init > virt_kvm_type > virt_set_memmap > machine_memory_devices_init > memory_region_add_subregion > memory_region_add_subregion_common > memory_region_update_container_subregions > memory_region_transaction_begin > qemu_flush_coalesced_mmio_buffer > kvm_flush_coalesced_mmio_buffer > > Fix it by bailing early in kvm_flush_coalesced_mmio_buffer() on the > uninitialized @kvm_state. With this applied, no crash is observed on > arm64. > > Fixes: 176d073029 ("hw/arm/virt: Use machine_memory_devices_init()") > Signed-off-by: Gavin Shan <gshan@redhat.com> > --- > v2: Bail early in kvm_flush_coalesced_mmio_buffer() on the uninitialized > @kvm_state and improved changelog (David/Peter) > --- > accel/kvm/kvm-all.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c > index 373d876c05..7b3da8dc3a 100644 > --- a/accel/kvm/kvm-all.c > +++ b/accel/kvm/kvm-all.c > @@ -2812,7 +2812,7 @@ void kvm_flush_coalesced_mmio_buffer(void) > { > KVMState *s = kvm_state; > > - if (s->coalesced_flush_in_progress) { > + if (!s || s->coalesced_flush_in_progress) { > return; > } > Thanks Gavin! Reviewed-by: David Hildenbrand <david@redhat.com> -- Cheers, David / dhildenb
On Mon, 31 Jul 2023 at 14:00, David Hildenbrand <david@redhat.com> wrote: > > On 31.07.23 14:59, Gavin Shan wrote: > > Runs into core dump on arm64 and the backtrace extracted from the > > core dump is shown as below. It's caused by accessing uninitialized > > @kvm_state in kvm_flush_coalesced_mmio_buffer() due to commit 176d073029 > > ("hw/arm/virt: Use machine_memory_devices_init()"), where the machine's > > memory region is added earlier than before. > > > > main > > qemu_init > > configure_accelerators > > qemu_opts_foreach > > do_configure_accelerator > > accel_init_machine > > kvm_init > > virt_kvm_type > > virt_set_memmap > > machine_memory_devices_init > > memory_region_add_subregion > > memory_region_add_subregion_common > > memory_region_update_container_subregions > > memory_region_transaction_begin > > qemu_flush_coalesced_mmio_buffer > > kvm_flush_coalesced_mmio_buffer > > > > Fix it by bailing early in kvm_flush_coalesced_mmio_buffer() on the > > uninitialized @kvm_state. With this applied, no crash is observed on > > arm64. > > > > Fixes: 176d073029 ("hw/arm/virt: Use machine_memory_devices_init()") > > Signed-off-by: Gavin Shan <gshan@redhat.com> > > --- > > v2: Bail early in kvm_flush_coalesced_mmio_buffer() on the uninitialized > > @kvm_state and improved changelog (David/Peter) > > --- > > accel/kvm/kvm-all.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/accel/kvm/kvm-all.c b/accel/kvm/kvm-all.c > > index 373d876c05..7b3da8dc3a 100644 > > --- a/accel/kvm/kvm-all.c > > +++ b/accel/kvm/kvm-all.c > > @@ -2812,7 +2812,7 @@ void kvm_flush_coalesced_mmio_buffer(void) > > { > > KVMState *s = kvm_state; > > > > - if (s->coalesced_flush_in_progress) { > > + if (!s || s->coalesced_flush_in_progress) { > > return; > > } > > > > Thanks Gavin! > > Reviewed-by: David Hildenbrand <david@redhat.com> Applied to target-arm.next, thanks. -- PMM
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