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kvm: Fix crash due to access uninitialized kvm_state

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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>
Reviewed-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-id: 20230731125946.2038742-1-gshan@redhat.com
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
This commit is contained in:
Gavin Shan 2023-07-31 22:59:46 +10:00 committed by Peter Maydell
parent 71054f72f1
commit fe6bda58e0
1 changed files with 1 additions and 1 deletions
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2
accel/kvm/kvm-all.c
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@ -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;
}