Re: [Qemu-devel] [PATCH] Main loop: Register a specific IO port to monitor guest linux os crash event

[Paolo Bonzini <pbonzini@redhat.com>]

On 12/04/2017 10:59, Huang Yong wrote:
> When guest os crash, there is no way to notify qemu on the host quickly (within 1s), and it is
> not convenient for libvirt management. We suggest to register a IO port (with specific addr) when
> qemu process be launched, on the other hand, a linux module which is comprised of kprobe hooks will
> be inserted in VM. When guest linux os crash, kprobe hooks write IO port mentioned above to notify
> qemu. With this approach, VM management component (e.g.libvirt) can monitor VM running state in time.

QEMU already supports this using the "pvpanic" device.  There is also a
driver in drivers/platform/x86/pvpanic.c.

Paolo

> Signed-off-by: Huang Yong<huang.yong@zte.com.cn>
> ---
>  vl.c | 35 +++++++++++++++++++++++++++++++++++
>  1 file changed, 35 insertions(+)
> 
> diff --git a/vl.c b/vl.c
> index 0b4ed52..2760c52 100644
> --- a/vl.c
> +++ b/vl.c
> @@ -129,9 +129,12 @@ int main(int argc, char **argv)
>  #include "sysemu/replay.h"
>  #include "qapi/qmp/qerror.h"
>  #include "sysemu/iothread.h"
> +#include "exec/memory.h"
> +#include "qapi/error.h"
>  
>  #define MAX_VIRTIO_CONSOLES 1
>  #define MAX_SCLP_CONSOLES 1
> +#define CRASH_IO_PORT (0xcff0)
>  
>  static const char *data_dir[16];
>  static int data_dir_idx;
> @@ -2939,6 +2942,37 @@ static int qemu_read_default_config_file(void)
>      return 0;
>  }
>  
> +static MemoryRegion crash_io;
> +
> +static uint64_t crash_io_read(void *opaque, hwaddr addr,
> +                              unsigned int size)
> +{
> +    return 0;
> +}
> +
> +static void crash_io_write(void *opaque, hwaddr addr,
> +                           uint64_t value, unsigned int size)
> +{
> +    qapi_event_send_guest_panicked(GUEST_PANIC_ACTION_PAUSE,
> +                                   false, NULL, &error_abort);
> +}
> +
> +static const MemoryRegionOps crash_io_ops = {
> +    .read = crash_io_read,
> +    .write = crash_io_write,
> +    .endianness = DEVICE_LITTLE_ENDIAN,
> +};
> +
> +static void init_crash_port(int port)
> +{
> +    int addr = port;
> +    MemoryRegion *system_io = get_system_io();
> +
> +    memory_region_init_io(&crash_io, NULL, &crash_io_ops,
> +                          NULL, "crash_event_port", 2);
> +    memory_region_add_subregion(system_io, addr, &crash_io);
> +}
> +
>  int main(int argc, char **argv, char **envp)
>  {
>      int i;
> @@ -4706,6 +4740,7 @@ int main(int argc, char **argv, char **envp)
>  
>      os_setup_post();
>  
> +    init_crash_port(CRASH_IO_PORT);
>      main_loop();
>      replay_disable_events();
>      iothread_stop_all();
>