Re: [PATCH 04/12] accel/mshv: install dummy handler for SIG_IPI

["Doru Blânzeanu" <dblanzeanu@linux.microsoft.com>]

On Fri, Jul 10, 2026 at 12:15:26PM +0200, Magnus Kulke wrote:
> This is similar to HVF's implementation. We want to interrupt the blocking
> vcpu run. The self-kick was effectively a no-op for mshv.
> 
> Signed-off-by: Magnus Kulke <magnuskulke@linux.microsoft.com>
> ---
>  accel/mshv/mshv-all.c | 16 ++++++----------
>  1 file changed, 6 insertions(+), 10 deletions(-)
> 
> diff --git a/accel/mshv/mshv-all.c b/accel/mshv/mshv-all.c
> index 7b3c13cf1e..f9511ca050 100644
> --- a/accel/mshv/mshv-all.c
> +++ b/accel/mshv/mshv-all.c
> @@ -621,17 +621,13 @@ static int mshv_cpu_exec(CPUState *cpu)
>  }
>  
>  /*
> - * The signal handler is triggered when QEMU's main thread receives a SIG_IPI
> - * (SIGUSR1). This signal causes the current CPU thread to be kicked, forcing a
> - * VM exit on the CPU. The VM exit generates an exit reason that breaks the loop
> - * (see mshv_cpu_exec). If the exit is due to a Ctrl+A+x command, the system
> - * will shut down. For other cases, the system will continue running.
> + * We need a dummy handler to make SIG_IPI a deliverable signal. The kernel
> + * handler will be woken up by the caught signal and instruct the hypervisor
> + * to suspend execution (the concrete mechanism differs between schedulers)
> + * and return to userspace.
>   */
> -static void sa_ipi_handler(int sig)
> +static void dummy_handler(int sig)
>  {
> -    /* TODO: call IOCTL to set_immediate_exit, once implemented. */
> -
> -    qemu_cpu_kick_self();
>  }
>  
>  static void init_signal(CPUState *cpu)
> @@ -641,7 +637,7 @@ static void init_signal(CPUState *cpu)
>      sigset_t set;
>  
>      memset(&sigact, 0, sizeof(sigact));
> -    sigact.sa_handler = sa_ipi_handler;
> +    sigact.sa_handler = dummy_handler;
>      sigaction(SIG_IPI, &sigact, NULL);
>  
>      pthread_sigmask(SIG_BLOCK, NULL, &set);
> -- 
> 2.34.1

Reviewed-by: Doru Blânzeanu <dblanzeanu@linux.microsoft.com>