Re: [Qemu-devel] [PATCH] SVM: acknowledge interrupt only after it is taken

[Alexander Graf <agraf@suse.de>]

Alexander Graf wrote:
> SVM specifies that the V_IRQ mask is only to be removed, if the
> interrupt that is to be delivered actually is delivered.
>
> As of the SVM rewrite, this mask is always unmasked when the main cpu
> loop is processed, leaving a corner case where calling the interrupt
> handler causes a #PF. In that case (booting Linux / starting gfxboot)
> the current implementation tells the VMM the interrupt is taken, even
> though it is not.
>
> This patch modifies the VIRQ unmasking to occur after do_interrupt,
> making gfxboot work again.
>   

(wow, I actually forgot that line even though working with git - phew)

Signed-off-by: Alexander Graf <agraf@suse.de>

> ---
>  cpu-exec.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
>
> diff --git a/cpu-exec.c b/cpu-exec.c
> index 9a35a59..981ba86 100644
> --- a/cpu-exec.c
> +++ b/cpu-exec.c
> @@ -401,11 +401,11 @@ int cpu_exec(CPUState *env1)
>                              int intno;
>                              /* FIXME: this should respect TPR */
>                              svm_check_intercept(SVM_EXIT_VINTR);
> -                            env->interrupt_request &= ~CPU_INTERRUPT_VIRQ;
>                              intno = ldl_phys(env->vm_vmcb + offsetof(struct vmcb, control.int_vector));
>                              if (loglevel & CPU_LOG_TB_IN_ASM)
>                                  fprintf(logfile, "Servicing virtual hardware INT=0x%02x\n", intno);
>                              do_interrupt(intno, 0, 0, 0, 1);
> +                            env->interrupt_request &= ~CPU_INTERRUPT_VIRQ;
>                              next_tb = 0;
>  #endif
>                          }
>