[Qemu-devel] Re: [PATCH] x86: svm: Always clear event_inj on vmexit

[Erik van der Kouwe <vdkouwe@cs.vu.nl>]

Hi,

 > We currently only clear SVM_EVTINJ_VALID after successful interrupt
 > delivery. This apparently does not match real hardware which clears the
 > whole event_inj field on every vmexit, including unsuccessful interrupt
 > delivery.

Thanks for the patch. It is a bit hard for me to test right now as I 
messed up my test setup, but I will do so ASAP and let you know.

However, I'm worried that this patch may introduce a new problem (I may 
be mistaken though). There is still this code to load the exit interrupt 
info:

stl_phys(env->vm_vmcb + offsetof(struct vmcb,
   control.exit_int_info_err),
   ldl_phys(env->vm_vmcb + offsetof(struct vmcb,
   control.event_inj_err)));

Now that event_inj is no longer loaded, won't this mean that 
exit_int_info and exit_int_info_err also won't be loaded?

With kind regards,
Erik

Jan Kiszka wrote:
> We currently only clear SVM_EVTINJ_VALID after successful interrupt
> delivery. This apparently does not match real hardware which clears the
> whole event_inj field on every vmexit, including unsuccessful interrupt
> delivery.
> 
> Reported-by: Erik van der Kouwe <vdkouwe@cs.vu.nl>
> Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
> ---
> 
> (before it gets lost)
> Erik, please confirm that this works for you.
> 
>  target-i386/op_helper.c |    8 +-------
>  1 files changed, 1 insertions(+), 7 deletions(-)
> 
> diff --git a/target-i386/op_helper.c b/target-i386/op_helper.c
> index dcbdfe7..caabdb4 100644
> --- a/target-i386/op_helper.c
> +++ b/target-i386/op_helper.c
> @@ -1263,13 +1263,6 @@ void do_interrupt(int intno, int is_int, int error_code,
>  #endif
>          do_interrupt_real(intno, is_int, error_code, next_eip);
>      }
> -
> -#if !defined(CONFIG_USER_ONLY)
> -    if (env->hflags & HF_SVMI_MASK) {
> -	    uint32_t event_inj = ldl_phys(env->vm_vmcb + offsetof(struct vmcb, control.event_inj));
> -	    stl_phys(env->vm_vmcb + offsetof(struct vmcb, control.event_inj), event_inj & ~SVM_EVTINJ_VALID);
> -    }
> -#endif
>  }
>  
>  /* This should come from sysemu.h - if we could include it here... */
> @@ -5388,6 +5381,7 @@ void helper_vmexit(uint32_t exit_code, uint64_t exit_info_1)
>               ldl_phys(env->vm_vmcb + offsetof(struct vmcb, control.event_inj)));
>      stl_phys(env->vm_vmcb + offsetof(struct vmcb, control.exit_int_info_err),
>               ldl_phys(env->vm_vmcb + offsetof(struct vmcb, control.event_inj_err)));
> +    stl_phys(env->vm_vmcb + offsetof(struct vmcb, control.event_inj), 0);
>  
>      env->hflags2 &= ~HF2_GIF_MASK;
>      /* FIXME: Resets the current ASID register to zero (host ASID). */