Re: [V0 PATCH 4/6] AMD-PVH: Do not get/set vlapic TPR

[Boris Ostrovsky <boris.ostrovsky@oracle.com>]

On 08/15/2014 09:53 PM, Mukesh Rathor wrote:
> PVH doesn't use apic emulation hence vlapic->regs ptr is not set for it.
>
> Signed-off-by: Mukesh Rathor <mukesh.rathor@oracle.com>
> ---
>   xen/arch/x86/hvm/svm/svm.c | 25 ++++++++++++++-----------
>   1 file changed, 14 insertions(+), 11 deletions(-)
>
> diff --git a/xen/arch/x86/hvm/svm/svm.c b/xen/arch/x86/hvm/svm/svm.c
> index dac16f4..4bb4ff2 100644
> --- a/xen/arch/x86/hvm/svm/svm.c
> +++ b/xen/arch/x86/hvm/svm/svm.c
> @@ -1052,7 +1052,7 @@ static void noreturn svm_do_resume(struct vcpu *v)
>           hvm_asid_flush_vcpu(v);
>       }
>   
> -    if ( !vcpu_guestmode )
> +    if ( !vcpu_guestmode && vcpu_vlapic(v)->regs )

I think checking explicitly for PVH (i.e. is_pvh_domain()) would be 
better. Here and below, obviously.

-boris

>       {
>           vintr_t intr;
>   
> @@ -2247,7 +2247,7 @@ void svm_vmexit_handler(struct cpu_user_regs *regs)
>        * NB. We need to preserve the low bits of the TPR to make checked builds
>        * of Windows work, even though they don't actually do anything.
>        */
> -    if ( !vcpu_guestmode ) {
> +    if ( !vcpu_guestmode && vcpu_vlapic(v)->regs ) {
>           intr = vmcb_get_vintr(vmcb);
>           vlapic_set_reg(vcpu_vlapic(v), APIC_TASKPRI,
>                      ((intr.fields.tpr & 0x0F) << 4) |
> @@ -2628,15 +2628,18 @@ void svm_vmexit_handler(struct cpu_user_regs *regs)
>       }
>   
>     out:
> -    if ( vcpu_guestmode )
> -        /* Don't clobber TPR of the nested guest. */
> -        return;
> -
> -    /* The exit may have updated the TPR: reflect this in the hardware vtpr */
> -    intr = vmcb_get_vintr(vmcb);
> -    intr.fields.tpr =
> -        (vlapic_get_reg(vcpu_vlapic(v), APIC_TASKPRI) & 0xFF) >> 4;
> -    vmcb_set_vintr(vmcb, intr);
> +    /* Don't clobber TPR of the nested guest. */
> +    if ( vcpu_guestmode && vcpu_vlapic(v)->regs )
> +    {
> +        /*
> +         * The exit may have updated the TPR: reflect this in the hardware
> +         * vtpr.
> +         */
> +        intr = vmcb_get_vintr(vmcb);
> +        intr.fields.tpr =
> +            (vlapic_get_reg(vcpu_vlapic(v), APIC_TASKPRI) & 0xFF) >> 4;
> +        vmcb_set_vintr(vmcb, intr);
> +    }
>   }
>   
>   void svm_trace_vmentry(void)