Re: [Xen-devel] [PATCH 2/7] x86/viridian: fix xen-hvmcrash when vp_assist page is present

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 17.03.17 at 10:57, <paul.durrant@xxxxxxxxxx> wrote:
> @@ -288,6 +304,14 @@ static void initialize_vp_assist(struct vcpu *v)
>       * enlightenment.
>       */
>  
> +    if ( v->arch.hvm_vcpu.viridian.vp_assist.va )
> +    {
> +        if ( v->arch.hvm_vcpu.viridian.vp_assist.gmfn == gmfn )
> +            return;

Is this shortcut valid? I.e. is it not valid for the guest to expect the
VP assist state to be fully reset if it calls this more than once on a
vCPU, yet possibly with the same GFN? (It also looks like this isn't
really part of the corrections you want to make here, according to
the description.)

> --- a/xen/include/asm-x86/hvm/viridian.h
> +++ b/xen/include/asm-x86/hvm/viridian.h
> @@ -23,6 +23,7 @@ struct viridian_vcpu
>  {
>      struct {
>          union viridian_vp_assist msr;
> +        unsigned long gmfn;

gfn_t ?

Jan


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