Re: [Xen-devel] [PATCH v2 2/2] vmx/hap: optimize CR4 trapping

[Razvan Cojocaru <rcojocaru@xxxxxxxxxxxxxxx>]

On 02/16/2018 02:10 PM, Roger Pau Monne wrote:
> diff --git a/xen/arch/x86/monitor.c b/xen/arch/x86/monitor.c
> index f229e69948..4317658c56 100644
> --- a/xen/arch/x86/monitor.c
> +++ b/xen/arch/x86/monitor.c
> @@ -189,10 +189,11 @@ int arch_monitor_domctl_event(struct domain *d,
>              ad->monitor.write_ctrlreg_enabled &= ~ctrlreg_bitmask;
>          }
>  
> -        if ( VM_EVENT_X86_CR3 == mop->u.mov_to_cr.index )
> +        if ( VM_EVENT_X86_CR3 == mop->u.mov_to_cr.index ||
> +             VM_EVENT_X86_CR4 == mop->u.mov_to_cr.index )
>          {
>              struct vcpu *v;
> -            /* Latches new CR3 mask through CR0 code. */
> +            /* Latches new CR3 or CR4 mask through CR0 code. */
>              for_each_vcpu ( d, v )
>                  hvm_update_guest_cr(v, 0);
>          }

Did you, by any chance, test this code with xen-access.c (it already has
a test for CR4 for the PGE stuff)? I'm not convinced the
hvm_update_guest_cr(v, 0); call suffices to enable CR4 load exits.


Thanks,
Razvan

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