Re: [PATCH 5/5] x86/PV: don't commit debug register values early in arch_set_info_guest()

[Andrew Cooper <andrew.cooper3@citrix.com>]

[-- Attachment #1.1: Type: text/plain, Size: 1354 bytes --]

On 10/12/13 15:48, Jan Beulich wrote:
> They're being taken care of later (via set_debugreg()), and temporarily
> copying them into struct vcpu means that bad values may end up getting
> loaded during context switch if the vCPU is already running and the
> function errors out between the premature and real commit step, leading
> to the same issue that XSA-12 dealt with.
>
> Signed-off-by: Jan Beulich <jbeulich@suse.com>
> Acked-by: Ian Campbell <ian.campbell@citrix.com>

Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>

>
> --- a/xen/arch/x86/domain.c
> +++ b/xen/arch/x86/domain.c
> @@ -740,11 +740,12 @@ int arch_set_info_guest(
>              XLAT_trap_info(v->arch.pv_vcpu.trap_ctxt + i,
>                             c.cmp->trap_ctxt + i);
>      }
> -    for ( i = 0; i < ARRAY_SIZE(v->arch.debugreg); ++i )
> -        v->arch.debugreg[i] = c(debugreg[i]);
>  
>      if ( has_hvm_container_vcpu(v) )
>      {
> +        for ( i = 0; i < ARRAY_SIZE(v->arch.debugreg); ++i )
> +            v->arch.debugreg[i] = c(debugreg[i]);
> +
>          /*
>           * NB: TF_kernel_mode is set unconditionally for HVM guests,
>           * so we always use the gs_base_kernel here. If we change this
>
>
>
>
>
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.xen.org
> http://lists.xen.org/xen-devel


[-- Attachment #1.2: Type: text/html, Size: 2331 bytes --]

[-- Attachment #2: Type: text/plain, Size: 126 bytes --]

_______________________________________________
Xen-devel mailing list
Xen-devel@lists.xen.org
http://lists.xen.org/xen-devel