Re: [Xen-devel] [PATCH] x86/MCE: bypass uninitialized vcpu in vMCE injection

["Egger, Christoph" <chegger@xxxxxxxxx>]

On 07.05.14 09:29, Kai Huang wrote:
> Dom0 may bring up less number of vCPUs than xen hypervisor actually created 
> for
> it, and in this case, on Intel platform, vMCE injection to dom0 will fail due 
> to
> injecting vMCE to uninitialized vcpu, and cause dom0 crash.
> 
> Signed-off-by: Kai Huang <kai.huang@xxxxxxxxxxxxxxx>
> ---
>  xen/arch/x86/cpu/mcheck/vmce.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/xen/arch/x86/cpu/mcheck/vmce.c b/xen/arch/x86/cpu/mcheck/vmce.c
> index c83375e..72fe924 100644
> --- a/xen/arch/x86/cpu/mcheck/vmce.c
> +++ b/xen/arch/x86/cpu/mcheck/vmce.c
> @@ -356,6 +356,10 @@ int inject_vmce(struct domain *d, int vcpu)
>          if ( vcpu != VMCE_INJECT_BROADCAST && vcpu != v->vcpu_id )
>              continue;
>  
> +        /* In case of broadcasting, don't inject to uninitialized VCPU */
> +        if ( vcpu == VMCE_INJECT_BROADCAST && !v->is_initialised )
> +            continue;
> +

What happens when you inject to exactly one uninitialized VCPU?
I think what you want is this:

           /* Don't inject to uninitialized VCPU */
           if ( !v->is_initialised )
               continue;

>          if ( (has_hvm_container_domain(d) ||
>                guest_has_trap_callback(d, v->vcpu_id, TRAP_machine_check)) &&
>               !test_and_set_bool(v->mce_pending) )
> 


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