Re: [Xen-devel] [PATCH for-4.10] xen/dom0: Fix latent dom0 construction bugs on all architectures

[Roger Pau Monné <roger.pau@xxxxxxxxxx>]

On Mon, Oct 16, 2017 at 03:38:03PM +0100, Andrew Cooper wrote:
>  * x86 PV and ARM dom0's must not clear _VPF_down from v->pause_flags until
>    all state is actually set up.  As it currently stands, d0v0 is eligible for
>    scheduling before its registers have been set.  This is latent as we also
>    hold a systemcontroller pause reference at the time which prevents d0 from
>    being scheduled.
> 
>  * x86 PVH dom0's must set v->is_initialised on d0v0, to prevent another vcpu
>    being able to call VCPUOP_initialise and modify state under the feet of the
>    running vcpu.  This is latent as PVH dom0 construction don't yet function.
> 
> Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>

LGTM, just one question.

> diff --git a/xen/arch/x86/hvm/dom0_build.c b/xen/arch/x86/hvm/dom0_build.c
> index e8f746c..a67071c 100644
> --- a/xen/arch/x86/hvm/dom0_build.c
> +++ b/xen/arch/x86/hvm/dom0_build.c
> @@ -614,6 +614,7 @@ static int __init pvh_setup_cpus(struct domain *d, 
> paddr_t entry,
>  
>      update_domain_wallclock_time(d);
>  
> +    v->is_initialised = 1;
>      clear_bit(_VPF_down, &v->pause_flags);

Don't you want to move this to the end of dom0_construct_pvh? In any
case, at this point the vCPU state is already setup correctly.

Thanks, Roger.

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