Re: [Xen-devel] [PATCH 1/3] xen: drop in_atomic()

["Jan Beulich" <JBeulich@xxxxxxxx>]

>>> On 22.05.19 at 11:45, <jgross@xxxxxxxx> wrote:
> --- a/xen/arch/x86/hvm/hvm.c
> +++ b/xen/arch/x86/hvm/hvm.c
> @@ -3185,22 +3185,6 @@ static enum hvm_translation_result __hvm_copy(
>  
>      ASSERT(is_hvm_vcpu(v));
>  
> -    /*
> -     * XXX Disable for 4.1.0: PV-on-HVM drivers will do grant-table ops
> -     * such as query_size. Grant-table code currently does copy_to/from_guest
> -     * accesses under the big per-domain lock, which this test would 
> disallow.
> -     * The test is not needed until we implement sleeping-on-waitqueue when
> -     * we access a paged-out frame, and that's post 4.1.0 now.
> -     */
> -#if 0
> -    /*
> -     * If the required guest memory is paged out, this function may sleep.
> -     * Hence we bail immediately if called from atomic context.
> -     */
> -    if ( in_atomic() )
> -        return HVMTRANS_unhandleable;
> -#endif

Dealing with this TODO item is of course much appreciated, but
should it really be deleted altogether? The big-domain-lock issue
is gone afair, in which case dropping the #if 0 would seem
possible to me, even if it's not strictly needed without the sleep-
on-waitqueue behavior mentioned.

Jan



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