Re: [PATCH 00/34] arch: barrier cleanup + __smp_xxx barriers for virt

David Miller
2015-12-30T21:59:13Z

From: "Michael S. Tsirkin" <mst@redhat.com>
Date: Wed, 30 Dec 2015 23:36:29 +0200

> On Wed, Dec 30, 2015 at 03:46:46PM -0500, David Miller wrote:
>> From: "Michael S. Tsirkin" <mst@redhat.com>
>> Date: Wed, 30 Dec 2015 14:58:19 +0200
>>
>> > -. Patch 1 documents the __smp APIs, and explains why they are
>> > useful for virt
>>
>> If virt is doing things like interacting with descriptors that are
>> shared with a (potentially SMP) host, why don't we just annotate those
>> specific cases?
>
> Using a bunch of per-arch ifdefs in virtio?
> That's fundamentally what we have now.

I was suggesting a generic interface to get what you want.

virt_mb() or something like that. You can name it something
else, that's not the important part.

> Or do you mean wrappers for __smp_XXX that explicitly
> say they are for talking to host?
> E.g. pv_mb() pv_rmb() etc.
> That sounds very reasonable to me.

Exactly!