On Wed, Aug 28, 2019 at 08:59:21AM -0700, Tim Chen wrote: > On 8/27/19 2:50 PM, Peter Zijlstra wrote: > > On Tue, Aug 27, 2019 at 10:14:17PM +0100, Matthew Garrett wrote: > >> Apple have provided a sysctl that allows applications to indicate that > >> specific threads should make use of core isolation while allowing > >> the rest of the system to make use of SMT, and browsers (Safari, Firefox > >> and Chrome, at least) are now making use of this. Trying to do something > >> similar using cgroups seems a bit awkward. Would something like this be > >> reasonable? > > > > Sure; like I wrote earlier; I only did the cgroup thing because I was > > lazy and it was the easiest interface to hack on in a hurry. > > > > The rest of the ABI nonsense can 'trivially' be done later; if when we > > decide to actually do this. > > > > And given MDS, I'm still not entirely convinced it all makes sense. If > > it were just L1TF, then yes, but now... > > > > For MDS, core-scheduler does prevent thread to thread > attack between user space threads running on sibling CPU threads. > Yes, it doesn't prevent the user to kernel attack from sibling > which will require additional mitigation measure. However, it does > block a major attack vector for MDS if HT is enabled.
I'm not sure what your argument is; the dike has two holes; you plug one, you still drown.
