On 24/01/2019 16:31, Wei Liu wrote: > On Wed, Jan 23, 2019 at 02:59:29PM +0000, Andrew Cooper wrote: >> The progression of multi-vcpu support in Xen (originally a single pointer, >> then an embedded d->vcpu[] array, then a dynamically allocated array) has >> resulted in a large quantity of ad-hoc code for looking a vcpu up by id, and >> a >> large number of ways that the toolstack can cause Xen to trip over a NULL >> pointer. Some of this has been addressed in Xen 4.12, and work is ongoing. >> >> Another property of looking a vcpu up by id is frequently done in >> unprivileged >> hypercall context, making it an attractive target for speculative sidechannel >> attacks. >> >> Introduce a helper to do the lookup correctly, and without speculative >> interference. For performance reasons, it is useful not to have an smp_rmb() >> in this helper on ARM, and luckily this is safe to do, because of the >> serialisation offered by the global domheap lock. > I think you mean domlist lock here?
I do indeed. ~Andrew _______________________________________________ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel
