On Wed, Dec 19, 2018 at 12:17:51PM +0000, Andrew Cooper wrote: > On 19/12/2018 12:10, Roger Pau Monné wrote: > > Hypercalls AFAIK have a single target (or subject) domain, so even if > > there's a stubdomain relation I'm not sure I see why that would > > require this kind of locking, any domain can perform hypercalls > > against a single subject domain, and the hypervisor itself doesn't > > even know about stubdomain relations. > > Grant copy has two domains, and neither need to be the callee. > Specifically, we discovered during the SILO work that dom0 occasonally > issues a dom1 => dom2 grant copy.
Grant copy doesn't attempt to lock multiple domains at the same time, it takes a reference of each page and maps it into Xen address space, but there's no cross domain mm locking at all AFAICT. It's indeed an operation that *could* do interleaved domain locks, but it doesn't. Roger. _______________________________________________ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel
