>>> On 05.12.17 at 15:00, <paul.durr...@citrix.com> wrote: >> From: Jan Beulich [mailto:jbeul...@suse.com] >> Sent: 05 December 2017 13:53 >> >>> On 28.11.17 at 15:05, <paul.durr...@citrix.com> wrote: >> rc = x86_emulate(&hvmemul_ctxt->ctxt, ops); >> >> if ( rc != X86EMUL_RETRY ) >> { >> vio->mmio_cache_count = 0; >> vio->mmio_insn_bytes = 0; >> } >> else >> { >> ... >> } >> if ( rc == X86EMUL_OKAY && vio->mmio_retry ) >> rc = X86EMUL_RETRY; >> > > But that's not safe is it? If we've only completed some of the reps of an > instruction then we can't flush the instruction cache and we can't allow the > guest to take interrupts, can we?
Of course we can, just like a repeated string insn may be interrupted on bare hardware between any two iterations (with RIP still pointing at that insn). In fact with EFLAGS.TF set it is a requirement to deliver #DB after every iteration. Jan _______________________________________________ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel
