On 07/08/2010 12:41 PM, Gleb Natapov wrote:
When shadow pages are in use sometimes KVM try to emulate an instruction when it accesses a shadowed page. If emulation fails KVM un-shadows the page and reenter guest to allow vcpu to execute the instruction. If page is not in shadow page hash KVM assumes that this was attempt to do MMIO and reports emulation failure to userspace since there is no way to fix the situation. This logic has a race though. If two vcpus tries to write to the same shadowed page simultaneously both will enter emulator, but only one of them will find the page in shadow page hash since the one who founds it also removes it from there, so another cpu will report failure to userspace and will abort the guest. Fix this by checking (in addition to checking shadowed page hash) that page that caused the emulation belongs to valid memory slot. If it is then reenter the guest to allow vcpu to reexecute the instruction.
Applied, thanks. -- error compiling committee.c: too many arguments to function -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
