On Tue, Dec 08, 2009 at 04:07:32PM +0200, Avi Kivity wrote: > On 12/08/2009 04:02 PM, Marcelo Tosatti wrote: >> On Sun, Dec 06, 2009 at 06:24:15PM +0100, Jan Kiszka wrote: >> >>> User space may not want to overwrite asynchronously changing VCPU event >>> states on write-back. So allow to skip nmi.pending and sipi_vector by >>> setting corresponding bits in the flags field of kvm_vcpu_events. >>> >>> Signed-off-by: Jan Kiszka<jan.kiszka@xxxxxxxxxxx> >>> >> Can't you handle this in userspace entirely, only updating vcpu_events >> state when appropriate? >> > > For what we do now I think you're right, it can be handled in userspace. > > But in general, there's currently no way to update vcpu_events without > overwriting nmi and sipi_vector, which can also be written concurrently > by other vcpus. So there's a hole in the interface. > >> Shouldnt the vcpu be stopped in the first place, when its state is >> updated? >> > > It is stopped, but other vcpus are not. I don't see the need for setting any state in kvm_vcpu_events automatically, on kernel entry (apparently there was consensus that saving similar state explicitly in qemu was the way to go). kvm_arch_put_registers in qemu saves mpstate now that way, and the same problem is present. The sites to load vcpu_events would be machine reset and cpu_load only, right? -- 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
