On Mon, Oct 19, 2009 at 06:32:54PM -0200, Marcelo Tosatti wrote:
> On Thu, Oct 15, 2009 at 07:05:36PM +0200, Jan Kiszka wrote:
> > This plugs an NMI-related hole in the VCPU synchronization between
> > kernel and user space. So far, neither pending NMIs nor the inhibit NMI
> > mask was properly read/set which was able to cause problems on
> > vmsave/restore, live migration and system reset. Fix it by making use
> > of the new VCPU substate interface.
> >
> > Signed-off-by: Jan Kiszka <[email protected]>
> > ---
> >
> > Documentation/kvm/api.txt | 12 ++++++++++++
> > arch/x86/include/asm/kvm.h | 7 +++++++
> > arch/x86/include/asm/kvm_host.h | 2 ++
> > arch/x86/kvm/svm.c | 22 ++++++++++++++++++++++
> > arch/x86/kvm/vmx.c | 30 ++++++++++++++++++++++++++++++
> > arch/x86/kvm/x86.c | 26 ++++++++++++++++++++++++++
> > 6 files changed, 99 insertions(+), 0 deletions(-)
> >
> > diff --git a/Documentation/kvm/api.txt b/Documentation/kvm/api.txt
> > index bee5bbd..e483edb 100644
> > --- a/Documentation/kvm/api.txt
> > +++ b/Documentation/kvm/api.txt
> > @@ -848,3 +848,15 @@ Deprecates: KVM_GET/SET_CPUID2
> > Architectures: x86
> > Payload: struct kvm_lapic
> > Deprecates: KVM_GET/SET_LAPIC
> > +
> > +6.8 KVM_X86_VCPU_STATE_NMI
> > +
> > +Architectures: x86
> > +Payload: struct kvm_nmi_state
> > +Deprecates: -
> > +
> > +struct kvm_nmi_state {
> > + __u8 pending;
> > + __u8 masked;
> > + __u8 pad1[6];
>
> Don't you also have to save "nmi_injected", in case of failure during
> NMI delivery.
>
> BTW, what happens to exceptions that fail to be delivered? Can't see
> where they are saved/restored across migration.
>
The instruction that caused an exception will be re-executed after
migration and exception will be regenerated. But I think we should
migrate exception anyway for completeness.
--
Gleb.
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