KVM: X86: Fix fpu state crash in kvm guest

The idea before commit 240c35a37 (which has just been reverted)
was that we have the following FPU states:

               userspace (QEMU)             guest
---------------------------------------------------------------------------
               processor                    vcpu->arch.guest_fpu
>>> KVM_RUN: kvm_load_guest_fpu
               vcpu->arch.user_fpu          processor
>>> preempt out
               vcpu->arch.user_fpu          current->thread.fpu
>>> preempt in
               vcpu->arch.user_fpu          processor
>>> back to userspace
>>> kvm_put_guest_fpu
               processor                    vcpu->arch.guest_fpu
---------------------------------------------------------------------------

With the new lazy model we want to get the state back to the processor
when schedule in from current->thread.fpu.

Reported-by: Thomas Lambertz <[email protected]>
Reported-by: anthony <[email protected]>
Tested-by: anthony <[email protected]>
Cc: Paolo Bonzini <[email protected]>
Cc: Radim Krčmář <[email protected]>
Cc: Thomas Lambertz <[email protected]>
Cc: anthony <[email protected]>
Cc: [email protected]
Fixes: 5f409e20b (x86/fpu: Defer FPU state load until return to userspace)
Signed-off-by: Wanpeng Li <[email protected]>
[Add a comment in front of the warning. - Paolo]
Signed-off-by: Paolo Bonzini <[email protected]>

0 files changed, 0 insertions, 0 deletions