[GIT PULL 2/2] arm/arm64: KVM: Complete WFI/WFE instructions

[Christoffer Dall]

The architecture specifies that when the processor wakes up from a WFE
or WFI instruction, the instruction is considered complete, however we
currrently return to EL1 (or EL0) at the WFI/WFE instruction itself.

While most guests may not be affected by this because their local
exception handler performs an exception returning setting the event bit
or with an interrupt pending, some guests like UEFI will get wedged due
this little mishap.

Simply skip the instruction when we have completed the emulation.

Cc: <stable at vger.kernel.org>
Acked-by: Marc Zyngier <marc.zyngier at arm.com>
Cc: Ard Biesheuvel <ard.biesheuvel at linaro.org>
Signed-off-by: Christoffer Dall <christoffer.dall at linaro.org>
---
 arch/arm/kvm/handle_exit.c   | 2 ++
 arch/arm64/kvm/handle_exit.c | 2 ++
 2 files changed, 4 insertions(+)

diff --git a/arch/arm/kvm/handle_exit.c b/arch/arm/kvm/handle_exit.c
index 4c979d4..a96a804 100644
--- a/arch/arm/kvm/handle_exit.c
+++ b/arch/arm/kvm/handle_exit.c
@@ -93,6 +93,8 @@ static int kvm_handle_wfx(struct kvm_vcpu *vcpu, struct kvm_run *run)
 	else
 		kvm_vcpu_block(vcpu);
 
+	kvm_skip_instr(vcpu, kvm_vcpu_trap_il_is32bit(vcpu));
+
 	return 1;
 }
 
diff --git a/arch/arm64/kvm/handle_exit.c b/arch/arm64/kvm/handle_exit.c
index e28be51..34b8bd0 100644
--- a/arch/arm64/kvm/handle_exit.c
+++ b/arch/arm64/kvm/handle_exit.c
@@ -66,6 +66,8 @@ static int kvm_handle_wfx(struct kvm_vcpu *vcpu, struct kvm_run *run)
 	else
 		kvm_vcpu_block(vcpu);
 
+	kvm_skip_instr(vcpu, kvm_vcpu_trap_il_is32bit(vcpu));
+
 	return 1;
 }
 
-- 
2.0.0