arm/arm64: KVM: Complete WFI/WFE instructions

Message ID 1411064308-28382-1-git-send-email-ard.biesheuvel@linaro.org
State New
Headers show

Commit Message

Ard Biesheuvel Sept. 18, 2014, 6:18 p.m.
From: Christoffer Dall <christoffer.dall@linaro.org>

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

Patch

diff --git a/arch/arm/kvm/handle_exit.c b/arch/arm/kvm/handle_exit.c
index 4c979d466cc1..a96a8043277c 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 e28be510380c..34b8bd0711e9 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;
 }