arm/arm64: KVM: Complete WFI/WFE instructions

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>

diff --git a/arch/arm/kvm/handle_exit.c b/arch/arm/kvm/handle_exit.c
index 4c979d466cc1681c4b3efc70623345eee5974b78..a96a8043277c3de69cc460a5b2a3f83a36fc30ed 100644 (file)
--- 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 e28be510380ca758f8cdb76a5da57892cb02e3bf..34b8bd0711e94295b3b8d629e2e032db8d8bce33 100644 (file)
--- 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;
 }