arm/arm64: KVM: Complete WFI/WFE instructions

commit 05e0127f9e362b36aa35f17b1a3d52bca9322a3a upstream.

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.

Acked-by: Marc Zyngier <marc.zyngier@arm.com>
Cc: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/arm/kvm/handle_exit.c b/arch/arm/kvm/handle_exit.c
index 0de91fc..ec4fa86 100644 (file)
--- a/arch/arm/kvm/handle_exit.c
+++ b/arch/arm/kvm/handle_exit.c
@@ -89,6 +89,8 @@ 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 7bc41ea..fd9aeba 100644 (file)
--- a/arch/arm64/kvm/handle_exit.c
+++ b/arch/arm64/kvm/handle_exit.c
@@ -62,6 +62,8 @@ 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;
 }