KVM: arm64: Add kvm_extable for vaxorcism code

KVM has a one instruction window where it will allow an SError exception
to be consumed by the hypervisor without treating it as a hypervisor bug.
This is used to consume asynchronous external abort that were caused by
the guest.

As we are about to add another location that survives unexpected exceptions,
generalise this code to make it behave like the host's extable.

KVM's version has to be mapped to EL2 to be accessible on nVHE systems.

The SError vaxorcism code is a one instruction window, so has two entries
in the extable. Because the KVM code is copied for VHE and nVHE, we end up
with four entries, half of which correspond with code that isn't mapped.

Signed-off-by: James Morse <james.morse@arm.com>
Reviewed-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>

1 files changed, 5 insertions, 0 deletions

diff --git a/arch/arm64/kvm/hyp/vhe/switch.c b/arch/arm64/kvm/hyp/vhe/switch.c
index c52d714e0d75..c1da4f86ccac 100644
--- a/arch/arm64/kvm/hyp/vhe/switch.c
+++ b/arch/arm64/kvm/hyp/vhe/switch.c
@@ -217,3 +217,8 @@ void __noreturn hyp_panic(struct kvm_cpu_context *host_ctxt)
 	__hyp_call_panic(spsr, elr, par, host_ctxt);
 	unreachable();
 }
+
+asmlinkage void kvm_unexpected_el2_exception(void)
+{
+	return __kvm_unexpected_el2_exception();
+}