arm: KVM: Handle async aborts delivered while at HYP

Just like for arm64, we can handle asynchronous aborts being
delivered at HYP while being caused by the guest. We use
the exact same method to catch such an abort, and soldier on.

Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>

arch/arm/kvm/hyp/entry.S

@@ -18,6 +18,7 @@
 #include <linux/linkage.h>
 #include <asm/asm-offsets.h>
 #include <asm/kvm_arm.h>
+#include <asm/kvm_asm.h>
 
 	.arch_extension     virt
 
@@ -63,6 +64,36 @@ ENTRY(__guest_exit)
 	ldr	lr, [r0, #4]
 
 	mov	r0, r1
+	mrs	r1, SPSR
+	mrs	r2, ELR_hyp
+	mrc	p15, 4, r3, c5, c2, 0	@ HSR
+
+	/*
+	 * Force loads and stores to complete before unmasking aborts
+	 * and forcing the delivery of the exception. This gives us a
+	 * single instruction window, which the handler will try to
+	 * match.
+	 */
+	dsb	sy
+	cpsie	a
+
+	.global	abort_guest_exit_start
+abort_guest_exit_start:
+
+	isb
+
+	.global	abort_guest_exit_end
+abort_guest_exit_end:
+
+	/*
+	 * If we took an abort, r0[31] will be set, and cmp will set
+	 * the N bit in PSTATE.
+	 */
+	cmp	r0, #0
+	msrmi	SPSR_cxsf, r1
+	msrmi	ELR_hyp, r2
+	mcrmi	p15, 4, r3, c5, c2, 0	@ HSR
+
 	bx	lr
 ENDPROC(__guest_exit)