[PATCH v1 1/2] kvm: arm64: handle single-step during SError exceptions

[Alex Bennée]

When an SError arrives during single-step it may be delivered before
the step completes. In that case the DBG_SPSR_SS bit will have flipped
as the instruction executed. After handling the abort in handle_exit()
we test to see if the bit is clear and we were single-stepping before
deciding if we need to exit to user space.

Signed-off-by: Alex Bennée <alex.bennee at linaro.org>
---
 arch/arm64/kvm/handle_exit.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/kvm/handle_exit.c b/arch/arm64/kvm/handle_exit.c
index 3e645ec9e751..3ba8c4a3bcff 100644
--- a/arch/arm64/kvm/handle_exit.c
+++ b/arch/arm64/kvm/handle_exit.c
@@ -28,6 +28,7 @@
 #include <asm/kvm_emulate.h>
 #include <asm/kvm_mmu.h>
 #include <asm/kvm_psci.h>
+#include <asm/debug-monitors.h>
 
 #define CREATE_TRACE_POINTS
 #include "trace.h"
@@ -250,7 +251,12 @@ int handle_exit(struct kvm_vcpu *vcpu, struct kvm_run *run,
 		return 1;
 	case ARM_EXCEPTION_EL1_SERROR:
 		kvm_inject_vabt(vcpu);
-		return 1;
+		/* We may still need to return for single-step */
+		if (!(*vcpu_cpsr(vcpu) & DBG_SPSR_SS)
+			&& kvm_arm_handle_step_debug(vcpu, run))
+			return 0;
+		else
+			return 1;
 	case ARM_EXCEPTION_TRAP:
 		return handle_trap_exceptions(vcpu, run);
 	case ARM_EXCEPTION_HYP_GONE:
-- 
2.15.0