[PATCH v2 19/28] ARM: KVM: Add panic handling code

Instead of spinning forever, let's "properly" handle any unexpected
exception ("properly" meaning "print a spat on the console and die").

This has proved useful quite a few times...

Signed-off-by: Marc Zyngier <redacted>
---
 arch/arm/kvm/hyp/hyp-entry.S | 28 +++++++++++++++++++++-------
 arch/arm/kvm/hyp/switch.c    | 38 ++++++++++++++++++++++++++++++++++++++
 2 files changed, 59 insertions(+), 7 deletions(-)

diff --git a/arch/arm/kvm/hyp/hyp-entry.S b/arch/arm/kvm/hyp/hyp-entry.S
index 44bc11f..ca412ad 100644
--- a/arch/arm/kvm/hyp/hyp-entry.S
+++ b/arch/arm/kvm/hyp/hyp-entry.S

@@ -75,15 +75,29 @@ __kvm_hyp_vector:
 
 .macro invalid_vector label, cause
 	.align
-\label:	b	.
+\label:	mov	r0, #\cause
+	b	__hyp_panic
 .endm
 
-	invalid_vector	hyp_reset
-	invalid_vector	hyp_undef
-	invalid_vector	hyp_svc
-	invalid_vector	hyp_pabt
-	invalid_vector	hyp_dabt
-	invalid_vector	hyp_fiq
+	invalid_vector	hyp_reset	ARM_EXCEPTION_RESET
+	invalid_vector	hyp_undef	ARM_EXCEPTION_UNDEFINED
+	invalid_vector	hyp_svc		ARM_EXCEPTION_SOFTWARE
+	invalid_vector	hyp_pabt	ARM_EXCEPTION_PREF_ABORT
+	invalid_vector	hyp_dabt	ARM_EXCEPTION_DATA_ABORT
+	invalid_vector	hyp_fiq		ARM_EXCEPTION_FIQ
+
+ENTRY(__hyp_do_panic)
+	mrs	lr, cpsr
+	bic	lr, lr, #MODE_MASK
+	orr	lr, lr, #SVC_MODE
+THUMB(	orr	lr, lr, #PSR_T_BIT	)
+	msr	spsr_cxsf, lr
+	ldr	lr, =panic
+	msr	ELR_hyp, lr
+	ldr	lr, =kvm_call_hyp
+	clrex
+	eret
+ENDPROC(__hyp_do_panic)
 
 hyp_hvc:
 	/*

diff --git a/arch/arm/kvm/hyp/switch.c b/arch/arm/kvm/hyp/switch.c
index 8bfd729..67f3944 100644
--- a/arch/arm/kvm/hyp/switch.c
+++ b/arch/arm/kvm/hyp/switch.c

@@ -188,3 +188,41 @@ again:
 }
 
 __alias(__guest_run) int __weak __kvm_vcpu_run(struct kvm_vcpu *vcpu);
+
+static const char * const __hyp_panic_string[] = {
+	[ARM_EXCEPTION_RESET]      = "\nHYP panic: RST?? PC:%08x CPSR:%08x",
+	[ARM_EXCEPTION_UNDEFINED]  = "\nHYP panic: UNDEF PC:%08x CPSR:%08x",
+	[ARM_EXCEPTION_SOFTWARE]   = "\nHYP panic: SVC?? PC:%08x CPSR:%08x",
+	[ARM_EXCEPTION_PREF_ABORT] = "\nHYP panic: PABRT PC:%08x CPSR:%08x",
+	[ARM_EXCEPTION_DATA_ABORT] = "\nHYP panic: DABRT PC:%08x ADDR:%08x",
+	[ARM_EXCEPTION_IRQ]        = "\nHYP panic: IRQ?? PC:%08x CPSR:%08x",
+	[ARM_EXCEPTION_FIQ]        = "\nHYP panic: FIQ?? PC:%08x CPSR:%08x",
+	[ARM_EXCEPTION_HVC]        = "\nHYP panic: HVC?? PC:%08x CPSR:%08x",