arm64: KVM: 32bit guest fault injection

Add fault injection capability for 32bit guests.

Reviewed-by: Christopher Covington <cov@codeaurora.org>
Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>
Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>

arch/arm64/kvm/inject_fault.c

@@ -1,5 +1,5 @@
 /*
- * Fault injection for 64bit guests.
+ * Fault injection for both 32 and 64bit guests.
  *
  * Copyright (C) 2012,2013 - ARM Ltd
  * Author: Marc Zyngier <marc.zyngier@arm.com>
@@ -29,6 +29,74 @@
 				 PSR_I_BIT | PSR_D_BIT)
 #define EL1_EXCEPT_SYNC_OFFSET	0x200
 
+static void prepare_fault32(struct kvm_vcpu *vcpu, u32 mode, u32 vect_offset)
+{
+	unsigned long cpsr;
+	unsigned long new_spsr_value = *vcpu_cpsr(vcpu);
+	bool is_thumb = (new_spsr_value & COMPAT_PSR_T_BIT);
+	u32 return_offset = (is_thumb) ? 4 : 0;
+	u32 sctlr = vcpu_cp15(vcpu, c1_SCTLR);
+
+	cpsr = mode | COMPAT_PSR_I_BIT;
+
+	if (sctlr & (1 << 30))
+		cpsr |= COMPAT_PSR_T_BIT;
+	if (sctlr & (1 << 25))
+		cpsr |= COMPAT_PSR_E_BIT;
+
+	*vcpu_cpsr(vcpu) = cpsr;
+
+	/* Note: These now point to the banked copies */
+	*vcpu_spsr(vcpu) = new_spsr_value;
+	*vcpu_reg(vcpu, 14) = *vcpu_pc(vcpu) + return_offset;
+
+	/* Branch to exception vector */
+	if (sctlr & (1 << 13))
+		vect_offset += 0xffff0000;
+	else /* always have security exceptions */
+		vect_offset += vcpu_cp15(vcpu, c12_VBAR);
+
+	*vcpu_pc(vcpu) = vect_offset;
+}
+
+static void inject_undef32(struct kvm_vcpu *vcpu)
+{
+	prepare_fault32(vcpu, COMPAT_PSR_MODE_UND, 4);
+}
+
+/*
+ * Modelled after TakeDataAbortException() and TakePrefetchAbortException
+ * pseudocode.
+ */
+static void inject_abt32(struct kvm_vcpu *vcpu, bool is_pabt,
+			 unsigned long addr)
+{
+	u32 vect_offset;
+	u32 *far, *fsr;
+	bool is_lpae;
+
+	if (is_pabt) {
+		vect_offset = 12;
+		far = &vcpu_cp15(vcpu, c6_IFAR);
+		fsr = &vcpu_cp15(vcpu, c5_IFSR);
+	} else { /* !iabt */
+		vect_offset = 16;
+		far = &vcpu_cp15(vcpu, c6_DFAR);
+		fsr = &vcpu_cp15(vcpu, c5_DFSR);
+	}
+
+	prepare_fault32(vcpu, COMPAT_PSR_MODE_ABT | COMPAT_PSR_A_BIT, vect_offset);
+
+	*far = addr;
+
+	/* Give the guest an IMPLEMENTATION DEFINED exception */
+	is_lpae = (vcpu_cp15(vcpu, c2_TTBCR) >> 31);
+	if (is_lpae)
+		*fsr = 1 << 9 | 0x34;
+	else
+		*fsr = 0x14;
+}
+
 static void inject_abt64(struct kvm_vcpu *vcpu, bool is_iabt, unsigned long addr)
 {
 	unsigned long cpsr = *vcpu_cpsr(vcpu);
@@ -98,6 +166,9 @@ static void inject_undef64(struct kvm_vcpu *vcpu)
  */
 void kvm_inject_dabt(struct kvm_vcpu *vcpu, unsigned long addr)
 {
+	if (!(vcpu->arch.hcr_el2 & HCR_RW))
+		inject_abt32(vcpu, false, addr);
+
 	inject_abt64(vcpu, false, addr);
 }
 
@@ -111,6 +182,9 @@ void kvm_inject_dabt(struct kvm_vcpu *vcpu, unsigned long addr)
  */
 void kvm_inject_pabt(struct kvm_vcpu *vcpu, unsigned long addr)
 {
+	if (!(vcpu->arch.hcr_el2 & HCR_RW))
+		inject_abt32(vcpu, true, addr);
+
 	inject_abt64(vcpu, true, addr);
 }
 
@@ -122,5 +196,8 @@ void kvm_inject_pabt(struct kvm_vcpu *vcpu, unsigned long addr)
  */
 void kvm_inject_undefined(struct kvm_vcpu *vcpu)
 {
+	if (!(vcpu->arch.hcr_el2 & HCR_RW))
+		inject_undef32(vcpu);
+
 	inject_undef64(vcpu);
 }