KVM: arm/arm64: Unify 32bit fault injection

Both arm and arm64 implementations are capable of injecting
faults, and yet have completely divergent implementations,
leading to different bugs and reduced maintainability.

Let's elect the arm64 version as the canonical one
and move it into aarch32.c, which is common to both
architectures.
Reviewed-by: NChristoffer Dall <christoffer.dall@linaro.org>
Signed-off-by: NMarc Zyngier <marc.zyngier@arm.com>
Signed-off-by: NChristoffer Dall <christoffer.dall@linaro.org>

arch/arm/include/asm/kvm_emulate.h

@@ -25,7 +25,22 @@
 #include <asm/kvm_arm.h>
 #include <asm/cputype.h>
 
+/* arm64 compatibility macros */
+#define COMPAT_PSR_MODE_ABT	ABT_MODE
+#define COMPAT_PSR_MODE_UND	UND_MODE
+#define COMPAT_PSR_T_BIT	PSR_T_BIT
+#define COMPAT_PSR_I_BIT	PSR_I_BIT
+#define COMPAT_PSR_A_BIT	PSR_A_BIT
+#define COMPAT_PSR_E_BIT	PSR_E_BIT
+#define COMPAT_PSR_IT_MASK	PSR_IT_MASK
+
 unsigned long *vcpu_reg(struct kvm_vcpu *vcpu, u8 reg_num);
+
+static inline unsigned long *vcpu_reg32(struct kvm_vcpu *vcpu, u8 reg_num)
+{
+	return vcpu_reg(vcpu, reg_num);
+}
+
 unsigned long *vcpu_spsr(struct kvm_vcpu *vcpu);
 
 static inline unsigned long vcpu_get_reg(struct kvm_vcpu *vcpu,
@@ -42,10 +57,25 @@ static inline void vcpu_set_reg(struct kvm_vcpu *vcpu, u8 reg_num,
 
 bool kvm_condition_valid32(const struct kvm_vcpu *vcpu);
 void kvm_skip_instr32(struct kvm_vcpu *vcpu, bool is_wide_instr);
-void kvm_inject_undefined(struct kvm_vcpu *vcpu);
+void kvm_inject_undef32(struct kvm_vcpu *vcpu);
+void kvm_inject_dabt32(struct kvm_vcpu *vcpu, unsigned long addr);
+void kvm_inject_pabt32(struct kvm_vcpu *vcpu, unsigned long addr);
 void kvm_inject_vabt(struct kvm_vcpu *vcpu);
-void kvm_inject_dabt(struct kvm_vcpu *vcpu, unsigned long addr);
-void kvm_inject_pabt(struct kvm_vcpu *vcpu, unsigned long addr);
+
+static inline void kvm_inject_undefined(struct kvm_vcpu *vcpu)
+{
+	kvm_inject_undef32(vcpu);
+}
+
+static inline void kvm_inject_dabt(struct kvm_vcpu *vcpu, unsigned long addr)
+{
+	kvm_inject_dabt32(vcpu, addr);
+}
+
+static inline void kvm_inject_pabt(struct kvm_vcpu *vcpu, unsigned long addr)
+{
+	kvm_inject_pabt32(vcpu, addr);
+}
 
 static inline bool kvm_condition_valid(const struct kvm_vcpu *vcpu)
 {

arch/arm/kvm/emulate.c

@@ -165,145 +165,6 @@ unsigned long *vcpu_spsr(struct kvm_vcpu *vcpu)
  * Inject exceptions into the guest
  */
 
-static u32 exc_vector_base(struct kvm_vcpu *vcpu)
-{
-	u32 sctlr = vcpu_cp15(vcpu, c1_SCTLR);
-	u32 vbar = vcpu_cp15(vcpu, c12_VBAR);
-
-	if (sctlr & SCTLR_V)
-		return 0xffff0000;
-	else /* always have security exceptions */
-		return vbar;
-}
-
-/*
- * Switch to an exception mode, updating both CPSR and SPSR. Follow
- * the logic described in AArch32.EnterMode() from the ARMv8 ARM.
- */
-static void kvm_update_psr(struct kvm_vcpu *vcpu, unsigned long mode)
-{
-	unsigned long cpsr = *vcpu_cpsr(vcpu);
-	u32 sctlr = vcpu_cp15(vcpu, c1_SCTLR);
-
-	*vcpu_cpsr(vcpu) = (cpsr & ~MODE_MASK) | mode;
-
-	switch (mode) {
-	case FIQ_MODE:
-		*vcpu_cpsr(vcpu) |= PSR_F_BIT;
-		/* Fall through */
-	case ABT_MODE:
-	case IRQ_MODE:
-		*vcpu_cpsr(vcpu) |= PSR_A_BIT;
-		/* Fall through */
-	default:
-		*vcpu_cpsr(vcpu) |= PSR_I_BIT;
-	}
-
-	*vcpu_cpsr(vcpu) &= ~(PSR_IT_MASK | PSR_J_BIT | PSR_E_BIT | PSR_T_BIT);
-
-	if (sctlr & SCTLR_TE)
-		*vcpu_cpsr(vcpu) |= PSR_T_BIT;
-	if (sctlr & SCTLR_EE)
-		*vcpu_cpsr(vcpu) |= PSR_E_BIT;
-
-	/* Note: These now point to the mode banked copies */
-	*vcpu_spsr(vcpu) = cpsr;
-}
-
-/**
- * kvm_inject_undefined - inject an undefined exception into the guest
- * @vcpu: The VCPU to receive the undefined exception
- *
- * It is assumed that this code is called from the VCPU thread and that the
- * VCPU therefore is not currently executing guest code.
- *
- * Modelled after TakeUndefInstrException() pseudocode.
- */
-void kvm_inject_undefined(struct kvm_vcpu *vcpu)
-{
-	unsigned long cpsr = *vcpu_cpsr(vcpu);
-	bool is_thumb = (cpsr & PSR_T_BIT);
-	u32 vect_offset = 4;
-	u32 return_offset = (is_thumb) ? 2 : 4;
-
-	kvm_update_psr(vcpu, UND_MODE);
-	*vcpu_reg(vcpu, 14) = *vcpu_pc(vcpu) - return_offset;
-
-	/* Branch to exception vector */
-	*vcpu_pc(vcpu) = exc_vector_base(vcpu) + vect_offset;
-}
-
-/*
- * Modelled after TakeDataAbortException() and TakePrefetchAbortException
- * pseudocode.
- */
-static void inject_abt(struct kvm_vcpu *vcpu, bool is_pabt, unsigned long addr)
-{
-	unsigned long cpsr = *vcpu_cpsr(vcpu);
-	bool is_thumb = (cpsr & PSR_T_BIT);
-	u32 vect_offset;
-	u32 return_offset = (is_thumb) ? 4 : 0;
-	bool is_lpae;
-
-	kvm_update_psr(vcpu, ABT_MODE);
-	*vcpu_reg(vcpu, 14) = *vcpu_pc(vcpu) + return_offset;
-
-	if (is_pabt)
-		vect_offset = 12;
-	else
-		vect_offset = 16;
-
-	/* Branch to exception vector */
-	*vcpu_pc(vcpu) = exc_vector_base(vcpu) + vect_offset;
-
-	if (is_pabt) {
-		/* Set IFAR and IFSR */
-		vcpu_cp15(vcpu, c6_IFAR) = addr;
-		is_lpae = (vcpu_cp15(vcpu, c2_TTBCR) >> 31);
-		/* Always give debug fault for now - should give guest a clue */
-		if (is_lpae)
-			vcpu_cp15(vcpu, c5_IFSR) = 1 << 9 | 0x22;
-		else
-			vcpu_cp15(vcpu, c5_IFSR) = 2;
-	} else { /* !iabt */
-		/* Set DFAR and DFSR */
-		vcpu_cp15(vcpu, c6_DFAR) = addr;
-		is_lpae = (vcpu_cp15(vcpu, c2_TTBCR) >> 31);
-		/* Always give debug fault for now - should give guest a clue */
-		if (is_lpae)
-			vcpu_cp15(vcpu, c5_DFSR) = 1 << 9 | 0x22;
-		else
-			vcpu_cp15(vcpu, c5_DFSR) = 2;
-	}
-
-}
-
-/**
- * kvm_inject_dabt - inject a data abort into the guest
- * @vcpu: The VCPU to receive the undefined exception
- * @addr: The address to report in the DFAR
- *
- * It is assumed that this code is called from the VCPU thread and that the
- * VCPU therefore is not currently executing guest code.
- */
-void kvm_inject_dabt(struct kvm_vcpu *vcpu, unsigned long addr)
-{
-	inject_abt(vcpu, false, addr);
-}
-
-/**
- * kvm_inject_pabt - inject a prefetch abort into the guest
- * @vcpu: The VCPU to receive the undefined exception
- * @addr: The address to report in the DFAR
- *
- * It is assumed that this code is called from the VCPU thread and that the
- * VCPU therefore is not currently executing guest code.
- */
-void kvm_inject_pabt(struct kvm_vcpu *vcpu, unsigned long addr)
-{
-	inject_abt(vcpu, true, addr);
-}
-
 /**
  * kvm_inject_vabt - inject an async abort / SError into the guest
  * @vcpu: The VCPU to receive the exception

arch/arm64/include/asm/kvm_emulate.h

@@ -41,6 +41,9 @@ void kvm_inject_undefined(struct kvm_vcpu *vcpu);
 void kvm_inject_vabt(struct kvm_vcpu *vcpu);
 void kvm_inject_dabt(struct kvm_vcpu *vcpu, unsigned long addr);
 void kvm_inject_pabt(struct kvm_vcpu *vcpu, unsigned long addr);
+void kvm_inject_undef32(struct kvm_vcpu *vcpu);
+void kvm_inject_dabt32(struct kvm_vcpu *vcpu, unsigned long addr);
+void kvm_inject_pabt32(struct kvm_vcpu *vcpu, unsigned long addr);
 
 static inline void vcpu_reset_hcr(struct kvm_vcpu *vcpu)
 {

arch/arm64/kvm/inject_fault.c

@@ -33,74 +33,6 @@
 #define LOWER_EL_AArch64_VECTOR		0x400
 #define LOWER_EL_AArch32_VECTOR		0x600
 
-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_reg32(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;
-}
-
 enum exception_type {
 	except_type_sync	= 0,
 	except_type_irq		= 0x80,
@@ -197,7 +129,7 @@ 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);
+		kvm_inject_dabt32(vcpu, addr);
 	else
 		inject_abt64(vcpu, false, addr);
 }
@@ -213,7 +145,7 @@ 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);
+		kvm_inject_pabt32(vcpu, addr);
 	else
 		inject_abt64(vcpu, true, addr);
 }
@@ -227,7 +159,7 @@ 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);
+		kvm_inject_undef32(vcpu);
 	else
 		inject_undef64(vcpu);
 }

virt/kvm/arm/aarch32.c

@@ -25,11 +25,6 @@
 #include <asm/kvm_emulate.h>
 #include <asm/kvm_hyp.h>
 
-#ifndef CONFIG_ARM64
-#define COMPAT_PSR_T_BIT	PSR_T_BIT
-#define COMPAT_PSR_IT_MASK	PSR_IT_MASK
-#endif
-
 /*
  * stolen from arch/arm/kernel/opcodes.c
  *
@@ -150,3 +145,95 @@ void __hyp_text kvm_skip_instr32(struct kvm_vcpu *vcpu, bool is_wide_instr)
 		*vcpu_pc(vcpu) += 4;
 	kvm_adjust_itstate(vcpu);
 }
+
+/*
+ * Table taken from ARMv8 ARM DDI0487B-B, table G1-10.
+ */
+static const u8 return_offsets[8][2] = {
+	[0] = { 0, 0 },		/* Reset, unused */
+	[1] = { 4, 2 },		/* Undefined */
+	[2] = { 0, 0 },		/* SVC, unused */
+	[3] = { 4, 4 },		/* Prefetch abort */
+	[4] = { 8, 8 },		/* Data abort */
+	[5] = { 0, 0 },		/* HVC, unused */
+	[6] = { 4, 4 },		/* IRQ, unused */
+	[7] = { 4, 4 },		/* FIQ, unused */
+};
+
+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 = return_offsets[vect_offset >> 2][is_thumb];
+	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_reg32(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;
+}
+
+void kvm_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;
+}
+
+void kvm_inject_dabt32(struct kvm_vcpu *vcpu, unsigned long addr)
+{
+	inject_abt32(vcpu, false, addr);
+}
+
+void kvm_inject_pabt32(struct kvm_vcpu *vcpu, unsigned long addr)
+{
+	inject_abt32(vcpu, true, addr);
+}