arm64: KVM: 32bit handling of coprocessor traps

Provide the necessary infrastructure to trap coprocessor accesses that
occur when running 32bit guests.

Also wire SMC and HVC trapped in 32bit mode while were at it.
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/include/asm/kvm_coproc.h

@@ -32,11 +32,16 @@ struct kvm_sys_reg_table {
 
 struct kvm_sys_reg_target_table {
 	struct kvm_sys_reg_table table64;
+	struct kvm_sys_reg_table table32;
 };
 
 void kvm_register_target_sys_reg_table(unsigned int target,
 				       struct kvm_sys_reg_target_table *table);
 
+int kvm_handle_cp14_load_store(struct kvm_vcpu *vcpu, struct kvm_run *run);
+int kvm_handle_cp14_access(struct kvm_vcpu *vcpu, struct kvm_run *run);
+int kvm_handle_cp15_32(struct kvm_vcpu *vcpu, struct kvm_run *run);
+int kvm_handle_cp15_64(struct kvm_vcpu *vcpu, struct kvm_run *run);
 int kvm_handle_sys_reg(struct kvm_vcpu *vcpu, struct kvm_run *run);
 
 #define kvm_coproc_table_init kvm_sys_reg_table_init

arch/arm64/kvm/handle_exit.c

@@ -62,6 +62,13 @@ static int kvm_handle_wfi(struct kvm_vcpu *vcpu, struct kvm_run *run)
 
 static exit_handle_fn arm_exit_handlers[] = {
 	[ESR_EL2_EC_WFI]	= kvm_handle_wfi,
+	[ESR_EL2_EC_CP15_32]	= kvm_handle_cp15_32,
+	[ESR_EL2_EC_CP15_64]	= kvm_handle_cp15_64,
+	[ESR_EL2_EC_CP14_MR]	= kvm_handle_cp14_access,
+	[ESR_EL2_EC_CP14_LS]	= kvm_handle_cp14_load_store,
+	[ESR_EL2_EC_CP14_64]	= kvm_handle_cp14_access,
+	[ESR_EL2_EC_HVC32]	= handle_hvc,
+	[ESR_EL2_EC_SMC32]	= handle_smc,
 	[ESR_EL2_EC_HVC64]	= handle_hvc,
 	[ESR_EL2_EC_SMC64]	= handle_smc,
 	[ESR_EL2_EC_SYS64]	= kvm_handle_sys_reg,

arch/arm64/kvm/sys_regs.c

@@ -38,6 +38,10 @@
  * types are different. My gut feeling is that it should be pretty
  * easy to merge, but that would be an ABI breakage -- again. VFP
  * would also need to be abstracted.
+ *
+ * For AArch32, we only take care of what is being trapped. Anything
+ * that has to do with init and userspace access has to go via the
+ * 64bit interface.
  */
 
 /* 3 bits per cache level, as per CLIDR, but non-existent caches always 0 */
@@ -166,6 +170,16 @@ static const struct sys_reg_desc sys_reg_descs[] = {
 	{ Op0(0b01), Op1(0b000), CRn(0b0111), CRm(0b1110), Op2(0b010),
 	  access_dcsw },
 
+	/* TEECR32_EL1 */
+	{ Op0(0b10), Op1(0b010), CRn(0b0000), CRm(0b0000), Op2(0b000),
+	  NULL, reset_val, TEECR32_EL1, 0 },
+	/* TEEHBR32_EL1 */
+	{ Op0(0b10), Op1(0b010), CRn(0b0001), CRm(0b0000), Op2(0b000),
+	  NULL, reset_val, TEEHBR32_EL1, 0 },
+	/* DBGVCR32_EL2 */
+	{ Op0(0b10), Op1(0b100), CRn(0b0000), CRm(0b0111), Op2(0b000),
+	  NULL, reset_val, DBGVCR32_EL2, 0 },
+
 	/* MPIDR_EL1 */
 	{ Op0(0b11), Op1(0b000), CRn(0b0000), CRm(0b0000), Op2(0b101),
 	  NULL, reset_mpidr, MPIDR_EL1 },
@@ -276,6 +290,39 @@ static const struct sys_reg_desc sys_reg_descs[] = {
 	/* TPIDRRO_EL0 */
 	{ Op0(0b11), Op1(0b011), CRn(0b1101), CRm(0b0000), Op2(0b011),
 	  NULL, reset_unknown, TPIDRRO_EL0 },
+
+	/* DACR32_EL2 */
+	{ Op0(0b11), Op1(0b100), CRn(0b0011), CRm(0b0000), Op2(0b000),
+	  NULL, reset_unknown, DACR32_EL2 },
+	/* IFSR32_EL2 */
+	{ Op0(0b11), Op1(0b100), CRn(0b0101), CRm(0b0000), Op2(0b001),
+	  NULL, reset_unknown, IFSR32_EL2 },
+	/* FPEXC32_EL2 */
+	{ Op0(0b11), Op1(0b100), CRn(0b0101), CRm(0b0011), Op2(0b000),
+	  NULL, reset_val, FPEXC32_EL2, 0x70 },
+};
+
+/* Trapped cp15 registers */
+static const struct sys_reg_desc cp15_regs[] = {
+	/*
+	 * DC{C,I,CI}SW operations:
+	 */
+	{ Op1( 0), CRn( 7), CRm( 6), Op2( 2), access_dcsw },
+	{ Op1( 0), CRn( 7), CRm(10), Op2( 2), access_dcsw },
+	{ Op1( 0), CRn( 7), CRm(14), Op2( 2), access_dcsw },
+	{ Op1( 0), CRn( 9), CRm(12), Op2( 0), pm_fake },
+	{ Op1( 0), CRn( 9), CRm(12), Op2( 1), pm_fake },
+	{ Op1( 0), CRn( 9), CRm(12), Op2( 2), pm_fake },
+	{ Op1( 0), CRn( 9), CRm(12), Op2( 3), pm_fake },
+	{ Op1( 0), CRn( 9), CRm(12), Op2( 5), pm_fake },
+	{ Op1( 0), CRn( 9), CRm(12), Op2( 6), pm_fake },
+	{ Op1( 0), CRn( 9), CRm(12), Op2( 7), pm_fake },
+	{ Op1( 0), CRn( 9), CRm(13), Op2( 0), pm_fake },
+	{ Op1( 0), CRn( 9), CRm(13), Op2( 1), pm_fake },
+	{ Op1( 0), CRn( 9), CRm(13), Op2( 2), pm_fake },
+	{ Op1( 0), CRn( 9), CRm(14), Op2( 0), pm_fake },
+	{ Op1( 0), CRn( 9), CRm(14), Op2( 1), pm_fake },
+	{ Op1( 0), CRn( 9), CRm(14), Op2( 2), pm_fake },
 };
 
 /* Target specific emulation tables */
@@ -288,13 +335,20 @@ void kvm_register_target_sys_reg_table(unsigned int target,
 }
 
 /* Get specific register table for this target. */
-static const struct sys_reg_desc *get_target_table(unsigned target, size_t *num)
+static const struct sys_reg_desc *get_target_table(unsigned target,
+						   bool mode_is_64,
+						   size_t *num)
 {
 	struct kvm_sys_reg_target_table *table;
 
 	table = target_tables[target];
+	if (mode_is_64) {
 		*num = table->table64.num;
 		return table->table64.table;
+	} else {
+		*num = table->table32.num;
+		return table->table32.table;
+	}
 }
 
 static const struct sys_reg_desc *find_reg(const struct sys_reg_params *params,
@@ -322,13 +376,126 @@ static const struct sys_reg_desc *find_reg(const struct sys_reg_params *params,
 	return NULL;
 }
 
+int kvm_handle_cp14_load_store(struct kvm_vcpu *vcpu, struct kvm_run *run)
+{
+	kvm_inject_undefined(vcpu);
+	return 1;
+}
+
+int kvm_handle_cp14_access(struct kvm_vcpu *vcpu, struct kvm_run *run)
+{
+	kvm_inject_undefined(vcpu);
+	return 1;
+}
+
+static void emulate_cp15(struct kvm_vcpu *vcpu,
+			 const struct sys_reg_params *params)
+{
+	size_t num;
+	const struct sys_reg_desc *table, *r;
+
+	table = get_target_table(vcpu->arch.target, false, &num);
+
+	/* Search target-specific then generic table. */
+	r = find_reg(params, table, num);
+	if (!r)
+		r = find_reg(params, cp15_regs, ARRAY_SIZE(cp15_regs));
+
+	if (likely(r)) {
+		/*
+		 * Not having an accessor means that we have
+		 * configured a trap that we don't know how to
+		 * handle. This certainly qualifies as a gross bug
+		 * that should be fixed right away.
+		 */
+		BUG_ON(!r->access);
+
+		if (likely(r->access(vcpu, params, r))) {
+			/* Skip instruction, since it was emulated */
+			kvm_skip_instr(vcpu, kvm_vcpu_trap_il_is32bit(vcpu));
+			return;
+		}
+		/* If access function fails, it should complain. */
+	}
+
+	kvm_err("Unsupported guest CP15 access at: %08lx\n", *vcpu_pc(vcpu));
+	print_sys_reg_instr(params);
+	kvm_inject_undefined(vcpu);
+}
+
+/**
+ * kvm_handle_cp15_64 -- handles a mrrc/mcrr trap on a guest CP15 access
+ * @vcpu: The VCPU pointer
+ * @run:  The kvm_run struct
+ */
+int kvm_handle_cp15_64(struct kvm_vcpu *vcpu, struct kvm_run *run)
+{
+	struct sys_reg_params params;
+	u32 hsr = kvm_vcpu_get_hsr(vcpu);
+	int Rt2 = (hsr >> 10) & 0xf;
+
+	params.CRm = (hsr >> 1) & 0xf;
+	params.Rt = (hsr >> 5) & 0xf;
+	params.is_write = ((hsr & 1) == 0);
+
+	params.Op0 = 0;
+	params.Op1 = (hsr >> 16) & 0xf;
+	params.Op2 = 0;
+	params.CRn = 0;
+
+	/*
+	 * Massive hack here. Store Rt2 in the top 32bits so we only
+	 * have one register to deal with. As we use the same trap
+	 * backends between AArch32 and AArch64, we get away with it.
+	 */
+	if (params.is_write) {
+		u64 val = *vcpu_reg(vcpu, params.Rt);
+		val &= 0xffffffff;
+		val |= *vcpu_reg(vcpu, Rt2) << 32;
+		*vcpu_reg(vcpu, params.Rt) = val;
+	}
+
+	emulate_cp15(vcpu, &params);
+
+	/* Do the opposite hack for the read side */
+	if (!params.is_write) {
+		u64 val = *vcpu_reg(vcpu, params.Rt);
+		val >>= 32;
+		*vcpu_reg(vcpu, Rt2) = val;
+	}
+
+	return 1;
+}
+
+/**
+ * kvm_handle_cp15_32 -- handles a mrc/mcr trap on a guest CP15 access
+ * @vcpu: The VCPU pointer
+ * @run:  The kvm_run struct
+ */
+int kvm_handle_cp15_32(struct kvm_vcpu *vcpu, struct kvm_run *run)
+{
+	struct sys_reg_params params;
+	u32 hsr = kvm_vcpu_get_hsr(vcpu);
+
+	params.CRm = (hsr >> 1) & 0xf;
+	params.Rt  = (hsr >> 5) & 0xf;
+	params.is_write = ((hsr & 1) == 0);
+	params.CRn = (hsr >> 10) & 0xf;
+	params.Op0 = 0;
+	params.Op1 = (hsr >> 14) & 0x7;
+	params.Op2 = (hsr >> 17) & 0x7;
+
+	emulate_cp15(vcpu, &params);
+	return 1;
+}
+
 static int emulate_sys_reg(struct kvm_vcpu *vcpu,
 			   const struct sys_reg_params *params)
 {
 	size_t num;
 	const struct sys_reg_desc *table, *r;
 
-	table = get_target_table(vcpu->arch.target, &num);
+	table = get_target_table(vcpu->arch.target, true, &num);
 
 	/* Search target-specific then generic table. */
 	r = find_reg(params, table, num);
@@ -438,7 +605,7 @@ static const struct sys_reg_desc *index_to_sys_reg_desc(struct kvm_vcpu *vcpu,
 	if (!index_to_params(id, &params))
 		return NULL;
 
-	table = get_target_table(vcpu->arch.target, &num);
+	table = get_target_table(vcpu->arch.target, true, &num);
 	r = find_reg(&params, table, num);
 	if (!r)
 		r = find_reg(&params, sys_reg_descs, ARRAY_SIZE(sys_reg_descs));
@@ -762,7 +929,7 @@ static int walk_sys_regs(struct kvm_vcpu *vcpu, u64 __user *uind)
 	size_t num;
 
 	/* We check for duplicates here, to allow arch-specific overrides. */
-	i1 = get_target_table(vcpu->arch.target, &num);
+	i1 = get_target_table(vcpu->arch.target, true, &num);
 	end1 = i1 + num;
 	i2 = sys_reg_descs;
 	end2 = sys_reg_descs + ARRAY_SIZE(sys_reg_descs);
@@ -874,7 +1041,7 @@ void kvm_reset_sys_regs(struct kvm_vcpu *vcpu)
 	/* Generic chip reset first (so target could override). */
 	reset_sys_reg_descs(vcpu, sys_reg_descs, ARRAY_SIZE(sys_reg_descs));
 
-	table = get_target_table(vcpu->arch.target, &num);
+	table = get_target_table(vcpu->arch.target, true, &num);
 	reset_sys_reg_descs(vcpu, table, num);
 
 	for (num = 1; num < NR_SYS_REGS; num++)