Merge branch kvm-arm64/feat_e2h0 into kvmarm/next

* kvm-arm64/feat_e2h0:
  : Support for FEAT_E2H0, courtesy of Marc Zyngier
  :
  : As described in the cover letter:
  :
  :   Since ARMv8.1, the architecture has grown the VHE feature, which makes
  :   EL2 a superset of EL1. With ARMv9.5 (and retroactively allowed from
  :   ARMv8.1), the architecture allows implementations to have VHE as the
  :   *only* implemented behaviour, meaning that HCR_EL2.E2H can be
  :   implemented as RES1. As a follow-up, HCR_EL2.NV1 can also be
  :   implemented as RES0, making the VHE-ness of the architecture
  :   recursive.
  :
  : This series adds support for detecting the architectural feature of E2H
  : being RES1, leveraging the existing infrastructure for handling
  : out-of-spec CPUs that are VHE-only. Additionally, the (incomplete) NV
  : infrastructure in KVM is updated to enforce E2H=1 for guest hypervisors
  : on implementations that do not support NV1.
  arm64: cpufeatures: Fix FEAT_NV check when checking for FEAT_NV1
  arm64: cpufeatures: Only check for NV1 if NV is present
  arm64: cpufeatures: Add missing ID_AA64MMFR4_EL1 to __read_sysreg_by_encoding()
  KVM: arm64: Handle Apple M2 as not having HCR_EL2.NV1 implemented
  KVM: arm64: Force guest's HCR_EL2.E2H RES1 when NV1 is not implemented
  KVM: arm64: Expose ID_AA64MMFR4_EL1 to guests
  arm64: Treat HCR_EL2.E2H as RES1 when ID_AA64MMFR4_EL1.E2H0 is negative
  arm64: cpufeature: Detect HCR_EL2.NV1 being RES0
  arm64: cpufeature: Add ID_AA64MMFR4_EL1 handling
  arm64: sysreg: Add layout for ID_AA64MMFR4_EL1
  arm64: cpufeature: Correctly display signed override values
  arm64: cpufeatures: Correctly handle signed values
  arm64: Add macro to compose a sysreg field value

Signed-off-by: Oliver Upton <oliver.upton@linux.dev>

Author: oupton

arch/arm64/include/asm/cpu.h

@@ -56,6 +56,7 @@ struct cpuinfo_arm64 {
 	u64		reg_id_aa64mmfr1;
 	u64		reg_id_aa64mmfr2;
 	u64		reg_id_aa64mmfr3;
+	u64		reg_id_aa64mmfr4;
 	u64		reg_id_aa64pfr0;
 	u64		reg_id_aa64pfr1;
 	u64		reg_id_aa64zfr0;

arch/arm64/include/asm/cpufeature.h

@@ -363,6 +363,7 @@ struct arm64_cpu_capabilities {
 			u8 field_pos;
 			u8 field_width;
 			u8 min_field_value;
+			u8 max_field_value;
 			u8 hwcap_type;
 			bool sign;
 			unsigned long hwcap;

arch/arm64/include/asm/kvm_emulate.h

@@ -209,7 +209,8 @@ static inline bool vcpu_is_el2(const struct kvm_vcpu *vcpu)
 
 static inline bool __vcpu_el2_e2h_is_set(const struct kvm_cpu_context *ctxt)
 {
-	return ctxt_sys_reg(ctxt, HCR_EL2) & HCR_E2H;
+	return (!cpus_have_final_cap(ARM64_HAS_HCR_NV1) ||
+		(ctxt_sys_reg(ctxt, HCR_EL2) & HCR_E2H));
 }
 
 static inline bool vcpu_el2_e2h_is_set(const struct kvm_vcpu *vcpu)

arch/arm64/include/asm/sysreg.h

@@ -1181,14 +1181,17 @@
 	par;								\
 })
 
+#define SYS_FIELD_VALUE(reg, field, val)	reg##_##field##_##val
+
 #define SYS_FIELD_GET(reg, field, val)		\
 		 FIELD_GET(reg##_##field##_MASK, val)
 
 #define SYS_FIELD_PREP(reg, field, val)		\
 		 FIELD_PREP(reg##_##field##_MASK, val)
 
 #define SYS_FIELD_PREP_ENUM(reg, field, val)		\
-		 FIELD_PREP(reg##_##field##_MASK, reg##_##field##_##val)
+		 FIELD_PREP(reg##_##field##_MASK,	\
+			    SYS_FIELD_VALUE(reg, field, val))
 
 #endif
 

arch/arm64/kernel/cpufeature.c

@@ -140,12 +140,42 @@ void dump_cpu_features(void)
 	pr_emerg("0x%*pb\n", ARM64_NCAPS, &system_cpucaps);
 }
 
+#define __ARM64_MAX_POSITIVE(reg, field)				\
+		((reg##_##field##_SIGNED ?				\
+		  BIT(reg##_##field##_WIDTH - 1) :			\
+		  BIT(reg##_##field##_WIDTH)) - 1)
+
+#define __ARM64_MIN_NEGATIVE(reg, field)  BIT(reg##_##field##_WIDTH - 1)
+
+#define __ARM64_CPUID_FIELDS(reg, field, min_value, max_value)		\
+		.sys_reg = SYS_##reg,					\
+		.field_pos = reg##_##field##_SHIFT,			\
+		.field_width = reg##_##field##_WIDTH,			\
+		.sign = reg##_##field##_SIGNED,				\
+		.min_field_value = min_value,				\
+		.max_field_value = max_value,
+
+/*
+ * ARM64_CPUID_FIELDS() encodes a field with a range from min_value to
+ * an implicit maximum that depends on the sign-ess of the field.
+ *
+ * An unsigned field will be capped at all ones, while a signed field
+ * will be limited to the positive half only.
+ */
 #define ARM64_CPUID_FIELDS(reg, field, min_value)			\
-		.sys_reg = SYS_##reg,							\
-		.field_pos = reg##_##field##_SHIFT,						\
-		.field_width = reg##_##field##_WIDTH,						\
-		.sign = reg##_##field##_SIGNED,							\
-		.min_field_value = reg##_##field##_##min_value,
+	__ARM64_CPUID_FIELDS(reg, field,				\
+			     SYS_FIELD_VALUE(reg, field, min_value),	\
+			     __ARM64_MAX_POSITIVE(reg, field))
+
+/*
+ * ARM64_CPUID_FIELDS_NEG() encodes a field with a range from an
+ * implicit minimal value to max_value. This should be used when
+ * matching a non-implemented property.
+ */
+#define ARM64_CPUID_FIELDS_NEG(reg, field, max_value)			\
+	__ARM64_CPUID_FIELDS(reg, field,				\
+			     __ARM64_MIN_NEGATIVE(reg, field),		\
+			     SYS_FIELD_VALUE(reg, field, max_value))
 
 #define __ARM64_FTR_BITS(SIGNED, VISIBLE, STRICT, TYPE, SHIFT, WIDTH, SAFE_VAL) \
 	{						\
@@ -407,6 +437,11 @@ static const struct arm64_ftr_bits ftr_id_aa64mmfr3[] = {
 	ARM64_FTR_END,
 };
 
+static const struct arm64_ftr_bits ftr_id_aa64mmfr4[] = {
+	S_ARM64_FTR_BITS(FTR_HIDDEN, FTR_STRICT, FTR_LOWER_SAFE, ID_AA64MMFR4_EL1_E2H0_SHIFT, 4, 0),
+	ARM64_FTR_END,
+};
+
 static const struct arm64_ftr_bits ftr_ctr[] = {
 	ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_EXACT, 31, 1, 1), /* RES1 */
 	ARM64_FTR_BITS(FTR_VISIBLE, FTR_STRICT, FTR_LOWER_SAFE, CTR_EL0_DIC_SHIFT, 1, 1),
@@ -724,6 +759,7 @@ static const struct __ftr_reg_entry {
 			       &id_aa64mmfr1_override),
 	ARM64_FTR_REG(SYS_ID_AA64MMFR2_EL1, ftr_id_aa64mmfr2),
 	ARM64_FTR_REG(SYS_ID_AA64MMFR3_EL1, ftr_id_aa64mmfr3),
+	ARM64_FTR_REG(SYS_ID_AA64MMFR4_EL1, ftr_id_aa64mmfr4),
 
 	/* Op1 = 1, CRn = 0, CRm = 0 */
 	ARM64_FTR_REG(SYS_GMID_EL1, ftr_gmid),
@@ -919,7 +955,8 @@ static void init_cpu_ftr_reg(u32 sys_reg, u64 new)
 				pr_warn("%s[%d:%d]: %s to %llx\n",
 					reg->name,
 					ftrp->shift + ftrp->width - 1,
-					ftrp->shift, str, tmp);
+					ftrp->shift, str,
+					tmp & (BIT(ftrp->width) - 1));
 		} else if ((ftr_mask & reg->override->val) == ftr_mask) {
 			reg->override->val &= ~ftr_mask;
 			pr_warn("%s[%d:%d]: impossible override, ignored\n",
@@ -1047,6 +1084,7 @@ void __init init_cpu_features(struct cpuinfo_arm64 *info)
 	init_cpu_ftr_reg(SYS_ID_AA64MMFR1_EL1, info->reg_id_aa64mmfr1);
 	init_cpu_ftr_reg(SYS_ID_AA64MMFR2_EL1, info->reg_id_aa64mmfr2);
 	init_cpu_ftr_reg(SYS_ID_AA64MMFR3_EL1, info->reg_id_aa64mmfr3);
+	init_cpu_ftr_reg(SYS_ID_AA64MMFR4_EL1, info->reg_id_aa64mmfr4);
 	init_cpu_ftr_reg(SYS_ID_AA64PFR0_EL1, info->reg_id_aa64pfr0);
 	init_cpu_ftr_reg(SYS_ID_AA64PFR1_EL1, info->reg_id_aa64pfr1);
 	init_cpu_ftr_reg(SYS_ID_AA64ZFR0_EL1, info->reg_id_aa64zfr0);
@@ -1418,6 +1456,7 @@ u64 __read_sysreg_by_encoding(u32 sys_id)
 	read_sysreg_case(SYS_ID_AA64MMFR1_EL1);
 	read_sysreg_case(SYS_ID_AA64MMFR2_EL1);
 	read_sysreg_case(SYS_ID_AA64MMFR3_EL1);
+	read_sysreg_case(SYS_ID_AA64MMFR4_EL1);
 	read_sysreg_case(SYS_ID_AA64ISAR0_EL1);
 	read_sysreg_case(SYS_ID_AA64ISAR1_EL1);
 	read_sysreg_case(SYS_ID_AA64ISAR2_EL1);
@@ -1451,11 +1490,28 @@ has_always(const struct arm64_cpu_capabilities *entry, int scope)
 static bool
 feature_matches(u64 reg, const struct arm64_cpu_capabilities *entry)
 {
-	int val = cpuid_feature_extract_field_width(reg, entry->field_pos,
-						    entry->field_width,
-						    entry->sign);
+	int val, min, max;
+	u64 tmp;
+
+	val = cpuid_feature_extract_field_width(reg, entry->field_pos,
+						entry->field_width,
+						entry->sign);
+
+	tmp = entry->min_field_value;
+	tmp <<= entry->field_pos;
 
-	return val >= entry->min_field_value;
+	min = cpuid_feature_extract_field_width(tmp, entry->field_pos,
+						entry->field_width,
+						entry->sign);
+
+	tmp = entry->max_field_value;
+	tmp <<= entry->field_pos;
+
+	max = cpuid_feature_extract_field_width(tmp, entry->field_pos,
+						entry->field_width,
+						entry->sign);
+
+	return val >= min && val <= max;
 }
 
 static u64
@@ -1739,6 +1795,28 @@ static bool unmap_kernel_at_el0(const struct arm64_cpu_capabilities *entry,
 	return !meltdown_safe;
 }
 
+static bool has_nv1(const struct arm64_cpu_capabilities *entry, int scope)
+{
+	/*
+	 * Although the Apple M2 family appears to support NV1, the
+	 * PTW barfs on the nVHE EL2 S1 page table format. Pretend
+	 * that it doesn't support NV1 at all.
+	 */
+	static const struct midr_range nv1_ni_list[] = {
+		MIDR_ALL_VERSIONS(MIDR_APPLE_M2_BLIZZARD),
+		MIDR_ALL_VERSIONS(MIDR_APPLE_M2_AVALANCHE),
+		MIDR_ALL_VERSIONS(MIDR_APPLE_M2_BLIZZARD_PRO),
+		MIDR_ALL_VERSIONS(MIDR_APPLE_M2_AVALANCHE_PRO),
+		MIDR_ALL_VERSIONS(MIDR_APPLE_M2_BLIZZARD_MAX),
+		MIDR_ALL_VERSIONS(MIDR_APPLE_M2_AVALANCHE_MAX),
+		{}
+	};
+
+	return (__system_matches_cap(ARM64_HAS_NESTED_VIRT) &&
+		!(has_cpuid_feature(entry, scope) ||
+		  is_midr_in_range_list(read_cpuid_id(), nv1_ni_list)));
+}
+
 #if defined(ID_AA64MMFR0_EL1_TGRAN_LPA2) && defined(ID_AA64MMFR0_EL1_TGRAN_2_SUPPORTED_LPA2)
 static bool has_lpa2_at_stage1(u64 mmfr0)
 {
@@ -2739,6 +2817,13 @@ static const struct arm64_cpu_capabilities arm64_features[] = {
 		.type = ARM64_CPUCAP_SYSTEM_FEATURE,
 		.matches = has_lpa2,
 	},
+	{
+		.desc = "NV1",
+		.capability = ARM64_HAS_HCR_NV1,
+		.type = ARM64_CPUCAP_SYSTEM_FEATURE,
+		.matches = has_nv1,
+		ARM64_CPUID_FIELDS_NEG(ID_AA64MMFR4_EL1, E2H0, NI_NV1)
+	},
 	{},
 };
 

arch/arm64/kernel/cpuinfo.c

@@ -447,6 +447,7 @@ static void __cpuinfo_store_cpu(struct cpuinfo_arm64 *info)
 	info->reg_id_aa64mmfr1 = read_cpuid(ID_AA64MMFR1_EL1);
 	info->reg_id_aa64mmfr2 = read_cpuid(ID_AA64MMFR2_EL1);
 	info->reg_id_aa64mmfr3 = read_cpuid(ID_AA64MMFR3_EL1);
+	info->reg_id_aa64mmfr4 = read_cpuid(ID_AA64MMFR4_EL1);
 	info->reg_id_aa64pfr0 = read_cpuid(ID_AA64PFR0_EL1);
 	info->reg_id_aa64pfr1 = read_cpuid(ID_AA64PFR1_EL1);
 	info->reg_id_aa64zfr0 = read_cpuid(ID_AA64ZFR0_EL1);

arch/arm64/kernel/head.S

@@ -584,25 +584,32 @@ SYM_INNER_LABEL(init_el2, SYM_L_LOCAL)
 	mov_q	x1, INIT_SCTLR_EL1_MMU_OFF
 
 	/*
-	 * Fruity CPUs seem to have HCR_EL2.E2H set to RES1,
-	 * making it impossible to start in nVHE mode. Is that
-	 * compliant with the architecture? Absolutely not!
+	 * Compliant CPUs advertise their VHE-onlyness with
+	 * ID_AA64MMFR4_EL1.E2H0 < 0. HCR_EL2.E2H can be
+	 * RES1 in that case.
+	 *
+	 * Fruity CPUs seem to have HCR_EL2.E2H set to RES1, but
+	 * don't advertise it (they predate this relaxation).
 	 */
+	mrs_s	x0, SYS_ID_AA64MMFR4_EL1
+	ubfx	x0, x0, #ID_AA64MMFR4_EL1_E2H0_SHIFT, #ID_AA64MMFR4_EL1_E2H0_WIDTH
+	tbnz	x0, #(ID_AA64MMFR4_EL1_E2H0_SHIFT + ID_AA64MMFR4_EL1_E2H0_WIDTH - 1), 1f
+
 	mrs	x0, hcr_el2
 	and	x0, x0, #HCR_E2H
-	cbz	x0, 1f
-
+	cbz	x0, 2f
+1:
 	/* Set a sane SCTLR_EL1, the VHE way */
 	pre_disable_mmu_workaround
 	msr_s	SYS_SCTLR_EL12, x1
 	mov	x2, #BOOT_CPU_FLAG_E2H
-	b	2f
+	b	3f
 
-1:
+2:
 	pre_disable_mmu_workaround
 	msr	sctlr_el1, x1
 	mov	x2, xzr
-2:
+3:
 	__init_el2_nvhe_prepare_eret
 
 	mov	w0, #BOOT_CPU_MODE_EL2

arch/arm64/kvm/nested.c

@@ -133,6 +133,13 @@ static u64 limit_nv_id_reg(u32 id, u64 val)
 		val |= FIELD_PREP(NV_FTR(MMFR2, TTL), 0b0001);
 		break;
 
+	case SYS_ID_AA64MMFR4_EL1:
+		val = 0;
+		if (!cpus_have_final_cap(ARM64_HAS_HCR_NV1))
+			val |= FIELD_PREP(NV_FTR(MMFR4, E2H0),
+					  ID_AA64MMFR4_EL1_E2H0_NI_NV1);
+		break;
+
 	case SYS_ID_AA64DFR0_EL1:
 		/* Only limited support for PMU, Debug, BPs and WPs */
 		val &= (NV_FTR(DFR0, PMUVer)	|

arch/arm64/kvm/sys_regs.c

@@ -1685,7 +1685,8 @@ static u64 read_sanitised_id_aa64pfr0_el1(struct kvm_vcpu *vcpu,
 	u64 __f_val = FIELD_GET(reg##_##field##_MASK, val);		       \
 	(val) &= ~reg##_##field##_MASK;					       \
 	(val) |= FIELD_PREP(reg##_##field##_MASK,			       \
-			min(__f_val, (u64)reg##_##field##_##limit));	       \
+			    min(__f_val,				       \
+				(u64)SYS_FIELD_VALUE(reg, field, limit)));     \
 	(val);								       \
 })
 
@@ -2174,6 +2175,16 @@ static bool access_spsr(struct kvm_vcpu *vcpu,
 	return true;
 }
 
+static u64 reset_hcr(struct kvm_vcpu *vcpu, const struct sys_reg_desc *r)
+{
+	u64 val = r->val;
+
+	if (!cpus_have_final_cap(ARM64_HAS_HCR_NV1))
+		val |= HCR_E2H;
+
+	return __vcpu_sys_reg(vcpu, r->reg) = val;
+}
+
 /*
  * Architected system registers.
  * Important: Must be sorted ascending by Op0, Op1, CRn, CRm, Op2
@@ -2349,7 +2360,7 @@ static const struct sys_reg_desc sys_reg_descs[] = {
 					ID_AA64MMFR2_EL1_NV |
 					ID_AA64MMFR2_EL1_CCIDX)),
 	ID_SANITISED(ID_AA64MMFR3_EL1),
-	ID_UNALLOCATED(7,4),
+	ID_SANITISED(ID_AA64MMFR4_EL1),
 	ID_UNALLOCATED(7,5),
 	ID_UNALLOCATED(7,6),
 	ID_UNALLOCATED(7,7),
@@ -2665,7 +2676,7 @@ static const struct sys_reg_desc sys_reg_descs[] = {
 	EL2_REG_VNCR(VMPIDR_EL2, reset_unknown, 0),
 	EL2_REG(SCTLR_EL2, access_rw, reset_val, SCTLR_EL2_RES1),
 	EL2_REG(ACTLR_EL2, access_rw, reset_val, 0),
-	EL2_REG_VNCR(HCR_EL2, reset_val, 0),
+	EL2_REG_VNCR(HCR_EL2, reset_hcr, 0),
 	EL2_REG(MDCR_EL2, access_rw, reset_val, 0),
 	EL2_REG(CPTR_EL2, access_rw, reset_val, CPTR_NVHE_EL2_RES1),
 	EL2_REG_VNCR(HSTR_EL2, reset_val, 0),

arch/arm64/tools/cpucaps

@@ -35,6 +35,7 @@ HAS_GENERIC_AUTH_IMP_DEF
 HAS_GIC_CPUIF_SYSREGS
 HAS_GIC_PRIO_MASKING
 HAS_GIC_PRIO_RELAXED_SYNC
+HAS_HCR_NV1
 HAS_HCX
 HAS_LDAPR
 HAS_LPA2