KVM: arm64: Rip out the vestiges of the 'old' ID register scheme

There's no longer a need for the baggage of the old scheme for handling
configurable ID register fields. Rip it all out in favor of the
generalized infrastructure.

Link: https://lore.kernel.org/r/20230609190054.1542113-12-oliver.upton@linux.dev
Signed-off-by: Oliver Upton <oliver.upton@linux.dev>

Author: oupton

arch/arm64/include/asm/kvm_host.h

@@ -241,10 +241,6 @@ struct kvm_arch {
 
 	cpumask_var_t supported_cpus;
 
-	u8 pfr0_csv2;
-	u8 pfr0_csv3;
-	u8 dfr0_pmuver;
-
 	/* Hypercall features firmware registers' descriptor */
 	struct kvm_smccc_features smccc_feat;
 	struct maple_tree smccc_filter;

arch/arm64/kvm/arm.c

@@ -102,22 +102,6 @@ static int kvm_arm_default_max_vcpus(void)
 	return vgic_present ? kvm_vgic_get_max_vcpus() : KVM_MAX_VCPUS;
 }
 
-static void set_default_spectre(struct kvm *kvm)
-{
-	/*
-	 * The default is to expose CSV2 == 1 if the HW isn't affected.
-	 * Although this is a per-CPU feature, we make it global because
-	 * asymmetric systems are just a nuisance.
-	 *
-	 * Userspace can override this as long as it doesn't promise
-	 * the impossible.
-	 */
-	if (arm64_get_spectre_v2_state() == SPECTRE_UNAFFECTED)
-		kvm->arch.pfr0_csv2 = 1;
-	if (arm64_get_meltdown_state() == SPECTRE_UNAFFECTED)
-		kvm->arch.pfr0_csv3 = 1;
-}
-
 /**
  * kvm_arch_init_vm - initializes a VM data structure
  * @kvm:	pointer to the KVM struct
@@ -161,15 +145,8 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
 	/* The maximum number of VCPUs is limited by the host's GIC model */
 	kvm->max_vcpus = kvm_arm_default_max_vcpus();
 
-	set_default_spectre(kvm);
 	kvm_arm_init_hypercalls(kvm);
 
-	/*
-	 * Initialise the default PMUver before there is a chance to
-	 * create an actual PMU.
-	 */
-	kvm->arch.dfr0_pmuver = kvm_arm_pmu_get_pmuver_limit();
-
 	bitmap_zero(kvm->arch.vcpu_features, KVM_VCPU_MAX_FEATURES);
 
 	return 0;

arch/arm64/kvm/sys_regs.c

@@ -1195,14 +1195,6 @@ static bool access_arch_timer(struct kvm_vcpu *vcpu,
 	return true;
 }
 
-static u8 vcpu_pmuver(const struct kvm_vcpu *vcpu)
-{
-	if (kvm_vcpu_has_pmu(vcpu))
-		return vcpu->kvm->arch.dfr0_pmuver;
-
-	return 0;
-}
-
 static s64 kvm_arm64_ftr_safe_value(u32 id, const struct arm64_ftr_bits *ftrp,
 				    s64 new, s64 cur)
 {
@@ -1288,19 +1280,6 @@ static int arm64_check_features(struct kvm_vcpu *vcpu,
 	return 0;
 }
 
-static u8 perfmon_to_pmuver(u8 perfmon)
-{
-	switch (perfmon) {
-	case ID_DFR0_EL1_PerfMon_PMUv3:
-		return ID_AA64DFR0_EL1_PMUVer_IMP;
-	case ID_DFR0_EL1_PerfMon_IMPDEF:
-		return ID_AA64DFR0_EL1_PMUVer_IMP_DEF;
-	default:
-		/* Anything ARMv8.1+ and NI have the same value. For now. */
-		return perfmon;
-	}
-}
-
 static u8 pmuver_to_perfmon(u8 pmuver)
 {
 	switch (pmuver) {
@@ -1327,19 +1306,6 @@ static u64 __kvm_read_sanitised_id_reg(const struct kvm_vcpu *vcpu,
 	val = read_sanitised_ftr_reg(id);
 
 	switch (id) {
-	case SYS_ID_AA64PFR0_EL1:
-		if (!vcpu_has_sve(vcpu))
-			val &= ~ARM64_FEATURE_MASK(ID_AA64PFR0_EL1_SVE);
-		val &= ~ARM64_FEATURE_MASK(ID_AA64PFR0_EL1_AMU);
-		val &= ~ARM64_FEATURE_MASK(ID_AA64PFR0_EL1_CSV2);
-		val |= FIELD_PREP(ARM64_FEATURE_MASK(ID_AA64PFR0_EL1_CSV2), (u64)vcpu->kvm->arch.pfr0_csv2);
-		val &= ~ARM64_FEATURE_MASK(ID_AA64PFR0_EL1_CSV3);
-		val |= FIELD_PREP(ARM64_FEATURE_MASK(ID_AA64PFR0_EL1_CSV3), (u64)vcpu->kvm->arch.pfr0_csv3);
-		if (kvm_vgic_global_state.type == VGIC_V3) {
-			val &= ~ARM64_FEATURE_MASK(ID_AA64PFR0_EL1_GIC);
-			val |= FIELD_PREP(ARM64_FEATURE_MASK(ID_AA64PFR0_EL1_GIC), 1);
-		}
-		break;
 	case SYS_ID_AA64PFR1_EL1:
 		if (!kvm_has_mte(vcpu->kvm))
 			val &= ~ARM64_FEATURE_MASK(ID_AA64PFR1_EL1_MTE);
@@ -1360,22 +1326,6 @@ static u64 __kvm_read_sanitised_id_reg(const struct kvm_vcpu *vcpu,
 		if (!cpus_have_final_cap(ARM64_HAS_WFXT))
 			val &= ~ARM64_FEATURE_MASK(ID_AA64ISAR2_EL1_WFxT);
 		break;
-	case SYS_ID_AA64DFR0_EL1:
-		/* Limit debug to ARMv8.0 */
-		val &= ~ARM64_FEATURE_MASK(ID_AA64DFR0_EL1_DebugVer);
-		val |= FIELD_PREP(ARM64_FEATURE_MASK(ID_AA64DFR0_EL1_DebugVer), 6);
-		/* Set PMUver to the required version */
-		val &= ~ARM64_FEATURE_MASK(ID_AA64DFR0_EL1_PMUVer);
-		val |= FIELD_PREP(ARM64_FEATURE_MASK(ID_AA64DFR0_EL1_PMUVer),
-				  vcpu_pmuver(vcpu));
-		/* Hide SPE from guests */
-		val &= ~ARM64_FEATURE_MASK(ID_AA64DFR0_EL1_PMSVer);
-		break;
-	case SYS_ID_DFR0_EL1:
-		val &= ~ARM64_FEATURE_MASK(ID_DFR0_EL1_PerfMon);
-		val |= FIELD_PREP(ARM64_FEATURE_MASK(ID_DFR0_EL1_PerfMon),
-				  pmuver_to_perfmon(vcpu_pmuver(vcpu)));
-		break;
 	case SYS_ID_AA64MMFR2_EL1:
 		val &= ~ID_AA64MMFR2_EL1_CCIDX_MASK;
 		break;
@@ -1505,26 +1455,6 @@ static u64 read_sanitised_id_aa64pfr0_el1(struct kvm_vcpu *vcpu,
 	return val;
 }
 
-static int set_id_aa64pfr0_el1(struct kvm_vcpu *vcpu,
-			       const struct sys_reg_desc *rd,
-			       u64 val)
-{
-	u8 csv2, csv3;
-	int r;
-
-	csv2 = cpuid_feature_extract_unsigned_field(val, ID_AA64PFR0_EL1_CSV2_SHIFT);
-	csv3 = cpuid_feature_extract_unsigned_field(val, ID_AA64PFR0_EL1_CSV3_SHIFT);
-
-	r = set_id_reg(vcpu, rd, val);
-	if (r)
-		return r;
-
-	vcpu->kvm->arch.pfr0_csv2 = csv2;
-	vcpu->kvm->arch.pfr0_csv3 = csv3;
-
-	return 0;
-}
-
 static u64 read_sanitised_id_aa64dfr0_el1(struct kvm_vcpu *vcpu,
 					  const struct sys_reg_desc *rd)
 {
@@ -1553,7 +1483,6 @@ static int set_id_aa64dfr0_el1(struct kvm_vcpu *vcpu,
 			       u64 val)
 {
 	u8 pmuver = SYS_FIELD_GET(ID_AA64DFR0_EL1, PMUVer, val);
-	int r;
 
 	/*
 	 * Prior to commit 3d0dba5764b9 ("KVM: arm64: PMU: Move the
@@ -1569,17 +1498,10 @@ static int set_id_aa64dfr0_el1(struct kvm_vcpu *vcpu,
 	 * surprising than an ill-guided PMU driver poking at impdef system
 	 * registers that end in an UNDEF...
 	 */
-	if (pmuver == ID_AA64DFR0_EL1_PMUVer_IMP_DEF) {
+	if (pmuver == ID_AA64DFR0_EL1_PMUVer_IMP_DEF)
 		val &= ~ID_AA64DFR0_EL1_PMUVer_MASK;
-		pmuver = 0;
-	}
 
-	r = set_id_reg(vcpu, rd, val);
-	if (r)
-		return r;
-
-	vcpu->kvm->arch.dfr0_pmuver = pmuver;
-	return 0;
+	return set_id_reg(vcpu, rd, val);
 }
 
 static u64 read_sanitised_id_dfr0_el1(struct kvm_vcpu *vcpu,
@@ -1600,7 +1522,6 @@ static int set_id_dfr0_el1(struct kvm_vcpu *vcpu,
 			   u64 val)
 {
 	u8 perfmon = SYS_FIELD_GET(ID_DFR0_EL1, PerfMon, val);
-	int r;
 
 	if (perfmon == ID_DFR0_EL1_PerfMon_IMPDEF) {
 		val &= ~ID_DFR0_EL1_PerfMon_MASK;
@@ -1616,12 +1537,7 @@ static int set_id_dfr0_el1(struct kvm_vcpu *vcpu,
 	if (perfmon != 0 && perfmon < ID_DFR0_EL1_PerfMon_PMUv3)
 		return -EINVAL;
 
-	r = set_id_reg(vcpu, rd, val);
-	if (r)
-		return r;
-
-	vcpu->kvm->arch.dfr0_pmuver = perfmon_to_pmuver(perfmon);
-	return 0;
+	return set_id_reg(vcpu, rd, val);
 }
 
 /*
@@ -2076,7 +1992,7 @@ static const struct sys_reg_desc sys_reg_descs[] = {
 	{ SYS_DESC(SYS_ID_AA64PFR0_EL1),
 	  .access = access_id_reg,
 	  .get_user = get_id_reg,
-	  .set_user = set_id_aa64pfr0_el1,
+	  .set_user = set_id_reg,
 	  .reset = read_sanitised_id_aa64pfr0_el1,
 	  .val = ID_AA64PFR0_EL1_CSV2_MASK | ID_AA64PFR0_EL1_CSV3_MASK, },
 	ID_SANITISED(ID_AA64PFR1_EL1),

include/kvm/arm_pmu.h

@@ -92,8 +92,12 @@ void kvm_vcpu_pmu_restore_host(struct kvm_vcpu *vcpu);
 /*
  * Evaluates as true when emulating PMUv3p5, and false otherwise.
  */
-#define kvm_pmu_is_3p5(vcpu)						\
-	(vcpu->kvm->arch.dfr0_pmuver >= ID_AA64DFR0_EL1_PMUVer_V3P5)
+#define kvm_pmu_is_3p5(vcpu) ({						\
+	u64 val = IDREG(vcpu->kvm, SYS_ID_AA64DFR0_EL1);		\
+	u8 pmuver = SYS_FIELD_GET(ID_AA64DFR0_EL1, PMUVer, val);	\
+									\
+	pmuver >= ID_AA64DFR0_EL1_PMUVer_V3P5;				\
+})
 
 u8 kvm_arm_pmu_get_pmuver_limit(void);