[PATCH v6 6/6] KVM: arm64: Refactor writings for PMUVer/CSV2/CSV3
Jing Zhang
jingzhangos at google.com
Mon Apr 3 20:53:44 PDT 2023
Refactor writings for ID_AA64PFR0_EL1.[CSV2|CSV3],
ID_AA64DFR0_EL1.PMUVer and ID_DFR0_ELF.PerfMon based on utilities
introduced by ID register descriptor array.
Signed-off-by: Jing Zhang <jingzhangos at google.com>
---
arch/arm64/include/asm/cpufeature.h | 1 +
arch/arm64/kernel/cpufeature.c | 2 +-
arch/arm64/kvm/id_regs.c | 284 ++++++++++++++++++++--------
3 files changed, 203 insertions(+), 84 deletions(-)
diff --git a/arch/arm64/include/asm/cpufeature.h b/arch/arm64/include/asm/cpufeature.h
index 6bf013fb110d..dc769c2eb7a4 100644
--- a/arch/arm64/include/asm/cpufeature.h
+++ b/arch/arm64/include/asm/cpufeature.h
@@ -915,6 +915,7 @@ static inline unsigned int get_vmid_bits(u64 mmfr1)
return 8;
}
+s64 arm64_ftr_safe_value(const struct arm64_ftr_bits *ftrp, s64 new, s64 cur);
struct arm64_ftr_reg *get_arm64_ftr_reg(u32 sys_id);
extern struct arm64_ftr_override id_aa64mmfr1_override;
diff --git a/arch/arm64/kernel/cpufeature.c b/arch/arm64/kernel/cpufeature.c
index 2e3e55139777..677ec4fe9f6b 100644
--- a/arch/arm64/kernel/cpufeature.c
+++ b/arch/arm64/kernel/cpufeature.c
@@ -791,7 +791,7 @@ static u64 arm64_ftr_set_value(const struct arm64_ftr_bits *ftrp, s64 reg,
return reg;
}
-static s64 arm64_ftr_safe_value(const struct arm64_ftr_bits *ftrp, s64 new,
+s64 arm64_ftr_safe_value(const struct arm64_ftr_bits *ftrp, s64 new,
s64 cur)
{
s64 ret = 0;
diff --git a/arch/arm64/kvm/id_regs.c b/arch/arm64/kvm/id_regs.c
index fe37b6786b4c..33968ada29bb 100644
--- a/arch/arm64/kvm/id_regs.c
+++ b/arch/arm64/kvm/id_regs.c
@@ -18,6 +18,66 @@
#include "sys_regs.h"
+/**
+ * arm64_check_features() - Check if a feature register value constitutes
+ * a subset of features indicated by the idreg's KVM sanitised limit.
+ *
+ * This function will check if each feature field of @val is the "safe" value
+ * against idreg's KVM sanitised limit return from reset() callback.
+ * If a field value in @val is the same as the one in limit, it is always
+ * considered the safe value regardless For register fields that are not in
+ * writable, only the value in limit is considered the safe value.
+ *
+ * Return: 0 if all the fields are safe. Otherwise, return negative errno.
+ */
+static int arm64_check_features(struct kvm_vcpu *vcpu,
+ const struct sys_reg_desc *rd,
+ u64 val)
+{
+ const struct arm64_ftr_reg *ftr_reg;
+ const struct arm64_ftr_bits *ftrp = NULL;
+ u32 id = reg_to_encoding(rd);
+ u64 writable_mask = rd->val;
+ u64 limit = 0;
+ u64 mask = 0;
+
+ /* For hidden and unallocated idregs without reset, only val = 0 is allowed. */
+ if (rd->reset) {
+ limit = rd->reset(vcpu, rd);
+ ftr_reg = get_arm64_ftr_reg(id);
+ if (!ftr_reg)
+ return -EINVAL;
+ ftrp = ftr_reg->ftr_bits;
+ }
+
+ for (; ftrp && ftrp->width; ftrp++) {
+ s64 f_val, f_lim, safe_val;
+ u64 ftr_mask;
+
+ ftr_mask = arm64_ftr_mask(ftrp);
+ if ((ftr_mask & writable_mask) != ftr_mask)
+ continue;
+
+ f_val = arm64_ftr_value(ftrp, val);
+ f_lim = arm64_ftr_value(ftrp, limit);
+ mask |= ftr_mask;
+
+ if (f_val == f_lim)
+ safe_val = f_val;
+ else
+ safe_val = arm64_ftr_safe_value(ftrp, f_val, f_lim);
+
+ if (safe_val != f_val)
+ return -E2BIG;
+ }
+
+ /* For fields that are not writable, values in limit are the safe values. */
+ if ((val & ~mask) != (limit & ~mask))
+ return -E2BIG;
+
+ return 0;
+}
+
static u8 vcpu_pmuver(const struct kvm_vcpu *vcpu)
{
if (kvm_vcpu_has_pmu(vcpu))
@@ -68,7 +128,6 @@ u64 kvm_arm_read_id_reg(const struct kvm_vcpu *vcpu, u32 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);
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);
@@ -95,15 +154,10 @@ u64 kvm_arm_read_id_reg(const struct kvm_vcpu *vcpu, u32 id)
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);
@@ -162,9 +216,14 @@ static int get_id_reg(struct kvm_vcpu *vcpu, const struct sys_reg_desc *rd,
static int set_id_reg(struct kvm_vcpu *vcpu, const struct sys_reg_desc *rd,
u64 val)
{
- /* This is what we mean by invariant: you can't change it. */
- if (val != read_id_reg(vcpu, rd))
- return -EINVAL;
+ u32 id = reg_to_encoding(rd);
+ int ret;
+
+ ret = arm64_check_features(vcpu, rd, val);
+ if (ret)
+ return ret;
+
+ IDREG(vcpu->kvm, id) = val;
return 0;
}
@@ -198,12 +257,40 @@ static unsigned int aa32_id_visibility(const struct kvm_vcpu *vcpu,
return id_visibility(vcpu, r);
}
+static u64 read_sanitised_id_aa64pfr0_el1(struct kvm_vcpu *vcpu,
+ const struct sys_reg_desc *rd)
+{
+ u64 val;
+ u32 id = reg_to_encoding(rd);
+
+ val = read_sanitised_ftr_reg(id);
+ /*
+ * 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) {
+ val &= ~ARM64_FEATURE_MASK(ID_AA64PFR0_EL1_CSV2);
+ val |= FIELD_PREP(ARM64_FEATURE_MASK(ID_AA64PFR0_EL1_CSV2), 1);
+ }
+ if (arm64_get_meltdown_state() == SPECTRE_UNAFFECTED) {
+ val &= ~ARM64_FEATURE_MASK(ID_AA64PFR0_EL1_CSV3);
+ val |= FIELD_PREP(ARM64_FEATURE_MASK(ID_AA64PFR0_EL1_CSV3), 1);
+ }
+
+ val &= ~ARM64_FEATURE_MASK(ID_AA64PFR0_EL1_AMU);
+
+ return val;
+}
+
static int set_id_aa64pfr0_el1(struct kvm_vcpu *vcpu,
const struct sys_reg_desc *rd,
u64 val)
{
u8 csv2, csv3;
- u64 sval = val;
/*
* Allow AA64PFR0_EL1.CSV2 to be set from userspace as long as
@@ -219,16 +306,30 @@ static int set_id_aa64pfr0_el1(struct kvm_vcpu *vcpu,
if (csv3 > 1 || (csv3 && arm64_get_meltdown_state() != SPECTRE_UNAFFECTED))
return -EINVAL;
- /* We can only differ with CSV[23], and anything else is an error */
- val ^= read_id_reg(vcpu, rd);
- val &= ~(ARM64_FEATURE_MASK(ID_AA64PFR0_EL1_CSV2) |
- ARM64_FEATURE_MASK(ID_AA64PFR0_EL1_CSV3));
- if (val)
- return -EINVAL;
+ return set_id_reg(vcpu, rd, val);
+}
+
+static u64 read_sanitised_id_aa64dfr0_el1(struct kvm_vcpu *vcpu,
+ const struct sys_reg_desc *rd)
+{
+ u64 val;
+ u32 id = reg_to_encoding(rd);
- IDREG(vcpu->kvm, reg_to_encoding(rd)) = sval;
+ val = read_sanitised_ftr_reg(id);
+ /* Limit debug to ARMv8.0 */
+ val &= ~ARM64_FEATURE_MASK(ID_AA64DFR0_EL1_DebugVer);
+ val |= FIELD_PREP(ARM64_FEATURE_MASK(ID_AA64DFR0_EL1_DebugVer), 6);
+ /*
+ * Initialise the default PMUver before there is a chance to
+ * create an actual PMU.
+ */
+ val &= ~ARM64_FEATURE_MASK(ID_AA64DFR0_EL1_PMUVer);
+ val |= FIELD_PREP(ARM64_FEATURE_MASK(ID_AA64DFR0_EL1_PMUVer),
+ kvm_arm_pmu_get_pmuver_limit());
+ /* Hide SPE from guests */
+ val &= ~ARM64_FEATURE_MASK(ID_AA64DFR0_EL1_PMSVer);
- return 0;
+ return val;
}
static int set_id_aa64dfr0_el1(struct kvm_vcpu *vcpu,
@@ -237,6 +338,7 @@ static int set_id_aa64dfr0_el1(struct kvm_vcpu *vcpu,
{
u8 pmuver, host_pmuver;
bool valid_pmu;
+ int ret;
host_pmuver = kvm_arm_pmu_get_pmuver_limit();
@@ -256,36 +358,61 @@ static int set_id_aa64dfr0_el1(struct kvm_vcpu *vcpu,
if (kvm_vcpu_has_pmu(vcpu) != valid_pmu)
return -EINVAL;
- /* We can only differ with PMUver, and anything else is an error */
- val ^= read_id_reg(vcpu, rd);
- val &= ~ARM64_FEATURE_MASK(ID_AA64DFR0_EL1_PMUVer);
- if (val)
- return -EINVAL;
+ if (!valid_pmu) {
+ /*
+ * Ignore the PMUVer filed in @val. The PMUVer would be determined
+ * by arch flags bit KVM_ARCH_FLAG_VCPU_HAS_IMP_DEF_PMU,
+ */
+ pmuver = FIELD_GET(ID_AA64DFR0_EL1_PMUVer_MASK, read_id_reg(vcpu, rd));
+ val &= ~ID_AA64DFR0_EL1_PMUVer_MASK;
+ val |= FIELD_PREP(ID_AA64DFR0_EL1_PMUVer_MASK, pmuver);
+ }
- if (valid_pmu) {
- mutex_lock(&vcpu->kvm->arch.config_lock);
- IDREG(vcpu->kvm, SYS_ID_AA64DFR0_EL1) &= ~ID_AA64DFR0_EL1_PMUVer_MASK;
- IDREG(vcpu->kvm, SYS_ID_AA64DFR0_EL1) |= FIELD_PREP(ID_AA64DFR0_EL1_PMUVer_MASK,
- pmuver);
+ mutex_lock(&vcpu->kvm->arch.config_lock);
- IDREG(vcpu->kvm, SYS_ID_DFR0_EL1) &= ~ID_DFR0_EL1_PerfMon_MASK;
- IDREG(vcpu->kvm, SYS_ID_DFR0_EL1) |= FIELD_PREP(ID_DFR0_EL1_PerfMon_MASK,
- pmuver_to_perfmon(pmuver));
+ ret = set_id_reg(vcpu, rd, val);
+ if (ret) {
mutex_unlock(&vcpu->kvm->arch.config_lock);
- } else {
+ return ret;
+ }
+
+ IDREG(vcpu->kvm, SYS_ID_DFR0_EL1) &= ~ID_DFR0_EL1_PerfMon_MASK;
+ IDREG(vcpu->kvm, SYS_ID_DFR0_EL1) |= FIELD_PREP(ID_DFR0_EL1_PerfMon_MASK,
+ pmuver_to_perfmon(pmuver));
+
+ if (!valid_pmu)
assign_bit(KVM_ARCH_FLAG_VCPU_HAS_IMP_DEF_PMU, &vcpu->kvm->arch.flags,
pmuver == ID_AA64DFR0_EL1_PMUVer_IMP_DEF);
- }
+
+ mutex_unlock(&vcpu->kvm->arch.config_lock);
return 0;
}
+static u64 read_sanitised_id_dfr0_el1(struct kvm_vcpu *vcpu,
+ const struct sys_reg_desc *rd)
+{
+ u64 val;
+ u32 id = reg_to_encoding(rd);
+
+ val = read_sanitised_ftr_reg(id);
+ /*
+ * Initialise the default PMUver before there is a chance to
+ * create an actual PMU.
+ */
+ val &= ~ARM64_FEATURE_MASK(ID_DFR0_EL1_PerfMon);
+ val |= FIELD_PREP(ARM64_FEATURE_MASK(ID_DFR0_EL1_PerfMon), kvm_arm_pmu_get_pmuver_limit());
+
+ return val;
+}
+
static int set_id_dfr0_el1(struct kvm_vcpu *vcpu,
const struct sys_reg_desc *rd,
u64 val)
{
u8 perfmon, host_perfmon;
bool valid_pmu;
+ int ret;
host_perfmon = pmuver_to_perfmon(kvm_arm_pmu_get_pmuver_limit());
@@ -306,25 +433,33 @@ static int set_id_dfr0_el1(struct kvm_vcpu *vcpu,
if (kvm_vcpu_has_pmu(vcpu) != valid_pmu)
return -EINVAL;
- /* We can only differ with PerfMon, and anything else is an error */
- val ^= read_id_reg(vcpu, rd);
- val &= ~ARM64_FEATURE_MASK(ID_DFR0_EL1_PerfMon);
- if (val)
- return -EINVAL;
+ if (!valid_pmu) {
+ /*
+ * Ignore the PerfMon filed in @val. The PerfMon would be determined
+ * by arch flags bit KVM_ARCH_FLAG_VCPU_HAS_IMP_DEF_PMU,
+ */
+ perfmon = FIELD_GET(ID_DFR0_EL1_PerfMon_MASK, read_id_reg(vcpu, rd));
+ val &= ~ID_DFR0_EL1_PerfMon_MASK;
+ val |= FIELD_PREP(ID_DFR0_EL1_PerfMon_MASK, perfmon);
+ }
- if (valid_pmu) {
- mutex_lock(&vcpu->kvm->arch.config_lock);
- IDREG(vcpu->kvm, SYS_ID_DFR0_EL1) &= ~ID_DFR0_EL1_PerfMon_MASK;
- IDREG(vcpu->kvm, SYS_ID_DFR0_EL1) |= FIELD_PREP(ID_DFR0_EL1_PerfMon_MASK, perfmon);
+ mutex_lock(&vcpu->kvm->arch.config_lock);
- IDREG(vcpu->kvm, SYS_ID_AA64DFR0_EL1) &= ~ID_AA64DFR0_EL1_PMUVer_MASK;
- IDREG(vcpu->kvm, SYS_ID_AA64DFR0_EL1) |= FIELD_PREP(ID_AA64DFR0_EL1_PMUVer_MASK,
- perfmon_to_pmuver(perfmon));
+ ret = set_id_reg(vcpu, rd, val);
+ if (ret) {
mutex_unlock(&vcpu->kvm->arch.config_lock);
- } else {
+ return ret;
+ }
+
+ IDREG(vcpu->kvm, SYS_ID_AA64DFR0_EL1) &= ~ID_AA64DFR0_EL1_PMUVer_MASK;
+ IDREG(vcpu->kvm, SYS_ID_AA64DFR0_EL1) |= FIELD_PREP(ID_AA64DFR0_EL1_PMUVer_MASK,
+ perfmon_to_pmuver(perfmon));
+
+ if (!valid_pmu)
assign_bit(KVM_ARCH_FLAG_VCPU_HAS_IMP_DEF_PMU, &vcpu->kvm->arch.flags,
perfmon == ID_DFR0_EL1_PerfMon_IMPDEF);
- }
+
+ mutex_unlock(&vcpu->kvm->arch.config_lock);
return 0;
}
@@ -402,9 +537,13 @@ const struct sys_reg_desc id_reg_descs[KVM_ARM_ID_REG_NUM] = {
/* CRm=1 */
AA32_ID_SANITISED(ID_PFR0_EL1),
AA32_ID_SANITISED(ID_PFR1_EL1),
- { SYS_DESC(SYS_ID_DFR0_EL1), .access = access_id_reg,
- .get_user = get_id_reg, .set_user = set_id_dfr0_el1,
- .visibility = aa32_id_visibility, },
+ { SYS_DESC(SYS_ID_DFR0_EL1),
+ .access = access_id_reg,
+ .get_user = get_id_reg,
+ .set_user = set_id_dfr0_el1,
+ .visibility = aa32_id_visibility,
+ .reset = read_sanitised_id_dfr0_el1,
+ .val = ID_DFR0_EL1_PerfMon_MASK, },
ID_HIDDEN(ID_AFR0_EL1),
AA32_ID_SANITISED(ID_MMFR0_EL1),
AA32_ID_SANITISED(ID_MMFR1_EL1),
@@ -433,8 +572,12 @@ const struct sys_reg_desc id_reg_descs[KVM_ARM_ID_REG_NUM] = {
/* AArch64 ID registers */
/* CRm=4 */
- { SYS_DESC(SYS_ID_AA64PFR0_EL1), .access = access_id_reg,
- .get_user = get_id_reg, .set_user = set_id_aa64pfr0_el1, },
+ { SYS_DESC(SYS_ID_AA64PFR0_EL1),
+ .access = access_id_reg,
+ .get_user = get_id_reg,
+ .set_user = set_id_aa64pfr0_el1,
+ .reset = read_sanitised_id_aa64pfr0_el1,
+ .val = ID_AA64PFR0_EL1_CSV2_MASK | ID_AA64PFR0_EL1_CSV3_MASK, },
ID_SANITISED(ID_AA64PFR1_EL1),
ID_UNALLOCATED(4, 2),
ID_UNALLOCATED(4, 3),
@@ -444,8 +587,12 @@ const struct sys_reg_desc id_reg_descs[KVM_ARM_ID_REG_NUM] = {
ID_UNALLOCATED(4, 7),
/* CRm=5 */
- { SYS_DESC(SYS_ID_AA64DFR0_EL1), .access = access_id_reg,
- .get_user = get_id_reg, .set_user = set_id_aa64dfr0_el1, },
+ { SYS_DESC(SYS_ID_AA64DFR0_EL1),
+ .access = access_id_reg,
+ .get_user = get_id_reg,
+ .set_user = set_id_aa64dfr0_el1,
+ .reset = read_sanitised_id_aa64dfr0_el1,
+ .val = ID_AA64DFR0_EL1_PMUVer_MASK, },
ID_SANITISED(ID_AA64DFR1_EL1),
ID_UNALLOCATED(5, 2),
ID_UNALLOCATED(5, 3),
@@ -520,33 +667,4 @@ void kvm_arm_init_id_regs(struct kvm *kvm)
IDREG(kvm, id) = val;
}
-
- /*
- * 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.
- */
- val = IDREG(kvm, SYS_ID_AA64PFR0_EL1);
-
- if (arm64_get_spectre_v2_state() == SPECTRE_UNAFFECTED) {
- val &= ~ARM64_FEATURE_MASK(ID_AA64PFR0_EL1_CSV2);
- val |= FIELD_PREP(ARM64_FEATURE_MASK(ID_AA64PFR0_EL1_CSV2), 1);
- }
- if (arm64_get_meltdown_state() == SPECTRE_UNAFFECTED) {
- val &= ~ARM64_FEATURE_MASK(ID_AA64PFR0_EL1_CSV3);
- val |= FIELD_PREP(ARM64_FEATURE_MASK(ID_AA64PFR0_EL1_CSV3), 1);
- }
-
- IDREG(kvm, SYS_ID_AA64PFR0_EL1) = val;
-
- /*
- * Initialise the default PMUver before there is a chance to
- * create an actual PMU.
- */
- IDREG(kvm, SYS_ID_AA64DFR0_EL1) &= ~ARM64_FEATURE_MASK(ID_AA64DFR0_EL1_PMUVer);
- IDREG(kvm, SYS_ID_AA64DFR0_EL1) |= FIELD_PREP(ARM64_FEATURE_MASK(ID_AA64DFR0_EL1_PMUVer),
- kvm_arm_pmu_get_pmuver_limit());
}
--
2.40.0.348.gf938b09366-goog
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