Re: [PATCH v8 6/6] KVM: arm64: Refactor writings for PMUVer/CSV2/CSV3
flat view
From: Jing Zhang <hidden>
Date: 2023-05-17 22:56:31
Also in:
kvm, kvmarm
Hi Suraj, On Wed, May 17, 2023 at 3:00 PM Jitindar Singh, Suraj [off-list ref] wrote:
On Wed, 2023-05-03 at 17:16 +0000, Jing Zhang wrote:quoted
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 <redacted> --- arch/arm64/include/asm/cpufeature.h | 1 + arch/arm64/kernel/cpufeature.c | 2 +- arch/arm64/kvm/id_regs.c | 361 ++++++++++++++++++-------- -- 3 files changed, 242 insertions(+), 122 deletions(-)[ SNIP ]quoted
+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) { - struct kvm_arch *arch = &vcpu->kvm->arch; - u64 sval = val; u8 csv2, csv3; - int ret = 0; /* * Allow AA64PFR0_EL1.CSV2 to be set from userspace as long as@@ -226,26 +338,30 @@ static int set_id_aa64pfr0_el1(struct kvm_vcpu*vcpu, if (csv3 > 1 || (csv3 && arm64_get_meltdown_state() != SPECTRE_UNAFFECTED)) return -EINVAL;Can't we remove the checking of csv[23] here as it will be checked by arm64_check_features()? i.e. in arm64_check_features() we will load the "limit" value from the "reset" function (read_sanitised_id_aa64pfr0_el1()) which has csv[23] set appropriately and limit it to a safe value basically performing the same check as we are here.
The limit and the check here might be different if like arm64_get_meltdown_state() is not SPECTRE_UNAFFECTED. i.e. if we remove the check here, theoretically, the csv3 can be set a value greater 1 if arm64_get_meltdown_state() is not SPECTRE_UNAFFECTED.
quoted
- mutex_lock(&arch->config_lock); - /* 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) { - ret = -EINVAL; - goto out; - } + return set_id_reg(vcpu, rd, val); +} - /* Only allow userspace to change the idregs before VM running */ - if (test_bit(KVM_ARCH_FLAG_HAS_RAN_ONCE, &vcpu->kvm-quoted
arch.flags)) {- if (sval != read_id_reg(vcpu, rd)) - ret = -EBUSY; - } else { - IDREG(vcpu->kvm, reg_to_encoding(rd)) = sval; - } -out: - mutex_unlock(&arch->config_lock); - return ret; +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); + + 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 val; } static int set_id_aa64dfr0_el1(struct kvm_vcpu *vcpu,@@ -255,7 +371,6 @@ static int set_id_aa64dfr0_el1(struct kvm_vcpu*vcpu, struct kvm_arch *arch = &vcpu->kvm->arch; u8 pmuver, host_pmuver; bool valid_pmu; - u64 sval = val; int ret = 0; host_pmuver = kvm_arm_pmu_get_pmuver_limit();@@ -277,40 +392,61 @@ static int set_id_aa64dfr0_el1(struct kvm_vcpu*vcpu, return -EINVAL; mutex_lock(&arch->config_lock); - /* 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) { - ret = -EINVAL; - goto out; - } - /* Only allow userspace to change the idregs before VM running */ if (test_bit(KVM_ARCH_FLAG_HAS_RAN_ONCE, &vcpu->kvm-quoted
arch.flags)) {- if (sval != read_id_reg(vcpu, rd)) + if (val != read_id_reg(vcpu, rd)) ret = -EBUSY; - } else { - if (valid_pmu) { - val = IDREG(vcpu->kvm, SYS_ID_AA64DFR0_EL1); - val &= ~ID_AA64DFR0_EL1_PMUVer_MASK; - val |= FIELD_PREP(ID_AA64DFR0_EL1_PMUVer_MASK, pmuver); - IDREG(vcpu->kvm, SYS_ID_AA64DFR0_EL1) = val; - - val = IDREG(vcpu->kvm, SYS_ID_DFR0_EL1); - val &= ~ID_DFR0_EL1_PerfMon_MASK; - val |= FIELD_PREP(ID_DFR0_EL1_PerfMon_MASK, pmuver_to_perfmon(pmuver)); - IDREG(vcpu->kvm, SYS_ID_DFR0_EL1) = val; - } else { - assign_bit(KVM_ARCH_FLAG_VCPU_HAS_IMP_DEF_PMU, &vcpu->kvm->arch.flags, - pmuver == ID_AA64DFR0_EL1_PMUVer_IMP_DEF); - } + goto out; + } + + if (!valid_pmu) { + /* + * Ignore the PMUVer filed in @val. The PMUVer wouldNit s/filed/field
Will fix.
quoted
be determined + * by arch flags bit KVM_ARCH_FLAG_VCPU_HAS_IMP_DEF_PMU, + */ + pmuver = FIELD_GET(ID_AA64DFR0_EL1_PMUVer_MASK, + IDREG(vcpu->kvm, SYS_ID_AA64DFR0_EL1)); + val &= ~ID_AA64DFR0_EL1_PMUVer_MASK; + val |= FIELD_PREP(ID_AA64DFR0_EL1_PMUVer_MASK, pmuver); } + ret = arm64_check_features(vcpu, rd, val); + if (ret) + goto out; + + IDREG(vcpu->kvm, SYS_ID_AA64DFR0_EL1) = val; + + val = IDREG(vcpu->kvm, SYS_ID_DFR0_EL1); + val &= ~ID_DFR0_EL1_PerfMon_MASK; + val |= FIELD_PREP(ID_DFR0_EL1_PerfMon_MASK, pmuver_to_perfmon(pmuver)); + IDREG(vcpu->kvm, SYS_ID_DFR0_EL1) = val; + + if (!valid_pmu) + assign_bit(KVM_ARCH_FLAG_VCPU_HAS_IMP_DEF_PMU, &vcpu-quoted
kvm->arch.flags,+ pmuver == ID_AA64DFR0_EL1_PMUVer_IMP_DEF); + out: mutex_unlock(&arch->config_lock); return ret; } +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)@@ -318,7 +454,6 @@ static int set_id_dfr0_el1(struct kvm_vcpu *vcpu, struct kvm_arch *arch = &vcpu->kvm->arch; u8 perfmon, host_perfmon; bool valid_pmu; - u64 sval = val; int ret = 0; host_perfmon =pmuver_to_perfmon(kvm_arm_pmu_get_pmuver_limit());@@ -341,35 +476,39 @@ static int set_id_dfr0_el1(struct kvm_vcpu*vcpu, return -EINVAL; mutex_lock(&arch->config_lock); - /* 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) { - ret = -EINVAL; - goto out; - } - /* Only allow userspace to change the idregs before VM running */ if (test_bit(KVM_ARCH_FLAG_HAS_RAN_ONCE, &vcpu->kvm-quoted
arch.flags)) {- if (sval != read_id_reg(vcpu, rd)) + if (val != read_id_reg(vcpu, rd)) ret = -EBUSY; - } else { - if (valid_pmu) { - val = IDREG(vcpu->kvm, SYS_ID_DFR0_EL1); - val &= ~ID_DFR0_EL1_PerfMon_MASK; - val |= FIELD_PREP(ID_DFR0_EL1_PerfMon_MASK, perfmon); - IDREG(vcpu->kvm, SYS_ID_DFR0_EL1) = val; - - val = IDREG(vcpu->kvm, SYS_ID_AA64DFR0_EL1); - val &= ~ID_AA64DFR0_EL1_PMUVer_MASK; - val |= FIELD_PREP(ID_AA64DFR0_EL1_PMUVer_MASK, perfmon_to_pmuver(perfmon)); - IDREG(vcpu->kvm, SYS_ID_AA64DFR0_EL1) = val; - } else { - assign_bit(KVM_ARCH_FLAG_VCPU_HAS_IMP_DEF_PMU, &vcpu->kvm->arch.flags, - perfmon == ID_DFR0_EL1_PerfMon_IMPDEF); - } + goto out; + } + + if (!valid_pmu) { + /* + * Ignore the PerfMon filed in @val. The PerfMonNit s/filed/field
Thanks, will fix it.
quoted
would be determined + * by arch flags bit KVM_ARCH_FLAG_VCPU_HAS_IMP_DEF_PMU, + */ + perfmon = FIELD_GET(ID_DFR0_EL1_PerfMon_MASK, + IDREG(vcpu->kvm, SYS_ID_DFR0_EL1)); + val &= ~ID_DFR0_EL1_PerfMon_MASK; + val |= FIELD_PREP(ID_DFR0_EL1_PerfMon_MASK, perfmon); } + ret = arm64_check_features(vcpu, rd, val); + if (ret) + goto out; + + IDREG(vcpu->kvm, SYS_ID_DFR0_EL1) = val; + + val = IDREG(vcpu->kvm, SYS_ID_AA64DFR0_EL1); + val &= ~ID_AA64DFR0_EL1_PMUVer_MASK; + val |= FIELD_PREP(ID_AA64DFR0_EL1_PMUVer_MASK, perfmon_to_pmuver(perfmon)); + IDREG(vcpu->kvm, SYS_ID_AA64DFR0_EL1) = val; + + if (!valid_pmu) + assign_bit(KVM_ARCH_FLAG_VCPU_HAS_IMP_DEF_PMU, &vcpu-quoted
kvm->arch.flags,+ perfmon == ID_DFR0_EL1_PerfMon_IMPDEF); + out: mutex_unlock(&arch->config_lock); return ret;Otherwise looks good! Thanks, Suraj
Thanks, Jing _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel