diff --git a/Documentation/virt/kvm/api.rst b/Documentation/virt/kvm/api.rst index edc682a94ca4f8a727c5cdecab763d67883de0f9..d75c9a7a7193c7840e320e8341e7b10840425c2e 100644 --- a/Documentation/virt/kvm/api.rst +++ b/Documentation/virt/kvm/api.rst @@ -3422,6 +3422,8 @@ return indicates the attribute is implemented. It does not necessarily indicate that the attribute can be read or written in the device's current state. "addr" is ignored. +.. _KVM_ARM_VCPU_INIT: + 4.82 KVM_ARM_VCPU_INIT ---------------------- @@ -6122,6 +6124,56 @@ writes to the CNTVCT_EL0 and CNTPCT_EL0 registers using the SET_ONE_REG interface. No error will be returned, but the resulting offset will not be applied. +.. _KVM_ARM_GET_REG_WRITABLE_MASKS: + +4.139 KVM_ARM_GET_REG_WRITABLE_MASKS +------------------------------------------- + +:Capability: KVM_CAP_ARM_SUPPORTED_REG_MASK_RANGES +:Architectures: arm64 +:Type: vm ioctl +:Parameters: struct reg_mask_range (in/out) +:Returns: 0 on success, < 0 on error + + +:: + + #define KVM_ARM_FEATURE_ID_RANGE 0 + #define KVM_ARM_FEATURE_ID_RANGE_SIZE (3 * 8 * 8) + + struct reg_mask_range { + __u64 addr; /* Pointer to mask array */ + __u32 range; /* Requested range */ + __u32 reserved[13]; + }; + +This ioctl copies the writable masks for a selected range of registers to +userspace. + +The ``addr`` field is a pointer to the destination array where KVM copies +the writable masks. + +The ``range`` field indicates the requested range of registers. +``KVM_CHECK_EXTENSION`` for the ``KVM_CAP_ARM_SUPPORTED_REG_MASK_RANGES`` +capability returns the supported ranges, expressed as a set of flags. Each +flag's bit index represents a possible value for the ``range`` field. +All other values are reserved for future use and KVM may return an error. + +The ``reserved[13]`` array is reserved for future use and should be 0, or +KVM may return an error. + +KVM_ARM_FEATURE_ID_RANGE (0) +^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +The Feature ID range is defined as the AArch64 System register space with +op0==3, op1=={0, 1, 3}, CRn==0, CRm=={0-7}, op2=={0-7}. + +The mask returned array pointed to by ``addr`` is indexed by the macro +``ARM64_FEATURE_ID_RANGE_IDX(op0, op1, crn, crm, op2)``, allowing userspace +to know what fields can be changed for the system register described by +``op0, op1, crn, crm, op2``. KVM rejects ID register values that describe a +superset of the features supported by the system. + 5. The kvm_run structure ======================== diff --git a/Documentation/virt/kvm/arm/index.rst b/Documentation/virt/kvm/arm/index.rst index e84848432158084f789b0c18764afd1f3fb547ac..7f231c724e16756f63b2a38e9e2df6a60727d2ee 100644 --- a/Documentation/virt/kvm/arm/index.rst +++ b/Documentation/virt/kvm/arm/index.rst @@ -11,3 +11,4 @@ ARM hypercalls pvtime ptp_kvm + vcpu-features diff --git a/Documentation/virt/kvm/arm/vcpu-features.rst b/Documentation/virt/kvm/arm/vcpu-features.rst new file mode 100644 index 0000000000000000000000000000000000000000..f7cc6d8d8b74052616acbf0dab3b92ec13badf22 --- /dev/null +++ b/Documentation/virt/kvm/arm/vcpu-features.rst @@ -0,0 +1,48 @@ +.. SPDX-License-Identifier: GPL-2.0 + +=============================== +vCPU feature selection on arm64 +=============================== + +KVM/arm64 provides two mechanisms that allow userspace to configure +the CPU features presented to the guest. + +KVM_ARM_VCPU_INIT +================= + +The ``KVM_ARM_VCPU_INIT`` ioctl accepts a bitmap of feature flags +(``struct kvm_vcpu_init::features``). Features enabled by this interface are +*opt-in* and may change/extend UAPI. See :ref:`KVM_ARM_VCPU_INIT` for complete +documentation of the features controlled by the ioctl. + +Otherwise, all CPU features supported by KVM are described by the architected +ID registers. + +The ID Registers +================ + +The Arm architecture specifies a range of *ID Registers* that describe the set +of architectural features supported by the CPU implementation. KVM initializes +the guest's ID registers to the maximum set of CPU features supported by the +system. The ID register values may be VM-scoped in KVM, meaning that the +values could be shared for all vCPUs in a VM. + +KVM allows userspace to *opt-out* of certain CPU features described by the ID +registers by writing values to them via the ``KVM_SET_ONE_REG`` ioctl. The ID +registers are mutable until the VM has started, i.e. userspace has called +``KVM_RUN`` on at least one vCPU in the VM. Userspace can discover what fields +are mutable in the ID registers using the ``KVM_ARM_GET_REG_WRITABLE_MASKS``. +See the :ref:`ioctl documentation ` for more +details. + +Userspace is allowed to *limit* or *mask* CPU features according to the rules +outlined by the architecture in DDI0487J.a D19.1.3 'Principles of the ID +scheme for fields in ID register'. KVM does not allow ID register values that +exceed the capabilities of the system. + +.. warning:: + It is **strongly recommended** that userspace modify the ID register values + before accessing the rest of the vCPU's CPU register state. KVM may use the + ID register values to control feature emulation. Interleaving ID register + modification with other system register accesses may lead to unpredictable + behavior. diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h index 8c64fa87279b9b43bf826272d21e29e222dd9b0a..ab005ceca231ea882864588af06c1e5b161c94a7 100644 --- a/arch/arm64/include/asm/kvm_host.h +++ b/arch/arm64/include/asm/kvm_host.h @@ -1146,6 +1146,8 @@ int kvm_vm_ioctl_mte_copy_tags(struct kvm *kvm, struct kvm_arm_copy_mte_tags *copy_tags); int kvm_vm_ioctl_set_counter_offset(struct kvm *kvm, struct kvm_arm_counter_offset *offset); +int kvm_vm_ioctl_get_reg_writable_masks(struct kvm *kvm, + struct reg_mask_range *range); /* Guest/host FPSIMD coordination helpers */ int kvm_arch_vcpu_run_map_fp(struct kvm_vcpu *vcpu); diff --git a/arch/arm64/include/uapi/asm/kvm.h b/arch/arm64/include/uapi/asm/kvm.h index f7ddd73a8c0fa2dabffd2782f674f3b484079875..89d2fc872d9f5e63dce2e2a74dfb422c9e255030 100644 --- a/arch/arm64/include/uapi/asm/kvm.h +++ b/arch/arm64/include/uapi/asm/kvm.h @@ -505,6 +505,38 @@ struct kvm_smccc_filter { #define KVM_HYPERCALL_EXIT_SMC (1U << 0) #define KVM_HYPERCALL_EXIT_16BIT (1U << 1) +/* + * Get feature ID registers userspace writable mask. + * + * From DDI0487J.a, D19.2.66 ("ID_AA64MMFR2_EL1, AArch64 Memory Model + * Feature Register 2"): + * + * "The Feature ID space is defined as the System register space in + * AArch64 with op0==3, op1=={0, 1, 3}, CRn==0, CRm=={0-7}, + * op2=={0-7}." + * + * This covers all currently known R/O registers that indicate + * anything useful feature wise, including the ID registers. + * + * If we ever need to introduce a new range, it will be described as + * such in the range field. + */ +#define KVM_ARM_FEATURE_ID_RANGE_IDX(op0, op1, crn, crm, op2) \ + ({ \ + __u64 __op1 = (op1) & 3; \ + __op1 -= (__op1 == 3); \ + (__op1 << 6 | ((crm) & 7) << 3 | (op2)); \ + }) + +#define KVM_ARM_FEATURE_ID_RANGE 0 +#define KVM_ARM_FEATURE_ID_RANGE_SIZE (3 * 8 * 8) + +struct reg_mask_range { + __u64 addr; /* Pointer to mask array */ + __u32 range; /* Requested range */ + __u32 reserved[13]; +}; + #endif #endif /* __ARM_KVM_H__ */ diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c index 859689e80ec445869635521c8b3e70f33a5f66a3..026c4de5d762d1f64af5e03beadeec8c8e7810c8 100644 --- a/arch/arm64/kvm/arm.c +++ b/arch/arm64/kvm/arm.c @@ -344,6 +344,9 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext) r = sdev_enable; break; #endif + case KVM_CAP_ARM_SUPPORTED_REG_MASK_RANGES: + r = BIT(0); + break; default: r = 0; } @@ -1748,6 +1751,13 @@ int kvm_arch_vm_ioctl(struct file *filp, unsigned int ioctl, unsigned long arg) return 0; } #endif + case KVM_ARM_GET_REG_WRITABLE_MASKS: { + struct reg_mask_range range; + + if (copy_from_user(&range, argp, sizeof(range))) + return -EFAULT; + return kvm_vm_ioctl_get_reg_writable_masks(kvm, &range); + } default: return -EINVAL; } diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c index b4608d1b08b5f6d6f83dce3419397acebf32a1a3..fbced3eeeeb8e181ccbe3eb6a0d94b025eb01cde 100644 --- a/arch/arm64/kvm/sys_regs.c +++ b/arch/arm64/kvm/sys_regs.c @@ -379,7 +379,7 @@ static bool trap_loregion(struct kvm_vcpu *vcpu, struct sys_reg_params *p, const struct sys_reg_desc *r) { - u64 val = read_sanitised_ftr_reg(SYS_ID_AA64MMFR1_EL1); + u64 val = IDREG(vcpu->kvm, SYS_ID_AA64MMFR1_EL1); u32 sr = reg_to_encoding(r); if (!(val & (0xfUL << ID_AA64MMFR1_EL1_LO_SHIFT))) { @@ -1241,8 +1241,14 @@ static s64 kvm_arm64_ftr_safe_value(u32 id, const struct arm64_ftr_bits *ftrp, /* Some features have different safe value type in KVM than host features */ switch (id) { case SYS_ID_AA64DFR0_EL1: - if (kvm_ftr.shift == ID_AA64DFR0_EL1_PMUVer_SHIFT) + switch (kvm_ftr.shift) { + case ID_AA64DFR0_EL1_PMUVer_SHIFT: kvm_ftr.type = FTR_LOWER_SAFE; + break; + case ID_AA64DFR0_EL1_DebugVer_SHIFT: + kvm_ftr.type = FTR_LOWER_SAFE; + break; + } break; case SYS_ID_DFR0_EL1: if (kvm_ftr.shift == ID_DFR0_EL1_PerfMon_SHIFT) @@ -1429,6 +1435,13 @@ static inline bool is_id_reg(u32 id) sys_reg_CRm(id) < 8); } +static inline bool is_aa32_id_reg(u32 id) +{ + return (sys_reg_Op0(id) == 3 && sys_reg_Op1(id) == 0 && + sys_reg_CRn(id) == 0 && sys_reg_CRm(id) >= 1 && + sys_reg_CRm(id) <= 3); +} + static unsigned int id_visibility(const struct kvm_vcpu *vcpu, const struct sys_reg_desc *r) { @@ -1533,14 +1546,21 @@ static u64 read_sanitised_id_aa64pfr0_el1(struct kvm_vcpu *vcpu, return val; } +#define ID_REG_LIMIT_FIELD_ENUM(val, reg, field, limit) \ +({ \ + 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)); \ + (val); \ +}) + static u64 read_sanitised_id_aa64dfr0_el1(struct kvm_vcpu *vcpu, const struct sys_reg_desc *rd) { u64 val = read_sanitised_ftr_reg(SYS_ID_AA64DFR0_EL1); - /* Limit debug to ARMv8.0 */ - val &= ~ID_AA64DFR0_EL1_DebugVer_MASK; - val |= SYS_FIELD_PREP_ENUM(ID_AA64DFR0_EL1, DebugVer, IMP); + val = ID_REG_LIMIT_FIELD_ENUM(val, ID_AA64DFR0_EL1, DebugVer, V8P8); /* * Only initialize the PMU version if the vCPU was configured with one. @@ -1560,6 +1580,7 @@ static int set_id_aa64dfr0_el1(struct kvm_vcpu *vcpu, const struct sys_reg_desc *rd, u64 val) { + u8 debugver = SYS_FIELD_GET(ID_AA64DFR0_EL1, DebugVer, val); u8 pmuver = SYS_FIELD_GET(ID_AA64DFR0_EL1, PMUVer, val); /* @@ -1579,6 +1600,13 @@ static int set_id_aa64dfr0_el1(struct kvm_vcpu *vcpu, if (pmuver == ID_AA64DFR0_EL1_PMUVer_IMP_DEF) val &= ~ID_AA64DFR0_EL1_PMUVer_MASK; + /* + * ID_AA64DFR0_EL1.DebugVer is one of those awkward fields with a + * nonzero minimum safe value. + */ + if (debugver < ID_AA64DFR0_EL1_DebugVer_IMP) + return -EINVAL; + return set_id_reg(vcpu, rd, val); } @@ -1592,6 +1620,8 @@ static u64 read_sanitised_id_dfr0_el1(struct kvm_vcpu *vcpu, if (kvm_vcpu_has_pmu(vcpu)) val |= SYS_FIELD_PREP(ID_DFR0_EL1, PerfMon, perfmon); + val = ID_REG_LIMIT_FIELD_ENUM(val, ID_DFR0_EL1, CopDbg, Debugv8p8); + return val; } @@ -1600,6 +1630,7 @@ static int set_id_dfr0_el1(struct kvm_vcpu *vcpu, u64 val) { u8 perfmon = SYS_FIELD_GET(ID_DFR0_EL1, PerfMon, val); + u8 copdbg = SYS_FIELD_GET(ID_DFR0_EL1, CopDbg, val); if (perfmon == ID_DFR0_EL1_PerfMon_IMPDEF) { val &= ~ID_DFR0_EL1_PerfMon_MASK; @@ -1615,6 +1646,9 @@ static int set_id_dfr0_el1(struct kvm_vcpu *vcpu, if (perfmon != 0 && perfmon < ID_DFR0_EL1_PerfMon_PMUv3) return -EINVAL; + if (copdbg < ID_DFR0_EL1_CopDbg_Armv8) + return -EINVAL; + return set_id_reg(vcpu, rd, val); } @@ -1881,11 +1915,14 @@ static unsigned int elx2_visibility(const struct kvm_vcpu *vcpu, * from userspace. */ -/* sys_reg_desc initialiser for known cpufeature ID registers */ -#define ID_SANITISED(name) { \ +#define ID_DESC(name) \ SYS_DESC(SYS_##name), \ .access = access_id_reg, \ - .get_user = get_id_reg, \ + .get_user = get_id_reg \ + +/* sys_reg_desc initialiser for known cpufeature ID registers */ +#define ID_SANITISED(name) { \ + ID_DESC(name), \ .set_user = set_id_reg, \ .visibility = id_visibility, \ .reset = kvm_read_sanitised_id_reg, \ @@ -1894,15 +1931,22 @@ static unsigned int elx2_visibility(const struct kvm_vcpu *vcpu, /* sys_reg_desc initialiser for known cpufeature ID registers */ #define AA32_ID_SANITISED(name) { \ - SYS_DESC(SYS_##name), \ - .access = access_id_reg, \ - .get_user = get_id_reg, \ + ID_DESC(name), \ .set_user = set_id_reg, \ .visibility = aa32_id_visibility, \ .reset = kvm_read_sanitised_id_reg, \ .val = 0, \ } +/* sys_reg_desc initialiser for writable ID registers */ +#define ID_WRITABLE(name, mask) { \ + ID_DESC(name), \ + .set_user = set_id_reg, \ + .visibility = id_visibility, \ + .reset = kvm_read_sanitised_id_reg, \ + .val = mask, \ +} + /* * sys_reg_desc initialiser for architecturally unallocated cpufeature ID * register with encoding Op0=3, Op1=0, CRn=0, CRm=crm, Op2=op2 @@ -1924,9 +1968,7 @@ static unsigned int elx2_visibility(const struct kvm_vcpu *vcpu, * RAZ for the guest. */ #define ID_HIDDEN(name) { \ - SYS_DESC(SYS_##name), \ - .access = access_id_reg, \ - .get_user = get_id_reg, \ + ID_DESC(name), \ .set_user = set_id_reg, \ .visibility = raz_visibility, \ .reset = kvm_read_sanitised_id_reg, \ @@ -2044,7 +2086,8 @@ static const struct sys_reg_desc sys_reg_descs[] = { .set_user = set_id_dfr0_el1, .visibility = aa32_id_visibility, .reset = read_sanitised_id_dfr0_el1, - .val = ID_DFR0_EL1_PerfMon_MASK, }, + .val = ID_DFR0_EL1_PerfMon_MASK | + ID_DFR0_EL1_CopDbg_MASK, }, ID_HIDDEN(ID_AFR0_EL1), AA32_ID_SANITISED(ID_MMFR0_EL1), AA32_ID_SANITISED(ID_MMFR1_EL1), @@ -2078,11 +2121,17 @@ static const struct sys_reg_desc sys_reg_descs[] = { .get_user = get_id_reg, .set_user = set_id_reg, .reset = read_sanitised_id_aa64pfr0_el1, - .val = ID_AA64PFR0_EL1_CSV2_MASK | ID_AA64PFR0_EL1_CSV3_MASK, }, + .val = ~(ID_AA64PFR0_EL1_AMU | + ID_AA64PFR0_EL1_MPAM | + ID_AA64PFR0_EL1_SVE | + ID_AA64PFR0_EL1_RAS | + ID_AA64PFR0_EL1_GIC | + ID_AA64PFR0_EL1_AdvSIMD | + ID_AA64PFR0_EL1_FP), }, ID_SANITISED(ID_AA64PFR1_EL1), ID_UNALLOCATED(4,2), ID_UNALLOCATED(4,3), - ID_SANITISED(ID_AA64ZFR0_EL1), + ID_WRITABLE(ID_AA64ZFR0_EL1, ~ID_AA64ZFR0_EL1_RES0), ID_HIDDEN(ID_AA64SMFR0_EL1), ID_UNALLOCATED(4,6), ID_UNALLOCATED(4,7), @@ -2093,7 +2142,8 @@ static const struct sys_reg_desc sys_reg_descs[] = { .get_user = get_id_reg, .set_user = set_id_aa64dfr0_el1, .reset = read_sanitised_id_aa64dfr0_el1, - .val = ID_AA64DFR0_EL1_PMUVer_MASK, }, + .val = ID_AA64DFR0_EL1_PMUVer_MASK | + ID_AA64DFR0_EL1_DebugVer_MASK, }, ID_SANITISED(ID_AA64DFR1_EL1), ID_UNALLOCATED(5,2), ID_UNALLOCATED(5,3), @@ -2103,9 +2153,15 @@ static const struct sys_reg_desc sys_reg_descs[] = { ID_UNALLOCATED(5,7), /* CRm=6 */ - ID_SANITISED(ID_AA64ISAR0_EL1), - ID_SANITISED(ID_AA64ISAR1_EL1), - ID_SANITISED(ID_AA64ISAR2_EL1), + ID_WRITABLE(ID_AA64ISAR0_EL1, ~ID_AA64ISAR0_EL1_RES0), + ID_WRITABLE(ID_AA64ISAR1_EL1, ~(ID_AA64ISAR1_EL1_GPI | + ID_AA64ISAR1_EL1_GPA | + ID_AA64ISAR1_EL1_API | + ID_AA64ISAR1_EL1_APA)), + ID_WRITABLE(ID_AA64ISAR2_EL1, ~(ID_AA64ISAR2_EL1_RES0 | + ID_AA64ISAR2_EL1_MOPS | + ID_AA64ISAR2_EL1_APA3 | + ID_AA64ISAR2_EL1_GPA3)), ID_UNALLOCATED(6,3), ID_UNALLOCATED(6,4), ID_UNALLOCATED(6,5), @@ -2113,9 +2169,23 @@ static const struct sys_reg_desc sys_reg_descs[] = { ID_UNALLOCATED(6,7), /* CRm=7 */ - ID_SANITISED(ID_AA64MMFR0_EL1), - ID_SANITISED(ID_AA64MMFR1_EL1), - ID_SANITISED(ID_AA64MMFR2_EL1), + ID_WRITABLE(ID_AA64MMFR0_EL1, ~(ID_AA64MMFR0_EL1_RES0 | + ID_AA64MMFR0_EL1_TGRAN4_2 | + ID_AA64MMFR0_EL1_TGRAN64_2 | + ID_AA64MMFR0_EL1_TGRAN16_2)), + ID_WRITABLE(ID_AA64MMFR1_EL1, ~(ID_AA64MMFR1_EL1_RES0 | + ID_AA64MMFR1_EL1_HCX | + ID_AA64MMFR1_EL1_XNX | + ID_AA64MMFR1_EL1_TWED | + ID_AA64MMFR1_EL1_XNX | + ID_AA64MMFR1_EL1_VH | + ID_AA64MMFR1_EL1_VMIDBits)), + ID_WRITABLE(ID_AA64MMFR2_EL1, ~(ID_AA64MMFR2_EL1_RES0 | + ID_AA64MMFR2_EL1_EVT | + ID_AA64MMFR2_EL1_FWB | + ID_AA64MMFR2_EL1_IDS | + ID_AA64MMFR2_EL1_NV | + ID_AA64MMFR2_EL1_CCIDX)), ID_SANITISED(ID_AA64MMFR3_EL1), ID_UNALLOCATED(7,4), ID_UNALLOCATED(7,5), @@ -2505,14 +2575,15 @@ static bool trap_dbgdidr(struct kvm_vcpu *vcpu, if (p->is_write) { return ignore_write(vcpu, p); } else { - u64 dfr = read_sanitised_ftr_reg(SYS_ID_AA64DFR0_EL1); - u64 pfr = read_sanitised_ftr_reg(SYS_ID_AA64PFR0_EL1); - u32 el3 = !!cpuid_feature_extract_unsigned_field(pfr, ID_AA64PFR0_EL1_EL3_SHIFT); - - p->regval = ((((dfr >> ID_AA64DFR0_EL1_WRPs_SHIFT) & 0xf) << 28) | - (((dfr >> ID_AA64DFR0_EL1_BRPs_SHIFT) & 0xf) << 24) | - (((dfr >> ID_AA64DFR0_EL1_CTX_CMPs_SHIFT) & 0xf) << 20) - | (6 << 16) | (1 << 15) | (el3 << 14) | (el3 << 12)); + u64 dfr = IDREG(vcpu->kvm, SYS_ID_AA64DFR0_EL1); + u64 pfr = IDREG(vcpu->kvm, SYS_ID_AA64PFR0_EL1); + u32 el3 = !!SYS_FIELD_GET(ID_AA64PFR0_EL1, EL3, pfr); + + p->regval = ((SYS_FIELD_GET(ID_AA64DFR0_EL1, WRPs, dfr) << 28) | + (SYS_FIELD_GET(ID_AA64DFR0_EL1, BRPs, dfr) << 24) | + (SYS_FIELD_GET(ID_AA64DFR0_EL1, CTX_CMPs, dfr) << 20) | + (SYS_FIELD_GET(ID_AA64DFR0_EL1, DebugVer, dfr) << 16) | + (1 << 15) | (el3 << 14) | (el3 << 12)); return true; } } @@ -3648,6 +3719,65 @@ int kvm_arm_copy_sys_reg_indices(struct kvm_vcpu *vcpu, u64 __user *uindices) return write_demux_regids(uindices); } +#define KVM_ARM_FEATURE_ID_RANGE_INDEX(r) \ + KVM_ARM_FEATURE_ID_RANGE_IDX(sys_reg_Op0(r), \ + sys_reg_Op1(r), \ + sys_reg_CRn(r), \ + sys_reg_CRm(r), \ + sys_reg_Op2(r)) + +static bool is_feature_id_reg(u32 encoding) +{ + return (sys_reg_Op0(encoding) == 3 && + (sys_reg_Op1(encoding) < 2 || sys_reg_Op1(encoding) == 3) && + sys_reg_CRn(encoding) == 0 && + sys_reg_CRm(encoding) <= 7); +} + +int kvm_vm_ioctl_get_reg_writable_masks(struct kvm *kvm, struct reg_mask_range *range) +{ + const void *zero_page = page_to_virt(ZERO_PAGE(0)); + u64 __user *masks = (u64 __user *)range->addr; + + /* Only feature id range is supported, reserved[13] must be zero. */ + if (range->range || + memcmp(range->reserved, zero_page, sizeof(range->reserved))) + return -EINVAL; + + /* Wipe the whole thing first */ + if (clear_user(masks, KVM_ARM_FEATURE_ID_RANGE_SIZE * sizeof(__u64))) + return -EFAULT; + + for (int i = 0; i < ARRAY_SIZE(sys_reg_descs); i++) { + const struct sys_reg_desc *reg = &sys_reg_descs[i]; + u32 encoding = reg_to_encoding(reg); + u64 val; + + if (!is_feature_id_reg(encoding) || !reg->set_user) + continue; + + /* + * For ID registers, we return the writable mask. Other feature + * registers return a full 64bit mask. That's not necessary + * compliant with a given revision of the architecture, but the + * RES0/RES1 definitions allow us to do that. + */ + if (is_id_reg(encoding)) { + if (!reg->val || + (is_aa32_id_reg(encoding) && !kvm_supports_32bit_el0())) + continue; + val = reg->val; + } else { + val = ~0UL; + } + + if (put_user(val, (masks + KVM_ARM_FEATURE_ID_RANGE_INDEX(encoding)))) + return -EFAULT; + } + + return 0; +} + int __init kvm_sys_reg_table_init(void) { struct sys_reg_params params; diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h index d2ab4a3d69934ad3f776825a3590886dfcb3387f..48b9cfda093a54f3c8102abffbd34a5055350178 100644 --- a/include/uapi/linux/kvm.h +++ b/include/uapi/linux/kvm.h @@ -1200,6 +1200,7 @@ struct kvm_ppc_resize_hpt { #define KVM_CAP_COUNTER_OFFSET 227 #define KVM_CAP_ARM_EAGER_SPLIT_CHUNK_SIZE 228 #define KVM_CAP_ARM_SUPPORTED_BLOCK_SIZES 229 +#define KVM_CAP_ARM_SUPPORTED_REG_MASK_RANGES 230 #define KVM_CAP_ARM_VIRT_MSI_BYPASS 799 @@ -1578,6 +1579,7 @@ struct kvm_s390_ucas_mapping { #define KVM_ARM_MTE_COPY_TAGS _IOR(KVMIO, 0xb4, struct kvm_arm_copy_mte_tags) /* Available with KVM_CAP_COUNTER_OFFSET */ #define KVM_ARM_SET_COUNTER_OFFSET _IOW(KVMIO, 0xb5, struct kvm_arm_counter_offset) +#define KVM_ARM_GET_REG_WRITABLE_MASKS _IOR(KVMIO, 0xb6, struct reg_mask_range) /* ioctl for SW vcpu init*/ #define KVM_SW64_VCPU_INIT _IO(KVMIO, 0xba)