From: Dave Martin Date: Fri, 28 Sep 2018 13:39:16 +0000 (+0100) Subject: KVM: arm64/sve: System register context switch and access support X-Git-Url: http://git.cdn.openwrt.org/?a=commitdiff_plain;h=73433762fcaeb9d59e84d299021c6b15466c96dd;p=openwrt%2Fstaging%2Fblogic.git KVM: arm64/sve: System register context switch and access support This patch adds the necessary support for context switching ZCR_EL1 for each vcpu. ZCR_EL1 is trapped alongside the FPSIMD/SVE registers, so it makes sense for it to be handled as part of the guest FPSIMD/SVE context for context switch purposes instead of handling it as a general system register. This means that it can be switched in lazily at the appropriate time. No effort is made to track host context for this register, since SVE requires VHE: thus the hosts's value for this register lives permanently in ZCR_EL2 and does not alias the guest's value at any time. The Hyp switch and fpsimd context handling code is extended appropriately. Accessors are added in sys_regs.c to expose the SVE system registers and ID register fields. Because these need to be conditionally visible based on the guest configuration, they are implemented separately for now rather than by use of the generic system register helpers. This may be abstracted better later on when/if there are more features requiring this model. ID_AA64ZFR0_EL1 is RO-RAZ for MRS/MSR when SVE is disabled for the guest, but for compatibility with non-SVE aware KVM implementations the register should not be enumerated at all for KVM_GET_REG_LIST in this case. For consistency we also reject ioctl access to the register. This ensures that a non-SVE-enabled guest looks the same to userspace, irrespective of whether the kernel KVM implementation supports SVE. Signed-off-by: Dave Martin Reviewed-by: Julien Thierry Tested-by: zhang.lei Signed-off-by: Marc Zyngier --- diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h index ad4f7f004498..22cf484b561f 100644 --- a/arch/arm64/include/asm/kvm_host.h +++ b/arch/arm64/include/asm/kvm_host.h @@ -121,6 +121,7 @@ enum vcpu_sysreg { SCTLR_EL1, /* System Control Register */ ACTLR_EL1, /* Auxiliary Control Register */ CPACR_EL1, /* Coprocessor Access Control */ + ZCR_EL1, /* SVE Control */ TTBR0_EL1, /* Translation Table Base Register 0 */ TTBR1_EL1, /* Translation Table Base Register 1 */ TCR_EL1, /* Translation Control Register */ diff --git a/arch/arm64/include/asm/sysreg.h b/arch/arm64/include/asm/sysreg.h index 5b267dec6194..4d6262df79bb 100644 --- a/arch/arm64/include/asm/sysreg.h +++ b/arch/arm64/include/asm/sysreg.h @@ -454,6 +454,9 @@ #define SYS_ICH_LR14_EL2 __SYS__LR8_EL2(6) #define SYS_ICH_LR15_EL2 __SYS__LR8_EL2(7) +/* VHE encodings for architectural EL0/1 system registers */ +#define SYS_ZCR_EL12 sys_reg(3, 5, 1, 2, 0) + /* Common SCTLR_ELx flags. */ #define SCTLR_ELx_DSSBS (_BITUL(44)) #define SCTLR_ELx_ENIA (_BITUL(31)) diff --git a/arch/arm64/kvm/fpsimd.c b/arch/arm64/kvm/fpsimd.c index 1cf4f0269471..7053bf402131 100644 --- a/arch/arm64/kvm/fpsimd.c +++ b/arch/arm64/kvm/fpsimd.c @@ -103,14 +103,21 @@ void kvm_arch_vcpu_ctxsync_fp(struct kvm_vcpu *vcpu) void kvm_arch_vcpu_put_fp(struct kvm_vcpu *vcpu) { unsigned long flags; + bool host_has_sve = system_supports_sve(); + bool guest_has_sve = vcpu_has_sve(vcpu); local_irq_save(flags); if (vcpu->arch.flags & KVM_ARM64_FP_ENABLED) { + u64 *guest_zcr = &vcpu->arch.ctxt.sys_regs[ZCR_EL1]; + /* Clean guest FP state to memory and invalidate cpu view */ fpsimd_save(); fpsimd_flush_cpu_state(); - } else if (system_supports_sve()) { + + if (guest_has_sve) + *guest_zcr = read_sysreg_s(SYS_ZCR_EL12); + } else if (host_has_sve) { /* * The FPSIMD/SVE state in the CPU has not been touched, and we * have SVE (and VHE): CPACR_EL1 (alias CPTR_EL2) has been diff --git a/arch/arm64/kvm/hyp/switch.c b/arch/arm64/kvm/hyp/switch.c index 3563fe655cd5..9d46066276b9 100644 --- a/arch/arm64/kvm/hyp/switch.c +++ b/arch/arm64/kvm/hyp/switch.c @@ -351,6 +351,9 @@ static bool __hyp_text __hyp_switch_fpsimd(struct kvm_vcpu *vcpu) __fpsimd_restore_state(&vcpu->arch.ctxt.gp_regs.fp_regs); + if (vcpu_has_sve(vcpu)) + write_sysreg_s(vcpu->arch.ctxt.sys_regs[ZCR_EL1], SYS_ZCR_EL12); + /* Skip restoring fpexc32 for AArch64 guests */ if (!(read_sysreg(hcr_el2) & HCR_RW)) write_sysreg(vcpu->arch.ctxt.sys_regs[FPEXC32_EL2], diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c index c86a7b0d3e6b..09e9b0625911 100644 --- a/arch/arm64/kvm/sys_regs.c +++ b/arch/arm64/kvm/sys_regs.c @@ -1051,10 +1051,7 @@ static u64 read_id_reg(const struct kvm_vcpu *vcpu, (u32)r->CRn, (u32)r->CRm, (u32)r->Op2); u64 val = raz ? 0 : read_sanitised_ftr_reg(id); - if (id == SYS_ID_AA64PFR0_EL1) { - if (val & (0xfUL << ID_AA64PFR0_SVE_SHIFT)) - kvm_debug("SVE unsupported for guests, suppressing\n"); - + if (id == SYS_ID_AA64PFR0_EL1 && !vcpu_has_sve(vcpu)) { val &= ~(0xfUL << ID_AA64PFR0_SVE_SHIFT); } else if (id == SYS_ID_AA64ISAR1_EL1) { const u64 ptrauth_mask = (0xfUL << ID_AA64ISAR1_APA_SHIFT) | @@ -1101,6 +1098,81 @@ static int reg_from_user(u64 *val, const void __user *uaddr, u64 id); static int reg_to_user(void __user *uaddr, const u64 *val, u64 id); static u64 sys_reg_to_index(const struct sys_reg_desc *reg); +/* Visibility overrides for SVE-specific control registers */ +static unsigned int sve_visibility(const struct kvm_vcpu *vcpu, + const struct sys_reg_desc *rd) +{ + if (vcpu_has_sve(vcpu)) + return 0; + + return REG_HIDDEN_USER | REG_HIDDEN_GUEST; +} + +/* Visibility overrides for SVE-specific ID registers */ +static unsigned int sve_id_visibility(const struct kvm_vcpu *vcpu, + const struct sys_reg_desc *rd) +{ + if (vcpu_has_sve(vcpu)) + return 0; + + return REG_HIDDEN_USER; +} + +/* Generate the emulated ID_AA64ZFR0_EL1 value exposed to the guest */ +static u64 guest_id_aa64zfr0_el1(const struct kvm_vcpu *vcpu) +{ + if (!vcpu_has_sve(vcpu)) + return 0; + + return read_sanitised_ftr_reg(SYS_ID_AA64ZFR0_EL1); +} + +static bool access_id_aa64zfr0_el1(struct kvm_vcpu *vcpu, + struct sys_reg_params *p, + const struct sys_reg_desc *rd) +{ + if (p->is_write) + return write_to_read_only(vcpu, p, rd); + + p->regval = guest_id_aa64zfr0_el1(vcpu); + return true; +} + +static int get_id_aa64zfr0_el1(struct kvm_vcpu *vcpu, + const struct sys_reg_desc *rd, + const struct kvm_one_reg *reg, void __user *uaddr) +{ + u64 val; + + if (!vcpu_has_sve(vcpu)) + return -ENOENT; + + val = guest_id_aa64zfr0_el1(vcpu); + return reg_to_user(uaddr, &val, reg->id); +} + +static int set_id_aa64zfr0_el1(struct kvm_vcpu *vcpu, + const struct sys_reg_desc *rd, + const struct kvm_one_reg *reg, void __user *uaddr) +{ + const u64 id = sys_reg_to_index(rd); + int err; + u64 val; + + if (!vcpu_has_sve(vcpu)) + return -ENOENT; + + err = reg_from_user(&val, uaddr, id); + if (err) + return err; + + /* This is what we mean by invariant: you can't change it. */ + if (val != guest_id_aa64zfr0_el1(vcpu)) + return -EINVAL; + + return 0; +} + /* * cpufeature ID register user accessors * @@ -1346,7 +1418,7 @@ static const struct sys_reg_desc sys_reg_descs[] = { ID_SANITISED(ID_AA64PFR1_EL1), ID_UNALLOCATED(4,2), ID_UNALLOCATED(4,3), - ID_UNALLOCATED(4,4), + { SYS_DESC(SYS_ID_AA64ZFR0_EL1), access_id_aa64zfr0_el1, .get_user = get_id_aa64zfr0_el1, .set_user = set_id_aa64zfr0_el1, .visibility = sve_id_visibility }, ID_UNALLOCATED(4,5), ID_UNALLOCATED(4,6), ID_UNALLOCATED(4,7), @@ -1383,6 +1455,7 @@ static const struct sys_reg_desc sys_reg_descs[] = { { SYS_DESC(SYS_SCTLR_EL1), access_vm_reg, reset_val, SCTLR_EL1, 0x00C50078 }, { SYS_DESC(SYS_CPACR_EL1), NULL, reset_val, CPACR_EL1, 0 }, + { SYS_DESC(SYS_ZCR_EL1), NULL, reset_val, ZCR_EL1, 0, .visibility = sve_visibility }, { SYS_DESC(SYS_TTBR0_EL1), access_vm_reg, reset_unknown, TTBR0_EL1 }, { SYS_DESC(SYS_TTBR1_EL1), access_vm_reg, reset_unknown, TTBR1_EL1 }, { SYS_DESC(SYS_TCR_EL1), access_vm_reg, reset_val, TCR_EL1, 0 },