From 473341469042b39535ee800a19c45110ebc46346 Mon Sep 17 00:00:00 2001 From: Jing Zhang Date: Fri, 9 Jun 2023 19:00:49 +0000 Subject: [PATCH] KVM: arm64: Save ID registers' sanitized value per guest Initialize the default ID register values upon the first call to KVM_ARM_VCPU_INIT. The vCPU feature flags are finalized at that point, so it is possible to determine the maximum feature set supported by a particular VM configuration. Do nothing with these values for now, as we need to rework the plumbing of what's already writable to be compatible with the generic infrastructure. Co-developed-by: Reiji Watanabe Signed-off-by: Reiji Watanabe Signed-off-by: Jing Zhang Link: https://lore.kernel.org/r/20230609190054.1542113-7-oliver.upton@linux.dev [Oliver: Hoist everything into KVM_ARM_VCPU_INIT time, so the features are final] Signed-off-by: Oliver Upton --- arch/arm64/include/asm/kvm_host.h | 15 +++++++++ arch/arm64/kvm/sys_regs.c | 56 +++++++++++++++++++++++++++++-- arch/arm64/kvm/sys_regs.h | 7 ++++ 3 files changed, 75 insertions(+), 3 deletions(-) diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h index 44da989435fcd..39270bc29a3fa 100644 --- a/arch/arm64/include/asm/kvm_host.h +++ b/arch/arm64/include/asm/kvm_host.h @@ -225,6 +225,8 @@ struct kvm_arch { #define KVM_ARCH_FLAG_TIMER_PPIS_IMMUTABLE 6 /* SMCCC filter initialized for the VM */ #define KVM_ARCH_FLAG_SMCCC_FILTER_CONFIGURED 7 + /* Initial ID reg values loaded */ +#define KVM_ARCH_FLAG_ID_REGS_INITIALIZED 8 unsigned long flags; /* VM-wide vCPU feature set */ @@ -247,6 +249,19 @@ struct kvm_arch { struct kvm_smccc_features smccc_feat; struct maple_tree smccc_filter; + /* + * Emulated CPU ID registers per VM + * (Op0, Op1, CRn, CRm, Op2) of the ID registers to be saved in it + * is (3, 0, 0, crm, op2), where 1<=crm<8, 0<=op2<8. + * + * These emulated idregs are VM-wide, but accessed from the context of a vCPU. + * Atomic access to multiple idregs are guarded by kvm_arch.config_lock. + */ +#define IDREG_IDX(id) (((sys_reg_CRm(id) - 1) << 3) | sys_reg_Op2(id)) +#define IDREG(kvm, id) ((kvm)->arch.id_regs[IDREG_IDX(id)]) +#define KVM_ARM_ID_REG_NUM (IDREG_IDX(sys_reg(3, 0, 0, 7, 7)) + 1) + u64 id_regs[KVM_ARM_ID_REG_NUM]; + /* * For an untrusted host VM, 'pkvm.handle' is used to lookup * the associated pKVM instance in the hypervisor. diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c index 9d37f16cfb7bc..3015c860deca4 100644 --- a/arch/arm64/kvm/sys_regs.c +++ b/arch/arm64/kvm/sys_regs.c @@ -1311,6 +1311,17 @@ static u64 read_id_reg(const struct kvm_vcpu *vcpu, const struct sys_reg_desc *r return __kvm_read_sanitised_id_reg(vcpu, r); } +/* + * Return true if the register's (Op0, Op1, CRn, CRm, Op2) is + * (3, 0, 0, crm, op2), where 1<=crm<8, 0<=op2<8. + */ +static inline bool is_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) < 8); +} + static unsigned int id_visibility(const struct kvm_vcpu *vcpu, const struct sys_reg_desc *r) { @@ -2303,6 +2314,8 @@ static const struct sys_reg_desc sys_reg_descs[] = { EL2_REG(SP_EL2, NULL, reset_unknown, 0), }; +static const struct sys_reg_desc *first_idreg; + static bool trap_dbgdidr(struct kvm_vcpu *vcpu, struct sys_reg_params *p, const struct sys_reg_desc *r) @@ -2993,6 +3006,28 @@ static bool emulate_sys_reg(struct kvm_vcpu *vcpu, return false; } +static void kvm_reset_id_regs(struct kvm_vcpu *vcpu) +{ + const struct sys_reg_desc *idreg = first_idreg; + u32 id = reg_to_encoding(idreg); + struct kvm *kvm = vcpu->kvm; + + if (test_bit(KVM_ARCH_FLAG_ID_REGS_INITIALIZED, &kvm->arch.flags)) + return; + + lockdep_assert_held(&kvm->arch.config_lock); + + /* Initialize all idregs */ + while (is_id_reg(id)) { + IDREG(kvm, id) = idreg->reset(vcpu, idreg); + + idreg++; + id = reg_to_encoding(idreg); + } + + set_bit(KVM_ARCH_FLAG_ID_REGS_INITIALIZED, &kvm->arch.flags); +} + /** * kvm_reset_sys_regs - sets system registers to reset value * @vcpu: The VCPU pointer @@ -3004,9 +3039,17 @@ void kvm_reset_sys_regs(struct kvm_vcpu *vcpu) { unsigned long i; - for (i = 0; i < ARRAY_SIZE(sys_reg_descs); i++) - if (sys_reg_descs[i].reset) - sys_reg_descs[i].reset(vcpu, &sys_reg_descs[i]); + kvm_reset_id_regs(vcpu); + + for (i = 0; i < ARRAY_SIZE(sys_reg_descs); i++) { + const struct sys_reg_desc *r = &sys_reg_descs[i]; + + if (is_id_reg(reg_to_encoding(r))) + continue; + + if (r->reset) + r->reset(vcpu, r); + } } /** @@ -3413,6 +3456,7 @@ int kvm_arm_copy_sys_reg_indices(struct kvm_vcpu *vcpu, u64 __user *uindices) int __init kvm_sys_reg_table_init(void) { + struct sys_reg_params params; bool valid = true; unsigned int i; @@ -3431,5 +3475,11 @@ int __init kvm_sys_reg_table_init(void) for (i = 0; i < ARRAY_SIZE(invariant_sys_regs); i++) invariant_sys_regs[i].reset(NULL, &invariant_sys_regs[i]); + /* Find the first idreg (SYS_ID_PFR0_EL1) in sys_reg_descs. */ + params = encoding_to_params(SYS_ID_PFR0_EL1); + first_idreg = find_reg(¶ms, sys_reg_descs, ARRAY_SIZE(sys_reg_descs)); + if (!first_idreg) + return -EINVAL; + return 0; } diff --git a/arch/arm64/kvm/sys_regs.h b/arch/arm64/kvm/sys_regs.h index 63bca7521dfd1..c65c129b35001 100644 --- a/arch/arm64/kvm/sys_regs.h +++ b/arch/arm64/kvm/sys_regs.h @@ -27,6 +27,13 @@ struct sys_reg_params { bool is_write; }; +#define encoding_to_params(reg) \ + ((struct sys_reg_params){ .Op0 = sys_reg_Op0(reg), \ + .Op1 = sys_reg_Op1(reg), \ + .CRn = sys_reg_CRn(reg), \ + .CRm = sys_reg_CRm(reg), \ + .Op2 = sys_reg_Op2(reg) }) + #define esr_sys64_to_params(esr) \ ((struct sys_reg_params){ .Op0 = ((esr) >> 20) & 3, \ .Op1 = ((esr) >> 14) & 0x7, \ -- 2.30.2