Hi Shameerali, On Thu, May 18, 2023 at 12:17 AM Shameerali Kolothum Thodi <shameerali.kolothum.thodi@xxxxxxxxxx> wrote: > > > > > -----Original Message----- > > From: Jing Zhang [mailto:jingzhangos@xxxxxxxxxx] > > Sent: 17 May 2023 07:10 > > To: KVM <kvm@xxxxxxxxxxxxxxx>; KVMARM <kvmarm@xxxxxxxxxxxxxxx>; > > ARMLinux <linux-arm-kernel@xxxxxxxxxxxxxxxxxxx>; Marc Zyngier > > <maz@xxxxxxxxxx>; Oliver Upton <oupton@xxxxxxxxxx> > > Cc: Will Deacon <will@xxxxxxxxxx>; Paolo Bonzini <pbonzini@xxxxxxxxxx>; > > James Morse <james.morse@xxxxxxx>; Alexandru Elisei > > <alexandru.elisei@xxxxxxx>; Suzuki K Poulose <suzuki.poulose@xxxxxxx>; > > Fuad Tabba <tabba@xxxxxxxxxx>; Reiji Watanabe <reijiw@xxxxxxxxxx>; > > Raghavendra Rao Ananta <rananta@xxxxxxxxxx>; Jing Zhang > > <jingzhangos@xxxxxxxxxx> > > Subject: [PATCH v9 1/5] KVM: arm64: Save ID registers' sanitized value per > > guest > > > > Introduce id_regs[] in kvm_arch as a storage of guest's ID registers, > > and save ID registers' sanitized value in the array at KVM_CREATE_VM. > > Use the saved ones when ID registers are read by the guest or > > userspace (via KVM_GET_ONE_REG). > > > > No functional change intended. > > > > Co-developed-by: Reiji Watanabe <reijiw@xxxxxxxxxx> > > Signed-off-by: Reiji Watanabe <reijiw@xxxxxxxxxx> > > Signed-off-by: Jing Zhang <jingzhangos@xxxxxxxxxx> > > --- > > arch/arm64/include/asm/kvm_host.h | 20 +++++++++ > > arch/arm64/kvm/arm.c | 1 + > > arch/arm64/kvm/sys_regs.c | 69 > > +++++++++++++++++++++++++------ > > arch/arm64/kvm/sys_regs.h | 7 ++++ > > 4 files changed, 85 insertions(+), 12 deletions(-) > > > > diff --git a/arch/arm64/include/asm/kvm_host.h > > b/arch/arm64/include/asm/kvm_host.h > > index 7e7e19ef6993..949a4a782844 100644 > > --- a/arch/arm64/include/asm/kvm_host.h > > +++ b/arch/arm64/include/asm/kvm_host.h > > @@ -178,6 +178,21 @@ struct kvm_smccc_features { > > unsigned long vendor_hyp_bmap; > > }; > > > > +/* > > + * 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. > > + * Access to id regs are guarded by kvm_arch.config_lock. > > + */ > > +#define KVM_ARM_ID_REG_NUM 56 > > +#define IDREG_IDX(id) (((sys_reg_CRm(id) - 1) << 3) | sys_reg_Op2(id)) > > +#define IDREG(kvm, id) ((kvm)->arch.idregs.regs[IDREG_IDX(id)]) > > +struct kvm_idregs { > > + u64 regs[KVM_ARM_ID_REG_NUM]; > > +}; > > > > Not sure we really need this struct here. Why can't this array be moved to > struct kvm_arch directly? It was put in kvm_arch directly before, then got into its own structure in v5 according to the comments here: https://lore.kernel.org/all/861qlaxzyw.wl-maz@xxxxxxxxxx/#t > > > typedef unsigned int pkvm_handle_t; > > > > struct kvm_protected_vm { > > @@ -253,6 +268,9 @@ struct kvm_arch { > > struct kvm_smccc_features smccc_feat; > > struct maple_tree smccc_filter; > > > > + /* Emulated CPU ID registers */ > > + struct kvm_idregs idregs; > > + > > /* > > * For an untrusted host VM, 'pkvm.handle' is used to lookup > > * the associated pKVM instance in the hypervisor. > > @@ -1045,6 +1063,8 @@ int kvm_vm_ioctl_mte_copy_tags(struct kvm > > *kvm, > > int kvm_vm_ioctl_set_counter_offset(struct kvm *kvm, > > struct kvm_arm_counter_offset *offset); > > > > +void kvm_arm_init_id_regs(struct kvm *kvm); > > + > > /* Guest/host FPSIMD coordination helpers */ > > int kvm_arch_vcpu_run_map_fp(struct kvm_vcpu *vcpu); > > void kvm_arch_vcpu_load_fp(struct kvm_vcpu *vcpu); > > diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c > > index 14391826241c..774656a0718d 100644 > > --- a/arch/arm64/kvm/arm.c > > +++ b/arch/arm64/kvm/arm.c > > @@ -163,6 +163,7 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned > > long type) > > > > set_default_spectre(kvm); > > kvm_arm_init_hypercalls(kvm); > > + kvm_arm_init_id_regs(kvm); > > > > /* > > * Initialise the default PMUver before there is a chance to > > diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c > > index 71b12094d613..d2ee3a1c7f03 100644 > > --- a/arch/arm64/kvm/sys_regs.c > > +++ b/arch/arm64/kvm/sys_regs.c > > @@ -41,6 +41,7 @@ > > * 64bit interface. > > */ > > > > +static u64 kvm_arm_read_id_reg(const struct kvm_vcpu *vcpu, u32 id); > > static u64 sys_reg_to_index(const struct sys_reg_desc *reg); > > > > static bool read_from_write_only(struct kvm_vcpu *vcpu, > > @@ -364,7 +365,7 @@ 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 = kvm_arm_read_id_reg(vcpu, SYS_ID_AA64MMFR1_EL1); > > u32 sr = reg_to_encoding(r); > > > > if (!(val & (0xfUL << ID_AA64MMFR1_EL1_LO_SHIFT))) { > > @@ -1208,16 +1209,9 @@ static u8 pmuver_to_perfmon(u8 pmuver) > > } > > } > > > > -/* Read a sanitised cpufeature ID register by sys_reg_desc */ > > -static u64 read_id_reg(const struct kvm_vcpu *vcpu, struct sys_reg_desc > > const *r) > > +static u64 kvm_arm_read_id_reg(const struct kvm_vcpu *vcpu, u32 id) > > { > > - u32 id = reg_to_encoding(r); > > - u64 val; > > - > > - if (sysreg_visible_as_raz(vcpu, r)) > > - return 0; > > - > > - val = read_sanitised_ftr_reg(id); > > + u64 val = IDREG(vcpu->kvm, id); > > > > switch (id) { > > case SYS_ID_AA64PFR0_EL1: > > @@ -1280,6 +1274,26 @@ static u64 read_id_reg(const struct kvm_vcpu > > *vcpu, struct sys_reg_desc const *r > > return val; > > } > > > > +/* Read a sanitised cpufeature ID register by sys_reg_desc */ > > +static u64 read_id_reg(const struct kvm_vcpu *vcpu, struct sys_reg_desc > > const *r) > > +{ > > + if (sysreg_visible_as_raz(vcpu, r)) > > + return 0; > > + > > + return kvm_arm_read_id_reg(vcpu, reg_to_encoding(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) > > { > > @@ -2244,8 +2258,8 @@ 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); > > + u64 dfr = kvm_arm_read_id_reg(vcpu, SYS_ID_AA64DFR0_EL1); > > + u64 pfr = kvm_arm_read_id_reg(vcpu, SYS_ID_AA64PFR0_EL1); > > Does this change the behavior slightly as now within the kvm_arm_read_id_reg() > the val will be further adjusted based on KVM/vCPU? That's a good question. Although the actual behavior would be the same no matter read idreg with read_sanitised_ftr_reg or kvm_arm_read_id_reg, it is possible that the behavior would change potentially in the future. Since now every guest has its own idregs, for every guest, the idregs should be read from kvm_arm_read_id_reg instead of read_sanitised_ftr_reg. The point is, for trap_dbgdidr, we should read AA64DFR0/AA64PFR0 from host or the VM-scope? > > Thanks, > Shameer > > > u32 el3 = !!cpuid_feature_extract_unsigned_field(pfr, > > ID_AA64PFR0_EL1_EL3_SHIFT); > > > > p->regval = ((((dfr >> ID_AA64DFR0_EL1_WRPs_SHIFT) & 0xf) << > > 28) | > > @@ -3343,6 +3357,37 @@ int kvm_arm_copy_sys_reg_indices(struct > > kvm_vcpu *vcpu, u64 __user *uindices) > > return write_demux_regids(uindices); > > } > > > > +/* > > + * Set the guest's ID registers with ID_SANITISED() to the host's sanitized > > value. > > + */ > > +void kvm_arm_init_id_regs(struct kvm *kvm) > > +{ > > + const struct sys_reg_desc *idreg; > > + struct sys_reg_params params; > > + u32 id; > > + > > + /* Find the first idreg (SYS_ID_PFR0_EL1) in sys_reg_descs. */ > > + id = SYS_ID_PFR0_EL1; > > + params = encoding_to_params(id); > > + idreg = find_reg(¶ms, sys_reg_descs, ARRAY_SIZE(sys_reg_descs)); > > + if (WARN_ON(!idreg)) > > + return; > > + > > + /* Initialize all idregs */ > > + while (is_id_reg(id)) { > > + /* > > + * Some hidden ID registers which are not in arm64_ftr_regs[] > > + * would cause warnings from read_sanitised_ftr_reg(). > > + * Skip those ID registers to avoid the warnings. > > + */ > > + if (idreg->visibility != raz_visibility) > > + IDREG(kvm, id) = read_sanitised_ftr_reg(id); > > + > > + idreg++; > > + id = reg_to_encoding(idreg); > > + } > > +} > > + > > int __init kvm_sys_reg_table_init(void) > > { > > bool valid = true; > > diff --git a/arch/arm64/kvm/sys_regs.h b/arch/arm64/kvm/sys_regs.h > > index 6b11f2cc7146..eba10de2e7ae 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, \ > > -- > > 2.40.1.606.ga4b1b128d6-goog > > > Thanks, Jing
