On Thu, Aug 13, 2020 at 02:05:15PM +0800, Peng Liang wrote:
> To emulate the ID registers, we need a place to storage the values of
> the ID regsiters. Maybe putting in kvm_arch_vcpu is a good idea.
>
> This commit has no functional changes but only code refactor. When
> initializing a vcpu, get the values of the ID registers from
> arm64_ftr_regs and storage them in kvm_arch_vcpu. And we just read
> the value from kvm_arch_vcpu when getting/setting the value of the ID
> regs.
>
> Signed-off-by: zhanghailiang <zhang.zhanghailiang@xxxxxxxxxx>
> Signed-off-by: Peng Liang <liangpeng10@xxxxxxxxxx>
> ---
> arch/arm64/include/asm/kvm_host.h | 2 ++
> arch/arm64/kvm/arm.c | 20 ++++++++++++++++++++
> arch/arm64/kvm/sys_regs.c | 27 +++++++++++++++++++++++----
> include/uapi/linux/kvm.h | 11 +++++++++++
> 4 files changed, 56 insertions(+), 4 deletions(-)
>
> diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
> index f81151ad3d3c..7f7bd36702f7 100644
> --- a/arch/arm64/include/asm/kvm_host.h
> +++ b/arch/arm64/include/asm/kvm_host.h
> @@ -336,6 +336,8 @@ struct kvm_vcpu_arch {
> u64 last_steal;
> gpa_t base;
> } steal;
> +
> + struct id_registers idregs;
> };
>
> /* Pointer to the vcpu's SVE FFR for sve_{save,load}_state() */
> diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
> index 73e12869afe3..18ebbe1c64ee 100644
> --- a/arch/arm64/kvm/arm.c
> +++ b/arch/arm64/kvm/arm.c
> @@ -262,6 +262,24 @@ int kvm_arch_vcpu_precreate(struct kvm *kvm, unsigned int id)
> return 0;
> }
>
> +static int get_cpu_ftr(u32 id, u64 val, void *argp)
> +{
> + struct id_registers *idregs = argp;
> +
> + /*
> + * (Op0, Op1, CRn, CRm, Op2) of ID registers is (3, 0, 0, crm, op2),
> + * where 1<=crm<8, 0<=op2<8.
> + */
> + if (sys_reg_Op0(id) == 3 && sys_reg_Op1(id) == 0 &&
> + sys_reg_CRn(id) == 0 && sys_reg_CRm(id) > 0) {
> + idregs->regs[idregs->num].sys_id = id;
> + idregs->regs[idregs->num].sys_val = val;
> + idregs->num++;
This num++ means we should ensure get_cpu_ftr() is only used once per
VCPU, but we don't need 'num'. The index can be derived: (crm<<3)|op2
> + }
> +
> + return 0;
> +}
> +
> int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu)
> {
> int err;
> @@ -285,6 +303,8 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu)
> if (err)
> return err;
>
> + arm64_cpu_ftr_regs_traverse(get_cpu_ftr, &vcpu->arch.idregs);
> +
> return create_hyp_mappings(vcpu, vcpu + 1, PAGE_HYP);
> }
>
> diff --git a/arch/arm64/kvm/sys_regs.c b/arch/arm64/kvm/sys_regs.c
> index 138961d7ebe3..776c2757a01e 100644
> --- a/arch/arm64/kvm/sys_regs.c
> +++ b/arch/arm64/kvm/sys_regs.c
> @@ -1092,13 +1092,32 @@ static bool access_arch_timer(struct kvm_vcpu *vcpu,
> return true;
> }
>
> +static struct id_reg_info *kvm_id_reg(struct kvm_vcpu *vcpu, u64 id)
> +{
> + int i;
> +
> + for (i = 0; i < vcpu->arch.idregs.num; ++i) {
> + if (vcpu->arch.idregs.regs[i].sys_id == id)
> + return &vcpu->arch.idregs.regs[i];
With a derived index we don't need to search. Just do
if (sys_reg_Op0(id) != 3 || sys_reg_Op1(id) != 0 ||
sys_reg_CRn(id) != 0 || sys_reg_CRm(id) == 0)
return NULL;
return &vcpu->arch.idregs.regs[(sys_reg_CRm(id)<<3) | sys_reg_Op2(id)];
> + }
> + return NULL;
> +}
> +
> +static u64 kvm_get_id_reg(struct kvm_vcpu *vcpu, u64 id)
> +{
> + struct id_reg_info *ri = kvm_id_reg(vcpu, id);
> +
> + BUG_ON(!ri);
> + return ri->sys_val;
> +}
> +
> /* Read a sanitised cpufeature ID register by sys_reg_desc */
> -static u64 read_id_reg(const struct kvm_vcpu *vcpu,
> +static u64 read_id_reg(struct kvm_vcpu *vcpu,
> struct sys_reg_desc const *r, bool raz)
> {
> u32 id = sys_reg((u32)r->Op0, (u32)r->Op1,
> (u32)r->CRn, (u32)r->CRm, (u32)r->Op2);
> - u64 val = raz ? 0 : read_sanitised_ftr_reg(id);
> + u64 val = raz ? 0 : kvm_get_id_reg(vcpu, id);
>
> if (id == SYS_ID_AA64PFR0_EL1) {
> if (!vcpu_has_sve(vcpu))
> @@ -1238,7 +1257,7 @@ static int set_id_aa64zfr0_el1(struct kvm_vcpu *vcpu,
> * are stored, and for set_id_reg() we don't allow the effective value
> * to be changed.
> */
> -static int __get_id_reg(const struct kvm_vcpu *vcpu,
> +static int __get_id_reg(struct kvm_vcpu *vcpu,
> const struct sys_reg_desc *rd, void __user *uaddr,
> bool raz)
> {
> @@ -1248,7 +1267,7 @@ static int __get_id_reg(const struct kvm_vcpu *vcpu,
> return reg_to_user(uaddr, &val, id);
> }
>
> -static int __set_id_reg(const struct kvm_vcpu *vcpu,
> +static int __set_id_reg(struct kvm_vcpu *vcpu,
> const struct sys_reg_desc *rd, void __user *uaddr,
> bool raz)
> {
> diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
> index f6d86033c4fa..1029444d04aa 100644
> --- a/include/uapi/linux/kvm.h
> +++ b/include/uapi/linux/kvm.h
> @@ -1272,6 +1272,17 @@ struct kvm_vfio_spapr_tce {
> __s32 tablefd;
> };
>
> +#define ID_REG_MAX_NUMS 64
> +struct id_reg_info {
> + uint64_t sys_id;
> + uint64_t sys_val;
I'm not sure the 'sys_' prefix is necessary.
> +};
> +
> +struct id_registers {
> + struct id_reg_info regs[ID_REG_MAX_NUMS];
> + uint64_t num;
> +};
> +
This is arch specific, so there should be ARMv8 in the names.
> /*
> * ioctls for VM fds
> */
> --
> 2.18.4
>
