On 8/13/2020 5:05 PM, Andrew Jones wrote:
> 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 <[email protected]>
>> Signed-off-by: Peng Liang <[email protected]>
>> ---
>> 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)];
>
>
Thank you for your suggestions.
>> + }
>> + 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.
Some names are not very suitable, I'll change them.
>
>> /*
>> * ioctls for VM fds
>> */
>> --
>> 2.18.4
>>
>
> .
>
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