On Thu, Aug 13, 2020 at 11:05:58AM +0200, 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 <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.
Also, why are id_reg_info and id_registers UAPI?
Thanks,
drew
>
> > /*
> > * ioctls for VM fds
> > */
> > --
> > 2.18.4
> >
>
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