On Fri, Aug 14, 2020 at 07:49:43PM +0800, Peng Liang wrote:
> On 8/13/2020 6:02 PM, Andrew Jones wrote:
> > 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
> >
>
> id_reg_info is for information of an ID register, and id_registers contains
> all the ID registers.
Obviously. But why is that UAPI? What user interface is using them?
>
> Thanks,
> Peng
>
> >>
> >>> /*
> >>> * ioctls for VM fds
> >>> */
> >>> --
> >>> 2.18.4
> >>>
> >>
> >
> > .
> >
>
