Re: [RFC 3/5] KVM: Add KVM_VCPU_GET_REG_LIST.

[Christoffer Dall <c.dall@xxxxxxxxxxxxxxxxxxxxxx>]

On Tue, Aug 28, 2012 at 4:47 PM, Rusty Russell <rusty.russell@xxxxxxxxxx> wrote:
> This is a generic interface to find out what you can use
> KVM_GET_ONE_REG/KVM_SET_ONE_REG on.  Arhs need to define
> KVM_HAVE_REG_LIST and then kvm_arch_num_regs() and
> kvm_arch_copy_reg_indices() functions.
>
> It's inspired by KVM_GET_MSR_INDEX_LIST, except it's a per-vcpu ioctl,
> and uses 64-bit indices.
>
> Signed-off-by: Rusty Russell <rusty.russell@xxxxxxxxxx>
>
> diff --git a/include/linux/kvm.h b/include/linux/kvm.h
> index 209b432..b607f60 100644
> --- a/include/linux/kvm.h
> +++ b/include/linux/kvm.h
> @@ -906,7 +906,7 @@ struct kvm_s390_ucas_mapping {
>  #define KVM_KVMCLOCK_CTRL        _IO(KVMIO,   0xad)
>  #define KVM_ARM_VCPU_INIT        _IOW(KVMIO,  0xae, struct kvm_vcpu_init)
>  #define KVM_VCPU_GET_MSR_INDEX_LIST    _IOWR(KVMIO, 0xaf, struct kvm_msr_list)
> +#define KVM_VCPU_GET_REG_LIST    _IOWR(KVMIO, 0xb0, struct kvm_reg_list)
>
>  #define KVM_DEV_ASSIGN_ENABLE_IOMMU    (1 << 0)
>  #define KVM_DEV_ASSIGN_PCI_2_3         (1 << 1)
> @@ -958,4 +958,9 @@ struct kvm_assigned_msix_entry {
>         __u16 padding[3];
>  };
>
> +/* For KVM_VCPU_GET_REG_LIST. */
> +struct kvm_reg_list {
> +       __u64 n; /* number of regs */
> +       __u64 reg[0];
> +};
>  #endif /* __LINUX_KVM_H */
> diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
> index f3d43c3..daa3838 100644
> --- a/include/linux/kvm_host.h
> +++ b/include/linux/kvm_host.h
> @@ -572,7 +572,10 @@ int kvm_arch_set_reg(struct kvm_vcpu *vcpu, const struct kvm_one_reg *reg);
>  #define KVM_REG_LEN(index)                                             \
>         (1U << (((index) & KVM_REG_SIZE_MASK) >> KVM_REG_SIZE_SHIFT))
>  #endif
> -
> +#ifdef KVM_HAVE_REG_LIST
> +unsigned long kvm_arch_num_regs(struct kvm_vcpu *vcpu);
> +int kvm_arch_copy_reg_indices(struct kvm_vcpu *vcpu, u64 __user *indices);
> +#endif
>  void kvm_free_physmem(struct kvm *kvm);
>
>  void *kvm_kvzalloc(unsigned long size);
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index ad67cf4..b220c74 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -1949,6 +1949,23 @@ out_free2:
>                 break;
>         }
>  #endif
> +#ifdef KVM_HAVE_REG_LIST
> +       case KVM_VCPU_GET_REG_LIST: {
> +               struct kvm_reg_list __user *user_list = argp;
> +               struct kvm_reg_list reg_list;
> +               unsigned n;
> +
> +               if (copy_from_user(&reg_list, user_list, sizeof reg_list))
> +                       return -EFAULT;
> +               n = reg_list.n;
> +               reg_list.n = kvm_arch_num_regs(vcpu);
> +               if (copy_to_user(user_list, &reg_list, sizeof reg_list))
> +                       return -EFAULT;
> +               if (n < reg_list.n)
> +                       return -E2BIG;
> +               return kvm_arch_copy_reg_indices(vcpu, user_list->reg);
> +       }
> +#endif
>
>         default:
>                 r = kvm_arch_vcpu_ioctl(filp, ioctl, arg);

looks fine, but don't you need to update the API documentation?

-Christoffer
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