[PATCH v3 07/13] RISC-V: KVM: Add support for SBI extension registers

Atish Patra atishp at atishpatra.org
Tue Dec 19 11:58:27 PST 2023


On Sun, Dec 17, 2023 at 12:40 PM Andrew Jones <ajones at ventanamicro.com> wrote:
>
> Some SBI extensions have state that needs to be saved / restored
> when migrating the VM. Provide a get/set-one-reg register type
> for SBI extension registers. Each SBI extension that uses this type
> will have its own subtype. There are currently no subtypes defined.
> The next patch introduces the first one.
>
> Reviewed-by: Anup Patel <anup at brainfault.org>
> Signed-off-by: Andrew Jones <ajones at ventanamicro.com>
> ---
>  arch/riscv/include/asm/kvm_vcpu_sbi.h |  4 ++
>  arch/riscv/include/uapi/asm/kvm.h     |  3 ++
>  arch/riscv/kvm/vcpu_onereg.c          | 42 +++++++++++++++++--
>  arch/riscv/kvm/vcpu_sbi.c             | 58 +++++++++++++++++++++++++++
>  4 files changed, 103 insertions(+), 4 deletions(-)
>
> diff --git a/arch/riscv/include/asm/kvm_vcpu_sbi.h b/arch/riscv/include/asm/kvm_vcpu_sbi.h
> index 99c23bb37a37..dd60f73b5c36 100644
> --- a/arch/riscv/include/asm/kvm_vcpu_sbi.h
> +++ b/arch/riscv/include/asm/kvm_vcpu_sbi.h
> @@ -60,6 +60,10 @@ int kvm_riscv_vcpu_set_reg_sbi_ext(struct kvm_vcpu *vcpu,
>                                    const struct kvm_one_reg *reg);
>  int kvm_riscv_vcpu_get_reg_sbi_ext(struct kvm_vcpu *vcpu,
>                                    const struct kvm_one_reg *reg);
> +int kvm_riscv_vcpu_set_reg_sbi(struct kvm_vcpu *vcpu,
> +                              const struct kvm_one_reg *reg);
> +int kvm_riscv_vcpu_get_reg_sbi(struct kvm_vcpu *vcpu,
> +                              const struct kvm_one_reg *reg);
>  const struct kvm_vcpu_sbi_extension *kvm_vcpu_sbi_find_ext(
>                                 struct kvm_vcpu *vcpu, unsigned long extid);
>  bool riscv_vcpu_supports_sbi_ext(struct kvm_vcpu *vcpu, int idx);
> diff --git a/arch/riscv/include/uapi/asm/kvm.h b/arch/riscv/include/uapi/asm/kvm.h
> index e961d79622fb..30f89a0e855f 100644
> --- a/arch/riscv/include/uapi/asm/kvm.h
> +++ b/arch/riscv/include/uapi/asm/kvm.h
> @@ -242,6 +242,9 @@ enum KVM_RISCV_SBI_EXT_ID {
>  #define KVM_REG_RISCV_VECTOR_REG(n)    \
>                 ((n) + sizeof(struct __riscv_v_ext_state) / sizeof(unsigned long))
>
> +/* Registers for specific SBI extensions are mapped as type 10 */
> +#define KVM_REG_RISCV_SBI              (0x0a << KVM_REG_RISCV_TYPE_SHIFT)
> +


nit comment: KVM_REG_RISCV_SBI looks bit odd when we already have
KVM_REG_RISCV_SBI_EXT for
extension enabling/disabling.

How about renaming this to KVM_REG_RISCV_SBI_EXT_STATE or something
similar indicate that this
for a specific extension state ?


>  /* Device Control API: RISC-V AIA */
>  #define KVM_DEV_RISCV_APLIC_ALIGN              0x1000
>  #define KVM_DEV_RISCV_APLIC_SIZE               0x4000
> diff --git a/arch/riscv/kvm/vcpu_onereg.c b/arch/riscv/kvm/vcpu_onereg.c
> index 11cdbf844291..901480e73817 100644
> --- a/arch/riscv/kvm/vcpu_onereg.c
> +++ b/arch/riscv/kvm/vcpu_onereg.c
> @@ -961,6 +961,29 @@ static unsigned long num_sbi_ext_regs(struct kvm_vcpu *vcpu)
>         return copy_sbi_ext_reg_indices(vcpu, NULL);
>  }
>
> +static inline unsigned long num_sbi_regs(struct kvm_vcpu *vcpu)
> +{
> +       return 0;
> +}
> +
> +static int copy_sbi_reg_indices(struct kvm_vcpu *vcpu, u64 __user *uindices)
> +{
> +       int n = num_sbi_regs(vcpu);
> +
> +       for (int i = 0; i < n; i++) {
> +               u64 reg = KVM_REG_RISCV | KVM_REG_SIZE_U64 |
> +                         KVM_REG_RISCV_SBI | i;
> +
> +               if (uindices) {
> +                       if (put_user(reg, uindices))
> +                               return -EFAULT;
> +                       uindices++;
> +               }
> +       }
> +
> +       return n;
> +}
> +
>  static inline unsigned long num_vector_regs(const struct kvm_vcpu *vcpu)
>  {
>         if (!riscv_isa_extension_available(vcpu->arch.isa, v))
> @@ -1028,6 +1051,7 @@ unsigned long kvm_riscv_vcpu_num_regs(struct kvm_vcpu *vcpu)
>         res += num_vector_regs(vcpu);
>         res += num_isa_ext_regs(vcpu);
>         res += num_sbi_ext_regs(vcpu);
> +       res += num_sbi_regs(vcpu);
>
>         return res;
>  }
> @@ -1083,6 +1107,12 @@ int kvm_riscv_vcpu_copy_reg_indices(struct kvm_vcpu *vcpu,
>         ret = copy_sbi_ext_reg_indices(vcpu, uindices);
>         if (ret < 0)
>                 return ret;
> +       uindices += ret;
> +
> +       ret = copy_sbi_reg_indices(vcpu, uindices);
> +       if (ret < 0)
> +               return ret;
> +       uindices += ret;
>
>         return 0;
>  }
> @@ -1105,12 +1135,14 @@ int kvm_riscv_vcpu_set_reg(struct kvm_vcpu *vcpu,
>         case KVM_REG_RISCV_FP_D:
>                 return kvm_riscv_vcpu_set_reg_fp(vcpu, reg,
>                                                  KVM_REG_RISCV_FP_D);
> +       case KVM_REG_RISCV_VECTOR:
> +               return kvm_riscv_vcpu_set_reg_vector(vcpu, reg);
>         case KVM_REG_RISCV_ISA_EXT:
>                 return kvm_riscv_vcpu_set_reg_isa_ext(vcpu, reg);
>         case KVM_REG_RISCV_SBI_EXT:
>                 return kvm_riscv_vcpu_set_reg_sbi_ext(vcpu, reg);
> -       case KVM_REG_RISCV_VECTOR:
> -               return kvm_riscv_vcpu_set_reg_vector(vcpu, reg);
> +       case KVM_REG_RISCV_SBI:
> +               return kvm_riscv_vcpu_set_reg_sbi(vcpu, reg);
>         default:
>                 break;
>         }
> @@ -1136,12 +1168,14 @@ int kvm_riscv_vcpu_get_reg(struct kvm_vcpu *vcpu,
>         case KVM_REG_RISCV_FP_D:
>                 return kvm_riscv_vcpu_get_reg_fp(vcpu, reg,
>                                                  KVM_REG_RISCV_FP_D);
> +       case KVM_REG_RISCV_VECTOR:
> +               return kvm_riscv_vcpu_get_reg_vector(vcpu, reg);
>         case KVM_REG_RISCV_ISA_EXT:
>                 return kvm_riscv_vcpu_get_reg_isa_ext(vcpu, reg);
>         case KVM_REG_RISCV_SBI_EXT:
>                 return kvm_riscv_vcpu_get_reg_sbi_ext(vcpu, reg);
> -       case KVM_REG_RISCV_VECTOR:
> -               return kvm_riscv_vcpu_get_reg_vector(vcpu, reg);
> +       case KVM_REG_RISCV_SBI:
> +               return kvm_riscv_vcpu_get_reg_sbi(vcpu, reg);
>         default:
>                 break;
>         }
> diff --git a/arch/riscv/kvm/vcpu_sbi.c b/arch/riscv/kvm/vcpu_sbi.c
> index 088daaa23dd8..834176242ddf 100644
> --- a/arch/riscv/kvm/vcpu_sbi.c
> +++ b/arch/riscv/kvm/vcpu_sbi.c
> @@ -325,6 +325,64 @@ int kvm_riscv_vcpu_get_reg_sbi_ext(struct kvm_vcpu *vcpu,
>         return 0;
>  }
>
> +int kvm_riscv_vcpu_set_reg_sbi(struct kvm_vcpu *vcpu,
> +                              const struct kvm_one_reg *reg)
> +{
> +       unsigned long __user *uaddr =
> +                       (unsigned long __user *)(unsigned long)reg->addr;
> +       unsigned long reg_num = reg->id & ~(KVM_REG_ARCH_MASK |
> +                                           KVM_REG_SIZE_MASK |
> +                                           KVM_REG_RISCV_SBI);
> +       unsigned long reg_subtype, reg_val;
> +
> +       if (KVM_REG_SIZE(reg->id) != sizeof(unsigned long))
> +               return -EINVAL;
> +
> +       if (copy_from_user(&reg_val, uaddr, KVM_REG_SIZE(reg->id)))
> +               return -EFAULT;
> +
> +       reg_subtype = reg_num & KVM_REG_RISCV_SUBTYPE_MASK;
> +       reg_num &= ~KVM_REG_RISCV_SUBTYPE_MASK;
> +
> +       switch (reg_subtype) {
> +       default:
> +               return -EINVAL;
> +       }
> +
> +       return 0;
> +}
> +
> +int kvm_riscv_vcpu_get_reg_sbi(struct kvm_vcpu *vcpu,
> +                              const struct kvm_one_reg *reg)
> +{
> +       unsigned long __user *uaddr =
> +                       (unsigned long __user *)(unsigned long)reg->addr;
> +       unsigned long reg_num = reg->id & ~(KVM_REG_ARCH_MASK |
> +                                           KVM_REG_SIZE_MASK |
> +                                           KVM_REG_RISCV_SBI);
> +       unsigned long reg_subtype, reg_val;
> +       int ret;
> +
> +       if (KVM_REG_SIZE(reg->id) != sizeof(unsigned long))
> +               return -EINVAL;
> +
> +       reg_subtype = reg_num & KVM_REG_RISCV_SUBTYPE_MASK;
> +       reg_num &= ~KVM_REG_RISCV_SUBTYPE_MASK;
> +
> +       switch (reg_subtype) {
> +       default:
> +               return -EINVAL;
> +       }
> +
> +       if (ret)
> +               return ret;
> +
> +       if (copy_to_user(uaddr, &reg_val, KVM_REG_SIZE(reg->id)))
> +               return -EFAULT;
> +
> +       return 0;
> +}
> +
>  const struct kvm_vcpu_sbi_extension *kvm_vcpu_sbi_find_ext(
>                                 struct kvm_vcpu *vcpu, unsigned long extid)
>  {
> --
> 2.43.0
>

Other than that, lgtm.

Reviewed-by: Atish Patra <atishp at rivosinc.com>

-- 
Regards,
Atish



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