On Mon, Nov 29, 2021 at 12:10 AM Anup Patel <anup.patel@xxxxxxx> wrote:
>
> The number of GPA bits supported for a RISC-V Guest/VM is based on the
> MMU mode used by the G-stage translation. The KVM RISC-V will detect and
> use the best possible MMU mode for the G-stage in kvm_arch_init().
>
> We add a generic VM capability KVM_CAP_VM_GPA_BITS which can be used by
> the KVM userspace to get the number of GPA (guest physical address) bits
> supported for a Guest/VM.
>
> Signed-off-by: Anup Patel <anup.patel@xxxxxxx>
> ---
> arch/riscv/include/asm/kvm_host.h | 1 +
> arch/riscv/kvm/mmu.c | 5 +++++
> arch/riscv/kvm/vm.c | 3 +++
> include/uapi/linux/kvm.h | 1 +
> 4 files changed, 10 insertions(+)
>
> diff --git a/arch/riscv/include/asm/kvm_host.h b/arch/riscv/include/asm/kvm_host.h
> index 37589b953bcb..ae5d238607fe 100644
> --- a/arch/riscv/include/asm/kvm_host.h
> +++ b/arch/riscv/include/asm/kvm_host.h
> @@ -221,6 +221,7 @@ void kvm_riscv_stage2_free_pgd(struct kvm *kvm);
> void kvm_riscv_stage2_update_hgatp(struct kvm_vcpu *vcpu);
> void kvm_riscv_stage2_mode_detect(void);
> unsigned long kvm_riscv_stage2_mode(void);
> +int kvm_riscv_stage2_gpa_size(void);
>
> void kvm_riscv_stage2_vmid_detect(void);
> unsigned long kvm_riscv_stage2_vmid_bits(void);
> diff --git a/arch/riscv/kvm/mmu.c b/arch/riscv/kvm/mmu.c
> index 9ffd0255af43..9b6d6465094f 100644
> --- a/arch/riscv/kvm/mmu.c
> +++ b/arch/riscv/kvm/mmu.c
> @@ -760,3 +760,8 @@ unsigned long kvm_riscv_stage2_mode(void)
> {
> return stage2_mode >> HGATP_MODE_SHIFT;
> }
> +
> +int kvm_riscv_stage2_gpa_size(void)
> +{
> + return stage2_gpa_bits;
> +}
The ioctl & the underlying stage2_gpa_bits has bits.
Maybe rename the function to kvm_riscv_stage2_gpa_bits as well ?
> diff --git a/arch/riscv/kvm/vm.c b/arch/riscv/kvm/vm.c
> index fb18af34a4b5..6f959639ec45 100644
> --- a/arch/riscv/kvm/vm.c
> +++ b/arch/riscv/kvm/vm.c
> @@ -82,6 +82,9 @@ int kvm_vm_ioctl_check_extension(struct kvm *kvm, long ext)
> case KVM_CAP_NR_MEMSLOTS:
> r = KVM_USER_MEM_SLOTS;
> break;
> + case KVM_CAP_VM_GPA_BITS:
> + r = kvm_riscv_stage2_gpa_size();
> + break;
> default:
> r = 0;
> break;
> diff --git a/include/uapi/linux/kvm.h b/include/uapi/linux/kvm.h
> index 1daa45268de2..469f05d69c8d 100644
> --- a/include/uapi/linux/kvm.h
> +++ b/include/uapi/linux/kvm.h
> @@ -1131,6 +1131,7 @@ struct kvm_ppc_resize_hpt {
> #define KVM_CAP_EXIT_ON_EMULATION_FAILURE 204
> #define KVM_CAP_ARM_MTE 205
> #define KVM_CAP_VM_MOVE_ENC_CONTEXT_FROM 206
> +#define KVM_CAP_VM_GPA_BITS 207
>
> #ifdef KVM_CAP_IRQ_ROUTING
>
> --
> 2.25.1
>
Other than that, it looks good to me.
Reviewed-by: Atish Patra <atishp@xxxxxxxxxxxx>
--
Regards,
Atish
