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SubjectRe: [PATCH v4 2/4] RISC-V: KVM: Add VM capability to allow userspace get GPA bits
On Fri, Dec 24, 2021 at 1:06 PM Anup Patel <anup.patel@wdc.com> 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@wdc.com>
> Reviewed-and-tested-by: Atish Patra <atishp@rivosinc.com>

Queued this patch for 5.17

Thanks,
Anup

> ---
> 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 247b761c72fd..ac38696abedf 100644
> --- a/arch/riscv/include/asm/kvm_host.h
> +++ b/arch/riscv/include/asm/kvm_host.h
> @@ -219,6 +219,7 @@ 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_bits(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 d0efdc2259dc..58a47c93e5f9 100644
> --- a/arch/riscv/kvm/mmu.c
> +++ b/arch/riscv/kvm/mmu.c
> @@ -766,3 +766,8 @@ unsigned long kvm_riscv_stage2_mode(void)
> {
> return stage2_mode >> HGATP_MODE_SHIFT;
> }
> +
> +int kvm_riscv_stage2_gpa_bits(void)
> +{
> + return stage2_gpa_bits;
> +}
> diff --git a/arch/riscv/kvm/vm.c b/arch/riscv/kvm/vm.c
> index fb18af34a4b5..1e12c19a7c6a 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_bits();
> + 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
>

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