Re: [PATCH v4 1/5] RISC-V: KVM: Add the split page cache for ioctl context

[Anup Patel]

On Wed, Jul 1, 2026 at 5:41 PM Wang Yechao <wang.yechao255@xxxxxxxxxx> wrote:
>
> Add the split page cache for dirty logging enablement and the
> KVM_CLEAR_DIRTY_LOG ioctl.
>
> Signed-off-by: Wang Yechao <wang.yechao255@xxxxxxxxxx>
> ---
>  arch/riscv/include/asm/kvm_host.h | 1 +
>  arch/riscv/kvm/mmu.c              | 1 +
>  arch/riscv/kvm/vm.c               | 6 ++++++
>  3 files changed, 8 insertions(+)
>
> diff --git a/arch/riscv/include/asm/kvm_host.h b/arch/riscv/include/asm/kvm_host.h
> index 60017ceec9d2a..69f73fd106a94 100644
> --- a/arch/riscv/include/asm/kvm_host.h
> +++ b/arch/riscv/include/asm/kvm_host.h
> @@ -86,6 +86,7 @@ struct kvm_arch {
>         pgd_t *pgd;
>         phys_addr_t pgd_phys;
>         unsigned long pgd_levels;
> +       struct kvm_mmu_memory_cache pgd_split_page_cache;
>
>         /* Guest Timer */
>         struct kvm_guest_timer timer;
> diff --git a/arch/riscv/kvm/mmu.c b/arch/riscv/kvm/mmu.c
> index 082f9b2617338..9cf69bc28b9c5 100644
> --- a/arch/riscv/kvm/mmu.c
> +++ b/arch/riscv/kvm/mmu.c
> @@ -676,6 +676,7 @@ int kvm_riscv_mmu_alloc_pgd(struct kvm *kvm)
>         kvm->arch.pgd = page_to_virt(pgd_page);
>         kvm->arch.pgd_phys = page_to_phys(pgd_page);
>         kvm->arch.pgd_levels = kvm_riscv_gstage_max_pgd_levels;
> +       kvm->arch.pgd_split_page_cache.gfp_zero = __GFP_ZERO;
>
>         return 0;
>  }
> diff --git a/arch/riscv/kvm/vm.c b/arch/riscv/kvm/vm.c
> index a9f083feeb767..be38f24a297d6 100644
> --- a/arch/riscv/kvm/vm.c
> +++ b/arch/riscv/kvm/vm.c
> @@ -54,6 +54,12 @@ void kvm_arch_destroy_vm(struct kvm *kvm)
>         kvm_destroy_vcpus(kvm);
>
>         kvm_riscv_aia_destroy_vm(kvm);
> +
> +       /*
> +        * Free the split page cache after all vCPUs and devices are destroyed.
> +        * At this point, there are no concurrent accesses to the cache.
> +        */
> +       kvm_mmu_free_memory_cache(&kvm->arch.pgd_split_page_cache);

Better to do this in kvm_riscv_mmu_free_pgd()

Regards,
Anup