Re: [PATCH v4 14/17] KVM: arm64: Alloc pkvm_hyp_vcpu using pKVM heap allocator

On Fri, 31 Jul 2026 at 15:36, 'Vincent Donnefort' via kernel-team
<[email protected]> wrote:
>
> Transition the allocation of the hypervisor vCPU state structure
> (pkvm_hyp_vcpu) from the host to the hypervisor using the new pKVM heap
> allocator (hyp_alloc()).
>
> Previously, the host was responsible for calculating the size of,
> allocating, and donating memory for pkvm_hyp_vcpu during VM creation.
> With the heap allocator in place, the hypervisor now allocates this
> structure dynamically at EL2.
>
> Use the pkvm_call_hyp_req() wrapper in the host to invoke
> __pkvm_create_hyp_vcpu, which automatically handles any top-up requests
> if the hypervisor runs out of heap memory during allocation.
>
> Tested-by: Fuad Tabba <[email protected]>
> Signed-off-by: Vincent Donnefort <[email protected]>

Reviewed-by: Fuad Tabba <[email protected]>

Cheers,
/fuad


>
> diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
> index caea8e9986d1..95e05cee0f3a 100644
> --- a/arch/arm64/include/asm/kvm_host.h
> +++ b/arch/arm64/include/asm/kvm_host.h
> @@ -268,7 +268,6 @@ typedef u16 pkvm_handle_t;
>
>  struct kvm_protected_vm {
>         pkvm_handle_t handle;
> -       struct kvm_hyp_memcache teardown_mc;
>         struct kvm_hyp_memcache stage2_teardown_mc;
>         bool is_protected;
>         bool is_created;
> diff --git a/arch/arm64/kvm/hyp/hyp-constants.c b/arch/arm64/kvm/hyp/hyp-constants.c
> index 501ab35a3840..b2caae21f271 100644
> --- a/arch/arm64/kvm/hyp/hyp-constants.c
> +++ b/arch/arm64/kvm/hyp/hyp-constants.c
> @@ -7,6 +7,5 @@
>  int main(void)
>  {
>         DEFINE(STRUCT_HYP_PAGE_SIZE,    sizeof(struct hyp_page));
> -       DEFINE(PKVM_HYP_VCPU_SIZE,      sizeof(struct pkvm_hyp_vcpu));
>         return 0;
>  }
> diff --git a/arch/arm64/kvm/hyp/include/nvhe/pkvm.h b/arch/arm64/kvm/hyp/include/nvhe/pkvm.h
> index 8e930c8729af..cfb6e409bf49 100644
> --- a/arch/arm64/kvm/hyp/include/nvhe/pkvm.h
> +++ b/arch/arm64/kvm/hyp/include/nvhe/pkvm.h
> @@ -83,8 +83,7 @@ void pkvm_hyp_vm_table_init(void *tbl);
>  int __pkvm_reserve_vm(void);
>  void __pkvm_unreserve_vm(pkvm_handle_t handle);
>  int __pkvm_init_vm(struct kvm *host_kvm, void *pgd);
> -int __pkvm_init_vcpu(pkvm_handle_t handle, struct kvm_vcpu *host_vcpu,
> -                    unsigned long vcpu_hva);
> +int __pkvm_init_vcpu(pkvm_handle_t handle, struct kvm_vcpu *host_vcpu);
>
>  int __pkvm_reclaim_dying_guest_page(pkvm_handle_t handle, u64 gfn);
>  int __pkvm_start_teardown_vm(pkvm_handle_t handle);
> diff --git a/arch/arm64/kvm/hyp/nvhe/hyp-main.c b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
> index c1aa6d773c26..9bab1e802281 100644
> --- a/arch/arm64/kvm/hyp/nvhe/hyp-main.c
> +++ b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
> @@ -610,10 +610,9 @@ static void handle___pkvm_init_vcpu(struct kvm_cpu_context *host_ctxt)
>  {
>         DECLARE_REG(pkvm_handle_t, handle, host_ctxt, 1);
>         DECLARE_REG(struct kvm_vcpu *, host_vcpu, host_ctxt, 2);
> -       DECLARE_REG(unsigned long, vcpu_hva, host_ctxt, 3);
>
>         host_vcpu = kern_hyp_va(host_vcpu);
> -       cpu_reg(host_ctxt, 1) = __pkvm_init_vcpu(handle, host_vcpu, vcpu_hva);
> +       errno_to_smccc(__pkvm_init_vcpu(handle, host_vcpu), host_ctxt);
>  }
>
>  static void handle___pkvm_vcpu_in_poison_fault(struct kvm_cpu_context *host_ctxt)
> diff --git a/arch/arm64/kvm/hyp/nvhe/pkvm.c b/arch/arm64/kvm/hyp/nvhe/pkvm.c
> index 09f609db8556..fffd2f4bc071 100644
> --- a/arch/arm64/kvm/hyp/nvhe/pkvm.c
> +++ b/arch/arm64/kvm/hyp/nvhe/pkvm.c
> @@ -645,30 +645,6 @@ static size_t pkvm_get_hyp_vm_size(unsigned int nr_vcpus)
>                 size_mul(sizeof(struct pkvm_hyp_vcpu *), nr_vcpus));
>  }
>
> -static void *map_donated_memory_noclear(unsigned long host_va, size_t size)
> -{
> -       void *va = (void *)kern_hyp_va(host_va);
> -
> -       if (!PAGE_ALIGNED(va))
> -               return NULL;
> -
> -       if (__pkvm_host_donate_hyp(hyp_virt_to_pfn(va),
> -                                  PAGE_ALIGN(size) >> PAGE_SHIFT))
> -               return NULL;
> -
> -       return va;
> -}
> -
> -static void *map_donated_memory(unsigned long host_va, size_t size)
> -{
> -       void *va = map_donated_memory_noclear(host_va, size);
> -
> -       if (va)
> -               memset(va, 0, size);
> -
> -       return va;
> -}
> -
>  static void __unmap_donated_memory(void *va, size_t size)
>  {
>         kvm_flush_dcache_to_poc(va, size);
> @@ -896,16 +872,15 @@ static int register_hyp_vcpu(struct pkvm_hyp_vm *hyp_vm,
>         return 0;
>  }
>
> -int __pkvm_init_vcpu(pkvm_handle_t handle, struct kvm_vcpu *host_vcpu,
> -                    unsigned long vcpu_hva)
> +int __pkvm_init_vcpu(pkvm_handle_t handle, struct kvm_vcpu *host_vcpu)
>  {
>         struct pkvm_hyp_vcpu *hyp_vcpu;
>         struct pkvm_hyp_vm *hyp_vm;
>         int ret;
>
> -       hyp_vcpu = map_donated_memory(vcpu_hva, sizeof(*hyp_vcpu));
> +       hyp_vcpu = hyp_alloc(sizeof(*hyp_vcpu));
>         if (!hyp_vcpu)
> -               return -ENOMEM;
> +               return hyp_alloc_errno();
>
>         hyp_spin_lock(&vm_table_lock);
>
> @@ -926,24 +901,12 @@ int __pkvm_init_vcpu(pkvm_handle_t handle, struct kvm_vcpu *host_vcpu,
>         }
>  unlock:
>         hyp_spin_unlock(&vm_table_lock);
> -
>         if (ret)
> -               unmap_donated_memory(hyp_vcpu, sizeof(*hyp_vcpu));
> +               hyp_free(hyp_vcpu);
> +
>         return ret;
>  }
>
> -static void
> -teardown_donated_memory(struct kvm_hyp_memcache *mc, void *addr, size_t size)
> -{
> -       size = PAGE_ALIGN(size);
> -       memset(addr, 0, size);
> -
> -       for (void *start = addr; start < addr + size; start += PAGE_SIZE)
> -               push_hyp_memcache(mc, start, hyp_virt_to_phys);
> -
> -       unmap_donated_memory_noclear(addr, size);
> -}
> -
>  int __pkvm_reclaim_dying_guest_page(pkvm_handle_t handle, u64 gfn)
>  {
>         struct pkvm_hyp_vm *hyp_vm = get_pkvm_hyp_vm(handle);
> @@ -993,7 +956,7 @@ int __pkvm_start_teardown_vm(pkvm_handle_t handle)
>
>  int __pkvm_finalize_teardown_vm(pkvm_handle_t handle)
>  {
> -       struct kvm_hyp_memcache *mc, *stage2_mc;
> +       struct kvm_hyp_memcache *stage2_mc;
>         struct pkvm_hyp_vm *hyp_vm;
>         struct kvm *host_kvm;
>         unsigned int idx;
> @@ -1014,7 +977,6 @@ int __pkvm_finalize_teardown_vm(pkvm_handle_t handle)
>         hyp_spin_unlock(&vm_table_lock);
>
>         /* Reclaim guest pages (including page-table pages) */
> -       mc = &host_kvm->arch.pkvm.teardown_mc;
>         stage2_mc = &host_kvm->arch.pkvm.stage2_teardown_mc;
>         reclaim_pgtable_pages(hyp_vm, stage2_mc);
>         unpin_host_vcpus(hyp_vm->vcpus, hyp_vm->kvm.created_vcpus);
> @@ -1036,7 +998,7 @@ int __pkvm_finalize_teardown_vm(pkvm_handle_t handle)
>                         unmap_donated_memory_noclear(addr, PAGE_SIZE);
>                 }
>
> -               teardown_donated_memory(mc, hyp_vcpu, sizeof(*hyp_vcpu));
> +               hyp_free(hyp_vcpu);
>         }
>
>         hyp_free(hyp_vm);
> diff --git a/arch/arm64/kvm/pkvm.c b/arch/arm64/kvm/pkvm.c
> index a9b85ad37787..3b29b3f43ffa 100644
> --- a/arch/arm64/kvm/pkvm.c
> +++ b/arch/arm64/kvm/pkvm.c
> @@ -153,28 +153,19 @@ static void __pkvm_destroy_hyp_vm(struct kvm *kvm)
>
>         kvm->arch.pkvm.handle = 0;
>         kvm->arch.pkvm.is_created = false;
> -       free_hyp_memcache(&kvm->arch.pkvm.teardown_mc);
>         free_hyp_memcache(&kvm->arch.pkvm.stage2_teardown_mc);
>  }
>
>  static int __pkvm_create_hyp_vcpu(struct kvm_vcpu *vcpu)
>  {
> -       size_t hyp_vcpu_sz = PAGE_ALIGN(PKVM_HYP_VCPU_SIZE);
>         pkvm_handle_t handle = vcpu->kvm->arch.pkvm.handle;
> -       void *hyp_vcpu;
>         int ret;
>
>         init_hyp_stage2_memcache(&vcpu->arch.pkvm_memcache);
>
> -       hyp_vcpu = alloc_pages_exact(hyp_vcpu_sz, GFP_KERNEL_ACCOUNT);
> -       if (!hyp_vcpu)
> -               return -ENOMEM;
> -
> -       ret = kvm_call_hyp_nvhe(__pkvm_init_vcpu, handle, vcpu, hyp_vcpu);
> +       ret = pkvm_call_hyp_req(__pkvm_init_vcpu, handle, vcpu);
>         if (!ret)
>                 vcpu_set_flag(vcpu, VCPU_PKVM_FINALIZED);
> -       else
> -               free_pages_exact(hyp_vcpu, hyp_vcpu_sz);
>
>         return ret;
>  }
> --
> 2.55.0.508.g3f0d502094-goog
>
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