Commit 1abc1ad5 authored by Fuad Tabba's avatar Fuad Tabba Committed by Marc Zyngier
Browse files

KVM: arm64: Separate allocation and insertion of pKVM VM table entries 



The current insert_vm_table_entry() function performs two actions at
once: it finds a free slot in the pKVM VM table and populates it with
the pkvm_hyp_vm pointer.

Refactor this function as a preparatory step for future work that will
require reserving a VM slot and its corresponding handle earlier in the
VM lifecycle, before the pkvm_hyp_vm structure is initialized and ready
to be inserted.

Split the function into a two-phase process:

- A new allocate_vm_table_entry() function finds an empty slot, marks it
  as reserved with a RESERVED_ENTRY placeholder, and returns a handle
  derived from the slot's index.

- The insert_vm_table_entry() function is repurposed to take the handle,
  validate that the corresponding slot is in the reserved state, and
  then populate it with the pkvm_hyp_vm pointer.

Signed-off-by: default avatarFuad Tabba <tabba@google.com>
Tested-by: default avatarMark Brown <broonie@kernel.org>
Signed-off-by: default avatarMarc Zyngier <maz@kernel.org>
parent 3c45b676

arch/arm64/kvm/hyp/nvhe/pkvm.c

+43 −9
Original line number Diff line number Diff line
@@ -192,6 +192,11 @@ static int pkvm_vcpu_init_traps(struct pkvm_hyp_vcpu *hyp_vcpu) 
 */

#define HANDLE_OFFSET 0x1000



/*

 * Marks a reserved but not yet used entry in the VM table.

 */

#define RESERVED_ENTRY ((void *)0xa110ca7ed)



static unsigned int vm_handle_to_idx(pkvm_handle_t handle)

{

	return handle - HANDLE_OFFSET;
@@ -231,6 +236,10 @@ static struct pkvm_hyp_vm *get_vm_by_handle(pkvm_handle_t handle) 
	if (unlikely(idx >= KVM_MAX_PVMS))

		return NULL;



	/* A reserved entry doesn't represent an initialized VM. */

	if (unlikely(vm_table[idx] == RESERVED_ENTRY))

		return NULL;



	return vm_table[idx];

}
@@ -481,7 +490,7 @@ static int init_pkvm_hyp_vcpu(struct pkvm_hyp_vcpu *hyp_vcpu, 
	return ret;

}



static int find_free_vm_table_entry(struct kvm *host_kvm)

static int find_free_vm_table_entry(void)

{

	int i;
@@ -494,15 +503,13 @@ static int find_free_vm_table_entry(struct kvm *host_kvm) 
}



/*

 * Allocate a VM table entry and insert a pointer to the new vm.

 * Reserve a VM table entry.

 *

 * Return a unique handle to the VM on success,

 * negative error code on failure.

 */

static pkvm_handle_t insert_vm_table_entry(struct kvm *host_kvm,

					   struct pkvm_hyp_vm *hyp_vm)

static int allocate_vm_table_entry(void)

{

	struct kvm_s2_mmu *mmu = &hyp_vm->kvm.arch.mmu;

	int idx;



	hyp_assert_lock_held(&vm_table_lock);
@@ -515,10 +522,30 @@ static pkvm_handle_t insert_vm_table_entry(struct kvm *host_kvm, 
	if (unlikely(!vm_table))

		return -EINVAL;



	idx = find_free_vm_table_entry(host_kvm);

	if (idx < 0)

	idx = find_free_vm_table_entry();

	if (unlikely(idx < 0))

		return idx;



	vm_table[idx] = RESERVED_ENTRY;



	return idx;

}



/*

 * Insert a pointer to the new VM into the VM table.

 *

 * Return 0 on success, or negative error code on failure.

 */

static int insert_vm_table_entry(struct kvm *host_kvm,

				 struct pkvm_hyp_vm *hyp_vm,

				 pkvm_handle_t handle)

{

	struct kvm_s2_mmu *mmu = &hyp_vm->kvm.arch.mmu;

	unsigned int idx;



	hyp_assert_lock_held(&vm_table_lock);



	idx = vm_handle_to_idx(handle);

	hyp_vm->kvm.arch.pkvm.handle = idx_to_vm_handle(idx);



	/* VMID 0 is reserved for the host */
@@ -528,7 +555,7 @@ static pkvm_handle_t insert_vm_table_entry(struct kvm *host_kvm, 
	mmu->pgt = &hyp_vm->pgt;



	vm_table[idx] = hyp_vm;

	return hyp_vm->kvm.arch.pkvm.handle;

	return 0;

}



/*
@@ -614,6 +641,7 @@ int __pkvm_init_vm(struct kvm *host_kvm, unsigned long vm_hva, 
	struct pkvm_hyp_vm *hyp_vm = NULL;

	size_t vm_size, pgd_size;

	unsigned int nr_vcpus;

	pkvm_handle_t handle;

	void *pgd = NULL;

	int ret;
@@ -643,10 +671,16 @@ int __pkvm_init_vm(struct kvm *host_kvm, unsigned long vm_hva, 
	init_pkvm_hyp_vm(host_kvm, hyp_vm, nr_vcpus);



	hyp_spin_lock(&vm_table_lock);

	ret = insert_vm_table_entry(host_kvm, hyp_vm);

	ret = allocate_vm_table_entry();

	if (ret < 0)

		goto err_unlock;



	handle = idx_to_vm_handle(ret);



	ret = insert_vm_table_entry(host_kvm, hyp_vm, handle);

	if (ret)

		goto err_unlock;



	ret = kvm_guest_prepare_stage2(hyp_vm, pgd);

	if (ret)

		goto err_remove_vm_table_entry;