[PATCH v3 14/17] KVM: arm64: Alloc pkvm_hyp_vcpu using pKVM heap allocator

[Vincent Donnefort <vdonnefort@google.com>]

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.

Signed-off-by: Vincent Donnefort <vdonnefort@google.com>

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 595db3a936fe..01e7ffc489f5 100644
--- a/arch/arm64/kvm/hyp/nvhe/hyp-main.c
+++ b/arch/arm64/kvm/hyp/nvhe/hyp-main.c
@@ -605,10 +605,9 @@ 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;
 }
-- 
2.55.0.229.g6434b31f56-goog