ANDROID: KVM: arm64: Check PGD alignment when creating a pVM Martijn reported a hypervisor crash when providing pKVM with an undersized PGD allocation. Indeed, although the size of the PGD allocation at EL2 is not under host control, a smaller host-side allocation can lead to providing pKVM with a misaligned PGD, which will cause the guest stage-2 init to fail in a bad way. Specifically, guest_s2_zalloc_pages_exact() expects a successful allocation from hyp_alloc_pages(), which can only happen if the pool has been pre-filled with a physically aligned high-order page. In order to guarantee allocation success in this path, check the host-provided PGD alignment early on. Bug: 443668075 Change-Id: I170963edc5721cf368a506bcdc4b2d0cdb462f78 Fixes: ab3b93a33d0e ("FROMLIST: KVM: arm64: Add infrastructure to create and track pKVM instances at EL2") Reported-by: Martijn Bogaard <martijnbogaard@google.com> Signed-off-by: Quentin Perret <qperret@google.com>

diff --git a/arch/arm64/kvm/hyp/nvhe/mem_protect.c b/arch/arm64/kvm/hyp/nvhe/mem_protect.c
index db34c79e..41712b6 100644
--- a/arch/arm64/kvm/hyp/nvhe/mem_protect.c
+++ b/arch/arm64/kvm/hyp/nvhe/mem_protect.c

@@ -210,7 +210,7 @@ static void *guest_s2_zalloc_pages_exact(size_t size)
 {
 	void *addr = hyp_alloc_pages(&current_vm->pool, get_order(size));
 
-	WARN_ON(size != (PAGE_SIZE << get_order(size)));
+	WARN_ON(!addr || size != (PAGE_SIZE << get_order(size)));
 	hyp_split_page(hyp_virt_to_page(addr));
 
 	return addr;

diff --git a/arch/arm64/kvm/hyp/nvhe/pkvm.c b/arch/arm64/kvm/hyp/nvhe/pkvm.c
index ba09c7d..614298c 100644
--- a/arch/arm64/kvm/hyp/nvhe/pkvm.c
+++ b/arch/arm64/kvm/hyp/nvhe/pkvm.c

@@ -730,6 +730,8 @@ int __pkvm_init_vm(struct kvm *host_kvm, unsigned long vm_hva,
 	vm_size = pkvm_get_hyp_vm_size(nr_vcpus);
 	last_ran_size = pkvm_get_last_ran_size();
 	pgd_size = kvm_pgtable_stage2_pgd_size(host_mmu.arch.vtcr);
+	if (!IS_ALIGNED(pgd_hva, pgd_size))
+		goto err_unpin_kvm;
 
 	ret = -ENOMEM;