Commit f2cc3273 authored by Marc Zyngier's avatar Marc Zyngier
Browse files

KVM: arm64: Avoid mapping size adjustment on permission fault 



Since we only support PMD-sized mappings for THP, getting
a permission fault on a level that results in a mapping
being larger than PAGE_SIZE is a sure indication that we have
already upgraded our mapping to a PMD.

In this case, there is no need to try and parse userspace page
tables, as the fault information already tells us everything.

Signed-off-by: default avatarMarc Zyngier <maz@kernel.org>
Reviewed-by: default avatarAlexandru Elisei <alexandru.elisei@arm.com>
Link: https://lore.kernel.org/r/20210726153552.1535838-4-maz@kernel.org
parent 6011cf68

arch/arm64/kvm/mmu.c

+8 −3
Original line number Diff line number Diff line
@@ -1076,9 +1076,14 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, 
	 * If we are not forced to use page mapping, check if we are

	 * backed by a THP and thus use block mapping if possible.

	 */

	if (vma_pagesize == PAGE_SIZE && !(force_pte || device))

		vma_pagesize = transparent_hugepage_adjust(kvm, memslot, hva,

							   &pfn, &fault_ipa);

	if (vma_pagesize == PAGE_SIZE && !(force_pte || device)) {

		if (fault_status == FSC_PERM && fault_granule > PAGE_SIZE)

			vma_pagesize = fault_granule;

		else

			vma_pagesize = transparent_hugepage_adjust(kvm, memslot,

								   hva, &pfn,

								   &fault_ipa);

	}



	if (fault_status != FSC_PERM && !device && kvm_has_mte(kvm)) {

		/* Check the VMM hasn't introduced a new VM_SHARED VMA */