Commit 2dbf12ae authored by Catalin Marinas's avatar Catalin Marinas Committed by Marc Zyngier
Browse files

KVM: arm64: Simplify the sanitise_mte_tags() logic 



Currently sanitise_mte_tags() checks if it's an online page before
attempting to sanitise the tags. Such detection should be done in the
caller via the VM_MTE_ALLOWED vma flag. Since kvm_set_spte_gfn() does
not have the vma, leave the page unmapped if not already tagged. Tag
initialisation will be done on a subsequent access fault in
user_mem_abort().

Signed-off-by: default avatarCatalin Marinas <catalin.marinas@arm.com>
[pcc@google.com: fix the page initializer]
Signed-off-by: default avatarPeter Collingbourne <pcc@google.com>
Reviewed-by: default avatarSteven Price <steven.price@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: Marc Zyngier <maz@kernel.org>
Cc: Peter Collingbourne <pcc@google.com>
Reviewed-by: default avatarCornelia Huck <cohuck@redhat.com>
Signed-off-by: default avatarMarc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20221104011041.290951-4-pcc@google.com
parent e059853d

arch/arm64/kvm/mmu.c

+15 −25
Original line number Diff line number Diff line
@@ -1091,23 +1091,14 @@ static int get_vma_page_shift(struct vm_area_struct *vma, unsigned long hva) 
 * - mmap_lock protects between a VM faulting a page in and the VMM performing

 *   an mprotect() to add VM_MTE

 */

static int sanitise_mte_tags(struct kvm *kvm, kvm_pfn_t pfn,

static void sanitise_mte_tags(struct kvm *kvm, kvm_pfn_t pfn,

			      unsigned long size)

{

	unsigned long i, nr_pages = size >> PAGE_SHIFT;

	struct page *page;

	struct page *page = pfn_to_page(pfn);



	if (!kvm_has_mte(kvm))

		return 0;



	/*

	 * pfn_to_online_page() is used to reject ZONE_DEVICE pages

	 * that may not support tags.

	 */

	page = pfn_to_online_page(pfn);



	if (!page)

		return -EFAULT;

		return;



	for (i = 0; i < nr_pages; i++, page++) {

		if (!page_mte_tagged(page)) {
@@ -1115,8 +1106,6 @@ static int sanitise_mte_tags(struct kvm *kvm, kvm_pfn_t pfn, 
			set_page_mte_tagged(page);

		}

	}



	return 0;

}



static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa,
@@ -1127,7 +1116,6 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, 
	bool write_fault, writable, force_pte = false;

	bool exec_fault;

	bool device = false;

	bool shared;

	unsigned long mmu_seq;

	struct kvm *kvm = vcpu->kvm;

	struct kvm_mmu_memory_cache *memcache = &vcpu->arch.mmu_page_cache;
@@ -1177,8 +1165,6 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, 
		vma_shift = get_vma_page_shift(vma, hva);

	}



	shared = (vma->vm_flags & VM_SHARED);



	switch (vma_shift) {

#ifndef __PAGETABLE_PMD_FOLDED

	case PUD_SHIFT:
@@ -1299,13 +1285,14 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, 


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

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

		if (!shared)

			ret = sanitise_mte_tags(kvm, pfn, vma_pagesize);

		else

		if ((vma->vm_flags & VM_MTE_ALLOWED) &&

		    !(vma->vm_flags & VM_SHARED)) {

			sanitise_mte_tags(kvm, pfn, vma_pagesize);

		} else {

			ret = -EFAULT;

		if (ret)

			goto out_unlock;

		}

	}



	if (writable)

		prot |= KVM_PGTABLE_PROT_W;
@@ -1526,15 +1513,18 @@ bool kvm_unmap_gfn_range(struct kvm *kvm, struct kvm_gfn_range *range) 
bool kvm_set_spte_gfn(struct kvm *kvm, struct kvm_gfn_range *range)

{

	kvm_pfn_t pfn = pte_pfn(range->pte);

	int ret;



	if (!kvm->arch.mmu.pgt)

		return false;



	WARN_ON(range->end - range->start != 1);



	ret = sanitise_mte_tags(kvm, pfn, PAGE_SIZE);

	if (ret)

	/*

	 * If the page isn't tagged, defer to user_mem_abort() for sanitising

	 * the MTE tags. The S2 pte should have been unmapped by

	 * mmu_notifier_invalidate_range_end().

	 */

	if (kvm_has_mte(kvm) && !page_mte_tagged(pfn_to_page(pfn)))

		return false;



	/*