Commit 509552e6 authored by Yanan Wang's avatar Yanan Wang Committed by Marc Zyngier
Browse files

KVM: arm64: Mark the page dirty only if the fault is handled successfully 



We now set the pfn dirty and mark the page dirty before calling fault
handlers in user_mem_abort(), so we might end up having spurious dirty
pages if update of permissions or mapping has failed. Let's move these
two operations after the fault handlers, and they will be done only if
the fault has been handled successfully.

When an -EAGAIN errno is returned from the map handler, we hope to the
vcpu to enter guest directly instead of exiting back to userspace, so
adjust the return value at the end of function.

Signed-off-by: default avatarYanan Wang <wangyanan55@huawei.com>
Signed-off-by: default avatarMarc Zyngier <maz@kernel.org>
Link: https://lore.kernel.org/r/20210114121350.123684-4-wangyanan55@huawei.com
parent 694d071f

arch/arm64/kvm/mmu.c

+8 −5
Original line number Diff line number Diff line
@@ -879,11 +879,8 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, 
	if (vma_pagesize == PAGE_SIZE && !force_pte)

		vma_pagesize = transparent_hugepage_adjust(memslot, hva,

							   &pfn, &fault_ipa);

	if (writable) {

	if (writable)

		prot |= KVM_PGTABLE_PROT_W;

		kvm_set_pfn_dirty(pfn);

		mark_page_dirty(kvm, gfn);

	}



	if (fault_status != FSC_PERM && !device)

		clean_dcache_guest_page(pfn, vma_pagesize);
@@ -911,11 +908,17 @@ static int user_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa, 
					     memcache);

	}



	/* Mark the page dirty only if the fault is handled successfully */

	if (writable && !ret) {

		kvm_set_pfn_dirty(pfn);

		mark_page_dirty(kvm, gfn);

	}



out_unlock:

	spin_unlock(&kvm->mmu_lock);

	kvm_set_pfn_accessed(pfn);

	kvm_release_pfn_clean(pfn);

	return ret;

	return ret != -EAGAIN ? ret : 0;

}



/* Resolve the access fault by making the page young again. */