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Commit 261874b0 authored by Alex Williamson's avatar Alex Williamson Committed by Gleb Natapov
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kvm: Force IOMMU remapping on memory slot read-only flag changes 



Memory slot flags can be altered without changing other parameters of
the slot.  The read-only attribute is the only one the IOMMU cares
about, so generate an un-map, re-map when this occurs.  This also
avoid unnecessarily re-mapping the slot when no IOMMU visible changes
are made.

Reviewed-by: default avatarXiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
Signed-off-by: default avatarAlex Williamson <alex.williamson@redhat.com>
Signed-off-by: default avatarGleb Natapov <gleb@redhat.com>
parent 3f0c3d0b

virt/kvm/kvm_main.c

+24 −4
Original line number Diff line number Diff line
@@ -731,6 +731,7 @@ int __kvm_set_memory_region(struct kvm *kvm, 
	struct kvm_memory_slot *slot;

	struct kvm_memory_slot old, new;

	struct kvm_memslots *slots = NULL, *old_memslots;

	bool old_iommu_mapped;



	r = check_memory_region_flags(mem);

	if (r)
@@ -772,6 +773,8 @@ int __kvm_set_memory_region(struct kvm *kvm, 
	new.npages = npages;

	new.flags = mem->flags;



	old_iommu_mapped = old.npages;



	/*

	 * Disallow changing a memory slot's size or changing anything about

	 * zero sized slots that doesn't involve making them non-zero.
@@ -835,6 +838,7 @@ int __kvm_set_memory_region(struct kvm *kvm, 


		/* slot was deleted or moved, clear iommu mapping */

		kvm_iommu_unmap_pages(kvm, &old);

		old_iommu_mapped = false;

		/* From this point no new shadow pages pointing to a deleted,

		 * or moved, memslot will be created.

		 *
@@ -863,12 +867,28 @@ int __kvm_set_memory_region(struct kvm *kvm, 
			goto out_free;

	}



	/* map new memory slot into the iommu */

	/*

	 * IOMMU mapping:  New slots need to be mapped.  Old slots need to be

	 * un-mapped and re-mapped if their base changes or if flags that the

	 * iommu cares about change (read-only).  Base change unmapping is

	 * handled above with slot deletion, so we only unmap incompatible

	 * flags here.  Anything else the iommu might care about for existing

	 * slots (size changes, userspace addr changes) is disallowed above,

	 * so any other attribute changes getting here can be skipped.

	 */

	if (npages) {

		if (old_iommu_mapped &&

		    ((new.flags ^ old.flags) & KVM_MEM_READONLY)) {

			kvm_iommu_unmap_pages(kvm, &old);

			old_iommu_mapped = false;

		}



		if (!old_iommu_mapped) {

			r = kvm_iommu_map_pages(kvm, &new);

			if (r)

				goto out_slots;

		}

	}



	/* actual memory is freed via old in kvm_free_physmem_slot below */

	if (!npages) {