Commit 13ea5255 authored by Sean Christopherson's avatar Sean Christopherson Committed by Paolo Bonzini
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KVM: Reinstall old memslots if arch preparation fails 



Reinstall the old memslots if preparing the new memory region fails
after invalidating a to-be-{re}moved memslot.

Remove the superfluous 'old_memslots' variable so that it's somewhat
clear that the error handling path needs to free the unused memslots,
not simply the 'old' memslots.

Fixes: bc6678a3 ("KVM: introduce kvm->srcu and convert kvm_set_memory_region to SRCU update")
Reviewed-by: default avatarChristoffer Dall <christoffer.dall@arm.com>
Reviewed-by: default avatarPeter Xu <peterx@redhat.com>
Signed-off-by: default avatarSean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: default avatarPaolo Bonzini <pbonzini@redhat.com>
parent edd4fa37

virt/kvm/kvm_main.c

+12 −11
Original line number Diff line number Diff line
@@ -999,7 +999,7 @@ int __kvm_set_memory_region(struct kvm *kvm, 
	unsigned long npages;

	struct kvm_memory_slot *slot;

	struct kvm_memory_slot old, new;

	struct kvm_memslots *slots = NULL, *old_memslots;

	struct kvm_memslots *slots;

	int as_id, id;

	enum kvm_mr_change change;
@@ -1107,7 +1107,13 @@ int __kvm_set_memory_region(struct kvm *kvm, 
		slot = id_to_memslot(slots, id);

		slot->flags |= KVM_MEMSLOT_INVALID;



		old_memslots = install_new_memslots(kvm, as_id, slots);

		/*

		 * We can re-use the old memslots, the only difference from the

		 * newly installed memslots is the invalid flag, which will get

		 * dropped by update_memslots anyway.  We'll also revert to the

		 * old memslots if preparing the new memory region fails.

		 */

		slots = install_new_memslots(kvm, as_id, slots);



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

		 * or moved, memslot will be created.
@@ -1117,13 +1123,6 @@ int __kvm_set_memory_region(struct kvm *kvm, 
		 *	- kvm_is_visible_gfn (mmu_check_root)

		 */

		kvm_arch_flush_shadow_memslot(kvm, slot);



		/*

		 * We can re-use the old_memslots from above, the only difference

		 * from the currently installed memslots is the invalid flag.  This

		 * will get overwritten by update_memslots anyway.

		 */

		slots = old_memslots;

	}



	r = kvm_arch_prepare_memory_region(kvm, &new, mem, change);
@@ -1137,15 +1136,17 @@ int __kvm_set_memory_region(struct kvm *kvm, 
	}



	update_memslots(slots, &new, change);

	old_memslots = install_new_memslots(kvm, as_id, slots);

	slots = install_new_memslots(kvm, as_id, slots);



	kvm_arch_commit_memory_region(kvm, mem, &old, &new, change);



	kvm_free_memslot(kvm, &old, &new);

	kvfree(old_memslots);

	kvfree(slots);

	return 0;



out_slots:

	if (change == KVM_MR_DELETE || change == KVM_MR_MOVE)

		slots = install_new_memslots(kvm, as_id, slots);

	kvfree(slots);

out_free:

	kvm_free_memslot(kvm, &new, &old);

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