Re: [PATCH] always assign userspace_addr

[Glauber Costa <glommer@redhat.com>]

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On Thu, Nov 20, 2008 at 01:02:39PM +0200, Avi Kivity wrote:
> Anthony Liguori wrote:
>>
>> That's not how I read the code.  I see:
>>
>>>
>>> static void kvm_free_physmem_slot(struct kvm_memory_slot *free,
>>>                   struct kvm_memory_slot *dont)
>>> {
>>>     if (!dont || free->rmap != dont->rmap)
>>>         vfree(free->rmap);
>>
>> And it's called as kvm_free_physmem_slot(&old, &new);
>>
>> new is assigned to old to start out with so old.rmap will equal new.rmap.
>>
>
> Hm, if !npages we should just kvm_free_physmem_slot(&old, NULL).
Actually, I believe we need a little bit more than that, because we can
have valid rmaps in flight.

Tell me what you think about this.



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diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index b1953ee..f605bba 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -735,11 +735,17 @@ int __kvm_set_memory_region(struct kvm *kvm,
 	base_gfn = mem->guest_phys_addr >> PAGE_SHIFT;
 	npages = mem->memory_size >> PAGE_SHIFT;
 
-	if (!npages)
-		mem->flags &= ~KVM_MEM_LOG_DIRTY_PAGES;
-
 	new = old = *memslot;
 
+        if (!npages) {
+                mem->flags &= ~KVM_MEM_LOG_DIRTY_PAGES;
+                kvm_arch_flush_shadow(kvm);
+                kvm_free_physmem_slot(memslot, NULL);
+                kvm_arch_set_memory_region(kvm, mem, old, user_alloc);
+                goto out;
+        }
+
+
 	new.base_gfn = base_gfn;
 	new.npages = npages;
 	new.flags = mem->flags;
@@ -812,9 +818,6 @@ int __kvm_set_memory_region(struct kvm *kvm,
 	}
 #endif /* not defined CONFIG_S390 */
 
-	if (!npages)
-		kvm_arch_flush_shadow(kvm);
-
 	spin_lock(&kvm->mmu_lock);
 	if (mem->slot >= kvm->nmemslots)
 		kvm->nmemslots = mem->slot + 1;