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KVM: Don't make a full copy of the old memslot in __kvm_set_memory_region()

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Stop making a full copy of the old memslot in __kvm_set_memory_region()
now that metadata updates are handled by kvm_set_memslot(), i.e. now that
the old memslot's dirty bitmap doesn't need to be referenced after the
memslot and its pointer is modified/invalidated by kvm_set_memslot().

No functional change intended.

Signed-off-by: Sean Christopherson <seanjc@google.com>
Reviewed-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>
Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>
Message-Id: <5dce0946b41bba8c83f6e3424c6955c56bcc9f86.1638817640.git.maciej.szmigiero@oracle.com>
This commit is contained in:
Sean Christopherson 2021-12-06 20:54:22 +01:00 committed by Paolo Bonzini
parent ec5c869766
commit 7cd08553ab
1 changed files with 13 additions and 22 deletions
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35
virt/kvm/kvm_main.c
View File

@ -1730,8 +1730,8 @@ static int kvm_set_memslot(struct kvm *kvm,
int __kvm_set_memory_region(struct kvm *kvm,
const struct kvm_userspace_memory_region *mem)
{
struct kvm_memory_slot old, new;
struct kvm_memory_slot *tmp;
struct kvm_memory_slot *old, *tmp;
struct kvm_memory_slot new;
enum kvm_mr_change change;
int as_id, id;
int r;
@ -1761,25 +1761,16 @@ int __kvm_set_memory_region(struct kvm *kvm,
return -EINVAL;
/*
* Make a full copy of the old memslot, the pointer will become stale
* when the memslots are re-sorted by update_memslots(), and the old
* memslot needs to be referenced after calling update_memslots(), e.g.
* to free its resources and for arch specific behavior.
* Note, the old memslot (and the pointer itself!) may be invalidated
* and/or destroyed by kvm_set_memslot().
*/
tmp = id_to_memslot(__kvm_memslots(kvm, as_id), id);
if (tmp) {
old = *tmp;
tmp = NULL;
} else {
memset(&old, 0, sizeof(old));
old.id = id;
}
old = id_to_memslot(__kvm_memslots(kvm, as_id), id);
if (!mem->memory_size) {
if (!old.npages)
if (!old || !old->npages)
return -EINVAL;
if (WARN_ON_ONCE(kvm->nr_memslot_pages < old.npages))
if (WARN_ON_ONCE(kvm->nr_memslot_pages < old->npages))
return -EIO;
memset(&new, 0, sizeof(new));
@ -1799,7 +1790,7 @@ int __kvm_set_memory_region(struct kvm *kvm,
if (new.npages > KVM_MEM_MAX_NR_PAGES)
return -EINVAL;
if (!old.npages) {
if (!old || !old->npages) {
change = KVM_MR_CREATE;
/*
@ -1809,14 +1800,14 @@ int __kvm_set_memory_region(struct kvm *kvm,
if ((kvm->nr_memslot_pages + new.npages) < kvm->nr_memslot_pages)
return -EINVAL;
} else { /* Modify an existing slot. */
if ((new.userspace_addr != old.userspace_addr) ||
(new.npages != old.npages) ||
((new.flags ^ old.flags) & KVM_MEM_READONLY))
if ((new.userspace_addr != old->userspace_addr) ||
(new.npages != old->npages) ||
((new.flags ^ old->flags) & KVM_MEM_READONLY))
return -EINVAL;
if (new.base_gfn != old.base_gfn)
if (new.base_gfn != old->base_gfn)
change = KVM_MR_MOVE;
else if (new.flags != old.flags)
else if (new.flags != old->flags)
change = KVM_MR_FLAGS_ONLY;
else /* Nothing to change. */
return 0;