[PATCH v6 07/22] KVM: Explicitly free allocated-but-unused dirty bitmap

From: Sean Christopherson
Date: Tue Feb 18 2020 - 16:08:13 EST

Explicitly free an allocated-but-unused dirty bitmap instead of relying
on kvm_free_memslot() if an error occurs in __kvm_set_memory_region().
There is no longer a need to abuse kvm_free_memslot() to free arch
specific resources as arch specific code is now called only after the
common flow is guaranteed to succeed. Arch code can still fail, but
it's responsible for its own cleanup in that case.

Eliminating the error path's abuse of kvm_free_memslot() paves the way
for simplifying kvm_free_memslot(), i.e. dropping its @dont param.

Reviewed-by: Peter Xu <peterx@xxxxxxxxxx>
Signed-off-by: Sean Christopherson <sean.j.christopherson@xxxxxxxxx>
virt/kvm/kvm_main.c | 7 ++++---
1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index fba171260ccb..42ec4dac99b3 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1093,7 +1093,7 @@ int __kvm_set_memory_region(struct kvm *kvm,

slots = kvzalloc(sizeof(struct kvm_memslots), GFP_KERNEL_ACCOUNT);
if (!slots)
- goto out_free;
+ goto out_bitmap;
memcpy(slots, __kvm_memslots(kvm, as_id), sizeof(struct kvm_memslots));

if ((change == KVM_MR_DELETE) || (change == KVM_MR_MOVE)) {
@@ -1141,8 +1141,9 @@ int __kvm_set_memory_region(struct kvm *kvm,
if (change == KVM_MR_DELETE || change == KVM_MR_MOVE)
slots = install_new_memslots(kvm, as_id, slots);
- kvm_free_memslot(kvm, &new, &old);
+ if (new.dirty_bitmap && !old.dirty_bitmap)
+ kvm_destroy_dirty_bitmap(&new);
return r;