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authorPaolo Bonzini <pbonzini@redhat.com>2022-11-17 20:25:02 +0300
committerPaolo Bonzini <pbonzini@redhat.com>2022-11-18 19:30:12 +0300
commit6c7b2202e4d11572ab23a89aeec49005b94bb966 (patch)
treeb47d8b0b67e8e9db088088efcfd969a48878832c /include/linux/kvm_host.h
parent771a579c6e74f305eff97752d91e9b05c4e46323 (diff)
downloadlinux-6c7b2202e4d11572ab23a89aeec49005b94bb966.tar.xz
KVM: x86: avoid memslot check in NX hugepage recovery if it cannot succeed
Since gfn_to_memslot() is relatively expensive, it helps to skip it if it the memslot cannot possibly have dirty logging enabled. In order to do this, add to struct kvm a counter of the number of log-page memslots. While the correct value can only be read with slots_lock taken, the NX recovery thread is content with using an approximate value. Therefore, the counter is an atomic_t. Based on https://lore.kernel.org/kvm/20221027200316.2221027-2-dmatlack@google.com/ by David Matlack. Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Diffstat (limited to 'include/linux/kvm_host.h')
-rw-r--r--include/linux/kvm_host.h5
1 files changed, 5 insertions, 0 deletions
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index e6e66c5e56f2..6f0f389f5f9c 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -722,6 +722,11 @@ struct kvm {
/* The current active memslot set for each address space */
struct kvm_memslots __rcu *memslots[KVM_ADDRESS_SPACE_NUM];
struct xarray vcpu_array;
+ /*
+ * Protected by slots_lock, but can be read outside if an
+ * incorrect answer is acceptable.
+ */
+ atomic_t nr_memslots_dirty_logging;
/* Used to wait for completion of MMU notifiers. */
spinlock_t mn_invalidate_lock;