On 04.11.2021 01:25, Sean Christopherson wrote:
From: Maciej S. Szmigiero <maciej.szmigiero@xxxxxxxxxx>
The current memslots implementation only allows quick binary search by gfn,
quick lookup by hva is not possible - the implementation has to do a linear
scan of the whole memslots array, even though the operation being performed
might apply just to a single memslot.
This significantly hurts performance of per-hva operations with higher
memslot counts.
Since hva ranges can overlap between memslots an interval tree is needed
for tracking them.
Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@xxxxxxxxxx>
[sean: handle interval tree updates in kvm_replace_memslot()]
Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
---
arch/arm64/kvm/Kconfig | 1 +
arch/mips/kvm/Kconfig | 1 +
arch/powerpc/kvm/Kconfig | 1 +
arch/s390/kvm/Kconfig | 1 +
arch/x86/kvm/Kconfig | 1 +
include/linux/kvm_host.h | 3 ++
virt/kvm/kvm_main.c | 60 +++++++++++++++++++++++++++++-----------
7 files changed, 52 insertions(+), 16 deletions(-)
(..)
@@ -1262,22 +1274,32 @@ static void kvm_replace_memslot(struct kvm_memslots *slots,
struct kvm_memory_slot *new)
{
/*
- * Remove the old memslot from the hash list, copying the node data
- * would corrupt the list.
+ * Remove the old memslot from the hash list and interval tree, copying
+ * the node data would corrupt the structures.
*/
if (old) {
hash_del(&old->id_node);
+ interval_tree_remove(&old->hva_node, &slots->hva_tree);
if (!new)
return;
}
- /* Copy the source *data*, not the pointer, to the destination. */
- if (old)
+ /*
+ * Copy the source *data*, not the pointer, to the destination. If
+ * @old is NULL, initialize @new's hva range.
+ */
+ if (old) {
*new = *old;
+ } else if (new) {
Unnecessary check - if "new" is NULL then the code will crash anyway
accessing this pointer unconditionally...
+ new->hva_node.start = new->userspace_addr;
+ new->hva_node.last = new->userspace_addr +
+ (new->npages << PAGE_SHIFT) - 1;
+ }
/* (Re)Add the new memslot. */
hash_add(slots->id_hash, &new->id_node, new->id);
+ interval_tree_insert(&new->hva_node, &slots->hva_tree);
...in these two lines above.
Thanks,
Maciej
