On 26.05.2021 19:33, Sean Christopherson wrote:
On Sun, May 16, 2021, Maciej S. Szmigiero wrote:
From: "Maciej S. Szmigiero" <maciej.szmigiero@xxxxxxxxxx>
Introduce a memslots gfn upper bound operation and use it to optimize
kvm_zap_gfn_range().
This way this handler can do a quick lookup for intersecting gfns and won't
have to do a linear scan of the whole memslot set.
Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@xxxxxxxxxx>
---
arch/x86/kvm/mmu/mmu.c | 41 ++++++++++++++++++++++++++++++++++++++--
include/linux/kvm_host.h | 22 +++++++++++++++++++++
2 files changed, 61 insertions(+), 2 deletions(-)
diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c
index 7222b552d139..f23398cf0316 100644
--- a/arch/x86/kvm/mmu/mmu.c
+++ b/arch/x86/kvm/mmu/mmu.c
@@ -5490,14 +5490,51 @@ void kvm_zap_gfn_range(struct kvm *kvm, gfn_t gfn_start, gfn_t gfn_end)
int i;
bool flush = false;
+ if (gfn_end == gfn_start || WARN_ON(gfn_end < gfn_start))
+ return;
+
write_lock(&kvm->mmu_lock);
for (i = 0; i < KVM_ADDRESS_SPACE_NUM; i++) {
- int ctr;
+ int idxactive;
+ struct rb_node *node;
slots = __kvm_memslots(kvm, i);
- kvm_for_each_memslot(memslot, ctr, slots) {
+ idxactive = kvm_memslots_idx(slots);
+
+ /*
+ * Find the slot with the lowest gfn that can possibly intersect with
+ * the range, so we'll ideally have slot start <= range start
+ */
+ node = kvm_memslots_gfn_upper_bound(slots, gfn_start);
+ if (node) {
+ struct rb_node *pnode;
+
+ /*
+ * A NULL previous node means that the very first slot
+ * already has a higher start gfn.
+ * In this case slot start > range start.
+ */
+ pnode = rb_prev(node);
+ if (pnode)
+ node = pnode;
+ } else {
+ /* a NULL node below means no slots */
+ node = rb_last(&slots->gfn_tree);
+ }
+
+ for ( ; node; node = rb_next(node)) {
gfn_t start, end;
Can this be abstracted into something like:
kvm_for_each_memslot_in_gfn_range(...) {
}
and share that implementation with kvm_check_memslot_overlap() in the next patch?
I really don't think arch code should be poking into gfn_tree, and ideally arch
code wouldn't even be aware that gfn_tree exists.
That's a good idea, will do.
Thanks,
Maciej
