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Message-Id: <a4795e5c2f624754e9c0aab023ebda1966feb3e1.1638817641.git.maciej.szmigiero@oracle.com>
Date: Mon, 6 Dec 2021 20:54:33 +0100
From: "Maciej S. Szmigiero" <mail@...iej.szmigiero.name>
To: Paolo Bonzini <pbonzini@...hat.com>,
Sean Christopherson <seanjc@...gle.com>
Cc: Vitaly Kuznetsov <vkuznets@...hat.com>,
Wanpeng Li <wanpengli@...cent.com>,
Jim Mattson <jmattson@...gle.com>,
Joerg Roedel <joro@...tes.org>,
Igor Mammedov <imammedo@...hat.com>,
Marc Zyngier <maz@...nel.org>,
James Morse <james.morse@....com>,
Julien Thierry <julien.thierry.kdev@...il.com>,
Suzuki K Poulose <suzuki.poulose@....com>,
Huacai Chen <chenhuacai@...nel.org>,
Aleksandar Markovic <aleksandar.qemu.devel@...il.com>,
Paul Mackerras <paulus@...abs.org>,
Christian Borntraeger <borntraeger@...ibm.com>,
Janosch Frank <frankja@...ux.ibm.com>,
David Hildenbrand <david@...hat.com>,
Cornelia Huck <cohuck@...hat.com>,
Claudio Imbrenda <imbrenda@...ux.ibm.com>,
Anup Patel <anup.patel@....com>,
Paul Walmsley <paul.walmsley@...ive.com>,
Palmer Dabbelt <palmer@...belt.com>,
Albert Ou <aou@...s.berkeley.edu>,
Alexandru Elisei <alexandru.elisei@....com>,
Ben Gardon <bgardon@...gle.com>, kvm@...r.kernel.org,
linux-kernel@...r.kernel.org
Subject: [PATCH v7 27/29] KVM: Optimize overlapping memslots check
From: "Maciej S. Szmigiero" <maciej.szmigiero@...cle.com>
Do a quick lookup for possibly overlapping gfns when creating or moving
a memslot instead of performing a linear scan of the whole memslot set.
Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@...cle.com>
[sean: tweaked params to avoid churn in future cleanup]
Reviewed-by: Sean Christopherson <seanjc@...gle.com>
---
virt/kvm/kvm_main.c | 36 ++++++++++++++++++++++--------------
1 file changed, 22 insertions(+), 14 deletions(-)
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 086f18969bc3..4cb97b31eac5 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1817,6 +1817,19 @@ static int kvm_set_memslot(struct kvm *kvm,
return 0;
}
+static bool kvm_check_memslot_overlap(struct kvm_memslots *slots, int id,
+ gfn_t start, gfn_t end)
+{
+ struct kvm_memslot_iter iter;
+
+ kvm_for_each_memslot_in_gfn_range(&iter, slots, start, end) {
+ if (iter.slot->id != id)
+ return true;
+ }
+
+ return false;
+}
+
/*
* Allocate some memory and give it an address in the guest physical address
* space.
@@ -1828,8 +1841,9 @@ 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, *tmp;
+ struct kvm_memory_slot *old;
struct kvm_memory_slot new;
+ struct kvm_memslots *slots;
enum kvm_mr_change change;
int as_id, id;
int r;
@@ -1858,11 +1872,13 @@ int __kvm_set_memory_region(struct kvm *kvm,
if (mem->guest_phys_addr + mem->memory_size < mem->guest_phys_addr)
return -EINVAL;
+ slots = __kvm_memslots(kvm, as_id);
+
/*
* Note, the old memslot (and the pointer itself!) may be invalidated
* and/or destroyed by kvm_set_memslot().
*/
- old = id_to_memslot(__kvm_memslots(kvm, as_id), id);
+ old = id_to_memslot(slots, id);
if (!mem->memory_size) {
if (!old || !old->npages)
@@ -1911,18 +1927,10 @@ int __kvm_set_memory_region(struct kvm *kvm,
return 0;
}
- if ((change == KVM_MR_CREATE) || (change == KVM_MR_MOVE)) {
- int bkt;
-
- /* Check for overlaps */
- kvm_for_each_memslot(tmp, bkt, __kvm_memslots(kvm, as_id)) {
- if (tmp->id == id)
- continue;
- if (!((new.base_gfn + new.npages <= tmp->base_gfn) ||
- (new.base_gfn >= tmp->base_gfn + tmp->npages)))
- return -EEXIST;
- }
- }
+ if ((change == KVM_MR_CREATE || change == KVM_MR_MOVE) &&
+ kvm_check_memslot_overlap(slots, id, new.base_gfn,
+ new.base_gfn + new.npages))
+ return -EEXIST;
return kvm_set_memslot(kvm, old, &new, change);
}
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