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From: "Maciej S. Szmigiero" <mail@maciej.szmigiero.name>
To: Paolo Bonzini <pbonzini@redhat.com>,
	Vitaly Kuznetsov <vkuznets@redhat.com>
Cc: Sean Christopherson <seanjc@google.com>,
	Wanpeng Li <wanpengli@tencent.com>,
	Jim Mattson <jmattson@google.com>,
	Igor Mammedov <imammedo@redhat.com>,
	Marc Zyngier <maz@kernel.org>, James Morse <james.morse@arm.com>,
	Julien Thierry <julien.thierry.kdev@gmail.com>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	Huacai Chen <chenhuacai@kernel.org>,
	Aleksandar Markovic <aleksandar.qemu.devel@gmail.com>,
	Paul Mackerras <paulus@ozlabs.org>,
	Christian Borntraeger <borntraeger@de.ibm.com>,
	Janosch Frank <frankja@linux.ibm.com>,
	David Hildenbrand <david@redhat.com>,
	Cornelia Huck <cohuck@redhat.com>,
	Claudio Imbrenda <imbrenda@linux.ibm.com>,
	Joerg Roedel <joro@8bytes.org>,
	kvm@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: [PATCH v4 07/13] KVM: Just resync arch fields when slots_arch_lock gets reacquired
Date: Fri, 13 Aug 2021 21:33:20 +0200	[thread overview]
Message-ID: <c7d7f681c2f978d03bddea7f5f0d684cdfdb2dd2.1628871413.git.maciej.szmigiero@oracle.com> (raw)
In-Reply-To: <cover.1628871411.git.maciej.szmigiero@oracle.com>

From: "Maciej S. Szmigiero" <maciej.szmigiero@oracle.com>

There is no need to copy the whole memslot data after releasing
slots_arch_lock for a moment to install temporary memslots copy in
kvm_set_memslot() since this lock only protects the arch field of each
memslot.

Just resync this particular field after reacquiring slots_arch_lock.

Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>
---
 virt/kvm/kvm_main.c | 17 ++++++++++++-----
 1 file changed, 12 insertions(+), 5 deletions(-)

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 7000efff1425..272bc86a0e69 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1494,6 +1494,15 @@ static void kvm_copy_memslots(struct kvm_memslots *to,
 	memcpy(to, from, kvm_memslots_size(from->used_slots));
 }
 
+static void kvm_copy_memslots_arch(struct kvm_memslots *to,
+				   struct kvm_memslots *from)
+{
+	int i;
+
+	for (i = 0; i < from->used_slots; i++)
+		to->memslots[i].arch = from->memslots[i].arch;
+}
+
 /*
  * Note, at a minimum, the current number of used slots must be allocated, even
  * when deleting a memslot, as we need a complete duplicate of the memslots for
@@ -1579,10 +1588,10 @@ static int kvm_set_memslot(struct kvm *kvm,
 		/*
 		 * The arch-specific fields of the memslots could have changed
 		 * between releasing the slots_arch_lock in
-		 * install_new_memslots and here, so get a fresh copy of the
-		 * slots.
+		 * install_new_memslots and here, so get a fresh copy of these
+		 * fields.
 		 */
-		kvm_copy_memslots(slots, __kvm_memslots(kvm, as_id));
+		kvm_copy_memslots_arch(slots, __kvm_memslots(kvm, as_id));
 	}
 
 	r = kvm_arch_prepare_memory_region(kvm, old, new, mem, change);
@@ -1599,8 +1608,6 @@ static int kvm_set_memslot(struct kvm *kvm,
 
 out_slots:
 	if (change == KVM_MR_DELETE || change == KVM_MR_MOVE) {
-		slot = id_to_memslot(slots, old->id);
-		slot->flags &= ~KVM_MEMSLOT_INVALID;
 		slots = install_new_memslots(kvm, as_id, slots);
 	} else {
 		mutex_unlock(&kvm->slots_arch_lock);

  parent reply	other threads:[~2021-08-13 20:02 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-13 19:33 [PATCH v4 00/13] KVM: Scalable memslots implementation Maciej S. Szmigiero
2021-08-13 19:33 ` [PATCH v4 01/13] KVM: x86: Cache total page count to avoid traversing the memslot array Maciej S. Szmigiero
2021-08-13 19:33 ` [PATCH v4 02/13] KVM: x86: Don't call kvm_mmu_change_mmu_pages() if the count hasn't changed Maciej S. Szmigiero
2021-08-13 19:33 ` [PATCH v4 03/13] KVM: Add "old" memslot parameter to kvm_arch_prepare_memory_region() Maciej S. Szmigiero
2021-08-13 19:33 ` [PATCH v4 04/13] KVM: x86: Move n_memslots_pages recalc " Maciej S. Szmigiero
2021-08-13 19:33 ` [PATCH v4 05/13] KVM: Integrate gfn_to_memslot_approx() into search_memslots() Maciej S. Szmigiero
2021-08-18 14:29   ` Claudio Imbrenda
2021-08-13 19:33 ` [PATCH v4 06/13] KVM: Move WARN on invalid memslot index to update_memslots() Maciej S. Szmigiero
2021-08-18 14:29   ` Claudio Imbrenda
2021-08-18 14:35   ` David Hildenbrand
2021-08-18 21:43     ` Maciej S. Szmigiero
2021-08-20  9:27       ` David Hildenbrand
2021-08-13 19:33 ` Maciej S. Szmigiero [this message]
2021-08-13 19:33 ` [PATCH v4 08/13] KVM: Resolve memslot ID via a hash table instead of via a static array Maciej S. Szmigiero
2021-08-13 19:33 ` [PATCH v4 09/13] KVM: Use interval tree to do fast hva lookup in memslots Maciej S. Szmigiero
2021-08-13 19:33 ` [PATCH v4 10/13] KVM: s390: Introduce kvm_s390_get_gfn_end() Maciej S. Szmigiero
2021-08-18 14:31   ` Claudio Imbrenda
2021-08-13 19:33 ` [PATCH v4 11/13] KVM: Keep memslots in tree-based structures instead of array-based ones Maciej S. Szmigiero
2021-08-13 19:33 ` [PATCH v4 12/13] KVM: Optimize gfn lookup in kvm_zap_gfn_range() Maciej S. Szmigiero
2021-08-13 19:33 ` [PATCH v4 13/13] KVM: Optimize overlapping memslots check Maciej S. Szmigiero

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