From: Alex Williamson <alex.williamson@redhat.com>
To: mtosatti@redhat.com, gleb@redhat.com
Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org
Subject: [PATCH v2 04/10] kvm: Minor memory slot optimization
Date: Mon, 10 Dec 2012 10:33:03 -0700 [thread overview]
Message-ID: <20121210173303.10461.47295.stgit@bling.home> (raw)
In-Reply-To: <20121210171417.10461.20079.stgit@bling.home>
If a slot is removed or moved in the guest physical address space, we
first allocate and install a new slot array with the invalidated
entry. The old array is then freed. We then proceed to allocate yet
another slot array to install the permanent replacement. Re-use the
original array when this occurs and avoid the extra kfree/kmalloc.
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
---
virt/kvm/kvm_main.c | 21 ++++++++++++++-------
1 file changed, 14 insertions(+), 7 deletions(-)
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 0f66a0e..2a80dac 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -711,7 +711,7 @@ int __kvm_set_memory_region(struct kvm *kvm,
unsigned long npages;
struct kvm_memory_slot *memslot, *slot;
struct kvm_memory_slot old, new;
- struct kvm_memslots *slots, *old_memslots;
+ struct kvm_memslots *slots = NULL, *old_memslots;
r = check_memory_region_flags(mem);
if (r)
@@ -827,18 +827,25 @@ int __kvm_set_memory_region(struct kvm *kvm,
* - kvm_is_visible_gfn (mmu_check_roots)
*/
kvm_arch_flush_shadow_memslot(kvm, slot);
- kfree(old_memslots);
+ slots = old_memslots;
}
r = kvm_arch_prepare_memory_region(kvm, &new, old, mem, user_alloc);
if (r)
- goto out_free;
+ goto out_slots;
r = -ENOMEM;
- slots = kmemdup(kvm->memslots, sizeof(struct kvm_memslots),
- GFP_KERNEL);
- if (!slots)
- goto out_free;
+ /*
+ * We can re-use the old_memslots from above, the only difference
+ * from the currently installed memslots is the invalid flag. This
+ * will get overwritten by update_memslots anyway.
+ */
+ if (!slots) {
+ slots = kmemdup(kvm->memslots, sizeof(struct kvm_memslots),
+ GFP_KERNEL);
+ if (!slots)
+ goto out_free;
+ }
/* map new memory slot into the iommu */
if (npages) {
next prev parent reply other threads:[~2012-12-10 17:33 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-12-10 17:32 [PATCH v2 00/10] kvm: memory slot cleanups, fix, and increase Alex Williamson
2012-12-10 17:32 ` [PATCH v2 01/10] kvm: Restrict non-existing slot state transitions Alex Williamson
2012-12-12 1:29 ` Marcelo Tosatti
2012-12-12 1:39 ` Marcelo Tosatti
2012-12-12 4:30 ` Alex Williamson
2012-12-10 17:32 ` [PATCH v2 02/10] kvm: Check userspace_addr when modifying a memory slot Alex Williamson
2012-12-10 17:32 ` [PATCH v2 03/10] kvm: Fix iommu map/unmap to handle memory slot moves Alex Williamson
2012-12-10 17:33 ` Alex Williamson [this message]
2012-12-10 17:33 ` [PATCH v2 05/10] kvm: Rename KVM_MEMORY_SLOTS -> KVM_USER_MEM_SLOTS Alex Williamson
2012-12-10 17:33 ` [PATCH v2 06/10] kvm: Make KVM_PRIVATE_MEM_SLOTS optional Alex Williamson
2012-12-10 17:33 ` [PATCH v2 07/10] kvm: struct kvm_memory_slot.user_alloc -> bool Alex Williamson
2012-12-10 17:33 ` [PATCH v2 08/10] kvm: struct kvm_memory_slot.flags -> u32 Alex Williamson
2012-12-10 17:33 ` [PATCH v2 09/10] kvm: struct kvm_memory_slot.id -> short Alex Williamson
2012-12-10 17:33 ` [PATCH v2 10/10] kvm: Increase user memory slots on x86 to 125 Alex Williamson
2012-12-12 2:11 ` [PATCH v2 00/10] kvm: memory slot cleanups, fix, and increase Marcelo Tosatti
2012-12-12 14:13 ` Gleb Natapov
2012-12-15 1:03 ` Marcelo Tosatti
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