lkml.org 
[lkml]   [2012]   [Dec]   [23]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
Date
From
SubjectRe: [PATCH] kvm: Fix memory slot generation updates
On Fri, Dec 21, 2012 at 08:20:16AM -0700, Alex Williamson wrote:
> Previous patch "kvm: Minor memory slot optimization" overlooked the
> generation field of the memory slots. Re-using the original memory
> slots left us with with two slightly different memory slots with the
> same generation. To fix this, make update_memslots() take a new
> parameter to specify the last generation. This also makes generation
> management more explicit to avoid such problems in the future.
>
> Reported-by: Takuya Yoshikawa <yoshikawa_takuya_b1@lab.ntt.co.jp>
> Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Applied, thanks. What about this small cleanup on to of the patch:


diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 14cbae8..e45c20c 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -702,6 +702,17 @@ static int check_memory_region_flags(struct kvm_userspace_memory_region *mem)
return 0;
}

+static struct kvm_memslots *install_new_memslots(struct kvm *kvm,
+ struct kvm_memslots *slots, struct kvm_memory_slot *new)
+{
+ struct kvm_memslots *old_memslots = kvm->memslots;
+
+ update_memslots(slots, new, kvm->memslots->generation);
+ rcu_assign_pointer(kvm->memslots, slots);
+ synchronize_srcu_expedited(&kvm->srcu);
+ return old_memslots;
+}
+
/*
* Allocate some memory and give it an address in the guest physical address
* space.
@@ -820,11 +831,8 @@ int __kvm_set_memory_region(struct kvm *kvm,
slot = id_to_memslot(slots, mem->slot);
slot->flags |= KVM_MEMSLOT_INVALID;

- update_memslots(slots, NULL, kvm->memslots->generation);
+ old_memslots = install_new_memslots(kvm, slots, NULL);

- old_memslots = kvm->memslots;
- rcu_assign_pointer(kvm->memslots, slots);
- synchronize_srcu_expedited(&kvm->srcu);
/* slot was deleted or moved, clear iommu mapping */
kvm_iommu_unmap_pages(kvm, &old);
/* From this point no new shadow pages pointing to a deleted,
@@ -868,10 +876,7 @@ int __kvm_set_memory_region(struct kvm *kvm,
memset(&new.arch, 0, sizeof(new.arch));
}

- update_memslots(slots, &new, kvm->memslots->generation);
- old_memslots = kvm->memslots;
- rcu_assign_pointer(kvm->memslots, slots);
- synchronize_srcu_expedited(&kvm->srcu);
+ old_memslots = install_new_memslots(kvm, slots, &new);

kvm_arch_commit_memory_region(kvm, mem, old, user_alloc);

--
Gleb.

\
 
 \ /
  Last update: 2012-12-23 10:21    [W:0.052 / U:3.696 seconds]
©2003-2017 Jasper Spaans. hosted at Digital OceanAdvertise on this site