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Subject[patch 10/58] KVM: Fix overlapping check for memory slots
2.6.29-stable review patch.  If anyone has any objections, please let us know.

------------------

From: Jan Kiszka <jan.kiszka@web.de>

upstream commit: 4cd481f68dde99ac416003b825c835f71e364393

When checking for overlapping slots on registration of a new one, kvm
currently also considers zero-length (ie. deleted) slots and rejects
requests incorrectly. This finally denies user space from joining slots.
Fix the check by skipping deleted slots and advertise this via a
KVM_CAP_JOIN_MEMORY_REGIONS_WORKS.

Cc: stable@kernel.org
Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
Signed-off-by: Avi Kivity <avi@redhat.com>
Signed-off-by: Chris Wright <chrisw@sous-sol.org>
---
include/linux/kvm.h | 2 ++
virt/kvm/kvm_main.c | 3 ++-
2 files changed, 4 insertions(+), 1 deletion(-)

--- a/include/linux/kvm.h
+++ b/include/linux/kvm.h
@@ -396,6 +396,8 @@ struct kvm_trace_rec {
#ifdef __KVM_HAVE_USER_NMI
#define KVM_CAP_USER_NMI 22
#endif
+/* Another bug in KVM_SET_USER_MEMORY_REGION fixed: */
+#define KVM_CAP_JOIN_MEMORY_REGIONS_WORKS 30

/*
* ioctls for VM fds
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -1005,7 +1005,7 @@ int __kvm_set_memory_region(struct kvm *
for (i = 0; i < KVM_MEMORY_SLOTS; ++i) {
struct kvm_memory_slot *s = &kvm->memslots[i];

- if (s == memslot)
+ if (s == memslot || !s->npages)
continue;
if (!((base_gfn + npages <= s->base_gfn) ||
(base_gfn >= s->base_gfn + s->npages)))
@@ -1997,6 +1997,7 @@ static long kvm_dev_ioctl_check_extensio
switch (arg) {
case KVM_CAP_USER_MEMORY:
case KVM_CAP_DESTROY_MEMORY_REGION_WORKS:
+ case KVM_CAP_JOIN_MEMORY_REGIONS_WORKS:
return 1;
default:
break;



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