From 4cd481f68dde99ac416003b825c835f71e364393 Mon Sep 17 00:00:00 2001
From: Jan Kiszka <jan.kiszka@web.de>
Date: Mon, 13 Apr 2009 11:59:32 +0200
Subject: [PATCH] KVM: Fix overlapping check for memory slots
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>
---
include/linux/kvm.h | 2 ++
virt/kvm/kvm_main.c | 3 ++-
2 files changed, 4 insertions(+), 1 deletion(-)
diff --git a/include/linux/kvm.h b/include/linux/kvm.h
index 311a073afe8a..8cc137911b34 100644
--- a/include/linux/kvm.h
+++ b/include/linux/kvm.h
@@ -409,6 +409,8 @@ struct kvm_trace_rec {
#ifdef __KVM_HAVE_DEVICE_ASSIGNMENT
#define KVM_CAP_DEVICE_DEASSIGNMENT 27
#endif
+/* Another bug in KVM_SET_USER_MEMORY_REGION fixed: */
+#define KVM_CAP_JOIN_MEMORY_REGIONS_WORKS 30
#ifdef KVM_CAP_IRQ_ROUTING
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 28d693a1ee8f..1ecbe2391c8b 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -961,7 +961,7 @@ int __kvm_set_memory_region(struct kvm *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)))
@@ -1983,6 +1983,7 @@ static long kvm_dev_ioctl_check_extension_generic(long arg)
switch (arg) {
case KVM_CAP_USER_MEMORY:
case KVM_CAP_DESTROY_MEMORY_REGION_WORKS:
+ case KVM_CAP_JOIN_MEMORY_REGIONS_WORKS:
return 1;
#ifdef CONFIG_HAVE_KVM_IRQCHIP
case KVM_CAP_IRQ_ROUTING:
--
2.30.9