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Commit 95c87e2b4460a488ec7ce42f273893e410ab385a

Authored by Sheng Yang
Committed by Avi Kivity
1 parent fef093bec0

KVM: Fix IOMMU memslot reference warning 

This patch fixes the following warning.

===================================================
[ INFO: suspicious rcu_dereference_check() usage. ]
---------------------------------------------------
include/linux/kvm_host.h:259 invoked rcu_dereference_check() without
protection!

other info that might help us debug this:

rcu_scheduler_active = 1, debug_locks = 0
no locks held by qemu-system-x86/29679.

stack backtrace:
Pid: 29679, comm: qemu-system-x86 Not tainted 2.6.35-rc3+ #200
Call Trace:
 [<ffffffff810a224e>] lockdep_rcu_dereference+0xa8/0xb1
 [<ffffffffa018a06f>] kvm_iommu_unmap_memslots+0xc9/0xde [kvm]
 [<ffffffffa018a0c4>] kvm_iommu_unmap_guest+0x40/0x4e [kvm]
 [<ffffffffa018f772>] kvm_arch_destroy_vm+0x1a/0x186 [kvm]
 [<ffffffffa01800d0>] kvm_put_kvm+0x110/0x167 [kvm]
 [<ffffffffa0180ecc>] kvm_vcpu_release+0x18/0x1c [kvm]
 [<ffffffff81156f5d>] fput+0x22a/0x3a0
 [<ffffffff81152288>] filp_close+0xb4/0xcd
 [<ffffffff8106599f>] put_files_struct+0x1b7/0x36b
 [<ffffffff81065830>] ? put_files_struct+0x48/0x36b
 [<ffffffff8131ee59>] ? do_raw_spin_unlock+0x118/0x160
 [<ffffffff81065bc0>] exit_files+0x6d/0x75
 [<ffffffff81068348>] do_exit+0x47d/0xc60
 [<ffffffff8177e7b5>] ? _raw_spin_unlock_irq+0x30/0x36
 [<ffffffff81068bfa>] do_group_exit+0xcf/0x134
 [<ffffffff81080790>] get_signal_to_deliver+0x732/0x81d
 [<ffffffff81095996>] ? cpu_clock+0x4e/0x60
 [<ffffffff81002082>] do_notify_resume+0x117/0xc43
 [<ffffffff810a2fa3>] ? trace_hardirqs_on+0xd/0xf
 [<ffffffff81080d79>] ? sys_rt_sigtimedwait+0x2b5/0x3bf
 [<ffffffff8177d9f2>] ? trace_hardirqs_off_thunk+0x3a/0x3c
 [<ffffffff81003221>] ? sysret_signal+0x5/0x3d
 [<ffffffff8100343b>] int_signal+0x12/0x17

Signed-off-by: Sheng Yang <sheng@linux.intel.com>
Signed-off-by: Marcelo Tosatti <mtosatti@redhat.com>

Showing 1 changed file with 6 additions and 2 deletions Side-by-side Diff

... ... @@ -126,9 +126,10 @@
126 126  
127 127 static int kvm_iommu_map_memslots(struct kvm *kvm)
128 128 {
129   - int i, r = 0;
  129 + int i, idx, r = 0;
130 130 struct kvm_memslots *slots;
131 131  
  132 + idx = srcu_read_lock(&kvm->srcu);
132 133 slots = kvm_memslots(kvm);
133 134  
134 135 for (i = 0; i < slots->nmemslots; i++) {
... ... @@ -136,6 +137,7 @@
136 137 if (r)
137 138 break;
138 139 }
  140 + srcu_read_unlock(&kvm->srcu, idx);
139 141  
140 142 return r;
141 143 }
142 144  
143 145  
... ... @@ -285,15 +287,17 @@
285 287  
286 288 static int kvm_iommu_unmap_memslots(struct kvm *kvm)
287 289 {
288   - int i;
  290 + int i, idx;
289 291 struct kvm_memslots *slots;
290 292  
  293 + idx = srcu_read_lock(&kvm->srcu);
291 294 slots = kvm_memslots(kvm);
292 295  
293 296 for (i = 0; i < slots->nmemslots; i++) {
294 297 kvm_iommu_put_pages(kvm, slots->memslots[i].base_gfn,
295 298 slots->memslots[i].npages);
296 299 }
  300 + srcu_read_unlock(&kvm->srcu, idx);
297 301  
298 302 return 0;
299 303 }