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authorAlexey Kardashevskiy <aik@ozlabs.ru>2017-10-11 08:00:34 +0300
committerPaul Mackerras <paulus@ozlabs.org>2017-10-14 03:35:41 +0300
commit8f6a9f0d0604817f7c8d4376fd51718f1bf192ee (patch)
tree930fee4777158b8a8099c4e5a46cea4149572c11 /arch/powerpc
parent2cde3716321ec64a1faeaf567bd94100c7b4160f (diff)
downloadlinux-8f6a9f0d0604817f7c8d4376fd51718f1bf192ee.tar.xz
KVM: PPC: Book3S: Protect kvmppc_gpa_to_ua() with SRCU
kvmppc_gpa_to_ua() accesses KVM memory slot array via srcu_dereference_check() and this produces warnings from RCU like below. This extends the existing srcu_read_lock/unlock to cover that kvmppc_gpa_to_ua() as well. We did not hit this before as this lock is not needed for the realmode handlers and hash guests would use the realmode path all the time; however the radix guests are always redirected to the virtual mode handlers and hence the warning. [ 68.253798] ./include/linux/kvm_host.h:575 suspicious rcu_dereference_check() usage! [ 68.253799] other info that might help us debug this: [ 68.253802] rcu_scheduler_active = 2, debug_locks = 1 [ 68.253804] 1 lock held by qemu-system-ppc/6413: [ 68.253806] #0: (&vcpu->mutex){+.+.}, at: [<c00800000e3c22f4>] vcpu_load+0x3c/0xc0 [kvm] [ 68.253826] stack backtrace: [ 68.253830] CPU: 92 PID: 6413 Comm: qemu-system-ppc Tainted: G W 4.14.0-rc3-00553-g432dcba58e9c-dirty #72 [ 68.253833] Call Trace: [ 68.253839] [c000000fd3d9f790] [c000000000b7fcc8] dump_stack+0xe8/0x160 (unreliable) [ 68.253845] [c000000fd3d9f7d0] [c0000000001924c0] lockdep_rcu_suspicious+0x110/0x180 [ 68.253851] [c000000fd3d9f850] [c0000000000e825c] kvmppc_gpa_to_ua+0x26c/0x2b0 [ 68.253858] [c000000fd3d9f8b0] [c00800000e3e1984] kvmppc_h_put_tce+0x12c/0x2a0 [kvm] Fixes: 121f80ba68f1 ("KVM: PPC: VFIO: Add in-kernel acceleration for VFIO") Cc: stable@vger.kernel.org # v4.12+ Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru> Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Diffstat (limited to 'arch/powerpc')
-rw-r--r--arch/powerpc/kvm/book3s_64_vio.c23
1 files changed, 14 insertions, 9 deletions
diff --git a/arch/powerpc/kvm/book3s_64_vio.c b/arch/powerpc/kvm/book3s_64_vio.c
index 8f2da8bba737..4dffa611376d 100644
--- a/arch/powerpc/kvm/book3s_64_vio.c
+++ b/arch/powerpc/kvm/book3s_64_vio.c
@@ -478,28 +478,30 @@ long kvmppc_h_put_tce(struct kvm_vcpu *vcpu, unsigned long liobn,
return ret;
dir = iommu_tce_direction(tce);
+
+ idx = srcu_read_lock(&vcpu->kvm->srcu);
+
if ((dir != DMA_NONE) && kvmppc_gpa_to_ua(vcpu->kvm,
- tce & ~(TCE_PCI_READ | TCE_PCI_WRITE), &ua, NULL))
- return H_PARAMETER;
+ tce & ~(TCE_PCI_READ | TCE_PCI_WRITE), &ua, NULL)) {
+ ret = H_PARAMETER;
+ goto unlock_exit;
+ }
entry = ioba >> stt->page_shift;
list_for_each_entry_lockless(stit, &stt->iommu_tables, next) {
- if (dir == DMA_NONE) {
+ if (dir == DMA_NONE)
ret = kvmppc_tce_iommu_unmap(vcpu->kvm,
stit->tbl, entry);
- } else {
- idx = srcu_read_lock(&vcpu->kvm->srcu);
+ else
ret = kvmppc_tce_iommu_map(vcpu->kvm, stit->tbl,
entry, ua, dir);
- srcu_read_unlock(&vcpu->kvm->srcu, idx);
- }
if (ret == H_SUCCESS)
continue;
if (ret == H_TOO_HARD)
- return ret;
+ goto unlock_exit;
WARN_ON_ONCE(1);
kvmppc_clear_tce(stit->tbl, entry);
@@ -507,7 +509,10 @@ long kvmppc_h_put_tce(struct kvm_vcpu *vcpu, unsigned long liobn,
kvmppc_tce_put(stt, entry, tce);
- return H_SUCCESS;
+unlock_exit:
+ srcu_read_unlock(&vcpu->kvm->srcu, idx);
+
+ return ret;
}
EXPORT_SYMBOL_GPL(kvmppc_h_put_tce);