diff options
| author | Alexey Kardashevskiy <aik@ozlabs.ru> | 2017-10-11 16:00:34 +1100 |
|---|---|---|
| committer | Paul Mackerras <paulus@ozlabs.org> | 2017-10-14 11:35:41 +1100 |
| commit | 8f6a9f0d0604817f7c8d4376fd51718f1bf192ee (patch) | |
| tree | 930fee4777158b8a8099c4e5a46cea4149572c11 /arch/powerpc/kvm | |
| parent | 2cde3716321ec64a1faeaf567bd94100c7b4160f (diff) | |
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/kvm')
| -rw-r--r-- | arch/powerpc/kvm/book3s_64_vio.c | 23 |
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); |