From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932434AbdJaJ71 (ORCPT ); Tue, 31 Oct 2017 05:59:27 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:40408 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754132AbdJaJ7W (ORCPT ); Tue, 31 Oct 2017 05:59:22 -0400 From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Alexey Kardashevskiy , Paul Mackerras Subject: [PATCH 4.13 09/43] KVM: PPC: Book3S: Protect kvmppc_gpa_to_ua() with SRCU Date: Tue, 31 Oct 2017 10:55:29 +0100 Message-Id: <20171031095530.902444612@linuxfoundation.org> X-Mailer: git-send-email 2.14.3 In-Reply-To: <20171031095530.520746935@linuxfoundation.org> References: <20171031095530.520746935@linuxfoundation.org> User-Agent: quilt/0.65 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.13-stable review patch. If anyone has any objections, please let me know. ------------------ From: Alexey Kardashevskiy commit 8f6a9f0d0604817f7c8d4376fd51718f1bf192ee upstream. 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: [] 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") Signed-off-by: Alexey Kardashevskiy Signed-off-by: Paul Mackerras Signed-off-by: Greg Kroah-Hartman --- arch/powerpc/kvm/book3s_64_vio.c | 23 ++++++++++++++--------- 1 file changed, 14 insertions(+), 9 deletions(-) --- a/arch/powerpc/kvm/book3s_64_vio.c +++ b/arch/powerpc/kvm/book3s_64_vio.c @@ -479,28 +479,30 @@ long kvmppc_h_put_tce(struct kvm_vcpu *v 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); @@ -508,7 +510,10 @@ long kvmppc_h_put_tce(struct kvm_vcpu *v 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);