From patchwork Sun May 10 05:18:34 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Qian Cai X-Patchwork-Id: 1286934 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=vger.kernel.org (client-ip=23.128.96.18; helo=vger.kernel.org; envelope-from=kvm-ppc-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=none (p=none dis=none) header.from=lca.pw Authentication-Results: ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=lca.pw header.i=@lca.pw header.a=rsa-sha256 header.s=google header.b=rmYgUAkv; dkim-atps=neutral Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by ozlabs.org (Postfix) with ESMTP id 49KXRG2tT3z9sNH for ; Sun, 10 May 2020 15:18:50 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725860AbgEJFSo (ORCPT ); Sun, 10 May 2020 01:18:44 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42184 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725810AbgEJFSo (ORCPT ); Sun, 10 May 2020 01:18:44 -0400 Received: from mail-qt1-x841.google.com (mail-qt1-x841.google.com [IPv6:2607:f8b0:4864:20::841]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 18A14C061A0E for ; Sat, 9 May 2020 22:18:44 -0700 (PDT) Received: by mail-qt1-x841.google.com with SMTP id v4so4259105qte.3 for ; Sat, 09 May 2020 22:18:44 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=lca.pw; s=google; h=from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=/lcyVkFvW6Q2XtFR89qoX9NO7slQxZQ5eBaDk/SNENo=; b=rmYgUAkvZpyFKZcqeGRIyvvBHeg1jJroQIIofbBodDDku0mcvJo/BQqa8SHRnYFJaI iqRx162shMpOm75JtRUCjAztD6+DXrguzJeHeiY0iDxuUsed8YT2MBAQ/dfri9YyfUp8 6bnqunS5v3p+wvBbGonBj8t9Z8x3KvRuUgMi8iC2VSOtO5C6jXY36T5uOUnPdGbG/1ZL 1X6XVaJ89ce89/aFmh9J7wCcKb+tPmp5rcuzf/s8MkrvYGJOaHuBeUmI9Q8OCZRdbTy4 Xmc6apEkT+68fWOBPlI1a52fi1BLx2dAZ1yz5z5Lo8NpgrnK32By/KQX+EBLeJ1rx1Va RFjA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:mime-version :content-transfer-encoding; bh=/lcyVkFvW6Q2XtFR89qoX9NO7slQxZQ5eBaDk/SNENo=; b=NXD6FQsGlQU9NRoQEhWEfApdD0nr8jWaDmVmuwVZpbvZSg8k86kzko0p/wTeTY56Gb YmGHtJL8zAFdpHJ7PaKkZNFgHYIZg4SnLnA51/Md2dVyd8KA8sMG8oS+d6RfSSJ+vSCS yetbqgBgAfGvcvjEWhChm/W2mKWnMAKIM80qPnCn4qYHVdmLSWs/XyR7JJlfkvgocEj0 njy8nv5ORGqssytS9I0kYcorMwFptLUJXnf5sgBSGUnjQ/JH5go3VB7NZhq9LMPHWlwg N8fRvP7OWkbmajDOgK2dOEOdmVh+5sGUuQsDvgcQU88UcXfKplBcDcBib/NtqCz4zIQq J08g== X-Gm-Message-State: AGi0PuaYk3nUKOvhiQ6mjFNYAFhFoJrMJ3mYQ/RSSlGVWHhhOzchdmtN 1mho0TXBXtORRcglzLyL+3CRnQ== X-Google-Smtp-Source: APiQypK5nCri8dvQyy2Srb2XSRl+X2gaOjzChXlYZVh4WI3iYi/fXLwXzIeA9OlCUfW0kVaa22XLVw== X-Received: by 2002:ac8:4987:: with SMTP id f7mr10426013qtq.160.1589087923115; Sat, 09 May 2020 22:18:43 -0700 (PDT) Received: from ovpn-112-80.rdu2.redhat.com (pool-71-184-117-43.bstnma.fios.verizon.net. [71.184.117.43]) by smtp.gmail.com with ESMTPSA id p31sm6067732qtf.11.2020.05.09.22.18.42 (version=TLS1_2 cipher=ECDHE-ECDSA-AES128-GCM-SHA256 bits=128/128); Sat, 09 May 2020 22:18:42 -0700 (PDT) From: Qian Cai To: mpe@ellerman.id.au Cc: benh@kernel.crashing.org, paulus@samba.org, aik@ozlabs.ru, paulmck@kernel.org, linuxppc-dev@lists.ozlabs.org, kvm-ppc@vger.kernel.org, linux-kernel@vger.kernel.org, Qian Cai Subject: [PATCH] powerpc/kvm/book3s64/vio: fix some RCU-list locks Date: Sun, 10 May 2020 01:18:34 -0400 Message-Id: <20200510051834.2011-1-cai@lca.pw> X-Mailer: git-send-email 2.21.0 (Apple Git-122.2) MIME-Version: 1.0 Sender: kvm-ppc-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm-ppc@vger.kernel.org It is unsafe to traverse kvm->arch.spapr_tce_tables and stt->iommu_tables without the RCU read lock held. Also, add cond_resched_rcu() in places with the RCU read lock held that could take a while to finish. arch/powerpc/kvm/book3s_64_vio.c:76 RCU-list traversed in non-reader section!! other info that might help us debug this: rcu_scheduler_active = 2, debug_locks = 1 no locks held by qemu-kvm/4265. stack backtrace: CPU: 96 PID: 4265 Comm: qemu-kvm Not tainted 5.7.0-rc4-next-20200508+ #2 Call Trace: [c000201a8690f720] [c000000000715948] dump_stack+0xfc/0x174 (unreliable) [c000201a8690f770] [c0000000001d9470] lockdep_rcu_suspicious+0x140/0x164 [c000201a8690f7f0] [c008000010b9fb48] kvm_spapr_tce_release_iommu_group+0x1f0/0x220 [kvm] [c000201a8690f870] [c008000010b8462c] kvm_spapr_tce_release_vfio_group+0x54/0xb0 [kvm] [c000201a8690f8a0] [c008000010b84710] kvm_vfio_destroy+0x88/0x140 [kvm] [c000201a8690f8f0] [c008000010b7d488] kvm_put_kvm+0x370/0x600 [kvm] [c000201a8690f990] [c008000010b7e3c0] kvm_vm_release+0x38/0x60 [kvm] [c000201a8690f9c0] [c0000000005223f4] __fput+0x124/0x330 [c000201a8690fa20] [c000000000151cd8] task_work_run+0xb8/0x130 [c000201a8690fa70] [c0000000001197e8] do_exit+0x4e8/0xfa0 [c000201a8690fb70] [c00000000011a374] do_group_exit+0x64/0xd0 [c000201a8690fbb0] [c000000000132c90] get_signal+0x1f0/0x1200 [c000201a8690fcc0] [c000000000020690] do_notify_resume+0x130/0x3c0 [c000201a8690fda0] [c000000000038d64] syscall_exit_prepare+0x1a4/0x280 [c000201a8690fe20] [c00000000000c8f8] system_call_common+0xf8/0x278 ==== arch/powerpc/kvm/book3s_64_vio.c:368 RCU-list traversed in non-reader section!! other info that might help us debug this: rcu_scheduler_active = 2, debug_locks = 1 2 locks held by qemu-kvm/4264: #0: c000201ae2d000d8 (&vcpu->mutex){+.+.}-{3:3}, at: kvm_vcpu_ioctl+0xdc/0x950 [kvm] #1: c000200c9ed0c468 (&kvm->srcu){....}-{0:0}, at: kvmppc_h_put_tce+0x88/0x340 [kvm] ==== arch/powerpc/kvm/book3s_64_vio.c:108 RCU-list traversed in non-reader section!! other info that might help us debug this: rcu_scheduler_active = 2, debug_locks = 1 1 lock held by qemu-kvm/4257: #0: c000200b1b363a40 (&kv->lock){+.+.}-{3:3}, at: kvm_vfio_set_attr+0x598/0x6c0 [kvm] ==== arch/powerpc/kvm/book3s_64_vio.c:146 RCU-list traversed in non-reader section!! other info that might help us debug this: rcu_scheduler_active = 2, debug_locks = 1 1 lock held by qemu-kvm/4257: #0: c000200b1b363a40 (&kv->lock){+.+.}-{3:3}, at: kvm_vfio_set_attr+0x598/0x6c0 [kvm] Signed-off-by: Qian Cai --- arch/powerpc/kvm/book3s_64_vio.c | 19 +++++++++++++++---- 1 file changed, 15 insertions(+), 4 deletions(-) diff --git a/arch/powerpc/kvm/book3s_64_vio.c b/arch/powerpc/kvm/book3s_64_vio.c index 50555ad1db93..4f5016bab723 100644 --- a/arch/powerpc/kvm/book3s_64_vio.c +++ b/arch/powerpc/kvm/book3s_64_vio.c @@ -73,6 +73,7 @@ extern void kvm_spapr_tce_release_iommu_group(struct kvm *kvm, struct kvmppc_spapr_tce_iommu_table *stit, *tmp; struct iommu_table_group *table_group = NULL; + rcu_read_lock(); list_for_each_entry_rcu(stt, &kvm->arch.spapr_tce_tables, list) { table_group = iommu_group_get_iommudata(grp); @@ -87,7 +88,9 @@ extern void kvm_spapr_tce_release_iommu_group(struct kvm *kvm, kref_put(&stit->kref, kvm_spapr_tce_liobn_put); } } + cond_resched_rcu(); } + rcu_read_unlock(); } extern long kvm_spapr_tce_attach_iommu_group(struct kvm *kvm, int tablefd, @@ -105,12 +108,14 @@ extern long kvm_spapr_tce_attach_iommu_group(struct kvm *kvm, int tablefd, if (!f.file) return -EBADF; + rcu_read_lock(); list_for_each_entry_rcu(stt, &kvm->arch.spapr_tce_tables, list) { if (stt == f.file->private_data) { found = true; break; } } + rcu_read_unlock(); fdput(f); @@ -143,6 +148,7 @@ extern long kvm_spapr_tce_attach_iommu_group(struct kvm *kvm, int tablefd, if (!tbl) return -EINVAL; + rcu_read_lock(); list_for_each_entry_rcu(stit, &stt->iommu_tables, next) { if (tbl != stit->tbl) continue; @@ -150,14 +156,17 @@ extern long kvm_spapr_tce_attach_iommu_group(struct kvm *kvm, int tablefd, if (!kref_get_unless_zero(&stit->kref)) { /* stit is being destroyed */ iommu_tce_table_put(tbl); + rcu_read_unlock(); return -ENOTTY; } /* * The table is already known to this KVM, we just increased * its KVM reference counter and can return. */ + rcu_read_unlock(); return 0; } + rcu_read_unlock(); stit = kzalloc(sizeof(*stit), GFP_KERNEL); if (!stit) { @@ -365,18 +374,20 @@ static long kvmppc_tce_validate(struct kvmppc_spapr_tce_table *stt, if (kvmppc_tce_to_ua(stt->kvm, tce, &ua)) return H_TOO_HARD; + rcu_read_lock(); list_for_each_entry_rcu(stit, &stt->iommu_tables, next) { unsigned long hpa = 0; struct mm_iommu_table_group_mem_t *mem; long shift = stit->tbl->it_page_shift; mem = mm_iommu_lookup(stt->kvm->mm, ua, 1ULL << shift); - if (!mem) - return H_TOO_HARD; - - if (mm_iommu_ua_to_hpa(mem, ua, shift, &hpa)) + if (!mem || mm_iommu_ua_to_hpa(mem, ua, shift, &hpa)) { + rcu_read_unlock(); return H_TOO_HARD; + } + cond_resched_rcu(); } + rcu_read_unlock(); return H_SUCCESS; }