From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.8 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3015CC28CC5 for ; Sat, 8 Jun 2019 12:15:18 +0000 (UTC) Received: from lists.ozlabs.org (lists.ozlabs.org [203.11.71.2]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id 74FD320693 for ; Sat, 8 Jun 2019 12:15:17 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="abHw9JoT" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 74FD320693 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Received: from lists.ozlabs.org (lists.ozlabs.org [IPv6:2401:3900:2:1::3]) by lists.ozlabs.org (Postfix) with ESMTP id 45LddH1K6mzDqyh for ; Sat, 8 Jun 2019 22:15:15 +1000 (AEST) Authentication-Results: lists.ozlabs.org; spf=pass (mailfrom) smtp.mailfrom=kernel.org (client-ip=198.145.29.99; helo=mail.kernel.org; envelope-from=sashal@kernel.org; receiver=) Authentication-Results: lists.ozlabs.org; dmarc=pass (p=none dis=none) header.from=kernel.org Authentication-Results: lists.ozlabs.org; dkim=pass (1024-bit key; unprotected) header.d=kernel.org header.i=@kernel.org header.b="abHw9JoT"; dkim-atps=neutral Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 45Ld374nP5zDqwV for ; Sat, 8 Jun 2019 21:49:07 +1000 (AEST) Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 010252168B; Sat, 8 Jun 2019 11:49:03 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1559994544; bh=Ga/Q2fsQ3x6HGX8E6Ru0cHNocZm+Y0qsmKRFrj5LVYs=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=abHw9JoTBttfanElTateLoHJZoBkk4b9PypJ6O4gmyKVpM39XWAVCOyp3syzad6WB dsHPXh1JYdby17SU/0wjz26F6jR+hg91cWJZFE2YTXoqLcjk1l/6ZKc86KW49eJFqO tBs/gPel0Ez7fa4wGjGO3eRCnfSVra4U6U68YBTo= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: [PATCH AUTOSEL 4.4 10/13] KVM: PPC: Book3S: Use new mutex to synchronize access to rtas token list Date: Sat, 8 Jun 2019 07:48:42 -0400 Message-Id: <20190608114847.9973-10-sashal@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190608114847.9973-1-sashal@kernel.org> References: <20190608114847.9973-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: Sasha Levin , linuxppc-dev@lists.ozlabs.org, kvm-ppc@vger.kernel.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" From: Paul Mackerras [ Upstream commit 1659e27d2bc1ef47b6d031abe01b467f18cb72d9 ] Currently the Book 3S KVM code uses kvm->lock to synchronize access to the kvm->arch.rtas_tokens list. Because this list is scanned inside kvmppc_rtas_hcall(), which is called with the vcpu mutex held, taking kvm->lock cause a lock inversion problem, which could lead to a deadlock. To fix this, we add a new mutex, kvm->arch.rtas_token_lock, which nests inside the vcpu mutexes, and use that instead of kvm->lock when accessing the rtas token list. This removes the lockdep_assert_held() in kvmppc_rtas_tokens_free(). At this point we don't hold the new mutex, but that is OK because kvmppc_rtas_tokens_free() is only called when the whole VM is being destroyed, and at that point nothing can be looking up a token in the list. Signed-off-by: Paul Mackerras Signed-off-by: Sasha Levin --- arch/powerpc/include/asm/kvm_host.h | 1 + arch/powerpc/kvm/book3s.c | 1 + arch/powerpc/kvm/book3s_rtas.c | 14 ++++++-------- 3 files changed, 8 insertions(+), 8 deletions(-) diff --git a/arch/powerpc/include/asm/kvm_host.h b/arch/powerpc/include/asm/kvm_host.h index a92d95aee42d..1883627eb12c 100644 --- a/arch/powerpc/include/asm/kvm_host.h +++ b/arch/powerpc/include/asm/kvm_host.h @@ -250,6 +250,7 @@ struct kvm_arch { #ifdef CONFIG_PPC_BOOK3S_64 struct list_head spapr_tce_tables; struct list_head rtas_tokens; + struct mutex rtas_token_lock; DECLARE_BITMAP(enabled_hcalls, MAX_HCALL_OPCODE/4 + 1); #endif #ifdef CONFIG_KVM_MPIC diff --git a/arch/powerpc/kvm/book3s.c b/arch/powerpc/kvm/book3s.c index 099c79d8c160..4aab1c9c83e1 100644 --- a/arch/powerpc/kvm/book3s.c +++ b/arch/powerpc/kvm/book3s.c @@ -809,6 +809,7 @@ int kvmppc_core_init_vm(struct kvm *kvm) #ifdef CONFIG_PPC64 INIT_LIST_HEAD(&kvm->arch.spapr_tce_tables); INIT_LIST_HEAD(&kvm->arch.rtas_tokens); + mutex_init(&kvm->arch.rtas_token_lock); #endif return kvm->arch.kvm_ops->init_vm(kvm); diff --git a/arch/powerpc/kvm/book3s_rtas.c b/arch/powerpc/kvm/book3s_rtas.c index ef27fbd5d9c5..b1b2273d1f6d 100644 --- a/arch/powerpc/kvm/book3s_rtas.c +++ b/arch/powerpc/kvm/book3s_rtas.c @@ -133,7 +133,7 @@ static int rtas_token_undefine(struct kvm *kvm, char *name) { struct rtas_token_definition *d, *tmp; - lockdep_assert_held(&kvm->lock); + lockdep_assert_held(&kvm->arch.rtas_token_lock); list_for_each_entry_safe(d, tmp, &kvm->arch.rtas_tokens, list) { if (rtas_name_matches(d->handler->name, name)) { @@ -154,7 +154,7 @@ static int rtas_token_define(struct kvm *kvm, char *name, u64 token) bool found; int i; - lockdep_assert_held(&kvm->lock); + lockdep_assert_held(&kvm->arch.rtas_token_lock); list_for_each_entry(d, &kvm->arch.rtas_tokens, list) { if (d->token == token) @@ -193,14 +193,14 @@ int kvm_vm_ioctl_rtas_define_token(struct kvm *kvm, void __user *argp) if (copy_from_user(&args, argp, sizeof(args))) return -EFAULT; - mutex_lock(&kvm->lock); + mutex_lock(&kvm->arch.rtas_token_lock); if (args.token) rc = rtas_token_define(kvm, args.name, args.token); else rc = rtas_token_undefine(kvm, args.name); - mutex_unlock(&kvm->lock); + mutex_unlock(&kvm->arch.rtas_token_lock); return rc; } @@ -232,7 +232,7 @@ int kvmppc_rtas_hcall(struct kvm_vcpu *vcpu) orig_rets = args.rets; args.rets = &args.args[be32_to_cpu(args.nargs)]; - mutex_lock(&vcpu->kvm->lock); + mutex_lock(&vcpu->kvm->arch.rtas_token_lock); rc = -ENOENT; list_for_each_entry(d, &vcpu->kvm->arch.rtas_tokens, list) { @@ -243,7 +243,7 @@ int kvmppc_rtas_hcall(struct kvm_vcpu *vcpu) } } - mutex_unlock(&vcpu->kvm->lock); + mutex_unlock(&vcpu->kvm->arch.rtas_token_lock); if (rc == 0) { args.rets = orig_rets; @@ -269,8 +269,6 @@ void kvmppc_rtas_tokens_free(struct kvm *kvm) { struct rtas_token_definition *d, *tmp; - lockdep_assert_held(&kvm->lock); - list_for_each_entry_safe(d, tmp, &kvm->arch.rtas_tokens, list) { list_del(&d->list); kfree(d); -- 2.20.1