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=-10.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,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 069A3C3A5A2 for ; Tue, 3 Sep 2019 16:38:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id D2122233A1 for ; Tue, 3 Sep 2019 16:38:26 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1567528706; bh=y4mtFdd/M4192J/pE0CJUfdZ9vvIJgvFr2RKFhXHTls=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=rcJ9sRvPl7/8FQ0zOcqgizBXnTfZYnJfw6gCCOZ98pJrG0JQa5rFZ61JKU+sG2Y57 6rNv62hwmYVCw9KjMco8XrxLVTivCbM+d7TI3/HNERLB58ac6qalOyQKEr1vSBdRQb z3SOurt7gW5RdYm6USgVEXmMCR1xjDIiUCUaXOj4= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730612AbfICQiZ (ORCPT ); Tue, 3 Sep 2019 12:38:25 -0400 Received: from mail.kernel.org ([198.145.29.99]:47158 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730608AbfICQ0V (ORCPT ); Tue, 3 Sep 2019 12:26:21 -0400 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 6859C23789; Tue, 3 Sep 2019 16:26:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1567527980; bh=y4mtFdd/M4192J/pE0CJUfdZ9vvIJgvFr2RKFhXHTls=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=YV291SDY9wCYYkPSkFbLAutuTU7aH7htRIc6Yv5pmSG0gTP85J9Dedevt/1nVpmoH yicNQinrOXx66W2P/Z5qDltgTt1+ZbcVA2DAWG1zJFFWFVmNYkIECRJE4LhyqODCrl uIVP1xJGmD9yUJjf+XEs5qiDatqps3jBvMP4E2Eg= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Paul Mackerras , Sasha Levin , kvm-ppc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org Subject: [PATCH AUTOSEL 4.19 035/167] KVM: PPC: Book3S HV: Fix race between kvm_unmap_hva_range and MMU mode switch Date: Tue, 3 Sep 2019 12:23:07 -0400 Message-Id: <20190903162519.7136-35-sashal@kernel.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190903162519.7136-1-sashal@kernel.org> References: <20190903162519.7136-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Paul Mackerras [ Upstream commit 234ff0b729ad882d20f7996591a964965647addf ] Testing has revealed an occasional crash which appears to be caused by a race between kvmppc_switch_mmu_to_hpt and kvm_unmap_hva_range_hv. The symptom is a NULL pointer dereference in __find_linux_pte() called from kvm_unmap_radix() with kvm->arch.pgtable == NULL. Looking at kvmppc_switch_mmu_to_hpt(), it does indeed clear kvm->arch.pgtable (via kvmppc_free_radix()) before setting kvm->arch.radix to NULL, and there is nothing to prevent kvm_unmap_hva_range_hv() or the other MMU callback functions from being called concurrently with kvmppc_switch_mmu_to_hpt() or kvmppc_switch_mmu_to_radix(). This patch therefore adds calls to spin_lock/unlock on the kvm->mmu_lock around the assignments to kvm->arch.radix, and makes sure that the partition-scoped radix tree or HPT is only freed after changing kvm->arch.radix. This also takes the kvm->mmu_lock in kvmppc_rmap_reset() to make sure that the clearing of each rmap array (one per memslot) doesn't happen concurrently with use of the array in the kvm_unmap_hva_range_hv() or the other MMU callbacks. Fixes: 18c3640cefc7 ("KVM: PPC: Book3S HV: Add infrastructure for running HPT guests on radix host") Cc: stable@vger.kernel.org # v4.15+ Signed-off-by: Paul Mackerras Signed-off-by: Sasha Levin --- arch/powerpc/kvm/book3s_64_mmu_hv.c | 3 +++ arch/powerpc/kvm/book3s_hv.c | 15 +++++++++++---- 2 files changed, 14 insertions(+), 4 deletions(-) diff --git a/arch/powerpc/kvm/book3s_64_mmu_hv.c b/arch/powerpc/kvm/book3s_64_mmu_hv.c index 68e14afecac85..a488c105b9234 100644 --- a/arch/powerpc/kvm/book3s_64_mmu_hv.c +++ b/arch/powerpc/kvm/book3s_64_mmu_hv.c @@ -744,12 +744,15 @@ void kvmppc_rmap_reset(struct kvm *kvm) srcu_idx = srcu_read_lock(&kvm->srcu); slots = kvm_memslots(kvm); kvm_for_each_memslot(memslot, slots) { + /* Mutual exclusion with kvm_unmap_hva_range etc. */ + spin_lock(&kvm->mmu_lock); /* * This assumes it is acceptable to lose reference and * change bits across a reset. */ memset(memslot->arch.rmap, 0, memslot->npages * sizeof(*memslot->arch.rmap)); + spin_unlock(&kvm->mmu_lock); } srcu_read_unlock(&kvm->srcu, srcu_idx); } diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c index 083dcedba11ce..9595db30e6b87 100644 --- a/arch/powerpc/kvm/book3s_hv.c +++ b/arch/powerpc/kvm/book3s_hv.c @@ -3813,12 +3813,15 @@ static int kvmppc_hv_setup_htab_rma(struct kvm_vcpu *vcpu) /* Must be called with kvm->lock held and mmu_ready = 0 and no vcpus running */ int kvmppc_switch_mmu_to_hpt(struct kvm *kvm) { + kvmppc_rmap_reset(kvm); + kvm->arch.process_table = 0; + /* Mutual exclusion with kvm_unmap_hva_range etc. */ + spin_lock(&kvm->mmu_lock); + kvm->arch.radix = 0; + spin_unlock(&kvm->mmu_lock); kvmppc_free_radix(kvm); kvmppc_update_lpcr(kvm, LPCR_VPM1, LPCR_VPM1 | LPCR_UPRT | LPCR_GTSE | LPCR_HR); - kvmppc_rmap_reset(kvm); - kvm->arch.radix = 0; - kvm->arch.process_table = 0; return 0; } @@ -3831,10 +3834,14 @@ int kvmppc_switch_mmu_to_radix(struct kvm *kvm) if (err) return err; + kvmppc_rmap_reset(kvm); + /* Mutual exclusion with kvm_unmap_hva_range etc. */ + spin_lock(&kvm->mmu_lock); + kvm->arch.radix = 1; + spin_unlock(&kvm->mmu_lock); kvmppc_free_hpt(&kvm->arch.hpt); kvmppc_update_lpcr(kvm, LPCR_UPRT | LPCR_GTSE | LPCR_HR, LPCR_VPM1 | LPCR_UPRT | LPCR_GTSE | LPCR_HR); - kvm->arch.radix = 1; return 0; } -- 2.20.1