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=-6.0 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, 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 36C5CC10F0E for ; Fri, 22 Mar 2019 12:28:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 03AA22054F for ; Fri, 22 Mar 2019 12:28:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1553257703; bh=IjlnTNmI66NfvTRigITNMKCaVuPFT5C/FBsTGZpqiqY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=tKhudg1duA0uShlVx4GGfgRa7TjK6bzV+mjBGi9icwld6du5C3wYXTIgGqQTTFhv2 S4bQFMpw5YgmvDDTKaSzfPZZJdQbbyyPhuTAqUGIHyiM4n1RCrfGXeWcSO81hmjRGl ETQ7uuvsjyvaDKtpzCBPZcDLLICopPWsbnSFXg40= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S2390081AbfCVMUt (ORCPT ); Fri, 22 Mar 2019 08:20:49 -0400 Received: from mail.kernel.org ([198.145.29.99]:59764 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2390759AbfCVMUq (ORCPT ); Fri, 22 Mar 2019 08:20:46 -0400 Received: from localhost (83-86-89-107.cable.dynamic.v4.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 21C0421900; Fri, 22 Mar 2019 12:20:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1553257245; bh=IjlnTNmI66NfvTRigITNMKCaVuPFT5C/FBsTGZpqiqY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=o6cSFvcCSlo4k6xaxb67po67bGqlmSpw+KtwYuPgxlZ13ap10oIR8iAgjoSnYuF+c tU4F6MAmJjVCcS3jEgcvalOBcNh56DUok54QBNRMNnMaRBQ/R4zhWrbD/8yM0yuD3e GL8/05b3FsjO59g0/WOTxXscPL46FDA/feQElOus= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Ben Gardon , Paolo Bonzini Subject: [PATCH 5.0 175/238] Revert "KVM/MMU: Flush tlb directly in the kvm_zap_gfn_range()" Date: Fri, 22 Mar 2019 12:16:34 +0100 Message-Id: <20190322111308.598088143@linuxfoundation.org> X-Mailer: git-send-email 2.21.0 In-Reply-To: <20190322111258.383569278@linuxfoundation.org> References: <20190322111258.383569278@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review X-Patchwork-Hint: ignore MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org 5.0-stable review patch. If anyone has any objections, please let me know. ------------------ From: Ben Gardon commit 92da008fa21034c369cdb8ca2b629fe5c196826b upstream. This reverts commit 71883a62fcd6c70639fa12cda733378b4d997409. The above commit contains an optimization to kvm_zap_gfn_range which uses gfn-limited TLB flushes, if enabled. If using these limited flushes, kvm_zap_gfn_range passes lock_flush_tlb=false to slot_handle_level_range which creates a race when the function unlocks to call cond_resched. See an example of this race below: CPU 0 CPU 1 CPU 3 // zap_direct_gfn_range mmu_lock() // *ptep == pte_1 *ptep = 0 if (lock_flush_tlb) flush_tlbs() mmu_unlock() // In invalidate range // MMU notifier mmu_lock() if (pte != 0) *ptep = 0 flush = true if (flush) flush_remote_tlbs() mmu_unlock() return // Host MM reallocates // page previously // backing guest memory. // Guest accesses // invalid page // through pte_1 // in its TLB!! Tested: Ran all kvm-unit-tests on a Intel Haswell machine with and without this patch. The patch introduced no new failures. Signed-off-by: Ben Gardon Cc: stable@vger.kernel.org Signed-off-by: Paolo Bonzini Signed-off-by: Greg Kroah-Hartman --- arch/x86/kvm/mmu.c | 16 +++------------- 1 file changed, 3 insertions(+), 13 deletions(-) --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -5635,13 +5635,8 @@ void kvm_zap_gfn_range(struct kvm *kvm, { struct kvm_memslots *slots; struct kvm_memory_slot *memslot; - bool flush_tlb = true; - bool flush = false; int i; - if (kvm_available_flush_tlb_with_range()) - flush_tlb = false; - spin_lock(&kvm->mmu_lock); for (i = 0; i < KVM_ADDRESS_SPACE_NUM; i++) { slots = __kvm_memslots(kvm, i); @@ -5653,17 +5648,12 @@ void kvm_zap_gfn_range(struct kvm *kvm, if (start >= end) continue; - flush |= slot_handle_level_range(kvm, memslot, - kvm_zap_rmapp, PT_PAGE_TABLE_LEVEL, - PT_MAX_HUGEPAGE_LEVEL, start, - end - 1, flush_tlb); + slot_handle_level_range(kvm, memslot, kvm_zap_rmapp, + PT_PAGE_TABLE_LEVEL, PT_MAX_HUGEPAGE_LEVEL, + start, end - 1, true); } } - if (flush) - kvm_flush_remote_tlbs_with_address(kvm, gfn_start, - gfn_end - gfn_start + 1); - spin_unlock(&kvm->mmu_lock); }