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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id C9503C433FE for ; Mon, 9 May 2022 08:45:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237319AbiEIIq2 (ORCPT ); Mon, 9 May 2022 04:46:28 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:47940 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237048AbiEIIdG (ORCPT ); Mon, 9 May 2022 04:33:06 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 267CD1CEECB for ; Mon, 9 May 2022 01:29:09 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id C54636148A for ; Mon, 9 May 2022 08:28:36 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id CF053C385A8; Mon, 9 May 2022 08:28:35 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1652084916; bh=UuypwZHerpWOOnDyTPcVkB++inpIl7qi6kvQrl1L3sQ=; h=Subject:To:Cc:From:Date:From; b=xWxmxWfmbd7LTtZJTAcK6QCBh1tBJR7TCrzItb53Olh/OF8UpCbikVNu2MFBodv5E oGmoEB2lZu5FDEe/XrIpAAmB0Sg/PUlix+q3Vf0VfDm+GOaXW6IdUxUMr/YTDh8KTJ R/JjlINJNrh1QfezEM6fqaIta2j/qRPZL6SG0sq0= Subject: FAILED: patch "[PATCH] KVM: x86/mmu: Don't treat fully writable SPTEs as volatile" failed to apply to 4.14-stable tree To: seanjc@google.com, pbonzini@redhat.com Cc: From: Date: Mon, 09 May 2022 10:28:25 +0200 Message-ID: <1652084905101184@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org The patch below does not apply to the 4.14-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 706c9c55e5a32800605eb6a864ef6e1ca0c6c179 Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Sat, 23 Apr 2022 03:47:41 +0000 Subject: [PATCH] KVM: x86/mmu: Don't treat fully writable SPTEs as volatile (modulo A/D) Don't treat SPTEs that are truly writable, i.e. writable in hardware, as being volatile (unless they're volatile for other reasons, e.g. A/D bits). KVM _sets_ the WRITABLE bit out of mmu_lock, but never _clears_ the bit out of mmu_lock, so if the WRITABLE bit is set, it cannot magically get cleared just because the SPTE is MMU-writable. Rename the wrapper of MMU-writable to be more literal, the previous name of spte_can_locklessly_be_made_writable() is wrong and misleading. Fixes: c7ba5b48cc8d ("KVM: MMU: fast path of handling guest page fault") Cc: stable@vger.kernel.org Signed-off-by: Sean Christopherson Message-Id: <20220423034752.1161007-2-seanjc@google.com> Signed-off-by: Paolo Bonzini diff --git a/arch/x86/kvm/mmu/mmu.c b/arch/x86/kvm/mmu/mmu.c index 64a2a7e2be90..48dcb6a782f4 100644 --- a/arch/x86/kvm/mmu/mmu.c +++ b/arch/x86/kvm/mmu/mmu.c @@ -484,13 +484,15 @@ static bool spte_has_volatile_bits(u64 spte) * also, it can help us to get a stable is_writable_pte() * to ensure tlb flush is not missed. */ - if (spte_can_locklessly_be_made_writable(spte) || - is_access_track_spte(spte)) + if (!is_writable_pte(spte) && is_mmu_writable_spte(spte)) + return true; + + if (is_access_track_spte(spte)) return true; if (spte_ad_enabled(spte)) { - if ((spte & shadow_accessed_mask) == 0 || - (is_writable_pte(spte) && (spte & shadow_dirty_mask) == 0)) + if (!(spte & shadow_accessed_mask) || + (is_writable_pte(spte) && !(spte & shadow_dirty_mask))) return true; } @@ -557,7 +559,7 @@ static bool mmu_spte_update(u64 *sptep, u64 new_spte) * we always atomically update it, see the comments in * spte_has_volatile_bits(). */ - if (spte_can_locklessly_be_made_writable(old_spte) && + if (is_mmu_writable_spte(old_spte) && !is_writable_pte(new_spte)) flush = true; @@ -1187,7 +1189,7 @@ static bool spte_write_protect(u64 *sptep, bool pt_protect) u64 spte = *sptep; if (!is_writable_pte(spte) && - !(pt_protect && spte_can_locklessly_be_made_writable(spte))) + !(pt_protect && is_mmu_writable_spte(spte))) return false; rmap_printk("spte %p %llx\n", sptep, *sptep); @@ -3196,8 +3198,7 @@ static int fast_page_fault(struct kvm_vcpu *vcpu, struct kvm_page_fault *fault) * be removed in the fast path only if the SPTE was * write-protected for dirty-logging or access tracking. */ - if (fault->write && - spte_can_locklessly_be_made_writable(spte)) { + if (fault->write && is_mmu_writable_spte(spte)) { new_spte |= PT_WRITABLE_MASK; /* diff --git a/arch/x86/kvm/mmu/spte.h b/arch/x86/kvm/mmu/spte.h index e4abeb5df1b1..c571784cb567 100644 --- a/arch/x86/kvm/mmu/spte.h +++ b/arch/x86/kvm/mmu/spte.h @@ -390,7 +390,7 @@ static inline void check_spte_writable_invariants(u64 spte) "kvm: Writable SPTE is not MMU-writable: %llx", spte); } -static inline bool spte_can_locklessly_be_made_writable(u64 spte) +static inline bool is_mmu_writable_spte(u64 spte) { return spte & shadow_mmu_writable_mask; }