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=-18.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT autolearn=ham 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 244E8C43470 for ; Mon, 12 Apr 2021 08:57:00 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E4A1B6136B for ; Mon, 12 Apr 2021 08:56:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238783AbhDLI5P (ORCPT ); Mon, 12 Apr 2021 04:57:15 -0400 Received: from mail.kernel.org ([198.145.29.99]:44272 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238941AbhDLIzO (ORCPT ); Mon, 12 Apr 2021 04:55:14 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 4982F6137E; Mon, 12 Apr 2021 08:53:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1618217629; bh=9OZmdO+5++FEOCETLaapv9jX7JCxl1wP21CfSmZC4hU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=OoM+joBoSlfohO0PGrHjjR2vvV4g04GDYpOg0olT9L+vfLhtDQHvku7BRvLn/prxa zZd3wjCnk2VPy0ocTYs7gHpC6J9IQShOruixvZYsdIKpoXW1aWS8gTwBzvqtNb09hK YKWnEwESmzBF7MiUAuHj05jY34wtvbpy2YiY/Uuc= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Peter Feiner , Ben Gardon , Paolo Bonzini , Sasha Levin Subject: [PATCH 5.10 086/188] KVM: x86/mmu: Yield in TDU MMU iter even if no SPTES changed Date: Mon, 12 Apr 2021 10:40:00 +0200 Message-Id: <20210412084016.507386640@linuxfoundation.org> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210412084013.643370347@linuxfoundation.org> References: <20210412084013.643370347@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Ben Gardon [ Upstream commit 1af4a96025b33587ca953c7ef12a1b20c6e70412 ] Given certain conditions, some TDP MMU functions may not yield reliably / frequently enough. For example, if a paging structure was very large but had few, if any writable entries, wrprot_gfn_range could traverse many entries before finding a writable entry and yielding because the check for yielding only happens after an SPTE is modified. Fix this issue by moving the yield to the beginning of the loop. Fixes: a6a0b05da9f3 ("kvm: x86/mmu: Support dirty logging for the TDP MMU") Reviewed-by: Peter Feiner Signed-off-by: Ben Gardon Message-Id: <20210202185734.1680553-15-bgardon@google.com> Signed-off-by: Paolo Bonzini Signed-off-by: Sasha Levin --- arch/x86/kvm/mmu/tdp_mmu.c | 32 ++++++++++++++++++++++---------- 1 file changed, 22 insertions(+), 10 deletions(-) diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c index f0bc5d3ce3d4..0d17457f1c84 100644 --- a/arch/x86/kvm/mmu/tdp_mmu.c +++ b/arch/x86/kvm/mmu/tdp_mmu.c @@ -462,6 +462,12 @@ static bool zap_gfn_range(struct kvm *kvm, struct kvm_mmu_page *root, bool flush_needed = false; tdp_root_for_each_pte(iter, root, start, end) { + if (can_yield && + tdp_mmu_iter_cond_resched(kvm, &iter, flush_needed)) { + flush_needed = false; + continue; + } + if (!is_shadow_present_pte(iter.old_spte)) continue; @@ -476,9 +482,7 @@ static bool zap_gfn_range(struct kvm *kvm, struct kvm_mmu_page *root, continue; tdp_mmu_set_spte(kvm, &iter, 0); - - flush_needed = !(can_yield && - tdp_mmu_iter_cond_resched(kvm, &iter, true)); + flush_needed = true; } return flush_needed; } @@ -838,6 +842,9 @@ static bool wrprot_gfn_range(struct kvm *kvm, struct kvm_mmu_page *root, for_each_tdp_pte_min_level(iter, root->spt, root->role.level, min_level, start, end) { + if (tdp_mmu_iter_cond_resched(kvm, &iter, false)) + continue; + if (!is_shadow_present_pte(iter.old_spte) || !is_last_spte(iter.old_spte, iter.level)) continue; @@ -846,8 +853,6 @@ static bool wrprot_gfn_range(struct kvm *kvm, struct kvm_mmu_page *root, tdp_mmu_set_spte_no_dirty_log(kvm, &iter, new_spte); spte_set = true; - - tdp_mmu_iter_cond_resched(kvm, &iter, false); } return spte_set; } @@ -891,6 +896,9 @@ static bool clear_dirty_gfn_range(struct kvm *kvm, struct kvm_mmu_page *root, bool spte_set = false; tdp_root_for_each_leaf_pte(iter, root, start, end) { + if (tdp_mmu_iter_cond_resched(kvm, &iter, false)) + continue; + if (spte_ad_need_write_protect(iter.old_spte)) { if (is_writable_pte(iter.old_spte)) new_spte = iter.old_spte & ~PT_WRITABLE_MASK; @@ -905,8 +913,6 @@ static bool clear_dirty_gfn_range(struct kvm *kvm, struct kvm_mmu_page *root, tdp_mmu_set_spte_no_dirty_log(kvm, &iter, new_spte); spte_set = true; - - tdp_mmu_iter_cond_resched(kvm, &iter, false); } return spte_set; } @@ -1014,6 +1020,9 @@ static bool set_dirty_gfn_range(struct kvm *kvm, struct kvm_mmu_page *root, bool spte_set = false; tdp_root_for_each_pte(iter, root, start, end) { + if (tdp_mmu_iter_cond_resched(kvm, &iter, false)) + continue; + if (!is_shadow_present_pte(iter.old_spte)) continue; @@ -1021,8 +1030,6 @@ static bool set_dirty_gfn_range(struct kvm *kvm, struct kvm_mmu_page *root, tdp_mmu_set_spte(kvm, &iter, new_spte); spte_set = true; - - tdp_mmu_iter_cond_resched(kvm, &iter, false); } return spte_set; @@ -1063,6 +1070,11 @@ static void zap_collapsible_spte_range(struct kvm *kvm, bool spte_set = false; tdp_root_for_each_pte(iter, root, start, end) { + if (tdp_mmu_iter_cond_resched(kvm, &iter, spte_set)) { + spte_set = false; + continue; + } + if (!is_shadow_present_pte(iter.old_spte) || !is_last_spte(iter.old_spte, iter.level)) continue; @@ -1075,7 +1087,7 @@ static void zap_collapsible_spte_range(struct kvm *kvm, tdp_mmu_set_spte(kvm, &iter, 0); - spte_set = !tdp_mmu_iter_cond_resched(kvm, &iter, true); + spte_set = true; } if (spte_set) -- 2.30.2