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 4B220C43600 for ; Mon, 12 Apr 2021 08:56:55 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 2448E61284 for ; Mon, 12 Apr 2021 08:56:55 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238747AbhDLI5L (ORCPT ); Mon, 12 Apr 2021 04:57:11 -0400 Received: from mail.kernel.org ([198.145.29.99]:44106 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238890AbhDLIzK (ORCPT ); Mon, 12 Apr 2021 04:55:10 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 9CA5661371; Mon, 12 Apr 2021 08:53:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1618217619; bh=hL28yrMRsRB24o/40aYluezkCGAQvP8h6jL6QnsmLFk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=LVROdIJPmAphJP1R8UwQ4YxmNIGjEabg7lBcDX+UeMMkp6KiBZMZifi7FgI3CPPu7 2GAypSrjPbFePXSrDH4VBkXbYixCdHsw8ldfehny8fLKK2rQPOQ86CfDz5S64/JOFF h6shesv6cqaMPLOVocwc7bQSeEkZOlymSD/gPZhs= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Peter Feiner , Paolo Bonzini , Ben Gardon , Sasha Levin Subject: [PATCH 5.10 082/188] KVM: x86/mmu: change TDP MMU yield function returns to match cond_resched Date: Mon, 12 Apr 2021 10:39:56 +0200 Message-Id: <20210412084016.370076281@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 e28a436ca4f65384cceaf3f4da0e00aa74244e6a ] Currently the TDP MMU yield / cond_resched functions either return nothing or return true if the TLBs were not flushed. These are confusing semantics, especially when making control flow decisions in calling functions. To clean things up, change both functions to have the same return value semantics as cond_resched: true if the thread yielded, false if it did not. If the function yielded in the _flush_ version, then the TLBs will have been flushed. Reviewed-by: Peter Feiner Acked-by: Paolo Bonzini Signed-off-by: Ben Gardon Message-Id: <20210202185734.1680553-2-bgardon@google.com> Signed-off-by: Paolo Bonzini Signed-off-by: Sasha Levin --- arch/x86/kvm/mmu/tdp_mmu.c | 39 ++++++++++++++++++++++++++++---------- 1 file changed, 29 insertions(+), 10 deletions(-) diff --git a/arch/x86/kvm/mmu/tdp_mmu.c b/arch/x86/kvm/mmu/tdp_mmu.c index ffa0bd0e033f..22efd016f05e 100644 --- a/arch/x86/kvm/mmu/tdp_mmu.c +++ b/arch/x86/kvm/mmu/tdp_mmu.c @@ -405,8 +405,15 @@ static inline void tdp_mmu_set_spte_no_dirty_log(struct kvm *kvm, _mmu->shadow_root_level, _start, _end) /* - * Flush the TLB if the process should drop kvm->mmu_lock. - * Return whether the caller still needs to flush the tlb. + * Flush the TLB and yield if the MMU lock is contended or this thread needs to + * return control to the scheduler. + * + * If this function yields, it will also reset the tdp_iter's walk over the + * paging structure and the calling function should allow the iterator to + * continue its traversal from the paging structure root. + * + * Return true if this function yielded, the TLBs were flushed, and the + * iterator's traversal was reset. Return false if a yield was not needed. */ static bool tdp_mmu_iter_flush_cond_resched(struct kvm *kvm, struct tdp_iter *iter) { @@ -414,18 +421,32 @@ static bool tdp_mmu_iter_flush_cond_resched(struct kvm *kvm, struct tdp_iter *it kvm_flush_remote_tlbs(kvm); cond_resched_lock(&kvm->mmu_lock); tdp_iter_refresh_walk(iter); - return false; - } else { return true; } + + return false; } -static void tdp_mmu_iter_cond_resched(struct kvm *kvm, struct tdp_iter *iter) +/* + * Yield if the MMU lock is contended or this thread needs to return control + * to the scheduler. + * + * If this function yields, it will also reset the tdp_iter's walk over the + * paging structure and the calling function should allow the iterator to + * continue its traversal from the paging structure root. + * + * Return true if this function yielded and the iterator's traversal was reset. + * Return false if a yield was not needed. + */ +static bool tdp_mmu_iter_cond_resched(struct kvm *kvm, struct tdp_iter *iter) { if (need_resched() || spin_needbreak(&kvm->mmu_lock)) { cond_resched_lock(&kvm->mmu_lock); tdp_iter_refresh_walk(iter); + return true; } + + return false; } /* @@ -461,10 +482,8 @@ static bool zap_gfn_range(struct kvm *kvm, struct kvm_mmu_page *root, tdp_mmu_set_spte(kvm, &iter, 0); - if (can_yield) - flush_needed = tdp_mmu_iter_flush_cond_resched(kvm, &iter); - else - flush_needed = true; + flush_needed = !can_yield || + !tdp_mmu_iter_flush_cond_resched(kvm, &iter); } return flush_needed; } @@ -1061,7 +1080,7 @@ static void zap_collapsible_spte_range(struct kvm *kvm, tdp_mmu_set_spte(kvm, &iter, 0); - spte_set = tdp_mmu_iter_flush_cond_resched(kvm, &iter); + spte_set = !tdp_mmu_iter_flush_cond_resched(kvm, &iter); } if (spte_set) -- 2.30.2