From patchwork Mon May 31 13:12:05 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 450936 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=-19.1 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, URIBL_BLOCKED, 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 8E5D0C47080 for ; Mon, 31 May 2021 14:38:36 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 747F76103E for ; Mon, 31 May 2021 14:38:36 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232548AbhEaOkL (ORCPT ); Mon, 31 May 2021 10:40:11 -0400 Received: from mail.kernel.org ([198.145.29.99]:36376 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233715AbhEaOha (ORCPT ); Mon, 31 May 2021 10:37:30 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 306A961C50; Mon, 31 May 2021 13:51:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1622469099; bh=F28ENUktMeBlIeqVNXhvaXUllT9A0puQItpPMb53VJ8=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=nSK1g8Jg01Fu72uVgO50T/jMf42Nx6GBam9Y2prITkwwipTcy5MhQybzxTzgAdqB+ YbKcJp/iNxq3TaifgkDvVBNoXfXjqw2YlVIuorlMeJro0RupECDnTilwQLw/y2NyoX elB1J5+6SaW6VRUt+CSqFKbjSNXfJ2MFblDxD/EI= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Sean Christopherson , Wanpeng Li , Paolo Bonzini Subject: [PATCH 5.12 070/296] KVM: X86: Fix vCPU preempted state from guests point of view Date: Mon, 31 May 2021 15:12:05 +0200 Message-Id: <20210531130706.200784834@linuxfoundation.org> X-Mailer: git-send-email 2.31.1 In-Reply-To: <20210531130703.762129381@linuxfoundation.org> References: <20210531130703.762129381@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Wanpeng Li commit 1eff0ada88b48e4ac1e3fe26483b3684fedecd27 upstream. Commit 66570e966dd9 (kvm: x86: only provide PV features if enabled in guest's CPUID) avoids to access pv tlb shootdown host side logic when this pv feature is not exposed to guest, however, kvm_steal_time.preempted not only leveraged by pv tlb shootdown logic but also mitigate the lock holder preemption issue. >From guest's point of view, vCPU is always preempted since we lose the reset of kvm_steal_time.preempted before vmentry if pv tlb shootdown feature is not exposed. This patch fixes it by clearing kvm_steal_time.preempted before vmentry. Fixes: 66570e966dd9 (kvm: x86: only provide PV features if enabled in guest's CPUID) Reviewed-by: Sean Christopherson Cc: stable@vger.kernel.org Signed-off-by: Wanpeng Li Message-Id: <1621339235-11131-3-git-send-email-wanpengli@tencent.com> Signed-off-by: Paolo Bonzini Signed-off-by: Greg Kroah-Hartman --- arch/x86/kvm/x86.c | 2 ++ 1 file changed, 2 insertions(+) --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -3015,6 +3015,8 @@ static void record_steal_time(struct kvm st->preempted & KVM_VCPU_FLUSH_TLB); if (xchg(&st->preempted, 0) & KVM_VCPU_FLUSH_TLB) kvm_vcpu_flush_tlb_guest(vcpu); + } else { + st->preempted = 0; } vcpu->arch.st.preempted = 0;