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=-9.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,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 5E2ACC2BB1D for ; Tue, 17 Mar 2020 04:54:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 2D69D20663 for ; Tue, 17 Mar 2020 04:54:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726707AbgCQEyb (ORCPT ); Tue, 17 Mar 2020 00:54:31 -0400 Received: from mga04.intel.com ([192.55.52.120]:34117 "EHLO mga04.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726949AbgCQExU (ORCPT ); Tue, 17 Mar 2020 00:53:20 -0400 IronPort-SDR: nYR2eiJM8rB468PzpJguwE52od/AyMWM3MfaM1FdBXc+UBCwUhrcHZj1smBLyRvZoknFatH7pF DQz9JJcanDMw== X-Amp-Result: SKIPPED(no attachment in message) X-Amp-File-Uploaded: False Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by fmsmga104.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 16 Mar 2020 21:53:19 -0700 IronPort-SDR: DK8Lwi9fXYsuCsnch1Nu2tPbvDX/rgWQS7eRWPcMyhxFeiKsMe+Om31vX31uIoiw6wG/5qq1Jz RfQIL5nmQgiA== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.70,563,1574150400"; d="scan'208";a="355252803" Received: from sjchrist-coffee.jf.intel.com ([10.54.74.202]) by fmsmga001.fm.intel.com with ESMTP; 16 Mar 2020 21:53:19 -0700 From: Sean Christopherson To: Paolo Bonzini Cc: Sean Christopherson , Vitaly Kuznetsov , Wanpeng Li , Jim Mattson , Joerg Roedel , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Ben Gardon , Junaid Shahid , Liran Alon , Boris Ostrovsky , John Haxby , Miaohe Lin , Tom Lendacky Subject: [PATCH v2 21/32] KVM: SVM: Document the ASID logic in svm_flush_tlb() Date: Mon, 16 Mar 2020 21:52:27 -0700 Message-Id: <20200317045238.30434-22-sean.j.christopherson@intel.com> X-Mailer: git-send-email 2.24.1 In-Reply-To: <20200317045238.30434-1-sean.j.christopherson@intel.com> References: <20200317045238.30434-1-sean.j.christopherson@intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Add a comment in svm_flush_tlb() to document why it flushes only the current ASID, even when it is invoked when flushing remote TLBs. Cc: Tom Lendacky Signed-off-by: Sean Christopherson --- arch/x86/kvm/svm.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/arch/x86/kvm/svm.c b/arch/x86/kvm/svm.c index dfa3b53f8437..8c3700b44eb4 100644 --- a/arch/x86/kvm/svm.c +++ b/arch/x86/kvm/svm.c @@ -5630,6 +5630,13 @@ static void svm_flush_tlb(struct kvm_vcpu *vcpu) { struct vcpu_svm *svm = to_svm(vcpu); + /* + * Flush only the current ASID even if the TLB flush was invoked via + * kvm_flush_remote_tlbs(). Although flushing remote TLBs requires all + * ASIDs to be flushed, KVM uses a single ASID for L1 and L2, and + * unconditionally does a TLB flush on both nested VM-Enter and nested + * VM-Exit (via kvm_mmu_reset_context()). + */ if (static_cpu_has(X86_FEATURE_FLUSHBYASID)) svm->vmcb->control.tlb_ctl = TLB_CONTROL_FLUSH_ASID; else -- 2.24.1