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 D9985C05027 for ; Mon, 6 Feb 2023 09:11:23 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229904AbjBFJLX (ORCPT ); Mon, 6 Feb 2023 04:11:23 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:51590 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229683AbjBFJLW (ORCPT ); Mon, 6 Feb 2023 04:11:22 -0500 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 3DA431716 for ; Mon, 6 Feb 2023 01:10:32 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1675674631; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=OENdwppPi/XCuQwjwywb1aHOM4xFMtUlUnm5Y/fK5F4=; b=DDRAvi8t9STFTyWgL6rrR+4uBZEk224trkqMov1/LrCaOQ75daU0VpzhLZtEX+mj8Q+0r5 Za0HTPLUOAT8LNlKPb3i9R+eBn8UF/o7p/T6yhsP3966/38D3kL5cnkiwCM7xYBEhv7gk2 QM5FJUHvp3REJ6ok9g41UUy/8l+bp0g= Received: from mail-wm1-f72.google.com (mail-wm1-f72.google.com [209.85.128.72]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_128_GCM_SHA256) id us-mta-658-OjSyRnbUPuGsqDn2iEgZ5Q-1; Mon, 06 Feb 2023 04:10:27 -0500 X-MC-Unique: OjSyRnbUPuGsqDn2iEgZ5Q-1 Received: by mail-wm1-f72.google.com with SMTP id ay19-20020a05600c1e1300b003dc54daba42so5445789wmb.7 for ; Mon, 06 Feb 2023 01:10:27 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:mime-version:user-agent:references :in-reply-to:date:to:from:subject:message-id:x-gm-message-state:from :to:cc:subject:date:message-id:reply-to; bh=OENdwppPi/XCuQwjwywb1aHOM4xFMtUlUnm5Y/fK5F4=; b=fOy7dbz1MFEh6XvMuv4+DfT/v+SW1eQywKXGgbaWZMkpjnDjZP0Nbxe2lQcV68kuPc hgUPtcOP4agreq6NcSTSC8TGYFTX2nHnsV8mG0xZt+9FLzRME4PgANJ4Wi1D1at3/tZC o++rvgVY6Um8nYcXPb0Br4CDNUqbRgKHfrOSJkieN20lbDfokHWPRnLnn2m+6Ap2Tk0f uPYlEaygRbs97NkXUJBhvMTGMa4KnYGSZRJyQ1alZBfxijeoGsPFt+5fkLDRPUA3OSko XvJnSSYCvdGAAdXseidRazZ7zoruZpL1smnnLvravxIvEFpI/wM2fX+a/8I3UdSlgPan roMw== X-Gm-Message-State: AO0yUKXJutCBZhP62t04m38SqF3xGqfX7jGbBm3hX0yRc/5jvdc4r1mE 0uv65TgsjRHhYU/a+sH5Q7m/NWj2SKBzxsxW8X/mKEmE1nEpfoWOCeKE2Uq6Jsy9pJ//5mWSvJP j+TzOVEDP114v X-Received: by 2002:a5d:5958:0:b0:2bf:1ec:a068 with SMTP id e24-20020a5d5958000000b002bf01eca068mr15680615wri.53.1675674625860; Mon, 06 Feb 2023 01:10:25 -0800 (PST) X-Google-Smtp-Source: AK7set/wxExR94jQuURa/jtlumOP5Tyx7OWInrvomdXMYnzrE7aaplkYhk/scfQ+9y2j3fLYLXQS9Q== X-Received: by 2002:a5d:5958:0:b0:2bf:1ec:a068 with SMTP id e24-20020a5d5958000000b002bf01eca068mr15680607wri.53.1675674625654; Mon, 06 Feb 2023 01:10:25 -0800 (PST) Received: from starship ([89.237.103.62]) by smtp.gmail.com with ESMTPSA id p4-20020a5d68c4000000b002c3e4f2ffdbsm3313757wrw.58.2023.02.06.01.10.24 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 06 Feb 2023 01:10:25 -0800 (PST) Message-ID: <8a9deed754bb45cf48fa8562850dadc511bbd4df.camel@redhat.com> Subject: Re: [RFC][PATCH] kvm: i8254: Deactivate APICv when using in-kernel PIT re-injection mode. From: Maxim Levitsky To: lirongqing@baidu.com, kvm@vger.kernel.org Date: Mon, 06 Feb 2023 11:10:23 +0200 In-Reply-To: <1675673814-23372-1-git-send-email-lirongqing@baidu.com> References: <1675673814-23372-1-git-send-email-lirongqing@baidu.com> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.36.5 (3.36.5-2.fc32) MIME-Version: 1.0 Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Mon, 2023-02-06 at 16:56 +0800, lirongqing@baidu.com wrote: > From: Li RongQing > > Intel VMX APICv accelerates EOI write and does not trap. This causes > in-kernel PIT re-injection mode to fail since it relies on irq-ack > notifier mechanism. So, APICv is activated only when in-kernel PIT > is in discard mode e.g. w/ qemu option: > > -global kvm-pit.lost_tick_policy=discard > > Signed-off-by: Li RongQing > --- > arch/x86/kvm/vmx/vmx.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c > index fe5615f..16952a9 100644 > --- a/arch/x86/kvm/vmx/vmx.c > +++ b/arch/x86/kvm/vmx/vmx.c > @@ -8051,7 +8051,8 @@ static bool vmx_check_apicv_inhibit_reasons(enum kvm_apicv_inhibit reason) > BIT(APICV_INHIBIT_REASON_HYPERV) | > BIT(APICV_INHIBIT_REASON_BLOCKIRQ) | > BIT(APICV_INHIBIT_REASON_APIC_ID_MODIFIED) | > - BIT(APICV_INHIBIT_REASON_APIC_BASE_MODIFIED); > + BIT(APICV_INHIBIT_REASON_APIC_BASE_MODIFIED) | > + BIT(APICV_INHIBIT_REASON_PIT_REINJ); > > return supported & BIT(reason); > } AFAIK, APICv has EOI exiting bitmap, for this exact purpose, it allows to trap only some vectors when EOI is performed. KVM uses it so APICv shouldn't need this inhibit but it is possible that something got broken. Take a look at vcpu_load_eoi_exitmap. Best regards, Maxim Levitsky