From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pj1-f73.google.com (mail-pj1-f73.google.com [209.85.216.73]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id BD3EA160794 for ; Wed, 24 Apr 2024 17:23:32 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.216.73 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1713979414; cv=none; b=lKGurPaZEQXqK7yRmf35IoLmLS10ZiKHxkoiYSmUDk6U93j0jdqNvclFSAOIXjheW4CmzjrXyRCVcVw1yKR/Xt/T2W9cR+d+VjaJcWnIRPfagdsrCdD5zY870nTJHJK89ngg8S22V401xN1K3Xr9HV2X5XCWE8wRSOtGpO457ko= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1713979414; c=relaxed/simple; bh=P0oeJnxbTvn6pPPOyFFSDDnkr9guCkdiyf02byNplKI=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=VEOYC0pkNuRFi/VEE2VTCTXsPgxYesIVg/oxtMnP/Jjktzlp6aq4ZsJNjuJRrx6dnhp2l11Fgx2N2OhdkXbegHK+I34jx+Nb58WQ0vdGD5N+oXm92Igh6lZq+thEyNbupLg5RzXhtO8KFO4cp7lFtEyZW4nw2ACgFYLsf8Stkvk= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--seanjc.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=WpNryyjv; arc=none smtp.client-ip=209.85.216.73 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--seanjc.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="WpNryyjv" Received: by mail-pj1-f73.google.com with SMTP id 98e67ed59e1d1-2a473ba0632so177348a91.0 for ; Wed, 24 Apr 2024 10:23:32 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1713979412; x=1714584212; darn=vger.kernel.org; h=content-transfer-encoding:cc:to:from:subject:message-id:references :mime-version:in-reply-to:date:from:to:cc:subject:date:message-id :reply-to; bh=ZO0d6wOTbBKxXnynFNVxHpThLpJ4G8Z760Bc6T07xNM=; b=WpNryyjvdaorIf+gazL8cCW91faGXyAhVlMeoFxLdbfJeAB7+rB/d2tUL9vhKPqCD8 s1Vo4+UsHJQXC0vfItz/QCUHGmNV2kzkj6hIUP61htN8Tq2Ku1tIbT8e5KEVItgODH9D CtBoZR7qwGGwPVYtasvFfDMco9Y2hAT0ozt+mMZ/5RQSg2CJyFnpA3xpLI3ka8AaLh1f Tf/GH//IMBLVvQ/jy0/UAsMSgb9JJNapy07SVHD3M/At0qQBCusgzWKghbTjT4f1L9SH zII9OkN/BQqgR69WQx1+bZY9KiJe383kPQNPtkxYsuvnDkDPX0GDtdgn/RD7EXvgVnMw vYnA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1713979412; x=1714584212; h=content-transfer-encoding:cc:to:from:subject:message-id:references :mime-version:in-reply-to:date:x-gm-message-state:from:to:cc:subject :date:message-id:reply-to; bh=ZO0d6wOTbBKxXnynFNVxHpThLpJ4G8Z760Bc6T07xNM=; b=HCn1J7AlExA+6Fc04nMavDUtPnC4+Ls4Ud8tS4D73PvhrVxJSLQZ/u25MrjrPS7B+B 3IUQz6+/Z9gbdlydKycQC6jGlxtZYGwbbOtjgSbWtOnTVN49Qo5SLMR8WiEneQugk+6l SrjFrUuYZ3Hb3vMDFUINBXYPoLPmdcyK3JqNS3PgOS34+q6MYNwY0+LL17xRxHX08+eA CMuJV0BBR5YfEMN4n2Ac8wS4oLWiu1yjt7cyhRDkSQu02cWQz971/sizva7PgLB4Atjc jgFLhLsNV2/SM4XXRF2DKhGXEkKpnR/SJZ8hzwybJgCIOEKVitiOgpLf76B8jUGB06Bb ITyA== X-Forwarded-Encrypted: i=1; AJvYcCU1EvmPP2q2oRhT2W2aWEUQRtideFNYV5TlMnjVBTrmrI/E16oceTE2T12u6gc24H8VB84fhm5kMhPG1S/a+f3QauUZ X-Gm-Message-State: AOJu0Yzt73WvKciMBYGKhRPXqrulCy2l/F+UpYe9rlpHsAa+fgJ48++V FqgxnU0t6A4lhUPOLZcBccm6MUAN8iSsIydePIZ9FUJLHr6sG8rVKMhNqCO/d/QvGy6sYiXg1kz HUA== X-Google-Smtp-Source: AGHT+IFLb/Jkoz6d/O3InlajLJrijyFnYCvcvHzvKbQYg9xjqAw0YfXYb31XQor7r51QWkPYwn7+3vaqaj0= X-Received: from zagreus.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:5c37]) (user=seanjc job=sendgmr) by 2002:a17:90a:f187:b0:2a5:57ec:2658 with SMTP id bv7-20020a17090af18700b002a557ec2658mr11546pjb.6.1713979412050; Wed, 24 Apr 2024 10:23:32 -0700 (PDT) Date: Wed, 24 Apr 2024 10:23:30 -0700 In-Reply-To: <26073e608fc450c6c0dcfe1f5cb1590f14c71e96.camel@intel.com> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <6fae9b07de98d7f56b903031be4490490042ff90.camel@intel.com> <26073e608fc450c6c0dcfe1f5cb1590f14c71e96.camel@intel.com> Message-ID: Subject: Re: [PATCH V4 0/4] KVM: x86: Make bus clock frequency for vAPIC timer configurable From: Sean Christopherson To: Rick P Edgecombe Cc: "jmattson@google.com" , Chao Gao , "linux-kernel@vger.kernel.org" , "vkuznets@redhat.com" , Vishal Annapurve , Xiaoyao Li , Reinette Chatre , Erdem Aktas , "pbonzini@redhat.com" , "mlevitsk@redhat.com" , Isaku Yamahata , "kvm@vger.kernel.org" Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable On Wed, Apr 24, 2024, Rick P Edgecombe wrote: > On Wed, 2024-04-24 at 09:13 -0700, Sean Christopherson wrote: > > On Tue, Apr 16, 2024, Rick P Edgecombe wrote: > > > On Thu, 2024-03-21 at 09:37 -0700, Reinette Chatre wrote: > > > >=20 > > > > Summary > > > > ------- > > > > Add KVM_CAP_X86_APIC_BUS_FREQUENCY capability to configure the APIC > > > > bus clock frequency for APIC timer emulation. > > > > Allow KVM_ENABLE_CAPABILITY(KVM_CAP_X86_APIC_BUS_FREQUENCY) to set = the > > > > frequency in nanoseconds. When using this capability, the user spac= e > > > > VMM should configure CPUID leaf 0x15 to advertise the frequency. > > >=20 > > > Looks good to me and... > > > Tested-by: Rick Edgecombe > > >=20 > > > The only thing missing is actually integrating it into TDX qemu patch= es and > > > testing the resulting TD. I think we are making a fair assumption tha= t the > > > problem should be resolved based on the analysis, but we have not act= ually > > > tested that part. Is that right? > >=20 > > Please tell me that Rick is wrong, and that this actually has been test= ed with > > a TDX guest.=C2=A0 I don't care _who_ tested it, or with what VMM it ha= s been > > tested, but _someone_ needs to verify that this actually fixes the TDX = issue. >=20 > It is in the process of getting a TDX test developed (or rather updated). > Agreed, it requires verification that it fixes the original TDX issue. Th= at is > why I raised it. >=20 > Reinette was working on this internally and some iterations were happenin= g, but > we are trying to work on the public list as much as possible per your ear= lier > comments. So that is why she posted it. I have no problem posting "early", but Documentation/process/maintainer-kvm= -x86.rst clearly states under Testing that: If you can't fully test a change, e.g. due to lack of hardware, clearly s= tate what level of testing you were able to do, e.g. in the cover letter. I was assuming that this was actually *fully* tested, because nothing sugge= sts otherwise. And _that_ is a problem, e.g. I was planning on applying this s= eries for 6.10, which would have made for quite the mess if it turns out that thi= s doesn't actually solve the TDX problem. > There was at least some level of TDX integration in the past. I'm not sur= e what > exactly was tested, but we are going to re-verify it with the latest ever= ything. Honest question, is it a big lift to re-test the QEMU+KVM TDX changes, e.g.= to verify this new capability actually does what we hope it does? If testing = is a big lift, what are the pain points? Or perhaps a better question is, is th= ere anything we (both upstream people, and end users like Google) can do to mak= e re-testing less awful?