From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pl1-f199.google.com (mail-pl1-f199.google.com [209.85.214.199]) (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 E3EDF56C639 for ; Thu, 10 Sep 2026 17:59:17 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.199 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789063159; cv=none; b=ZKcEb8YK8abdnxaRGyWwYV7Cg9qfjw2XHq07FsRgICuwDjsoDsua9/RVA4KWlt973utGubY32SRSpwSicwFBHoSc53f5qqvIlz18ZDU7PX1gtg3699PIlR4nqzaNwIdCVevei+p15YXA0Jf7ASytbTKAjy3ebmKX7LMzgeZEYeE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789063159; c=relaxed/simple; bh=iihdVpeTD7xqvFs81N5pzrr3yHNO8lXqn++m5NS1tpY=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Content-Type; b=GS9aPbE9EbFZy6leO0dyYlqdcwPCiErS9YGm8nBbgz9oAAnXRQzuIoLWW1x3Asi2WIVsgN6MLXP5ElcniXKVdoDEJKIKov9kP74vjAhu+hCsExFTUyi1exhooWeyJwtY+qu3S4X2Cz/Rd2iGGzyP9OO67x1JPgjfKcJCT0WuDLQ= 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=WiVU1+Kh; arc=none smtp.client-ip=209.85.214.199 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="WiVU1+Kh" Received: by mail-pl1-f199.google.com with SMTP id d9443c01a7336-2ccb6823efcso76293755ad.0 for ; Thu, 10 Sep 2026 10:59:17 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1789063157; x=1789667957; darn=lists.linux.dev; h=content-type:to:from:subject:message-id:references:mime-version :in-reply-to:date:from:to:cc:subject:date:message-id:reply-to :content-type; bh=VdUk7xT6Q2S0XYOIdYUuypvFM5moeaGi7+AJeTxN8N4=; b=WiVU1+KhiMKvY+vrMibTfWVArgQGJreiueW7+hMxHgiWvCKvxACzbDkAS6txwgC2FS rOp/ElgHC0Icd8QRqjGWH8lcR9Ko22chnjZsGk2rFA8usIYgMJrzcSoyrlv4xakDuV7O ++DlksJmwtDvxmQZf1Ty1i/SjbK05d1nxuL7+1pjzgMSi2MZc5mQqYhzeanIYmCoF93Q cTbBcTs67IGZS4ft1tfM10q/Va47blT+ODYtvZr0IFWrVEfJ6sULsg2fEQ2oDCDIzBF0 RGFPab2hgkAxfQJ/EjDZBsexF03n70ta2v9eRdN0xVWs+xnLLpx9uymk+3GWM5HXPAPd +KMA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1789063157; x=1789667957; h=content-type: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:content-type; bh=VdUk7xT6Q2S0XYOIdYUuypvFM5moeaGi7+AJeTxN8N4=; b=SE5kWNGYfbgFHsaohqqcw9YQKGMZlQuxEHkfdd4Z8F3MXSdw0Fzw+WJY2ilvFsa0yU mi5Oo6IpccX/0rOKrQt3xsHkDUmofBvsSt+Sy9RR/vxCWAkBkdEk5KWK7zsCDG1kh84J LQ8HoPi6utPityO51oJiWYKqJuuOUCFvrjN0O4Wg02f/bsWdMhw39oaR/LrX/zrSBWQK 5GML33Yxl3Ii0oQE3wGN8aVaiwpe+nAKxgAdpnHSlZl7RxOsw3qa9wPiGZcdRB720/ix rs8x/QMKPx9kPHo62RVKRvjm/rFVhXRQWGVATsnU5ePyzm1x39ONaeZ+eXObi5dOkdYn gdXw== X-Forwarded-Encrypted: i=1; AKwUvByRvMLtdzv7aTcssNhNyS9TE0RuxT4mq0T4Cb+WMCRH9+/jcEw0eFLav3RhR4NcbgdTE2kSpmEgVSUX@lists.linux.dev X-Gm-Message-State: AFuF++kyhFiOQo3hgQj+1Bi18Zp3YkCIX/7DDLljF2mD1saTn9cWJ2Tx kFpimK5HeSGi7n28ur348ztwecS06IqAaCsWh9qoa2cmYRz9+SeMGagFlAibztpXbCDX2ZO5gZK vyuLq4Q== X-Received: from pleg13.prod.google.com ([2002:a17:902:e38d:b0:2c9:b703:3bfb]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a17:902:ce8b:b0:2d7:2edd:d140 with SMTP id d9443c01a7336-2dd2a1c3e42mr9017035ad.3.1789063156725; Thu, 10 Sep 2026 10:59:16 -0700 (PDT) Date: Thu, 10 Sep 2026 10:59:16 -0700 In-Reply-To: <20260806233609.212337-1-seanjc@google.com> Precedence: bulk X-Mailing-List: linux-coco@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260806233609.212337-1-seanjc@google.com> Message-ID: Subject: Re: [PATCH v6 00/51] x86: Try to wrangle PV clocks vs. TSC From: Sean Christopherson To: Kiryl Shutsemau , Rick Edgecombe , Paolo Bonzini , "K. Y. Srinivasan" , Haiyang Zhang , Wei Liu , Dexuan Cui , Long Li , Ajay Kaher , Alexey Makhalov , Jan Kiszka , Dave Hansen , Andy Lutomirski , Peter Zijlstra , Juergen Gross , Daniel Lezcano , Thomas Gleixner , John Stultz , Vitaly Kuznetsov , Broadcom internal kernel review list , Boris Ostrovsky , Stephen Boyd , Miroslav Lichvar , x86@kernel.org, linux-coco@lists.linux.dev, kvm@vger.kernel.org, linux-hyperv@vger.kernel.org, virtualization@lists.linux.dev, linux-kernel@vger.kernel.org, xen-devel@lists.xenproject.org, Michael Kelley , Tom Lendacky , Nikunj A Dadhania , David Woodhouse , David Woodhouse , Thomas Gleixner Content-Type: text/plain; charset="us-ascii" On Thu, Aug 06, 2026, Sean Christopherson wrote: > The primary goal of this series to fix flaws with SNP and TDX guests where a > PV clock provided by the untrusted hypervisor is used instead of the secure > TSC that is controlled by trusted firmware. > > The secondary goal is modernize running under KVM. Currently, KVM guests will > use TSC for clocksource, but not sched_clock. And Linux-as-a-KVM-guest doesn't > support paravirt enumeration of the TSC/APIC frequencies, even though QEMU > provides that information by default. > > The tertiary goal is to clean up the PV clock code to deduplicate logic across > hypervisors, and to hopefully make it all easier to maintain going forward. > > The quaternary goal is to clean up the TSC calibration code, which was made > stupidly hard to follow by hypervisor code mixing in with the native > calibration routines, instead of being implemented as a pure alternative. > > Note, the VMware and Xen changes still probably should get acks from those > maintainers, as my understanding of what they're trying to do may be flawed. This (thankfully) still applies cleanly. What can I do to help move this forward?