From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pf1-f199.google.com (mail-pf1-f199.google.com [209.85.210.199]) (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 A5850429CE0 for ; Wed, 5 Aug 2026 16:52:15 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.210.199 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785948737; cv=none; b=s5nETH3iKIoXip2HPGKpo+vc/89JAVewn9ZikfQa+iUOkK8PC6PU7G3m0V4Aja7IOFYGD1hrXAlgC5t25q/zFm5nlstpTbxKm6xJy0CPwXdf/ekcofKyKbR3K9lr7EB6TLR/3E4zJB+Vh7FSxbqvxCcO/GO4KhcbfYr8NXKb+M4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785948737; c=relaxed/simple; bh=pmjp1fyQk8GtgiG5KTih78HTvnIKMpL2AU2Lt+zdXv4=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=Mc13Mer58Huq/PBc7+arm6iHnE4TwEDDSx7Gnq72UxoOQmFtr4LPe6MqPd0kyZ40Wckg/DmPQioMOE1o3Jasq8HilMMfy8/bk3nCk+QWjtpieFMKYwyUnqTprzAiXn7qYlDyWuInDskoh8/Dl5j11KmZFYga7kaNMfENiTvUgjo= 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=OpD14nZG; arc=none smtp.client-ip=209.85.210.199 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="OpD14nZG" Received: by mail-pf1-f199.google.com with SMTP id d2e1a72fcca58-84870e7f498so1323393b3a.3 for ; Wed, 05 Aug 2026 09:52:15 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1785948735; x=1786553535; darn=vger.kernel.org; h=content-type:cc:to:from:subject:message-id:references:mime-version :in-reply-to:date:from:to:cc:subject:date:message-id:reply-to :content-type; bh=o2GGvdkYnkkMqly/LuwEFC1oKwFLrXMppSjIDsjal6o=; b=OpD14nZG+PzulF2fGrrjs3NmN1PQtZXq3A1eXIx9OBpDONrzKXGN0TeeziYRaoFD/9 7xz87SkJ161DUWWu7fptDsHxmIQx0Z5vROzU33+HtRZn+zcMAYarPiVR6R53MMNVEBtl m21WMtfW4PvZ5xvZ70L4zTQSdDQykxtaJbTtoAgI7JZ+Ak5jHs7+Bn7m4+qlIm8h9QBl bzMgJDpFUJFZRwrAvUxgezNf6sStrPRfvF1Df2snSvzNh0UFgjR/2EWP26F3PnXfS6us DSSwqJAkEUSfbesp7A4K/hT6i8PH/o74GOYPFH5E5iDrkdwpk2nXlfJiYHq+GXMF26dV +Mhw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1785948735; x=1786553535; h=content-type: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:content-type; bh=o2GGvdkYnkkMqly/LuwEFC1oKwFLrXMppSjIDsjal6o=; b=Y1S7dLMSVQuahLyOhBqTHSvuUcnvY54ncsjukMJArw8xXJtXIC0ZnzM1MscaCujIMl aVT86f0qAfGvnlpGgbICwHJVAgBNd++yhEFqr94AlGcf3sbgjBCL/e3bYfcMR+4jsW3q UfmdwsfmE2YdSlRfL7G22D9VU9vM+u+BYJWURbiYY8Lcut4UiOvluUyd/b3ZjMFgqKh5 QSGZ4NrjvN8HgmWe1DJRdtX0TP96mmMDP1evREnM7bT3DJ7lSSOJlCIQkmK9Y0/Ttksp 5kMCHx/a37lMajymgIG3a6unCAr5QCh6QGO56xytGexPSsMNuBAh9SZx8fLrShBUzWJV VAjQ== X-Forwarded-Encrypted: i=1; AHgh+RqGg0LniqJVWiJbiY/GWj1/pNTAohybT6VKRnh9IxfsNhfrKxPCJPWuacgKYut3GYQ0FkiJ8akTCdV36Pc=@vger.kernel.org X-Gm-Message-State: AOJu0Yy1daLUZd/HGVEhKeIJTHIuNhmVaRz2K/QrJz2cVYernEeHlPE8 arPcYRXZrRAjm380PEeXFv/cuSPXeBFvZx0kjmgC1b2CTYBgd7BGjUlJ8wQuL24x6LS4I9OtL3A z66YSFA== X-Received: from pgnd13.prod.google.com ([2002:a63:734d:0:b0:cbb:5dd3:9904]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6a00:2c9:b0:848:498b:e0d4 with SMTP id d2e1a72fcca58-84f2e12ce9fmr9433773b3a.38.1785948734635; Wed, 05 Aug 2026 09:52:14 -0700 (PDT) Date: Wed, 5 Aug 2026 09:46:13 -0700 In-Reply-To: <20260731171926.2629627-1-seanjc@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260731171926.2629627-1-seanjc@google.com> X-Mailer: git-send-email 2.55.0.571.g244d577d93-goog Message-ID: <178594834697.3639604.11123768104931379395.b4-ty@google.com> Subject: Re: [PATCH v7 0/2] KVM: VMX: Workaround VMX preemption timer erratum From: Sean Christopherson To: Sean Christopherson , Paolo Bonzini Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Binbin Wu , Chao Gao , Jim Mattson Content-Type: text/plain; charset="utf-8" On Fri, 31 Jul 2026 10:19:24 -0700, Sean Christopherson wrote: > Due to a widespread Intel erratum (e.g. EMR158), programming the VMX > preemption timer with certain large values may cause the timer to expire > earlier than expected. The recommended workaround is to cap the timer value > to strictly less than 2^25 * CPUID.15H:EBX[31:0] / CPUID.15H:EAX[31:0]. > > v7: > - Ensure the timer doesn't exceed the architectural max. [Sashiko] > > [...] Applied to kvm-x86 vmx, thanks! [1/2] KVM: VMX: Bury all of the VMX preemption timer code under CONFIG_X86_64=y https://github.com/kvm-x86/linux/commit/d0dea3ed847c [2/2] KVM: VMX: Cap VMX preemption timer to work around Intel erratum https://github.com/kvm-x86/linux/commit/0aaedada606a -- https://github.com/kvm-x86/linux/tree/next