From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-wr1-f53.google.com (mail-wr1-f53.google.com [209.85.221.53]) (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 4ED7D414DCB for ; Wed, 5 Aug 2026 09:55:19 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.221.53 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785923721; cv=none; b=g5IN5WnjWIjvRik/6zeYh2SwK18d/V9W6yLMl+MkoglkzkxZUdrPRQTUM25rHob/TzZEfI4Ks8gzzZEHfzbeC5vitrsqMmDITzZXQUjiaJfm7bR5n3K5r9spIEBDp8GaBEnJ2g5FJSLZkIGdJNWO6BGZlF7NP2Oy9gshjoYmDI4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1785923721; c=relaxed/simple; bh=zwj2yCqvbzKMDNC/5cA1nbGLq7xJdkhDRrkr1FAamEk=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=SJtFix/s0aDLn3s2fy08upqX+Qt+fVrrFwkzGd0zIpU+twxaK5bSGCiqFj/fgSRwoR3FVUHlmPTIs6oz25szUB6O58nuMmFJh9vG7xLKw1JKy8ic5uXc6tGaRdzxx5aKYEBFi6Ew1tyLUmRTArvAxzjkRXYa5vHxJ9g7NFwSwYg= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=suse.com; spf=pass smtp.mailfrom=suse.com; dkim=pass (2048-bit key) header.d=suse.com header.i=@suse.com header.b=VxV0MOj5; arc=none smtp.client-ip=209.85.221.53 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=suse.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=suse.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=suse.com header.i=@suse.com header.b="VxV0MOj5" Received: by mail-wr1-f53.google.com with SMTP id ffacd0b85a97d-47fe89fb333so453986f8f.3 for ; Wed, 05 Aug 2026 02:55:19 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=google; t=1785923717; x=1786528517; darn=vger.kernel.org; h=content-transfer-encoding:content-type:in-reply-to:autocrypt:from :content-language:references:cc:to:subject:user-agent:mime-version :date:message-id:from:to:cc:subject:date:message-id:reply-to :content-type; bh=7k23JfBGtG8w8FZKJzglvJRq6dDsmFwVnAzVqjhZ8JM=; b=VxV0MOj5m/i44PXrsnkZErMl7toTL915RC8/evM9C8rjje/iRU49Qsi2zgckXJB6a4 hnfPlofRkstO7tptCnk1OlS/5s/U2jdbvbg7HG3Xo/m3lr5ywGht3Zed8F3vdlL+Gykn Bbwvm4o45r4Dwzf+la1zuJCif/XkEvx9ag1nbGs8AlzIs5McxdWFAbvo5/eLPOUZ/J2J ehd4lghUXXr1kJQDfvDgCCsX6JegnyV68xFMnNQTNN9dDh6Bi68dD+invONyTEn1Jwcd V2Gy/Qb/dVrC1Q4oi+TeYbR39smnUQLJnp4opANFosN80dp1FveY9bILu5XHoMs65ftd rKiQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1785923717; x=1786528517; h=content-transfer-encoding:content-type:in-reply-to:autocrypt:from :content-language:references:cc:to:subject:user-agent:mime-version :date:message-id:x-gm-gg:x-gm-message-state:from:to:cc:subject:date :message-id:reply-to:content-type; bh=7k23JfBGtG8w8FZKJzglvJRq6dDsmFwVnAzVqjhZ8JM=; b=J1nBhtHq1rVlw9cZR/x7sHf7EhmPiY+8bA0iXgrX+Y0zPSrrI58g0xUROoRF6wZGa2 JmifRB2YJngGG4oMIpjOgwGUTnkRY8NPESzF65XFMXjLiYnJ1s/Prryr4LW9T7PJ0rbH /PtvCGMHvoRhC2tes7n9zOdCvRww6D6taLKSbEWE02TGpsZG84WNFFvCNGNRXp0R8LnV fMFlzkrlcIRgE+MwvF385Z/yOnuDa78myeDmLBQzB4BbhOHgVHErk/d5gQq3U7pY3bro 0gIbxn47Jqo6VZETKIIKoYweRC1NQdW8KBp23tOy7MGAs2AcO3J0NUiUvTFIb0gpPIoo CqJA== X-Forwarded-Encrypted: i=1; AHgh+Rq8jAcpjUWRIFA3AdY6VE7gB4gP5YEMVnQgP4jSPPCtrLNA8R1KHeDQVxhtdyR9hCwwAGpy9QCbN1NX2yM=@vger.kernel.org X-Gm-Message-State: AOJu0Yw4Oo1ZIQZPEoyG61G0Jph6oJohee0yLeW/Ckd+vn1T1tNw1hTI sa1eKGMNgGDrB/aCLVc3WXQVEselBNcjHitgmGOvS9nMpP3RpAIEDODBvdRzfw9Neg== X-Gm-Gg: AR+sD123HL+sUJ54IKlvOGIpJ2wA2xdJsvknQzbY1qiJXdBreCjrVgiXPhxytYQAKzN u/I9TfN1qAIjFbx6XKf8Jm1wuZ2nHCw0a0VIYIKjE/5ytyBXJsQIfTKB9wzAkmQjf1fvxsbYntw c7jtKG3845nB+/T9ZVpMRwhFkKoG9yAX+RnNG6sn53IiqJJMYBF20xkiVfmk23UhWGIKXdxJnlt z1WIfXCtD9/ufDKQl8+xnmi9IS5t1tZN+xnHidaVxE/01LTBTEWVSkNgYA13GKHw34sibEvs4bD YfKXym9yUaE48tv6cVK3KKl6oH9nKu7wbzHhKHZf04SyqjiyFr9aHBDYQrY/NJVULqCIQdW6CHV oCZ19P4/zc9dsdlTDBi3IQrxot/u0ko/WBc6ifFDdNc8Nd/fhuaA6Td5ITcBBmmhyexUDlHWpXo R6CCmAkJpYU2qqU1Md3xEFUYM7aORXYEBEe7s+vnYZS/HDAetWBxHf/Y/yg9/Vn9hkFtkhb+7ar 6Gdj19SOYBdK3jNOsDs4DPd7x65qZxJjZY90l9ooaJoDlbqkmYD X-Received: by 2002:a05:600c:1383:b0:493:bfad:9d99 with SMTP id 5b1f17b1804b1-4994e7caf7cmr55828995e9.13.1785923716237; Wed, 05 Aug 2026 02:55:16 -0700 (PDT) Received: from [10.156.60.236] (ip-037-024-206-209.um08.pools.vodafone-ip.de. [37.24.206.209]) by smtp.gmail.com with ESMTPSA id ffacd0b85a97d-47fec24a24fsm8080783f8f.36.2026.08.05.02.55.15 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 05 Aug 2026 02:55:15 -0700 (PDT) Message-ID: <38863d15-c6d3-426d-b09c-3dbed9f2f0b0@suse.com> Date: Wed, 5 Aug 2026 11:55:14 +0200 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 4/4] x86/xen: Drop CONFIG_XEN_PVHVM_SMP To: =?UTF-8?B?SsO8cmdlbiBHcm/Dnw==?= Cc: Boris Ostrovsky , xen-devel@lists.xenproject.org, Thomas Gleixner , IngoMolnar , Borislav Petkov , Dave Hansen , "H. Peter Anvin" , lkml , X86 ML References: <20260805082137.1214967-1-jgross@suse.com> <20260805082137.1214967-5-jgross@suse.com> <5febc2c0-4355-48d9-9342-52d590041500@suse.com> Content-Language: en-US From: Jan Beulich Autocrypt: addr=jbeulich@suse.com; keydata= xsDiBFk3nEQRBADAEaSw6zC/EJkiwGPXbWtPxl2xCdSoeepS07jW8UgcHNurfHvUzogEq5xk hu507c3BarVjyWCJOylMNR98Yd8VqD9UfmX0Hb8/BrA+Hl6/DB/eqGptrf4BSRwcZQM32aZK 7Pj2XbGWIUrZrd70x1eAP9QE3P79Y2oLrsCgbZJfEwCgvz9JjGmQqQkRiTVzlZVCJYcyGGsD /0tbFCzD2h20ahe8rC1gbb3K3qk+LpBtvjBu1RY9drYk0NymiGbJWZgab6t1jM7sk2vuf0Py O9Hf9XBmK0uE9IgMaiCpc32XV9oASz6UJebwkX+zF2jG5I1BfnO9g7KlotcA/v5ClMjgo6Gl MDY4HxoSRu3i1cqqSDtVlt+AOVBJBACrZcnHAUSuCXBPy0jOlBhxPqRWv6ND4c9PH1xjQ3NP nxJuMBS8rnNg22uyfAgmBKNLpLgAGVRMZGaGoJObGf72s6TeIqKJo/LtggAS9qAUiuKVnygo 3wjfkS9A3DRO+SpU7JqWdsveeIQyeyEJ/8PTowmSQLakF+3fote9ybzd880fSmFuIEJldWxp Y2ggPGpiZXVsaWNoQHN1c2UuY29tPsJgBBMRAgAgBQJZN5xEAhsDBgsJCAcDAgQVAggDBBYC AwECHgECF4AACgkQoDSui/t3IH4J+wCfQ5jHdEjCRHj23O/5ttg9r9OIruwAn3103WUITZee e7Sbg12UgcQ5lv7SzsFNBFk3nEQQCACCuTjCjFOUdi5Nm244F+78kLghRcin/awv+IrTcIWF hUpSs1Y91iQQ7KItirz5uwCPlwejSJDQJLIS+QtJHaXDXeV6NI0Uef1hP20+y8qydDiVkv6l IreXjTb7DvksRgJNvCkWtYnlS3mYvQ9NzS9PhyALWbXnH6sIJd2O9lKS1Mrfq+y0IXCP10eS FFGg+Av3IQeFatkJAyju0PPthyTqxSI4lZYuJVPknzgaeuJv/2NccrPvmeDg6Coe7ZIeQ8Yj t0ARxu2xytAkkLCel1Lz1WLmwLstV30g80nkgZf/wr+/BXJW/oIvRlonUkxv+IbBM3dX2OV8 AmRv1ySWPTP7AAMFB/9PQK/VtlNUJvg8GXj9ootzrteGfVZVVT4XBJkfwBcpC/XcPzldjv+3 HYudvpdNK3lLujXeA5fLOH+Z/G9WBc5pFVSMocI71I8bT8lIAzreg0WvkWg5V2WZsUMlnDL9 mpwIGFhlbM3gfDMs7MPMu8YQRFVdUvtSpaAs8OFfGQ0ia3LGZcjA6Ik2+xcqscEJzNH+qh8V m5jjp28yZgaqTaRbg3M/+MTbMpicpZuqF4rnB0AQD12/3BNWDR6bmh+EkYSMcEIpQmBM51qM EKYTQGybRCjpnKHGOxG0rfFY1085mBDZCH5Kx0cl0HVJuQKC+dV2ZY5AqjcKwAxpE75MLFkr wkkEGBECAAkFAlk3nEQCGwwACgkQoDSui/t3IH7nnwCfcJWUDUFKdCsBH/E5d+0ZnMQi+G0A nAuWpQkjM1ASeQwSHEeAWPgskBQL In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit On 05.08.2026 11:44, Jürgen Groß wrote: > On 05.08.26 11:04, Jan Beulich wrote: >> On 05.08.2026 10:55, Juergen Gross wrote: >>> On 05.08.26 10:44, Jan Beulich wrote: >>>> On 05.08.2026 10:21, Juergen Gross wrote: >>>>> --- a/arch/x86/xen/Makefile >>>>> +++ b/arch/x86/xen/Makefile >>>>> @@ -37,8 +37,8 @@ obj-$(CONFIG_XEN_PVH) += enlighten_pvh.o >>>>> obj-$(CONFIG_EVENT_TRACING) += trace.o >>>>> >>>>> obj-$(CONFIG_SMP) += smp.o >>>>> +obj-$(CONFIG_SMP) += smp_hvm.o >>>>> obj-$(CONFIG_XEN_PV_SMP) += smp_pv.o >>>>> -obj-$(CONFIG_XEN_PVHVM_SMP) += smp_hvm.o >>>> >>>> Similar issue here - in a PV-only config smp_hvm.o doesn't want / shouldn't >>>> need building. >>> >>> Note that I didn't change any functionality. >>> >>> I agree that it seems a little bit strange, but in the end I believe >>> the current status is okay-ish. PV-only hasn't been something in upstream >>> Linux since Xen support was added, as PV was always meant to be an >>> alternative to bare metal support via paravirt patching. It might have >>> been possible to build a kernel not really functional on bare metal, but >>> this was more like the ability to build a x86 kernel not working on any >>> existing machine. >>> >>> IMO the Xen kernel config options should allow for adding Xen-specific >>> features, but minimum Xen support should always have basic HVM support, >>> which includes the Xen specific performance enhancements. >> >> I fear I don't understand this. If I want a kernel just to run as PV Dom0, >> why would it need to carry anything HVM-ish? That is (or should be) >> entirely unrelated to being able to also run this same kernel on baremetal >> then. > > The fact is that Xen PV-mode was always a feature not really liked especially > by x86 maintainers (this is the polite way to phrase it). > > Changing something outside of xen-specific parts of the kernel in favor of PV is > nearly always a fight and I'm pretty sure I only get changes in by playing nice > (not changing more than absolutely necessary and cleaning up constantly). I will > certainly not try to push for a "PV-only" kernel while the hope of the x86 > maintainers is more "PV will go away some time in future". > > The capability to configure the kernel without HVM stuff but with Xen support > is the way it has been since many years now. Nobody has missed a PV-only kernel, > so I conclude there is no need for that. Just FTR - I did, even if maybe I never said so explicitly. But as it's just me ... Jan > The closest we will get here is a PVH > only kernel, and this is possible by not enabling CONFIG_XEN_PVHVM_GUEST. > > > Juergen