From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from sipsolutions.net (s3.sipsolutions.net [168.119.38.16]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 42B323290CA; Fri, 27 Feb 2026 07:40:33 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=168.119.38.16 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772178034; cv=none; b=EG9OjANfqOQ/X5RsplimQjEXNRRHmUvdlUiO1b8QNmMyCdtxTMgf2QhfAbFQ5Zx218q3QyHAdtj/oCUZP8GDAEn/kbbW0921N1XfmmXF26+IJiPRiIXDUQT9UMtmzeTtMsjdfqwyYac9lWK5e4sC8CMjxjF5ZGcO2yf1grWVuQQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1772178034; c=relaxed/simple; bh=6TeB+wxnECTY0tW0ZKEAuaK+iy41tgHYSXrYQbS68lU=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=p2bBCehUPWRt0WmV+q9r40cU80XRtl3eWzk3mjO9qe8fi0g2KkIZdHQbN2GvF7yQqHMjAFX45nOcr79FVamfOk6ey2kmYszRkzOH2cF/CHEDWgx+CImXPuh5IHWaAWTNdQkV6sBhMrsz3Z/29UwIeuXyp7NDKVDbNZ8dsOiZ+h4= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=sipsolutions.net; spf=pass smtp.mailfrom=sipsolutions.net; dkim=pass (2048-bit key) header.d=sipsolutions.net header.i=@sipsolutions.net header.b=olls9gHq; arc=none smtp.client-ip=168.119.38.16 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=sipsolutions.net Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=sipsolutions.net Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=sipsolutions.net header.i=@sipsolutions.net header.b="olls9gHq" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=sipsolutions.net; s=mail; h=MIME-Version:Content-Transfer-Encoding: Content-Type:References:In-Reply-To:Date:Cc:To:From:Subject:Message-ID:Sender :Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From:Resent-To: Resent-Cc:Resent-Message-ID; bh=V6J0SL9RsbUQWhN8iu+ey8pLnEs4VtLYMczUYtzIoAc=; t=1772178033; x=1773387633; b=olls9gHq4SfXvD7rB7T8SpHOijo2QBHoX6MRNp3DUbo+0Im y+q06hN04UokGh0RMfdWm1bYFHKotymTHTa1+GjC7ZCe9l8+McnJ5AS76iQnFZdD3wIA5nOR/cg+k 8mTWhwYPXLtuFofRu8uph/xh82gjsE6JsS8m7BbSPM0AW+jUdVwDOKgniqinilyZzKsJrQNNw0Y1V CqVnb2bf8xsLxTVcXNAnoiny1SFp+03CShFkZt4M+0+1i8G97TFjPLnTj58ZaSPJtdh/Lx9ZNj8ds mUhPCVLTDnmgVy1evl8fzWNhiXKjnq4cBZTCGmJtBl7XRJudvEpAWYezHg0MCAXw==; Received: by sipsolutions.net with esmtpsa (TLS1.3:ECDHE_X25519__RSA_PSS_RSAE_SHA256__AES_256_GCM:256) (Exim 4.98.2) (envelope-from ) id 1vvsRx-00000003Eus-2oGQ; Fri, 27 Feb 2026 08:39:49 +0100 Message-ID: <4f69d30f952bc374e69f44786f662886c30058e9.camel@sipsolutions.net> Subject: Re: [PATCH 03/25] um/xor: don't override XOR_SELECT_TEMPLATE From: Johannes Berg To: Richard Weinberger , hch Cc: Andrew Morton , Richard Henderson , Matt Turner , Magnus Lindholm , Russell King , Catalin Marinas , will , Huacai Chen , WANG Xuerui , Madhavan Srinivasan , Michael Ellerman , Nicholas Piggin , "Christophe Leroy (CS GROUP)" , Paul Walmsley , Palmer Dabbelt , Albert Ou , Alexandre Ghiti , Heiko Carstens , Vasily Gorbik , Alexander Gordeev , Christian Borntraeger , Sven Schnelle , davem , Andreas Larsson , anton ivanov , Thomas Gleixner , mingo , bp , dave hansen , x86 , hpa , Herbert Xu , dan j williams , Chris Mason , David Sterba , Arnd Bergmann , Song Liu , Yu Kuai , Li Nan , linux-alpha , linux-kernel , linux-arm-kernel , loongarch , linuxppc-dev , linux-riscv , linux-s390 , sparclinux , linux-um , Linux Crypto Mailing List , linux-btrfs , linux-arch , linux-raid , Ard Biesheuvel Date: Fri, 27 Feb 2026 08:39:47 +0100 In-Reply-To: <445921547.2198.1772142326749.JavaMail.zimbra@nod.at> References: <20260226151106.144735-1-hch@lst.de> <20260226151106.144735-4-hch@lst.de> <445921547.2198.1772142326749.JavaMail.zimbra@nod.at> Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable User-Agent: Evolution 3.58.3 (3.58.3-1.fc43) Precedence: bulk X-Mailing-List: linux-arch@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-malware-bazaar: not-scanned On Thu, 2026-02-26 at 22:45 +0100, Richard Weinberger wrote: > ----- Urspr=C3=BCngliche Mail ----- > > Von: "hch" > > XOR_SELECT_TEMPLATE is only ever called with a NULL argument, so all th= e > > ifdef'ery doesn't do anything. With our without this, the time travel > > mode should work fine on CPUs that support AVX2, as the AVX2 > > implementation is forced in this case, and won't work otherwise. >=20 > IIRC Johannes added XOR_SELECT_TEMPLATE() here to skip > the template selection logic because it didn't work with time travel mode= . >=20 > Johannes, can you please test whether this change does not break > time travel mode? It does work, even if it reports nonsense (as you'd expect): xor: measuring software checksum speed prefetch64-sse : 12816000 MB/sec sse : 12816000 MB/sec xor: using function: prefetch64-sse (12816000 MB/sec) I think it works now because the loop is using ktime and is bounded by REPS, since commit c055e3eae0f1 ("crypto: xor - use ktime for template benchmarking"). The RAID speed select still hangs, but we've gotten that removed via Kconfig, so that's already handled. Perhaps raid6_choose_gen() should use a similar algorithm? But for UML it doesn't really matter since CONFIG_RAID6_PQ_BENCHMARK exists. As far as AVX2 is concerned, yeah, I guess that was a bug, but evidently nobody (who configured time-travel) ever cared - what _did_ matter though in practice is that the boot not get stuck entirely... Two completely separate issues. johannes