From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (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 72202130E30 for ; Tue, 6 Feb 2024 13:51:00 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1707227462; cv=none; b=Qb1FM/coPwHYiyeaG8scdhmWKFu9O0s4YE4d6s3A1IBrASB/I+fA0wsVegxtDEVaxb/anlWFltMhlBUk/IXk9z1qiCXJ5+d+uA1OpQq/9js0iCyOXIqmNXTRlT6c/o2zw0ZTDKAzbU8JHHqpUlGA+cefWhopCMV53+6mHGNG0mM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1707227462; c=relaxed/simple; bh=JrTLEj/P/bLggB2CYtICvyRY2gy+ysmhmplkgnJ5umM=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=EUzHDK2vgnaNdbOGSs9S0PsWw8cs2F/WJifhiLdBiFqouiyZ9VwvKUKueqXZGHjrw3H7OjGMaJki1Xoi/ccWQOtznDix6p4QoBAyc3usDbPwXVHR9BGtDOsE165sA0Yf42Ey/B996FLn3THIpXH1eBJIhZ6PZMDVMalGspsKFpU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=BPCbsBYh; arc=none smtp.client-ip=170.10.133.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="BPCbsBYh" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1707227459; h=from:from:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type:in-reply-to:in-reply-to: references:references; bh=hDAT/zjFR+rsqu0eNuA+lIlhinoDTvsuZK32rJjfCLY=; b=BPCbsBYhk6Zl6xBzBytdAnHE0R4wfoMgp7yeRvCb1W0yJcsMNsx1AzSw1piv1N6NbHYeVY zktFgIyBoZUO9CIe/g4Ol+u2le+xYQWJwWO7DHjuG68mRSthPdk3uCkl6hoeKxD+VxX1DU npvYZs4KzedEG0a/tgyfRRf0hmFXEsw= Received: from mimecast-mx02.redhat.com (mx-ext.redhat.com [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-656-gy3Ie8tlPyqbcmXNnrbXxQ-1; Tue, 06 Feb 2024 08:50:56 -0500 X-MC-Unique: gy3Ie8tlPyqbcmXNnrbXxQ-1 Received: from smtp.corp.redhat.com (int-mx10.intmail.prod.int.rdu2.redhat.com [10.11.54.10]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 100BA383DCD6; Tue, 6 Feb 2024 13:50:55 +0000 (UTC) Received: from redhat.com (unknown [10.42.28.53]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 73F74492BF0; Tue, 6 Feb 2024 13:50:52 +0000 (UTC) Date: Tue, 6 Feb 2024 13:50:50 +0000 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: "Dr. Greg" Cc: "Reshetova, Elena" , "Jason A. Donenfeld" , "Hansen, Dave" , "Kirill A. Shutemov" , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , "H. Peter Anvin" , "x86@kernel.org" , Theodore Ts'o , Kuppuswamy Sathyanarayanan , "Nakajima, Jun" , Tom Lendacky , "Kalra, Ashish" , Sean Christopherson , "linux-coco@lists.linux.dev" , "linux-kernel@vger.kernel.org" Subject: Re: [PATCH 2/2] x86/random: Issue a warning if RDRAND or RDSEED fails Message-ID: Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= References: <20240130083007.1876787-2-kirill.shutemov@linux.intel.com> <88a72370-e300-4bbc-8077-acd1cc831fe7@intel.com> <20240206011247.GA29224@wind.enjellic.com> <20240206120445.GA1247@wind.enjellic.com> Precedence: bulk X-Mailing-List: linux-coco@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20240206120445.GA1247@wind.enjellic.com> User-Agent: Mutt/2.2.12 (2023-09-09) X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.10 On Tue, Feb 06, 2024 at 06:04:45AM -0600, Dr. Greg wrote: > On Tue, Feb 06, 2024 at 08:04:57AM +0000, Daniel P. Berrang?? wrote: > > Good morning to everyone. > > > On Mon, Feb 05, 2024 at 07:12:47PM -0600, Dr. Greg wrote: > > > > > > Actually, I now believe there is clear evidence that the problem is > > > indeed Intel specific. In light of our testing, it will be > > > interesting to see what your 'AR' returns with respect to an official > > > response from Intel engineering on this issue. > > > > > > One of the very bright young engineers collaborating on Quixote, who > > > has been following this conversation, took it upon himself to do some > > > very methodical engineering analysis on this issue. I'm the messenger > > > but this is very much his work product. > > > > > > Executive summary is as follows: > > > > > > - No RDRAND depletion failures were observable with either the Intel > > > or AMD hardware that was load tested. > > > > > > - RDSEED depletion is an Intel specific issue, AMD's RDSEED > > > implementation could not be provoked into failure. > > > My colleague ran a multithread parallel stress test program on his > > 16core/2HT AMD Ryzen (Zen4 uarch) and saw a 80% failure rate in > > RDSEED. > > Interesting datapoint, thanks for forwarding it along, so the issue > shows up on at least some AMD platforms as well. I got access to a couple more AMD machines. An EPYC 24core/2HT (Zen-1 uarch) and an EPYC 2socket/16core/2HT (Zen-3 uarch). Both of these show 100% success with RDSEED. So there's clearly some variance across AMD SKUs. So perhaps this is an EPYC vs Ryzen distinction, with the server focused EPYCs able to sustain RDSEED. With regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|