From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 5ADF2E77198 for ; Mon, 6 Jan 2025 18:43:48 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1tUs4f-0007e0-Pj; Mon, 06 Jan 2025 13:43:38 -0500 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1tUs4d-0007dc-Lr for qemu-devel@nongnu.org; Mon, 06 Jan 2025 13:43:35 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1tUs4b-0003lE-2n for qemu-devel@nongnu.org; Mon, 06 Jan 2025 13:43:35 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1736189010; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=h8CUEWGfMWhswPp+8A7KBzJX5t8jJtjAdO9JGUMUfSQ=; b=DVyPZJbODRyoR/71/TXU9EO0Tgjf7TPa1QDH4mNm7Tp0ENw0XnJVRcqfXy5Klg3HA1z9Zn t+cxHzlInA18bwh/prc3be1exC20FKS/VKtmtBI0ikf/fOWJ2y/83z5rvJZIhsoWk2NI5I 9lzmj5MNi0nOEbK9zqWcpdqSoLagvwM= Received: from mx-prod-mc-03.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-690-00Ajf755Nda8h86CdxubMw-1; Mon, 06 Jan 2025 13:43:23 -0500 X-MC-Unique: 00Ajf755Nda8h86CdxubMw-1 X-Mimecast-MFC-AGG-ID: 00Ajf755Nda8h86CdxubMw Received: from mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.12]) (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 mx-prod-mc-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id BB53719772C9; Mon, 6 Jan 2025 18:43:15 +0000 (UTC) Received: from redhat.com (unknown [10.42.28.124]) by mx-prod-int-03.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id D20BB19560A2; Mon, 6 Jan 2025 18:43:11 +0000 (UTC) Date: Mon, 6 Jan 2025 18:43:07 +0000 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Phil Dennis-Jordan Cc: Philippe =?utf-8?Q?Mathieu-Daud=C3=A9?= , qemu-devel@nongnu.org, Thomas Huth , Daniel Henrique Barboza , Richard Henderson , Paolo Bonzini Subject: Re: [PATCH] system: Try hardware accelerators (KVM, HVF) before software one (TCG) Message-ID: References: <20250103150558.1473-1-philmd@linaro.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/2.2.13 (2024-03-09) X-Scanned-By: MIMEDefang 3.0 on 10.30.177.12 Received-SPF: pass client-ip=170.10.133.124; envelope-from=berrange@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -24 X-Spam_score: -2.5 X-Spam_bar: -- X-Spam_report: (-2.5 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.446, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H2=-0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Sat, Jan 04, 2025 at 12:28:14PM +0100, Phil Dennis-Jordan wrote: > On Fri, 3 Jan 2025 at 16:16, Daniel P. Berrangé wrote: > > > On Fri, Jan 03, 2025 at 04:05:58PM +0100, Philippe Mathieu-Daudé wrote: > > > As Daniel suggested [*]: > > > > > > > We should consider to rank HVF above TCG, on the basis > > > > that HW acceleration is faster and should provide a > > > > host<->guest security boundary that we don't claim for TCG > > > > > > [*] https://lore.kernel.org/qemu-devel/Z07YASl2Pd3CPtjE@redhat.com/ > > > > Note, my statement above was on the basis that HVF passes all our > > functional tests, thus indicating a decent level of confidence > > in the correctness of the HVF impl. > > > > If anyone knows any show stopper problems with HVF that would > > justify blocking its promotion ahead of TCG.... say now. > > > > I don't know about showstoppers, but: > > 1. As far as I'm aware there are/were problems with the virtual IOMMU > devices in HVF. It's been a while (~half a year?) since I tried them, but I > had problems getting guests booted with intel_iommu etc. I think that vIOMMU is niche enough that we can merely consider it a nice-to-fix bug, and not block promoting HVF. > 2. I think there might also be a few remaining edge cases where the x86 > instruction emulation on fault/trap is incomplete. Most notably, MMIO using > SSE/AVX/etc. instructions will, I think, fail. In practice this is a fairly > obscure use case - I'm not aware of any guest OS that actually performs > MMIO using these instructions. I have a patch kicking around that adds > support for missing 64-bit variants of common scalar arithmetic > instructions with memory operands. I can dig that up and post it - do we > have a good way of adding tests for this kind of thing? Not sure how best to test this, other than finding a guest OS that exhibits this ? Others probably have better suggestions... > 3. As far as I'm aware, there's no CI happening on HVF? Or has that > changed? macOS is notoriously a pain in the rear in terms of CI thanks to > its licensing, and the big cloud CI platforms tend to run it in a VM which > in turn typically doesn't support nested HVF. I've been working on an > on-prem solution to provisioning bare-metal Macs to run clean-slate OS > images for CI. This has been a side project though and I haven't had the > resources to focus on that project to see it through. It might be possible > to do this in the cloud on Amazon's EC2 Mac Minis as well, but those aren't > exactly cheap. The only CI we have is running under Cirrus CI which uses VMs on real mac aarch64 hardware, but I don't think we can test HVF there. Mostly we rely on regular contributors periodically running tests and reporting on problems. This is not ideal, but also not a blocker for enabling HVF - it just means macOS isn't a full tier 1 platform for us. 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 :|