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 960FDC48297 for ; Mon, 12 Feb 2024 17:19:34 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1rZZxR-0001YZ-Vc; Mon, 12 Feb 2024 12:19:05 -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 1rZZxM-0001Xh-PZ; Mon, 12 Feb 2024 12:19:00 -0500 Received: from dfw.source.kernel.org ([139.178.84.217]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1rZZxL-0005fq-3Z; Mon, 12 Feb 2024 12:19:00 -0500 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by dfw.source.kernel.org (Postfix) with ESMTP id 99E5560F9F; Mon, 12 Feb 2024 17:18:47 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id D6A57C433C7; Mon, 12 Feb 2024 17:18:45 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1707758325; bh=V9l0zQ5i8oB0x7537ZCInnxfHXbuws1rjzVUecT7Nes=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=UtpUGtq44Iu7WFGUxVR8Sc5TqXKOQkN8AIlAj8WK8/I/fv1hVjEhNS+o+wR+nKJ+L V/WTDdnKocyPCN5Xuqlruukuf3gNZx/zIDIKBh0yxy5L+kl/9aaPO6PY7xVZuZ9Cv1 Jns5lacvKD90sVTY6MppI0FEpyFvAe5hCf6nHVf5HSMqp0TUGEu47G3Q1DIaki4bKS 7TpexyyLeGzUXNN88Fah25UKk2nD90VxYxsFBvUsHRh43R6lKxlXrGBejPK1OyDBE5 qjkoG9FUFIaHE0nPUvCqqTjGrRB8YLxx/7I+GdaSu3TVtluOxEBO35JJO/Id/oWm52 qCfp08vdojZYA== Received: from disco-boy.misterjones.org ([217.182.43.188] helo=www.loen.fr) by disco-boy.misterjones.org with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.95) (envelope-from ) id 1rZZx5-002Uv5-5s; Mon, 12 Feb 2024 17:18:43 +0000 MIME-Version: 1.0 Date: Mon, 12 Feb 2024 17:18:41 +0000 From: Marc Zyngier To: Peter Maydell Cc: Eric Auger , eric.auger.pro@gmail.com, qemu-devel@nongnu.org, qemu-arm@nongnu.org, miguel.luis@oracle.com, haibo.xu@linaro.org, richard.henderson@linaro.org, gkulkarni@amperecomputing.com Subject: Re: [RFC v2 0/5] ARM Nested Virt Support In-Reply-To: References: <20240209160039.677865-1-eric.auger@redhat.com> User-Agent: Roundcube Webmail/1.4.15 Message-ID: X-Sender: maz@kernel.org Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 7bit X-SA-Exim-Connect-IP: 217.182.43.188 X-SA-Exim-Rcpt-To: peter.maydell@linaro.org, eric.auger@redhat.com, eric.auger.pro@gmail.com, qemu-devel@nongnu.org, qemu-arm@nongnu.org, miguel.luis@oracle.com, haibo.xu@linaro.org, richard.henderson@linaro.org, gkulkarni@amperecomputing.com X-SA-Exim-Mail-From: maz@kernel.org X-SA-Exim-Scanned: No (on disco-boy.misterjones.org); SAEximRunCond expanded to false Received-SPF: pass client-ip=139.178.84.217; envelope-from=maz@kernel.org; helo=dfw.source.kernel.org X-Spam_score_int: -78 X-Spam_score: -7.9 X-Spam_bar: ------- X-Spam_report: (-7.9 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.774, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_HI=-5, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 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: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On 2024-02-09 18:57, Peter Maydell wrote: > On Fri, 9 Feb 2024 at 16:00, Eric Auger wrote: >> >> This series adds ARM Nested Virtualization support in KVM mode. >> This is a respin of previous contributions from Miguel [1] and Haibo >> [2]. >> >> This was tested with Marc's v11 [3] on Ampere HW with fedora L1 guest >> and >> L2 guests booted without EDK2. However it does not work yet with >> EDK2 but it looks unrelated to this qemu integration (host hard >> lockups). >> >> The host needs to be booted with "kvm-arm.mode=nested" option and >> qemu needs to be invoked with : >> >> -machine virt,virtualization=on >> >> There is a known issue with hosts supporting SVE. Kernel does not >> support both >> SVE and NV2 and the current qemu integration has an issue with the >> scratch_host_vcpu startup because both are enabled if exposed by the >> kernel. >> This is independent on whether sve is disabled on the command line. >> Unfortunately >> I lost access to the HW that expose that issue so I couldn't fix it in >> this >> version. > > You can probably repro that by running the whole setup under > QEMU's FEAT_NV emulation, which will be able to give you a CPU > with both FEAT_NV and SVE. > > Personally I think that this is a kernel missing-feature that > should really be fixed as part of getting the kernel patches > upstreamed. There's no cause to force every userspace VMM to > develop extra complications for this. I don't plan to make NV visible to userspace before this is fixed. Which may delay KVM NV by another year or five, but I don't think anyone is really waiting for it anyway. M. -- Jazz is not dead. It just smells funny...