From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (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 D56ED1DE894 for ; Mon, 28 Oct 2024 16:09:44 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730131787; cv=none; b=Sx0+uNtBCt8CX11m5f+9DVxKXy8ZJxhhzf+MEMonmbiLwBIT69RCu2W9gIXpBOogXVdNDeV2MhOsZ3G560S/tTtzzEaNyYjqF0pepzSurSX9t0aWcw+Xsmc81u/J7u5IsD3Flb0ltnxsDpwqWjrsCHC4plCcelJSyQFJlSCvUxY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730131787; c=relaxed/simple; bh=9B2Fhr9ot5U91JhbLWdLBB1gmU6HOU9dJmW2hZ/cud0=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=t/L8sDYOdB/r81jbDMiGP542X7KHZXVbkwqTe2vkrfPvG8MqRUCLLfw0x0ctmQYH0Uf4APJ6VmENvFiJwgdj49AFqawOM5956cFJ2m/M08F6DEc48hLOi7MGYDK5BrN175i1KbhZxammQALV5vNloUVY50bNauxq4WMLT4Lw0h4= 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=F4dLl1LU; arc=none smtp.client-ip=170.10.129.124 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="F4dLl1LU" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1730131783; 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=ea6G5wtzKMhZ2E+87Bpxxtu+p19GIanpiqAsDf/FIog=; b=F4dLl1LUBojrJMi9146mItNDAr1HcpYWbraLjRQUjQLVQQRkc+n2DKn8sEMjgmoAkgYBHE WzdMwb2n6Bqw1kDPgEaCVrRTRPAthNj8rX14d64qMVki7wqqbP7E5Qw2hchwozbhvTnSsp 3s68s71B1fJRzrmj3lc/ZC9dCjQfvBk= Received: from mx-prod-mc-04.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-53-MFjKr2uwM3GR5URt0I5N1A-1; Mon, 28 Oct 2024 12:09:40 -0400 X-MC-Unique: MFjKr2uwM3GR5URt0I5N1A-1 Received: from mx-prod-int-04.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-04.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.40]) (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-04.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 9EE4619560BD; Mon, 28 Oct 2024 16:09:38 +0000 (UTC) Received: from redhat.com (unknown [10.42.28.86]) by mx-prod-int-04.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 2B18619560AA; Mon, 28 Oct 2024 16:09:31 +0000 (UTC) Date: Mon, 28 Oct 2024 16:09:29 +0000 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Cornelia Huck Cc: Eric Auger , eric.auger.pro@gmail.com, qemu-devel@nongnu.org, qemu-arm@nongnu.org, kvmarm@lists.linux.dev, peter.maydell@linaro.org, richard.henderson@linaro.org, alex.bennee@linaro.org, maz@kernel.org, oliver.upton@linux.dev, sebott@redhat.com, shameerali.kolothum.thodi@huawei.com, armbru@redhat.com, abologna@redhat.com, jdenemar@redhat.com, shahuang@redhat.com, mark.rutland@arm.com, philmd@linaro.org, pbonzini@redhat.com Subject: Re: [RFC 21/21] arm/cpu-features: Document custom vcpu model Message-ID: Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= References: <20241025101959.601048-1-eric.auger@redhat.com> <20241025101959.601048-22-eric.auger@redhat.com> <0700af51-a1a6-4b11-a4bf-0eaf6e279c6d@redhat.com> <87y128nrfr.fsf@redhat.com> Precedence: bulk X-Mailing-List: kvmarm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <87y128nrfr.fsf@redhat.com> User-Agent: Mutt/2.2.12 (2023-09-09) X-Scanned-By: MIMEDefang 3.0 on 10.30.177.40 On Mon, Oct 28, 2024 at 05:05:44PM +0100, Cornelia Huck wrote: > On Fri, Oct 25 2024, Daniel P. Berrangé wrote: > > > On Fri, Oct 25, 2024 at 03:28:35PM +0200, Eric Auger wrote: > >> Hi Daniel, > >> > >> On 10/25/24 15:13, Daniel P. Berrangé wrote: > >> > On Fri, Oct 25, 2024 at 12:17:40PM +0200, Eric Auger wrote: > >> >> From: Cornelia Huck > >> >> > >> >> Add some documentation for the custom model. > >> >> > >> >> Signed-off-by: Eric Auger > >> >> Signed-off-by: Cornelia Huck > >> >> --- > >> >> docs/system/arm/cpu-features.rst | 55 +++++++++++++++++++++++++++----- > >> >> 1 file changed, 47 insertions(+), 8 deletions(-) > >> > > >> >> @@ -167,6 +196,16 @@ disabling many SVE vector lengths would be quite verbose, the ``sve`` CPU > >> >> properties have special semantics (see "SVE CPU Property Parsing > >> >> Semantics"). > >> >> > >> >> +The ``custom`` CPU model needs to be configured via individual ID register > >> >> +field properties, for example:: > >> >> + > >> >> + $ qemu-system-aarch64 -M virt -cpu custom,SYSREG_ID_AA64ISAR0_EL1_DP=0x0 > >> >> + > >> >> +This forces ID_AA64ISAR0_EL1 DP field to 0. > >> > What is the "baseline" featureset implied by 'custom' ? > >> there is no baseline at the moment. By default this is a host > >> passthrough model. > > > > Why do we need to create "custom" at all, as opposed to just letting > > users toggle features on "-cpu host" ? > > We could consolidate that to the current "host" model, once we figure > out how to handle the currently already existing properties. Models > based on the different architecture extensions would probably be more > useable in the long run; maybe "custom" has a place for testing. If you can set the features against "host", then any testing could be done with "host" surely, making 'custom' pointless ? 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 :|