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 C19B818A939 for ; Mon, 28 Oct 2024 16:05:57 +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=1730131559; cv=none; b=oJ5+73oQt+N9BqZh36aHBJessqTsvlx1DzWyzdMeKfKlMVXfCTkmoJbksh99dGtXhRvYoh63e4HfglGX9h4Xx20aD8NHi67OnkKmYriKpNH/BO9Oub3/u9uRb8Cc4Y98lO8qx6nsg5egn2TT33gtt00JxZ1V5YEuNy9PUdwW6zU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730131559; c=relaxed/simple; bh=VXi9d7DdurwPEhh6cowqKwk8yzizKcMfUiPzrgVIt7c=; h=From:To:Cc:Subject:In-Reply-To:References:Date:Message-ID: MIME-Version:Content-Type; b=j7Mkk51WG67lHrGAEtqJHTIq1ui6Gz6X4y6r1svhUuBBADRJPw/fe9Oal1no06QGFkfOPNK3NrvurrtqfTr8BD4NG4neWCchEZtZOnK45WDfHLSzVE7sHX5kbC22SKg5dIdS7Gn6Ol0JdlFlNVyXRNe6Adt43oUdv2wb3EZVcrk= 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=g5F77KMJ; 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="g5F77KMJ" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1730131556; h=from:from: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=mPM1TjkdR42ttNSOcT/XXx5F503EX3B6Jz0za4NGXRM=; b=g5F77KMJ7x3jmX0IX5718tCclypFJAiDdrMiEc9/A38e5CvRTPf/sAtlwFGLqtrjHVYaYG uKC2+HO5MQr1l0DRpJs6B3RDru3lhlAr4++Igh2262NnfzRmzxNfztIEsEJI4vvRYHKUm8 /jp4W0lyHJnsNvzre9/s60LBPiNmGJ8= 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-93-MBchNRQhP9KV0AytdjcjgA-1; Mon, 28 Oct 2024 12:05:53 -0400 X-MC-Unique: MBchNRQhP9KV0AytdjcjgA-1 Received: from mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.4]) (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 6E98A1955F45; Mon, 28 Oct 2024 16:05:51 +0000 (UTC) Received: from localhost (unknown [10.22.88.106]) by mx-prod-int-01.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id B12AA300018D; Mon, 28 Oct 2024 16:05:46 +0000 (UTC) From: Cornelia Huck To: =?utf-8?Q?Daniel_P=2E_Berrang=C3=A9?= , Eric Auger Cc: 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 In-Reply-To: Organization: "Red Hat GmbH, Sitz: Werner-von-Siemens-Ring 12, D-85630 Grasbrunn, Handelsregister: Amtsgericht =?utf-8?Q?M=C3=BCnchen=2C?= HRB 153243, =?utf-8?Q?Gesch=C3=A4ftsf=C3=BChrer=3A?= Ryan Barnhart, Charles Cachera, Michael O'Neill, Amy Ross" References: <20241025101959.601048-1-eric.auger@redhat.com> <20241025101959.601048-22-eric.auger@redhat.com> <0700af51-a1a6-4b11-a4bf-0eaf6e279c6d@redhat.com> User-Agent: Notmuch/0.38.3 (https://notmuchmail.org) Date: Mon, 28 Oct 2024 17:05:44 +0100 Message-ID: <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-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.4 On Fri, Oct 25 2024, Daniel P. Berrang=C3=A9 wrote: > On Fri, Oct 25, 2024 at 03:28:35PM +0200, Eric Auger wrote: >> Hi Daniel, >>=20 >> On 10/25/24 15:13, Daniel P. Berrang=C3=A9 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"). >> >>=20=20 >> >> +The ``custom`` CPU model needs to be configured via individual ID re= gister >> >> +field properties, for example:: >> >> + >> >> + $ qemu-system-aarch64 -M virt -cpu custom,SYSREG_ID_AA64ISAR0_EL1_= DP=3D0x0 >> >> + >> >> +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" ?=20 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.