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 229CBD33998 for ; Mon, 28 Oct 2024 16:29:57 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1t5ScP-0005lC-1d; Mon, 28 Oct 2024 12:29:25 -0400 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 1t5ScN-0005kT-B2 for qemu-devel@nongnu.org; Mon, 28 Oct 2024 12:29:23 -0400 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 1t5ScM-0008Iz-02 for qemu-devel@nongnu.org; Mon, 28 Oct 2024 12:29:23 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1730132961; 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=mkkVElKn3Spk/fVm1hzjR0gsXNh0JNd5hSe/vYQwfCU=; b=UxnT4oD7C2X4Cn7SPrQSEaFpst1tk3nHFqcVG9bg2tv/NVdUmImAb9w1fxIoqUXI4SjMzY xDxcHSbnXwqtELJ2Rh9CMJ+Ulz01cRmS/5xezUotvHfPOsE9+IF4qZ42O0TxMP4ew6+6Ok 4s80602c0Fi82TU7kvxllaT7lwo53GA= Received: from mx-prod-mc-02.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-26-LhHf3dMWMJeGWk7sEJHcIQ-1; Mon, 28 Oct 2024 12:29:18 -0400 X-MC-Unique: LhHf3dMWMJeGWk7sEJHcIQ-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-02.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 1572F1955D4A; Mon, 28 Oct 2024 16:29:16 +0000 (UTC) Received: from localhost (unknown [10.22.88.106]) by mx-prod-int-04.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 52E9919560AA; Mon, 28 Oct 2024 16:29:14 +0000 (UTC) From: Cornelia Huck To: =?utf-8?Q?Daniel_P=2E_Berrang=C3=A9?= 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 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> <87y128nrfr.fsf@redhat.com> User-Agent: Notmuch/0.38.3 (https://notmuchmail.org) Date: Mon, 28 Oct 2024 17:29:11 +0100 Message-ID: <87plnknqco.fsf@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.0 on 10.30.177.40 Received-SPF: pass client-ip=170.10.133.124; envelope-from=cohuck@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=-0.373, 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_H3=0.001, RCVD_IN_MSPIKE_WL=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=unavailable 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 Mon, Oct 28 2024, Daniel P. Berrang=C3=A9 wrote: > On Mon, Oct 28, 2024 at 05:05:44PM +0100, Cornelia Huck wrote: >> On Fri, Oct 25 2024, Daniel P. Berrang=C3=A9 wrote: >>=20 >> > 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 qu= ite 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= register >> >> >> +field properties, for example:: >> >> >> + >> >> >> + $ qemu-system-aarch64 -M virt -cpu custom,SYSREG_ID_AA64ISAR0_E= L1_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 >>=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. > > If you can set the features against "host", then any testing could > be done with "host" surely, making 'custom' pointless ? We might differentiate between "do some consistency checks" and "allow a completely weird wolpertinger"; if we agree that we don't need it, then we surely could drop it again.