From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) (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 68C1418893C for ; Mon, 28 Oct 2024 16:29:22 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.133.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730132964; cv=none; b=d1DLzdaThkenpKRSlNQ9OZXLke1cz7vpsM/ZQarSRr5o9Fwt1MWc5CYLJPdNOXGMap7qpFRRDPGCYbO23LYodRQJLVdCbD/Pcmj2GmnCRSB8eMndk1n954TXVFt940UjjDfUfTZzcjIGfpYgyO/Kn/sk8AhOaIWAh6qJCRF1tB0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1730132964; c=relaxed/simple; bh=mWMB9u+W2V6dTh3jud0NeAKsAEjUv+CqtCPFeltEcUI=; h=From:To:Cc:Subject:In-Reply-To:References:Date:Message-ID: MIME-Version:Content-Type; b=fyYEGQR/ljX9uDI4IJFzycI1BqclGKPUHQSHHePn4e2je3kHGWpPt2xhIxIUD3zEqSsPcpZ7zEJCjALAykZ+b2iJBEXkImQ6ck5oWbtjIVzjdZyHlcGhv2f4XqjyIRhrJU4UD3mIdwLNdXc5uZ6EezrdvBVfRvxRAKx/9Z6F+Dk= 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=UxnT4oD7; arc=none smtp.client-ip=170.10.133.124 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="UxnT4oD7" 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> 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 3.0 on 10.30.177.40 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.