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 21428C54E58 for ; Thu, 14 Mar 2024 02:44:13 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1rkb41-0004BZ-Nt; Wed, 13 Mar 2024 22:43:25 -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 1rkb3x-000468-Q2; Wed, 13 Mar 2024 22:43:21 -0400 Received: from mail.ozlabs.org ([2404:9400:2221:ea00::3] helo=gandalf.ozlabs.org) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1rkb3m-0007Oa-F6; Wed, 13 Mar 2024 22:43:17 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gibson.dropbear.id.au; s=202312; t=1710384178; bh=03iqoUpzm8H4OTZ/G4RII5H020u487IQc1QO+eAex+w=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=i0zn7Bba5LXOeLO/8kJA8IBflAakhMYM7+RvK+P9ZySbtsdKY/B5lq7C7iLTXkxa2 rbPlaH+ja0U4fCwqRZ3ry2rjvC8qkXNC0bSO7fSb4yapCwRUCocxI4q2CbrRCKcLYl 0cqvv+NaZh/8qcweST5GWWczzU4Zybsf6HYNwwte7q8bTst48sn/g47o/kgLp91GYg cv+Pp7dldW+rQVuXLukLpzyBGCEmttNOHFbrB+sRWXoFprioJbOLj7PQoSAVwBizNH Sg7XBfTwf1nB8dvOo+eMABU6MEFk/uu2z87F4L7SKUJg01qICWqqXkoXErhuVslJ+U TFPeMvlrbE6MQ== Received: by gandalf.ozlabs.org (Postfix, from userid 1007) id 4TwBWQ3yRLz4wnr; Thu, 14 Mar 2024 13:42:58 +1100 (AEDT) Date: Thu, 14 Mar 2024 13:34:38 +1100 From: David Gibson To: Nicholas Piggin Cc: qemu-ppc@nongnu.org, qemu-devel@nongnu.org, Daniel Henrique Barboza , Harsh Prateek Bora Subject: Re: [PATCH v2 03/10] ppc/spapr|pnv: Remove SAO from pa-features Message-ID: References: <20240312131419.2196845-1-npiggin@gmail.com> <20240312131419.2196845-4-npiggin@gmail.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="D8SlqsQjoTB4xEiS" Content-Disposition: inline In-Reply-To: <20240312131419.2196845-4-npiggin@gmail.com> Received-SPF: pass client-ip=2404:9400:2221:ea00::3; envelope-from=dgibson@gandalf.ozlabs.org; helo=gandalf.ozlabs.org X-Spam_score_int: -40 X-Spam_score: -4.1 X-Spam_bar: ---- X-Spam_report: (-4.1 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, HEADER_FROM_DIFFERENT_DOMAINS=0.249, RCVD_IN_DNSWL_MED=-2.3, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01, T_SPF_HELO_TEMPERROR=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 --D8SlqsQjoTB4xEiS Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Tue, Mar 12, 2024 at 11:14:12PM +1000, Nicholas Piggin wrote: > SAO is a page table attribute that strengthens the memory ordering of > accesses. QEMU with MTTCG does not implement this, so clear it in > ibm,pa-features. This is an obscure feature that has been removed from > POWER10 ISA v3.1, there isn't much concern with removing it. >=20 > Reviewed-by: Harsh Prateek Bora > Signed-off-by: Nicholas Piggin Usually altering a user visible feature like this without versioning would be a no-no. However, I think it's probably ok here: AFAICT the feature was basically never used, it didn't work in some cases anyway, and it's now gone away. > --- > hw/ppc/pnv.c | 2 +- > hw/ppc/spapr.c | 14 ++++++++++---- > 2 files changed, 11 insertions(+), 5 deletions(-) >=20 > diff --git a/hw/ppc/pnv.c b/hw/ppc/pnv.c > index 0b47b92baa..aa9786e970 100644 > --- a/hw/ppc/pnv.c > +++ b/hw/ppc/pnv.c > @@ -150,7 +150,7 @@ static void pnv_dt_core(PnvChip *chip, PnvCore *pc, v= oid *fdt) > uint32_t page_sizes_prop[64]; > size_t page_sizes_prop_size; > const uint8_t pa_features[] =3D { 24, 0, > - 0xf6, 0x3f, 0xc7, 0xc0, 0x80, 0xf0, > + 0xf6, 0x3f, 0xc7, 0xc0, 0x00, 0xf0, > 0x80, 0x00, 0x00, 0x00, 0x00, 0x00, > 0x00, 0x00, 0x00, 0x00, 0x80, 0x00, > 0x80, 0x00, 0x80, 0x00, 0x80, 0x00 }; > diff --git a/hw/ppc/spapr.c b/hw/ppc/spapr.c > index 55263f0815..3108d7c532 100644 > --- a/hw/ppc/spapr.c > +++ b/hw/ppc/spapr.c > @@ -233,17 +233,23 @@ static void spapr_dt_pa_features(SpaprMachineState = *spapr, > PowerPCCPU *cpu, > void *fdt, int offset) > { > + /* > + * SSO (SAO) ordering is supported on KVM and thread=3Dsingle hosts, > + * but not MTTCG, so disable it. To advertise it, a cap would have > + * to be added, or support implemented for MTTCG. > + */ > + > uint8_t pa_features_206[] =3D { 6, 0, > - 0xf6, 0x1f, 0xc7, 0x00, 0x80, 0xc0 }; > + 0xf6, 0x1f, 0xc7, 0x00, 0x00, 0xc0 }; > uint8_t pa_features_207[] =3D { 24, 0, > - 0xf6, 0x1f, 0xc7, 0xc0, 0x80, 0xf0, > + 0xf6, 0x1f, 0xc7, 0xc0, 0x00, 0xf0, > 0x80, 0x00, 0x00, 0x00, 0x00, 0x00, > 0x00, 0x00, 0x00, 0x00, 0x80, 0x00, > 0x80, 0x00, 0x80, 0x00, 0x00, 0x00 }; > uint8_t pa_features_300[] =3D { 66, 0, > /* 0: MMU|FPU|SLB|RUN|DABR|NX, 1: fri[nzpm]|DABRX|SPRG3|SLB0|PP1= 10 */ > - /* 2: VPM|DS205|PPR|DS202|DS206, 3: LSD|URG, SSO, 5: LE|CFAR|EB|= LSQ */ > - 0xf6, 0x1f, 0xc7, 0xc0, 0x80, 0xf0, /* 0 - 5 */ > + /* 2: VPM|DS205|PPR|DS202|DS206, 3: LSD|URG, 5: LE|CFAR|EB|LSQ */ > + 0xf6, 0x1f, 0xc7, 0xc0, 0x00, 0xf0, /* 0 - 5 */ > /* 6: DS207 */ > 0x80, 0x00, 0x00, 0x00, 0x00, 0x00, /* 6 - 11 */ > /* 16: Vector */ --=20 David Gibson | I'll have my music baroque, and my code david AT gibson.dropbear.id.au | minimalist, thank you. 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