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 DDB1BC77B7A for ; Fri, 19 May 2023 16:25:00 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1q02tt-0006ds-CI; Fri, 19 May 2023 12:24:17 -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 1q02tr-0006dP-DC for qemu-devel@nongnu.org; Fri, 19 May 2023 12:24:15 -0400 Received: from frasgout.his.huawei.com ([185.176.79.56]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1q02to-0007ie-0R for qemu-devel@nongnu.org; Fri, 19 May 2023 12:24:14 -0400 Received: from lhrpeml500005.china.huawei.com (unknown [172.18.147.201]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4QNBw10VsDz67fpR; Sat, 20 May 2023 00:22:57 +0800 (CST) Received: from localhost (10.202.227.76) by lhrpeml500005.china.huawei.com (7.191.163.240) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.23; Fri, 19 May 2023 17:24:04 +0100 Date: Fri, 19 May 2023 17:24:04 +0100 To: Philippe =?ISO-8859-1?Q?Mathieu-Daud=E9?= CC: , Michael Tsirkin , Fan Ni , , , "Ira Weiny" , Michael Roth , "Dave Jiang" , Markus Armbruster , "Daniel P . =?ISO-8859-1?Q?Berrang=E9?=" , Eric Blake , Mike Maslenkin , =?ISO-8859-1?Q?Marc-Andr=E9?= Lureau , "Thomas Huth" Subject: Re: [PATCH v6 1/4] bswap: Add the ability to store to an unaligned 24 bit field Message-ID: <20230519172404.0000649e@Huawei.com> In-Reply-To: <27f9ad4f-bdde-f548-860b-34e52493faa2@linaro.org> References: <20230519141803.29713-1-Jonathan.Cameron@huawei.com> <20230519141803.29713-2-Jonathan.Cameron@huawei.com> <27f9ad4f-bdde-f548-860b-34e52493faa2@linaro.org> Organization: Huawei Technologies Research and Development (UK) Ltd. X-Mailer: Claws Mail 4.1.0 (GTK 3.24.33; x86_64-w64-mingw32) MIME-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: quoted-printable X-Originating-IP: [10.202.227.76] X-ClientProxiedBy: lhrpeml100006.china.huawei.com (7.191.160.224) To lhrpeml500005.china.huawei.com (7.191.163.240) X-CFilter-Loop: Reflected Received-SPF: pass client-ip=185.176.79.56; envelope-from=jonathan.cameron@huawei.com; helo=frasgout.his.huawei.com X-Spam_score_int: -41 X-Spam_score: -4.2 X-Spam_bar: ---- X-Spam_report: (-4.2 / 5.0 requ) BAYES_00=-1.9, RCVD_IN_DNSWL_MED=-2.3, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-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: , Reply-to: Jonathan Cameron From: Jonathan Cameron via Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Fri, 19 May 2023 18:08:30 +0200 Philippe Mathieu-Daud=E9 wrote: > On 19/5/23 16:18, Jonathan Cameron wrote: > > From: Ira Weiny > >=20 > > CXL has 24 bit unaligned fields which need to be stored to. CXL is > > specified as little endian. > >=20 > > Define st24_le_p() and the supporting functions to store such a field > > from a 32 bit host native value. > >=20 > > The use of b, w, l, q as the size specifier is limiting. So "24" was > > used for the size part of the function name. > >=20 > > Signed-off-by: Ira Weiny > > Signed-off-by: Jonathan Cameron > > --- > > docs/devel/loads-stores.rst | 1 + > > include/qemu/bswap.h | 27 +++++++++++++++++++++++++++ > > 2 files changed, 28 insertions(+) > >=20 > > diff --git a/docs/devel/loads-stores.rst b/docs/devel/loads-stores.rst > > index d2cefc77a2..82a79e91d9 100644 > > --- a/docs/devel/loads-stores.rst > > +++ b/docs/devel/loads-stores.rst > > @@ -36,6 +36,7 @@ store: ``st{size}_{endian}_p(ptr, val)`` > > ``size`` > > - ``b`` : 8 bits > > - ``w`` : 16 bits > > + - ``24`` : 24 bits > > - ``l`` : 32 bits > > - ``q`` : 64 bits > > =20 > > diff --git a/include/qemu/bswap.h b/include/qemu/bswap.h > > index 15a78c0db5..f546b1fc06 100644 > > --- a/include/qemu/bswap.h > > +++ b/include/qemu/bswap.h > > @@ -8,11 +8,25 @@ > > #undef bswap64 > > #define bswap64(_x) __builtin_bswap64(_x) > > =20 > > +static inline uint32_t bswap24(uint32_t x) > > +{ > > + assert((x & 0xff000000U) =3D=3D 0); =20 >=20 > Asserting here is a bit violent. In particular because there is no > contract description that x should be less than N bits for bswapN() > in "qemu/bswap.h" API. >=20 > But if you rather to assert ... I'm fine either way. You asked for it when reviewing v4... https://lore.kernel.org/all/28a9d97a-b252-a33f-1ac0-cd36264b29ab@linaro.org/ >=20 > > + > > + return (((x & 0x000000ffU) << 16) | > > + ((x & 0x0000ff00U) << 0) | > > + ((x & 0x00ff0000U) >> 16)); > > +} > > + > > static inline void bswap16s(uint16_t *s) > > { > > *s =3D __builtin_bswap16(*s); > > } > > =20 > > +static inline void bswap24s(uint32_t *s) > > +{ > > + *s =3D bswap24(*s & 0x00ffffffU); =20 >=20 > ... and sanitize the value here ... >=20 > > +} > > + > > static inline void bswap32s(uint32_t *s) > > { > > *s =3D __builtin_bswap32(*s); > > @@ -26,11 +40,13 @@ static inline void bswap64s(uint64_t *s) > > #if HOST_BIG_ENDIAN > > #define be_bswap(v, size) (v) > > #define le_bswap(v, size) glue(__builtin_bswap, size)(v) > > +#define le_bswap24(v) bswap24(v) =20 >=20 > ... then shouldn't you sanitize also here? >=20 Good point. I forgot that detail whilst fighting with s390 cross builds earlier ;) > Personally I'd just drop the assertion. I'm fine with doing that. Jonathan >=20 > > #define be_bswaps(v, size) > > #define le_bswaps(p, size) \ > > do { *p =3D glue(__builtin_bswap, size)(*p); } while (0) > > #else > > #define le_bswap(v, size) (v) > > +#define le_bswap24(v) (v) > > #define be_bswap(v, size) glue(__builtin_bswap, size)(v) > > #define le_bswaps(v, size) > > #define be_bswaps(p, size) \ > > @@ -176,6 +192,7 @@ CPU_CONVERT(le, 64, uint64_t) > > * size is: > > * b: 8 bits > > * w: 16 bits > > + * 24: 24 bits > > * l: 32 bits > > * q: 64 bits > > * > > @@ -248,6 +265,11 @@ static inline void stw_he_p(void *ptr, uint16_t v) > > __builtin_memcpy(ptr, &v, sizeof(v)); > > } > > =20 > > +static inline void st24_he_p(void *ptr, uint32_t v) > > +{ > > + __builtin_memcpy(ptr, &v, 3); > > +} > > + > > static inline int ldl_he_p(const void *ptr) > > { > > int32_t r; > > @@ -297,6 +319,11 @@ static inline void stw_le_p(void *ptr, uint16_t v) > > stw_he_p(ptr, le_bswap(v, 16)); > > } > > =20 > > +static inline void st24_le_p(void *ptr, uint32_t v) > > +{ > > + st24_he_p(ptr, le_bswap24(v)); > > +} > > + > > static inline void stl_le_p(void *ptr, uint32_t v) > > { > > stl_he_p(ptr, le_bswap(v, 32)); =20 >=20 > Conditional to removing the assertion in bswap24(): > Reviewed-by: Philippe Mathieu-Daud=E9 >=20