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 32EEFCDB482 for ; Thu, 12 Oct 2023 12:10:40 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1qquVl-00075S-Q0; Thu, 12 Oct 2023 08:09:54 -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 1qquVf-000759-CB for qemu-devel@nongnu.org; Thu, 12 Oct 2023 08:09:48 -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 1qquVc-00080C-At for qemu-devel@nongnu.org; Thu, 12 Oct 2023 08:09:47 -0400 Received: from lhrpeml500005.china.huawei.com (unknown [172.18.147.201]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4S5pMv75bLz6K90h; Thu, 12 Oct 2023 20:09:15 +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 15.1.2507.31; Thu, 12 Oct 2023 13:09:38 +0100 Date: Thu, 12 Oct 2023 13:09:36 +0100 To: "Michael S. Tsirkin" CC: Michael Tokarev , , Fan Ni , Philippe =?ISO-8859-1?Q?Mathieu-Daud=E9?= , Subject: Re: [PATCH v3 2/4] hw/cxl: Use switch statements for read and write of cachemem registers Message-ID: <20231012130936.00004f9a@Huawei.com> In-Reply-To: <20231003163747-mutt-send-email-mst@kernel.org> References: <20230919093434.1194-1-Jonathan.Cameron@huawei.com> <20230919093434.1194-3-Jonathan.Cameron@huawei.com> <20231003163747-mutt-send-email-mst@kernel.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="US-ASCII" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.202.227.76] X-ClientProxiedBy: lhrpeml100004.china.huawei.com (7.191.162.219) 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, RCVD_IN_MSPIKE_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 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 Tue, 3 Oct 2023 16:42:37 -0400 "Michael S. Tsirkin" wrote: > On Tue, Sep 19, 2023 at 10:34:32AM +0100, Jonathan Cameron wrote: > > Establishing that only register accesses of size 4 and 8 can occur > > using these functions requires looking at their callers. Make it > > easier to see that by using switch statements. > > Assertions are used to enforce that the register storage is of the > > matching size, allowing fixed values to be used for divisors of > > the array indices. > > > > Suggested-by: Michael Tokarev > > Signed-off-by: Jonathan Cameron > > Reviewed-by: Fan Ni > > --- > > hw/cxl/cxl-component-utils.c | 65 +++++++++++++++++++++++------------- > > 1 file changed, 42 insertions(+), 23 deletions(-) > > > > diff --git a/hw/cxl/cxl-component-utils.c b/hw/cxl/cxl-component-utils.c > > index f3bbf0fd13..7ef3ef2bd6 100644 > > --- a/hw/cxl/cxl-component-utils.c > > +++ b/hw/cxl/cxl-component-utils.c > > @@ -67,16 +67,24 @@ static uint64_t cxl_cache_mem_read_reg(void *opaque, hwaddr offset, > > CXLComponentState *cxl_cstate = opaque; > > ComponentRegisters *cregs = &cxl_cstate->crb; > > > > - if (size == 8) { > > + switch (size) { > > + case 4: > > + if (cregs->special_ops && cregs->special_ops->read) { > > + return cregs->special_ops->read(cxl_cstate, offset, 4); > > + } else { > > + static_assert(sizeof(*cregs->cache_mem_registers) == 4); > > In C currently static_assert needs a message. I switched to QEMU_BUILD_BUG_ON() which seems better + doesn't need a additional message. > > In fact clang warns: > ../hw/cxl/cxl-component-utils.c:75:67: error: '_Static_assert' with no message is a C2x extension [-Werror,-Wc2x-extensions] > static_assert(sizeof(*cregs->cache_mem_registers) == 4); > Thanks, Jonathan > > > + return cregs->cache_mem_registers[offset / 4]; > > + } > > + case 8: > > qemu_log_mask(LOG_UNIMP, > > "CXL 8 byte cache mem registers not implemented\n"); > > return 0; > > - } > > - > > - if (cregs->special_ops && cregs->special_ops->read) { > > - return cregs->special_ops->read(cxl_cstate, offset, size); > > - } else { > > - return cregs->cache_mem_registers[offset / sizeof(*cregs->cache_mem_registers)]; > > + default: > > + /* > > + * In line with specifiction limitaions on access sizes, this > > + * routine is not called with other sizes. > > + */ > > + g_assert_not_reached(); > > } > > } > > > > @@ -117,25 +125,36 @@ static void cxl_cache_mem_write_reg(void *opaque, hwaddr offset, uint64_t value, > > ComponentRegisters *cregs = &cxl_cstate->crb; > > uint32_t mask; > > > > - if (size == 8) { > > + switch (size) { > > + case 4: > > + static_assert(sizeof(*cregs->cache_mem_regs_write_mask) == 4); > > + static_assert(sizeof(*cregs->cache_mem_registers) == 4); > > + mask = cregs->cache_mem_regs_write_mask[offset / 4]; > > + value &= mask; > > + /* RO bits should remain constant. Done by reading existing value */ > > + value |= ~mask & cregs->cache_mem_registers[offset / 4]; > > + if (cregs->special_ops && cregs->special_ops->write) { > > + cregs->special_ops->write(cxl_cstate, offset, value, size); > > + return; > > + } > > + > > + if (offset >= A_CXL_HDM_DECODER_CAPABILITY && > > + offset <= A_CXL_HDM_DECODER3_TARGET_LIST_HI) { > > + dumb_hdm_handler(cxl_cstate, offset, value); > > + } else { > > + cregs->cache_mem_registers[offset / 4] = value; > > + } > > + return; > > + case 8: > > qemu_log_mask(LOG_UNIMP, > > "CXL 8 byte cache mem registers not implemented\n"); > > return; > > - } > > - mask = cregs->cache_mem_regs_write_mask[offset / sizeof(*cregs->cache_mem_regs_write_mask)]; > > - value &= mask; > > - /* RO bits should remain constant. Done by reading existing value */ > > - value |= ~mask & cregs->cache_mem_registers[offset / sizeof(*cregs->cache_mem_registers)]; > > - if (cregs->special_ops && cregs->special_ops->write) { > > - cregs->special_ops->write(cxl_cstate, offset, value, size); > > - return; > > - } > > - > > - if (offset >= A_CXL_HDM_DECODER_CAPABILITY && > > - offset <= A_CXL_HDM_DECODER3_TARGET_LIST_HI) { > > - dumb_hdm_handler(cxl_cstate, offset, value); > > - } else { > > - cregs->cache_mem_registers[offset / sizeof(*cregs->cache_mem_registers)] = value; > > + default: > > + /* > > + * In line with specifiction limitaions on access sizes, this > > + * routine is not called with other sizes. > > + */ > > + g_assert_not_reached(); > > } > > } > > > > -- > > 2.39.2 > From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from list by lists.gnu.org with archive (Exim 4.90_1) id 1qquVj-00075P-5o for mharc-qemu-devel@gnu.org; Thu, 12 Oct 2023 08:09:51 -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 1qquVf-000759-CB for qemu-devel@nongnu.org; Thu, 12 Oct 2023 08:09:48 -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 1qquVc-00080C-At for qemu-devel@nongnu.org; Thu, 12 Oct 2023 08:09:47 -0400 Received: from lhrpeml500005.china.huawei.com (unknown [172.18.147.201]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4S5pMv75bLz6K90h; Thu, 12 Oct 2023 20:09:15 +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 15.1.2507.31; Thu, 12 Oct 2023 13:09:38 +0100 Date: Thu, 12 Oct 2023 13:09:36 +0100 From: Jonathan Cameron To: "Michael S. Tsirkin" CC: Michael Tokarev , , Fan Ni , Philippe =?ISO-8859-1?Q?Mathieu-Daud=E9?= , Subject: Re: [PATCH v3 2/4] hw/cxl: Use switch statements for read and write of cachemem registers Message-ID: <20231012130936.00004f9a@Huawei.com> In-Reply-To: <20231003163747-mutt-send-email-mst@kernel.org> References: <20230919093434.1194-1-Jonathan.Cameron@huawei.com> <20230919093434.1194-3-Jonathan.Cameron@huawei.com> <20231003163747-mutt-send-email-mst@kernel.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="US-ASCII" Content-Transfer-Encoding: 7bit X-Originating-IP: [10.202.227.76] X-ClientProxiedBy: lhrpeml100004.china.huawei.com (7.191.162.219) 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, RCVD_IN_MSPIKE_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 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: , X-List-Received-Date: Thu, 12 Oct 2023 12:09:48 -0000 Message-ID: <20231012120936.9v_zZtZ5foCLg1ufvXncpgCvPjNouJvzmSmG7ivJmQ4@z> On Tue, 3 Oct 2023 16:42:37 -0400 "Michael S. Tsirkin" wrote: > On Tue, Sep 19, 2023 at 10:34:32AM +0100, Jonathan Cameron wrote: > > Establishing that only register accesses of size 4 and 8 can occur > > using these functions requires looking at their callers. Make it > > easier to see that by using switch statements. > > Assertions are used to enforce that the register storage is of the > > matching size, allowing fixed values to be used for divisors of > > the array indices. > > > > Suggested-by: Michael Tokarev > > Signed-off-by: Jonathan Cameron > > Reviewed-by: Fan Ni > > --- > > hw/cxl/cxl-component-utils.c | 65 +++++++++++++++++++++++------------- > > 1 file changed, 42 insertions(+), 23 deletions(-) > > > > diff --git a/hw/cxl/cxl-component-utils.c b/hw/cxl/cxl-component-utils.c > > index f3bbf0fd13..7ef3ef2bd6 100644 > > --- a/hw/cxl/cxl-component-utils.c > > +++ b/hw/cxl/cxl-component-utils.c > > @@ -67,16 +67,24 @@ static uint64_t cxl_cache_mem_read_reg(void *opaque, hwaddr offset, > > CXLComponentState *cxl_cstate = opaque; > > ComponentRegisters *cregs = &cxl_cstate->crb; > > > > - if (size == 8) { > > + switch (size) { > > + case 4: > > + if (cregs->special_ops && cregs->special_ops->read) { > > + return cregs->special_ops->read(cxl_cstate, offset, 4); > > + } else { > > + static_assert(sizeof(*cregs->cache_mem_registers) == 4); > > In C currently static_assert needs a message. I switched to QEMU_BUILD_BUG_ON() which seems better + doesn't need a additional message. > > In fact clang warns: > ../hw/cxl/cxl-component-utils.c:75:67: error: '_Static_assert' with no message is a C2x extension [-Werror,-Wc2x-extensions] > static_assert(sizeof(*cregs->cache_mem_registers) == 4); > Thanks, Jonathan > > > + return cregs->cache_mem_registers[offset / 4]; > > + } > > + case 8: > > qemu_log_mask(LOG_UNIMP, > > "CXL 8 byte cache mem registers not implemented\n"); > > return 0; > > - } > > - > > - if (cregs->special_ops && cregs->special_ops->read) { > > - return cregs->special_ops->read(cxl_cstate, offset, size); > > - } else { > > - return cregs->cache_mem_registers[offset / sizeof(*cregs->cache_mem_registers)]; > > + default: > > + /* > > + * In line with specifiction limitaions on access sizes, this > > + * routine is not called with other sizes. > > + */ > > + g_assert_not_reached(); > > } > > } > > > > @@ -117,25 +125,36 @@ static void cxl_cache_mem_write_reg(void *opaque, hwaddr offset, uint64_t value, > > ComponentRegisters *cregs = &cxl_cstate->crb; > > uint32_t mask; > > > > - if (size == 8) { > > + switch (size) { > > + case 4: > > + static_assert(sizeof(*cregs->cache_mem_regs_write_mask) == 4); > > + static_assert(sizeof(*cregs->cache_mem_registers) == 4); > > + mask = cregs->cache_mem_regs_write_mask[offset / 4]; > > + value &= mask; > > + /* RO bits should remain constant. Done by reading existing value */ > > + value |= ~mask & cregs->cache_mem_registers[offset / 4]; > > + if (cregs->special_ops && cregs->special_ops->write) { > > + cregs->special_ops->write(cxl_cstate, offset, value, size); > > + return; > > + } > > + > > + if (offset >= A_CXL_HDM_DECODER_CAPABILITY && > > + offset <= A_CXL_HDM_DECODER3_TARGET_LIST_HI) { > > + dumb_hdm_handler(cxl_cstate, offset, value); > > + } else { > > + cregs->cache_mem_registers[offset / 4] = value; > > + } > > + return; > > + case 8: > > qemu_log_mask(LOG_UNIMP, > > "CXL 8 byte cache mem registers not implemented\n"); > > return; > > - } > > - mask = cregs->cache_mem_regs_write_mask[offset / sizeof(*cregs->cache_mem_regs_write_mask)]; > > - value &= mask; > > - /* RO bits should remain constant. Done by reading existing value */ > > - value |= ~mask & cregs->cache_mem_registers[offset / sizeof(*cregs->cache_mem_registers)]; > > - if (cregs->special_ops && cregs->special_ops->write) { > > - cregs->special_ops->write(cxl_cstate, offset, value, size); > > - return; > > - } > > - > > - if (offset >= A_CXL_HDM_DECODER_CAPABILITY && > > - offset <= A_CXL_HDM_DECODER3_TARGET_LIST_HI) { > > - dumb_hdm_handler(cxl_cstate, offset, value); > > - } else { > > - cregs->cache_mem_registers[offset / sizeof(*cregs->cache_mem_registers)] = value; > > + default: > > + /* > > + * In line with specifiction limitaions on access sizes, this > > + * routine is not called with other sizes. > > + */ > > + g_assert_not_reached(); > > } > > } > > > > -- > > 2.39.2 >