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Tue, 11 Jun 2024 19:25:25 -0700 (PDT) X-Google-Smtp-Source: AGHT+IFvsdxEZWF7nQaJvnp0jXD7OQPULgKJoZVoyhvmNSjfLpNgTUMBdxgW2j4+TmPdWC9WVsAG4g== X-Received: by 2002:a05:6a21:3295:b0:1b7:889d:f206 with SMTP id adf61e73a8af0-1b8a9bbda24mr780875637.28.1718159125164; Tue, 11 Jun 2024 19:25:25 -0700 (PDT) Received: from [192.168.68.50] ([43.252.112.224]) by smtp.gmail.com with ESMTPSA id d9443c01a7336-1f6bd7fdd53sm110391655ad.293.2024.06.11.19.25.20 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 11 Jun 2024 19:25:24 -0700 (PDT) Message-ID: Date: Wed, 12 Jun 2024 12:25:18 +1000 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3] hw/arm/virt: Avoid unexpected warning from Linux guest on host with Fujitsu CPUs To: Zhenyu Zhang , qemu-arm@nongnu.org Cc: qemu-devel@nongnu.org, peter.maydell@linaro.org, robin.murphy@arm.com, Jonathan.Cameron@huawei.com, eauger@redhat.com, sebott@redhat.com, cohuck@redhat.com, ddutile@redhat.com, shahuang@redhat.com References: <20240612020506.307793-1-zhenyzha@redhat.com> Content-Language: en-US From: Gavin Shan In-Reply-To: <20240612020506.307793-1-zhenyzha@redhat.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Received-SPF: pass client-ip=170.10.133.124; envelope-from=gshan@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -21 X-Spam_score: -2.2 X-Spam_bar: -- X-Spam_report: (-2.2 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.141, 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_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 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 6/12/24 12:05, Zhenyu Zhang wrote: > Multiple warning messages and corresponding backtraces are observed when Linux > guest is booted on the host with Fujitsu CPUs. One of them is shown as below. > > [ 0.032443] ------------[ cut here ]------------ > [ 0.032446] uart-pl011 9000000.pl011: ARCH_DMA_MINALIGN smaller than > CTR_EL0.CWG (128 < 256) > [ 0.032454] WARNING: CPU: 0 PID: 1 at arch/arm64/mm/dma-mapping.c:54 > arch_setup_dma_ops+0xbc/0xcc > [ 0.032470] Modules linked in: > [ 0.032475] CPU: 0 PID: 1 Comm: swapper/0 Not tainted 5.14.0-452.el9.aarch64 > [ 0.032481] Hardware name: linux,dummy-virt (DT) > [ 0.032484] pstate: 60400005 (nZCv daif +PAN -UAO -TCO -DIT -SSBS BTYPE=--) > [ 0.032490] pc : arch_setup_dma_ops+0xbc/0xcc > [ 0.032496] lr : arch_setup_dma_ops+0xbc/0xcc > [ 0.032501] sp : ffff80008003b860 > [ 0.032503] x29: ffff80008003b860 x28: 0000000000000000 x27: ffffaae4b949049c > [ 0.032510] x26: 0000000000000000 x25: 0000000000000000 x24: 0000000000000000 > [ 0.032517] x23: 0000000000000100 x22: 0000000000000000 x21: 0000000000000000 > [ 0.032523] x20: 0000000100000000 x19: ffff2f06c02ea400 x18: ffffffffffffffff > [ 0.032529] x17: 00000000208a5f76 x16: 000000006589dbcb x15: ffffaae4ba071c89 > [ 0.032535] x14: 0000000000000000 x13: ffffaae4ba071c84 x12: 455f525443206e61 > [ 0.032541] x11: 68742072656c6c61 x10: 0000000000000029 x9 : ffffaae4b7d21da4 > [ 0.032547] x8 : 0000000000000029 x7 : 4c414e494d5f414d x6 : 0000000000000029 > [ 0.032553] x5 : 000000000000000f x4 : ffffaae4b9617a00 x3 : 0000000000000001 > [ 0.032558] x2 : 0000000000000000 x1 : 0000000000000000 x0 : ffff2f06c029be40 > [ 0.032564] Call trace: > [ 0.032566] arch_setup_dma_ops+0xbc/0xcc > [ 0.032572] of_dma_configure_id+0x138/0x300 > [ 0.032591] amba_dma_configure+0x34/0xc0 > [ 0.032600] really_probe+0x78/0x3dc > [ 0.032614] __driver_probe_device+0x108/0x160 > [ 0.032619] driver_probe_device+0x44/0x114 > [ 0.032624] __device_attach_driver+0xb8/0x14c > [ 0.032629] bus_for_each_drv+0x88/0xe4 > [ 0.032634] __device_attach+0xb0/0x1e0 > [ 0.032638] device_initial_probe+0x18/0x20 > [ 0.032643] bus_probe_device+0xa8/0xb0 > [ 0.032648] device_add+0x4b4/0x6c0 > [ 0.032652] amba_device_try_add.part.0+0x48/0x360 > [ 0.032657] amba_device_add+0x104/0x144 > [ 0.032662] of_amba_device_create.isra.0+0x100/0x1c4 > [ 0.032666] of_platform_bus_create+0x294/0x35c > [ 0.032669] of_platform_populate+0x5c/0x150 > [ 0.032672] of_platform_default_populate_init+0xd0/0xec > [ 0.032697] do_one_initcall+0x4c/0x2e0 > [ 0.032701] do_initcalls+0x100/0x13c > [ 0.032707] kernel_init_freeable+0x1c8/0x21c > [ 0.032712] kernel_init+0x28/0x140 > [ 0.032731] ret_from_fork+0x10/0x20 > [ 0.032735] ---[ end trace 0000000000000000 ]--- > > In Linux, a check is applied to every device which is exposed through > device-tree node. The warning message is raised when the device isn't > DMA coherent and the cache line size is larger than ARCH_DMA_MINALIGN > (128 bytes). The cache line is sorted from CTR_EL0[CWG], which corresponds > to 256 bytes on the guest CPUs. The DMA coherent capability is claimed > through 'dma-coherent' in their device-tree nodes or parent nodes. > > Fix the issue by adding 'dma-coherent' property to the device-tree root > node, meaning all devices are capable of DMA coherent by default. > > Signed-off-by: Zhenyu Zhang > --- > v3: Add comments explaining why we add 'dma-coherent' property (Peter) > --- > hw/arm/virt.c | 11 +++++++++++ > 1 file changed, 11 insertions(+) > Reviewed-by: Gavin Shan