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([2404:f801:9000:18:efec::50b]) by smtp.gmail.com with ESMTPSA id m184sm4248180pga.61.2021.12.03.23.26.39 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 03 Dec 2021 23:26:49 -0800 (PST) Message-ID: <877e6f24-2004-0681-f9f3-241fb6ace427@gmail.com> Date: Sat, 4 Dec 2021 15:26:36 +0800 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:91.0) Gecko/20100101 Thunderbird/91.3.2 Subject: Re: [PATCH V3 3/5] hyperv/IOMMU: Enable swiotlb bounce buffer for Isolation VM Content-Language: en-US To: "Michael Kelley (LINUX)" , KY Srinivasan , Haiyang Zhang , Stephen Hemminger , "wei.liu@kernel.org" , Dexuan Cui , "tglx@linutronix.de" , "mingo@redhat.com" , "bp@alien8.de" , "dave.hansen@linux.intel.com" , "x86@kernel.org" , "hpa@zytor.com" , "jgross@suse.com" , "sstabellini@kernel.org" , "boris.ostrovsky@oracle.com" , "joro@8bytes.org" , "will@kernel.org" , "davem@davemloft.net" , "kuba@kernel.org" , "jejb@linux.ibm.com" , "martin.petersen@oracle.com" , "arnd@arndb.de" , "hch@infradead.org" , "m.szyprowski@samsung.com" , "robin.murphy@arm.com" , Tianyu Lan , "thomas.lendacky@amd.com" , "xen-devel@lists.xenproject.org" Cc: "iommu@lists.linux-foundation.org" , "linux-arch@vger.kernel.org" , "linux-hyperv@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "linux-scsi@vger.kernel.org" , "netdev@vger.kernel.org" , vkuznets , "brijesh.singh@amd.com" , "konrad.wilk@oracle.com" , "hch@lst.de" , "parri.andrea@gmail.com" , "dave.hansen@intel.com" References: <20211201160257.1003912-1-ltykernel@gmail.com> <20211201160257.1003912-4-ltykernel@gmail.com> From: Tianyu Lan In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/4/2021 3:17 AM, Michael Kelley (LINUX) wrote: >> +static void __init hyperv_iommu_swiotlb_init(void) >> +{ >> + unsigned long hyperv_io_tlb_size; >> + void *hyperv_io_tlb_start; >> + >> + /* >> + * Allocate Hyper-V swiotlb bounce buffer at early place >> + * to reserve large contiguous memory. >> + */ >> + hyperv_io_tlb_size = swiotlb_size_or_default(); >> + hyperv_io_tlb_start = memblock_alloc(hyperv_io_tlb_size, PAGE_SIZE); >> + >> + if (!hyperv_io_tlb_start) >> + pr_warn("Fail to allocate Hyper-V swiotlb buffer.\n"); > In the error case, won't swiotlb_init_with_tlb() end up panic'ing when > it tries to zero out the memory? The only real choice here is to > return immediately after printing the message, and not call > swiotlb_init_with_tlb(). > Yes, agree. Will update.