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([2404:f801:9000:1a:efea::4b1]) by smtp.gmail.com with ESMTPSA id g7sm6679837pfv.66.2021.08.02.05.56.32 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 02 Aug 2021 05:56:45 -0700 (PDT) Subject: Re: [PATCH 04/13] HV: Mark vmbus ring buffer visible to host in Isolation VM To: Joerg Roedel Cc: kys@microsoft.com, haiyangz@microsoft.com, sthemmin@microsoft.com, wei.liu@kernel.org, decui@microsoft.com, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, x86@kernel.org, hpa@zytor.com, dave.hansen@linux.intel.com, luto@kernel.org, peterz@infradead.org, konrad.wilk@oracle.com, boris.ostrovsky@oracle.com, jgross@suse.com, sstabellini@kernel.org, will@kernel.org, davem@davemloft.net, kuba@kernel.org, jejb@linux.ibm.com, martin.petersen@oracle.com, arnd@arndb.de, hch@lst.de, m.szyprowski@samsung.com, robin.murphy@arm.com, thomas.lendacky@amd.com, brijesh.singh@amd.com, ardb@kernel.org, Tianyu.Lan@microsoft.com, rientjes@google.com, martin.b.radev@gmail.com, akpm@linux-foundation.org, rppt@kernel.org, kirill.shutemov@linux.intel.com, aneesh.kumar@linux.ibm.com, krish.sadhukhan@oracle.com, saravanand@fb.com, xen-devel@lists.xenproject.org, pgonda@google.com, david@redhat.com, keescook@chromium.org, hannes@cmpxchg.org, sfr@canb.auug.org.au, michael.h.kelley@microsoft.com, 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@redhat.com, anparri@microsoft.com References: <20210728145232.285861-1-ltykernel@gmail.com> <20210728145232.285861-5-ltykernel@gmail.com> From: Tianyu Lan Message-ID: <173823d1-280c-d34e-be2c-157b55bb6bc3@gmail.com> Date: Mon, 2 Aug 2021 20:56:29 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.12.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 8/2/2021 8:07 PM, Joerg Roedel wrote: > On Wed, Jul 28, 2021 at 10:52:19AM -0400, Tianyu Lan wrote: >> + if (type == HV_GPADL_BUFFER) >> + index = 0; >> + else >> + index = channel->gpadl_range[1].gpadlhandle ? 2 : 1; > > Hmm... This doesn't look very robust. Can you set fixed indexes for > different buffer types? HV_GPADL_BUFFER already has fixed index 0. But > as it is implemented here you risk that index 2 gets overwritten by > subsequent calls. Both second and third are HV_GPADL_RING type. One is send ring and the other is receive ring. The driver keeps the order to allocate rx and tx buffer. You are right this is not robust and will add a mutex to keep the order.