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[87.11.75.174]) by smtp.gmail.com with ESMTPSA id ke11-20020a17090798eb00b006e7fbf53398sm3531341ejc.129.2022.04.06.21.32.07 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 06 Apr 2022 21:32:08 -0700 (PDT) From: "Andrea Parri (Microsoft)" To: KY Srinivasan , Haiyang Zhang , Stephen Hemminger , Wei Liu , Dexuan Cui , Michael Kelley , Wei Hu , Lorenzo Pieralisi , Rob Herring , Krzysztof Wilczynski , Bjorn Helgaas Cc: linux-hyperv@vger.kernel.org, linux-pci@vger.kernel.org, linux-kernel@vger.kernel.org, "Andrea Parri (Microsoft)" Subject: [PATCH 1/6] Drivers: hv: vmbus: Fix handling of messages with transaction ID of zero Date: Thu, 7 Apr 2022 06:30:23 +0200 Message-Id: <20220407043028.379534-2-parri.andrea@gmail.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20220407043028.379534-1-parri.andrea@gmail.com> References: <20220407043028.379534-1-parri.andrea@gmail.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-pci@vger.kernel.org vmbus_request_addr() returns 0 (zero) if the transaction ID passed to as argument is 0. This is unfortunate for two reasons: first, netvsc_send_completion() does not check for a NULL cmd_rqst (before dereferencing the corresponding NVSP message); second, 0 is a *valid* value of cmd_rqst in netvsc_send_tx_complete(), cf. the call of vmbus_sendpacket() in netvsc_send_pkt(). vmbus_request_addr() has included the code in question since its introduction with commit e8b7db38449ac ("Drivers: hv: vmbus: Add vmbus_requestor data structure for VMBus hardening"); such code was motivated by the early use of vmbus_requestor by hv_storvsc. Since hv_storvsc moved to a tag-based mechanism to generate and retrieve transaction IDs with commit bf5fd8cae3c8f ("scsi: storvsc: Use blk_mq_unique_tag() to generate requestIDs"), vmbus_request_addr() can be modified to return VMBUS_RQST_ERROR if the ID is 0. This change solves the issues in hv_netvsc (and makes the handling of messages with transaction ID of 0 consistent with the semantics "the ID is not contained in the requestor/invalid ID"). vmbus_next_request_id(), vmbus_request_addr() should still reserve the ID of 0 for Hyper-V, because Hyper-V will "ignore" (not respond to) VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED packets/requests with transaction ID of 0 from the guest. Fixes: bf5fd8cae3c8f ("scsi: storvsc: Use blk_mq_unique_tag() to generate requestIDs") Signed-off-by: Andrea Parri (Microsoft) Reviewed-by: Michael Kelley --- The above hv_netvsc issues precede bf5fd8cae3c8f; however, these changes should not be backported to earlier commits since such a back-port would 'break' hv_storvsc. drivers/hv/channel.c | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/drivers/hv/channel.c b/drivers/hv/channel.c index dc5c35210c16a..20fc8d50a0398 100644 --- a/drivers/hv/channel.c +++ b/drivers/hv/channel.c @@ -1245,7 +1245,9 @@ u64 vmbus_next_request_id(struct vmbus_channel *channel, u64 rqst_addr) /* * Cannot return an ID of 0, which is reserved for an unsolicited - * message from Hyper-V. + * message from Hyper-V; Hyper-V does not acknowledge (respond to) + * VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED requests with ID of + * 0 sent by the guest. */ return current_id + 1; } @@ -1270,7 +1272,7 @@ u64 vmbus_request_addr(struct vmbus_channel *channel, u64 trans_id) /* Hyper-V can send an unsolicited message with ID of 0 */ if (!trans_id) - return trans_id; + return VMBUS_RQST_ERROR; spin_lock_irqsave(&rqstor->req_lock, flags);