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Drivers: hv: vmbus: Cleanup hv_post_message()
Minimize failures in this function by pre-allocating the buffer for posting messages. The hypercall for posting the message can fail for a number of reasons: 1. Transient resource related issues 2. Buffer alignment 3. Buffer cannot span a page boundry We address issues 2 and 3 by preallocating a per-cpu page for the buffer. Transient resource related failures are handled by retrying by the callers of this function. This patch is based on the investigation done by Dexuan Cui <decui@microsoft.com>. I would like to thank Sitsofe Wheeler <sitsofe@yahoo.com> for reporting the issue and helping in debuggging. Signed-off-by: K. Y. Srinivasan <kys@microsoft.com> Reported-by: Sitsofe Wheeler <sitsofe@yahoo.com> Cc: <stable@vger.kernel.org> Tested-by: Sitsofe Wheeler <sitsofe@yahoo.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
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@ -138,6 +138,8 @@ int hv_init(void)
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memset(hv_context.synic_event_page, 0, sizeof(void *) * NR_CPUS);
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memset(hv_context.synic_message_page, 0,
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sizeof(void *) * NR_CPUS);
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memset(hv_context.post_msg_page, 0,
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sizeof(void *) * NR_CPUS);
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memset(hv_context.vp_index, 0,
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sizeof(int) * NR_CPUS);
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memset(hv_context.event_dpc, 0,
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@ -217,26 +219,18 @@ int hv_post_message(union hv_connection_id connection_id,
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enum hv_message_type message_type,
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void *payload, size_t payload_size)
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{
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struct aligned_input {
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u64 alignment8;
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struct hv_input_post_message msg;
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};
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struct hv_input_post_message *aligned_msg;
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u16 status;
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unsigned long addr;
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if (payload_size > HV_MESSAGE_PAYLOAD_BYTE_COUNT)
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return -EMSGSIZE;
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addr = (unsigned long)kmalloc(sizeof(struct aligned_input), GFP_ATOMIC);
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if (!addr)
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return -ENOMEM;
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aligned_msg = (struct hv_input_post_message *)
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(ALIGN(addr, HV_HYPERCALL_PARAM_ALIGN));
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hv_context.post_msg_page[get_cpu()];
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aligned_msg->connectionid = connection_id;
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aligned_msg->reserved = 0;
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aligned_msg->message_type = message_type;
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aligned_msg->payload_size = payload_size;
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memcpy((void *)aligned_msg->payload, payload, payload_size);
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@ -244,8 +238,7 @@ int hv_post_message(union hv_connection_id connection_id,
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status = do_hypercall(HVCALL_POST_MESSAGE, aligned_msg, NULL)
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& 0xFFFF;
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kfree((void *)addr);
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put_cpu();
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return status;
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}
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@ -294,6 +287,14 @@ int hv_synic_alloc(void)
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pr_err("Unable to allocate SYNIC event page\n");
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goto err;
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}
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hv_context.post_msg_page[cpu] =
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(void *)get_zeroed_page(GFP_ATOMIC);
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if (hv_context.post_msg_page[cpu] == NULL) {
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pr_err("Unable to allocate post msg page\n");
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goto err;
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}
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}
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return 0;
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@ -308,6 +309,8 @@ static void hv_synic_free_cpu(int cpu)
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free_page((unsigned long)hv_context.synic_event_page[cpu]);
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if (hv_context.synic_message_page[cpu])
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free_page((unsigned long)hv_context.synic_message_page[cpu]);
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if (hv_context.post_msg_page[cpu])
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free_page((unsigned long)hv_context.post_msg_page[cpu]);
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}
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void hv_synic_free(void)
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@ -515,6 +515,10 @@ struct hv_context {
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* per-cpu list of the channels based on their CPU affinity.
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*/
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struct list_head percpu_list[NR_CPUS];
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/*
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* buffer to post messages to the host.
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*/
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void *post_msg_page[NR_CPUS];
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};
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extern struct hv_context hv_context;
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