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0001 // SPDX-License-Identifier: GPL-2.0-only
0002 /*
0003  * Copyright (c) 2009, Microsoft Corporation.
0004  *
0005  * Authors:
0006  *   Haiyang Zhang <haiyangz@microsoft.com>
0007  *   Hank Janssen  <hjanssen@microsoft.com>
0008  */
0009 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
0010 
0011 #include <linux/kernel.h>
0012 #include <linux/sched.h>
0013 #include <linux/wait.h>
0014 #include <linux/mm.h>
0015 #include <linux/slab.h>
0016 #include <linux/module.h>
0017 #include <linux/hyperv.h>
0018 #include <linux/uio.h>
0019 #include <linux/interrupt.h>
0020 #include <linux/set_memory.h>
0021 #include <asm/page.h>
0022 #include <asm/mshyperv.h>
0023 
0024 #include "hyperv_vmbus.h"
0025 
0026 /*
0027  * hv_gpadl_size - Return the real size of a gpadl, the size that Hyper-V uses
0028  *
0029  * For BUFFER gpadl, Hyper-V uses the exact same size as the guest does.
0030  *
0031  * For RING gpadl, in each ring, the guest uses one PAGE_SIZE as the header
0032  * (because of the alignment requirement), however, the hypervisor only
0033  * uses the first HV_HYP_PAGE_SIZE as the header, therefore leaving a
0034  * (PAGE_SIZE - HV_HYP_PAGE_SIZE) gap. And since there are two rings in a
0035  * ringbuffer, the total size for a RING gpadl that Hyper-V uses is the
0036  * total size that the guest uses minus twice of the gap size.
0037  */
0038 static inline u32 hv_gpadl_size(enum hv_gpadl_type type, u32 size)
0039 {
0040     switch (type) {
0041     case HV_GPADL_BUFFER:
0042         return size;
0043     case HV_GPADL_RING:
0044         /* The size of a ringbuffer must be page-aligned */
0045         BUG_ON(size % PAGE_SIZE);
0046         /*
0047          * Two things to notice here:
0048          * 1) We're processing two ring buffers as a unit
0049          * 2) We're skipping any space larger than HV_HYP_PAGE_SIZE in
0050          * the first guest-size page of each of the two ring buffers.
0051          * So we effectively subtract out two guest-size pages, and add
0052          * back two Hyper-V size pages.
0053          */
0054         return size - 2 * (PAGE_SIZE - HV_HYP_PAGE_SIZE);
0055     }
0056     BUG();
0057     return 0;
0058 }
0059 
0060 /*
0061  * hv_ring_gpadl_send_hvpgoffset - Calculate the send offset (in unit of
0062  *                                 HV_HYP_PAGE) in a ring gpadl based on the
0063  *                                 offset in the guest
0064  *
0065  * @offset: the offset (in bytes) where the send ringbuffer starts in the
0066  *               virtual address space of the guest
0067  */
0068 static inline u32 hv_ring_gpadl_send_hvpgoffset(u32 offset)
0069 {
0070 
0071     /*
0072      * For RING gpadl, in each ring, the guest uses one PAGE_SIZE as the
0073      * header (because of the alignment requirement), however, the
0074      * hypervisor only uses the first HV_HYP_PAGE_SIZE as the header,
0075      * therefore leaving a (PAGE_SIZE - HV_HYP_PAGE_SIZE) gap.
0076      *
0077      * And to calculate the effective send offset in gpadl, we need to
0078      * substract this gap.
0079      */
0080     return (offset - (PAGE_SIZE - HV_HYP_PAGE_SIZE)) >> HV_HYP_PAGE_SHIFT;
0081 }
0082 
0083 /*
0084  * hv_gpadl_hvpfn - Return the Hyper-V page PFN of the @i th Hyper-V page in
0085  *                  the gpadl
0086  *
0087  * @type: the type of the gpadl
0088  * @kbuffer: the pointer to the gpadl in the guest
0089  * @size: the total size (in bytes) of the gpadl
0090  * @send_offset: the offset (in bytes) where the send ringbuffer starts in the
0091  *               virtual address space of the guest
0092  * @i: the index
0093  */
0094 static inline u64 hv_gpadl_hvpfn(enum hv_gpadl_type type, void *kbuffer,
0095                  u32 size, u32 send_offset, int i)
0096 {
0097     int send_idx = hv_ring_gpadl_send_hvpgoffset(send_offset);
0098     unsigned long delta = 0UL;
0099 
0100     switch (type) {
0101     case HV_GPADL_BUFFER:
0102         break;
0103     case HV_GPADL_RING:
0104         if (i == 0)
0105             delta = 0;
0106         else if (i <= send_idx)
0107             delta = PAGE_SIZE - HV_HYP_PAGE_SIZE;
0108         else
0109             delta = 2 * (PAGE_SIZE - HV_HYP_PAGE_SIZE);
0110         break;
0111     default:
0112         BUG();
0113         break;
0114     }
0115 
0116     return virt_to_hvpfn(kbuffer + delta + (HV_HYP_PAGE_SIZE * i));
0117 }
0118 
0119 /*
0120  * vmbus_setevent- Trigger an event notification on the specified
0121  * channel.
0122  */
0123 void vmbus_setevent(struct vmbus_channel *channel)
0124 {
0125     struct hv_monitor_page *monitorpage;
0126 
0127     trace_vmbus_setevent(channel);
0128 
0129     /*
0130      * For channels marked as in "low latency" mode
0131      * bypass the monitor page mechanism.
0132      */
0133     if (channel->offermsg.monitor_allocated && !channel->low_latency) {
0134         vmbus_send_interrupt(channel->offermsg.child_relid);
0135 
0136         /* Get the child to parent monitor page */
0137         monitorpage = vmbus_connection.monitor_pages[1];
0138 
0139         sync_set_bit(channel->monitor_bit,
0140             (unsigned long *)&monitorpage->trigger_group
0141                     [channel->monitor_grp].pending);
0142 
0143     } else {
0144         vmbus_set_event(channel);
0145     }
0146 }
0147 EXPORT_SYMBOL_GPL(vmbus_setevent);
0148 
0149 /* vmbus_free_ring - drop mapping of ring buffer */
0150 void vmbus_free_ring(struct vmbus_channel *channel)
0151 {
0152     hv_ringbuffer_cleanup(&channel->outbound);
0153     hv_ringbuffer_cleanup(&channel->inbound);
0154 
0155     if (channel->ringbuffer_page) {
0156         __free_pages(channel->ringbuffer_page,
0157                  get_order(channel->ringbuffer_pagecount
0158                        << PAGE_SHIFT));
0159         channel->ringbuffer_page = NULL;
0160     }
0161 }
0162 EXPORT_SYMBOL_GPL(vmbus_free_ring);
0163 
0164 /* vmbus_alloc_ring - allocate and map pages for ring buffer */
0165 int vmbus_alloc_ring(struct vmbus_channel *newchannel,
0166              u32 send_size, u32 recv_size)
0167 {
0168     struct page *page;
0169     int order;
0170 
0171     if (send_size % PAGE_SIZE || recv_size % PAGE_SIZE)
0172         return -EINVAL;
0173 
0174     /* Allocate the ring buffer */
0175     order = get_order(send_size + recv_size);
0176     page = alloc_pages_node(cpu_to_node(newchannel->target_cpu),
0177                 GFP_KERNEL|__GFP_ZERO, order);
0178 
0179     if (!page)
0180         page = alloc_pages(GFP_KERNEL|__GFP_ZERO, order);
0181 
0182     if (!page)
0183         return -ENOMEM;
0184 
0185     newchannel->ringbuffer_page = page;
0186     newchannel->ringbuffer_pagecount = (send_size + recv_size) >> PAGE_SHIFT;
0187     newchannel->ringbuffer_send_offset = send_size >> PAGE_SHIFT;
0188 
0189     return 0;
0190 }
0191 EXPORT_SYMBOL_GPL(vmbus_alloc_ring);
0192 
0193 /* Used for Hyper-V Socket: a guest client's connect() to the host */
0194 int vmbus_send_tl_connect_request(const guid_t *shv_guest_servie_id,
0195                   const guid_t *shv_host_servie_id)
0196 {
0197     struct vmbus_channel_tl_connect_request conn_msg;
0198     int ret;
0199 
0200     memset(&conn_msg, 0, sizeof(conn_msg));
0201     conn_msg.header.msgtype = CHANNELMSG_TL_CONNECT_REQUEST;
0202     conn_msg.guest_endpoint_id = *shv_guest_servie_id;
0203     conn_msg.host_service_id = *shv_host_servie_id;
0204 
0205     ret = vmbus_post_msg(&conn_msg, sizeof(conn_msg), true);
0206 
0207     trace_vmbus_send_tl_connect_request(&conn_msg, ret);
0208 
0209     return ret;
0210 }
0211 EXPORT_SYMBOL_GPL(vmbus_send_tl_connect_request);
0212 
0213 static int send_modifychannel_without_ack(struct vmbus_channel *channel, u32 target_vp)
0214 {
0215     struct vmbus_channel_modifychannel msg;
0216     int ret;
0217 
0218     memset(&msg, 0, sizeof(msg));
0219     msg.header.msgtype = CHANNELMSG_MODIFYCHANNEL;
0220     msg.child_relid = channel->offermsg.child_relid;
0221     msg.target_vp = target_vp;
0222 
0223     ret = vmbus_post_msg(&msg, sizeof(msg), true);
0224     trace_vmbus_send_modifychannel(&msg, ret);
0225 
0226     return ret;
0227 }
0228 
0229 static int send_modifychannel_with_ack(struct vmbus_channel *channel, u32 target_vp)
0230 {
0231     struct vmbus_channel_modifychannel *msg;
0232     struct vmbus_channel_msginfo *info;
0233     unsigned long flags;
0234     int ret;
0235 
0236     info = kzalloc(sizeof(struct vmbus_channel_msginfo) +
0237                 sizeof(struct vmbus_channel_modifychannel),
0238                GFP_KERNEL);
0239     if (!info)
0240         return -ENOMEM;
0241 
0242     init_completion(&info->waitevent);
0243     info->waiting_channel = channel;
0244 
0245     msg = (struct vmbus_channel_modifychannel *)info->msg;
0246     msg->header.msgtype = CHANNELMSG_MODIFYCHANNEL;
0247     msg->child_relid = channel->offermsg.child_relid;
0248     msg->target_vp = target_vp;
0249 
0250     spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
0251     list_add_tail(&info->msglistentry, &vmbus_connection.chn_msg_list);
0252     spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
0253 
0254     ret = vmbus_post_msg(msg, sizeof(*msg), true);
0255     trace_vmbus_send_modifychannel(msg, ret);
0256     if (ret != 0) {
0257         spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
0258         list_del(&info->msglistentry);
0259         spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
0260         goto free_info;
0261     }
0262 
0263     /*
0264      * Release channel_mutex; otherwise, vmbus_onoffer_rescind() could block on
0265      * the mutex and be unable to signal the completion.
0266      *
0267      * See the caller target_cpu_store() for information about the usage of the
0268      * mutex.
0269      */
0270     mutex_unlock(&vmbus_connection.channel_mutex);
0271     wait_for_completion(&info->waitevent);
0272     mutex_lock(&vmbus_connection.channel_mutex);
0273 
0274     spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
0275     list_del(&info->msglistentry);
0276     spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
0277 
0278     if (info->response.modify_response.status)
0279         ret = -EAGAIN;
0280 
0281 free_info:
0282     kfree(info);
0283     return ret;
0284 }
0285 
0286 /*
0287  * Set/change the vCPU (@target_vp) the channel (@child_relid) will interrupt.
0288  *
0289  * CHANNELMSG_MODIFYCHANNEL messages are aynchronous.  When VMbus version 5.3
0290  * or later is negotiated, Hyper-V always sends an ACK in response to such a
0291  * message.  For VMbus version 5.2 and earlier, it never sends an ACK.  With-
0292  * out an ACK, we can not know when the host will stop interrupting the "old"
0293  * vCPU and start interrupting the "new" vCPU for the given channel.
0294  *
0295  * The CHANNELMSG_MODIFYCHANNEL message type is supported since VMBus version
0296  * VERSION_WIN10_V4_1.
0297  */
0298 int vmbus_send_modifychannel(struct vmbus_channel *channel, u32 target_vp)
0299 {
0300     if (vmbus_proto_version >= VERSION_WIN10_V5_3)
0301         return send_modifychannel_with_ack(channel, target_vp);
0302     return send_modifychannel_without_ack(channel, target_vp);
0303 }
0304 EXPORT_SYMBOL_GPL(vmbus_send_modifychannel);
0305 
0306 /*
0307  * create_gpadl_header - Creates a gpadl for the specified buffer
0308  */
0309 static int create_gpadl_header(enum hv_gpadl_type type, void *kbuffer,
0310                    u32 size, u32 send_offset,
0311                    struct vmbus_channel_msginfo **msginfo)
0312 {
0313     int i;
0314     int pagecount;
0315     struct vmbus_channel_gpadl_header *gpadl_header;
0316     struct vmbus_channel_gpadl_body *gpadl_body;
0317     struct vmbus_channel_msginfo *msgheader;
0318     struct vmbus_channel_msginfo *msgbody = NULL;
0319     u32 msgsize;
0320 
0321     int pfnsum, pfncount, pfnleft, pfncurr, pfnsize;
0322 
0323     pagecount = hv_gpadl_size(type, size) >> HV_HYP_PAGE_SHIFT;
0324 
0325     /* do we need a gpadl body msg */
0326     pfnsize = MAX_SIZE_CHANNEL_MESSAGE -
0327           sizeof(struct vmbus_channel_gpadl_header) -
0328           sizeof(struct gpa_range);
0329     pfncount = pfnsize / sizeof(u64);
0330 
0331     if (pagecount > pfncount) {
0332         /* we need a gpadl body */
0333         /* fill in the header */
0334         msgsize = sizeof(struct vmbus_channel_msginfo) +
0335               sizeof(struct vmbus_channel_gpadl_header) +
0336               sizeof(struct gpa_range) + pfncount * sizeof(u64);
0337         msgheader =  kzalloc(msgsize, GFP_KERNEL);
0338         if (!msgheader)
0339             goto nomem;
0340 
0341         INIT_LIST_HEAD(&msgheader->submsglist);
0342         msgheader->msgsize = msgsize;
0343 
0344         gpadl_header = (struct vmbus_channel_gpadl_header *)
0345             msgheader->msg;
0346         gpadl_header->rangecount = 1;
0347         gpadl_header->range_buflen = sizeof(struct gpa_range) +
0348                      pagecount * sizeof(u64);
0349         gpadl_header->range[0].byte_offset = 0;
0350         gpadl_header->range[0].byte_count = hv_gpadl_size(type, size);
0351         for (i = 0; i < pfncount; i++)
0352             gpadl_header->range[0].pfn_array[i] = hv_gpadl_hvpfn(
0353                 type, kbuffer, size, send_offset, i);
0354         *msginfo = msgheader;
0355 
0356         pfnsum = pfncount;
0357         pfnleft = pagecount - pfncount;
0358 
0359         /* how many pfns can we fit */
0360         pfnsize = MAX_SIZE_CHANNEL_MESSAGE -
0361               sizeof(struct vmbus_channel_gpadl_body);
0362         pfncount = pfnsize / sizeof(u64);
0363 
0364         /* fill in the body */
0365         while (pfnleft) {
0366             if (pfnleft > pfncount)
0367                 pfncurr = pfncount;
0368             else
0369                 pfncurr = pfnleft;
0370 
0371             msgsize = sizeof(struct vmbus_channel_msginfo) +
0372                   sizeof(struct vmbus_channel_gpadl_body) +
0373                   pfncurr * sizeof(u64);
0374             msgbody = kzalloc(msgsize, GFP_KERNEL);
0375 
0376             if (!msgbody) {
0377                 struct vmbus_channel_msginfo *pos = NULL;
0378                 struct vmbus_channel_msginfo *tmp = NULL;
0379                 /*
0380                  * Free up all the allocated messages.
0381                  */
0382                 list_for_each_entry_safe(pos, tmp,
0383                     &msgheader->submsglist,
0384                     msglistentry) {
0385 
0386                     list_del(&pos->msglistentry);
0387                     kfree(pos);
0388                 }
0389 
0390                 goto nomem;
0391             }
0392 
0393             msgbody->msgsize = msgsize;
0394             gpadl_body =
0395                 (struct vmbus_channel_gpadl_body *)msgbody->msg;
0396 
0397             /*
0398              * Gpadl is u32 and we are using a pointer which could
0399              * be 64-bit
0400              * This is governed by the guest/host protocol and
0401              * so the hypervisor guarantees that this is ok.
0402              */
0403             for (i = 0; i < pfncurr; i++)
0404                 gpadl_body->pfn[i] = hv_gpadl_hvpfn(type,
0405                     kbuffer, size, send_offset, pfnsum + i);
0406 
0407             /* add to msg header */
0408             list_add_tail(&msgbody->msglistentry,
0409                       &msgheader->submsglist);
0410             pfnsum += pfncurr;
0411             pfnleft -= pfncurr;
0412         }
0413     } else {
0414         /* everything fits in a header */
0415         msgsize = sizeof(struct vmbus_channel_msginfo) +
0416               sizeof(struct vmbus_channel_gpadl_header) +
0417               sizeof(struct gpa_range) + pagecount * sizeof(u64);
0418         msgheader = kzalloc(msgsize, GFP_KERNEL);
0419         if (msgheader == NULL)
0420             goto nomem;
0421 
0422         INIT_LIST_HEAD(&msgheader->submsglist);
0423         msgheader->msgsize = msgsize;
0424 
0425         gpadl_header = (struct vmbus_channel_gpadl_header *)
0426             msgheader->msg;
0427         gpadl_header->rangecount = 1;
0428         gpadl_header->range_buflen = sizeof(struct gpa_range) +
0429                      pagecount * sizeof(u64);
0430         gpadl_header->range[0].byte_offset = 0;
0431         gpadl_header->range[0].byte_count = hv_gpadl_size(type, size);
0432         for (i = 0; i < pagecount; i++)
0433             gpadl_header->range[0].pfn_array[i] = hv_gpadl_hvpfn(
0434                 type, kbuffer, size, send_offset, i);
0435 
0436         *msginfo = msgheader;
0437     }
0438 
0439     return 0;
0440 nomem:
0441     kfree(msgheader);
0442     kfree(msgbody);
0443     return -ENOMEM;
0444 }
0445 
0446 /*
0447  * __vmbus_establish_gpadl - Establish a GPADL for a buffer or ringbuffer
0448  *
0449  * @channel: a channel
0450  * @type: the type of the corresponding GPADL, only meaningful for the guest.
0451  * @kbuffer: from kmalloc or vmalloc
0452  * @size: page-size multiple
0453  * @send_offset: the offset (in bytes) where the send ring buffer starts,
0454  *              should be 0 for BUFFER type gpadl
0455  * @gpadl_handle: some funky thing
0456  */
0457 static int __vmbus_establish_gpadl(struct vmbus_channel *channel,
0458                    enum hv_gpadl_type type, void *kbuffer,
0459                    u32 size, u32 send_offset,
0460                    struct vmbus_gpadl *gpadl)
0461 {
0462     struct vmbus_channel_gpadl_header *gpadlmsg;
0463     struct vmbus_channel_gpadl_body *gpadl_body;
0464     struct vmbus_channel_msginfo *msginfo = NULL;
0465     struct vmbus_channel_msginfo *submsginfo, *tmp;
0466     struct list_head *curr;
0467     u32 next_gpadl_handle;
0468     unsigned long flags;
0469     int ret = 0;
0470 
0471     next_gpadl_handle =
0472         (atomic_inc_return(&vmbus_connection.next_gpadl_handle) - 1);
0473 
0474     ret = create_gpadl_header(type, kbuffer, size, send_offset, &msginfo);
0475     if (ret)
0476         return ret;
0477 
0478     ret = set_memory_decrypted((unsigned long)kbuffer,
0479                    PFN_UP(size));
0480     if (ret) {
0481         dev_warn(&channel->device_obj->device,
0482              "Failed to set host visibility for new GPADL %d.\n",
0483              ret);
0484         return ret;
0485     }
0486 
0487     init_completion(&msginfo->waitevent);
0488     msginfo->waiting_channel = channel;
0489 
0490     gpadlmsg = (struct vmbus_channel_gpadl_header *)msginfo->msg;
0491     gpadlmsg->header.msgtype = CHANNELMSG_GPADL_HEADER;
0492     gpadlmsg->child_relid = channel->offermsg.child_relid;
0493     gpadlmsg->gpadl = next_gpadl_handle;
0494 
0495 
0496     spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
0497     list_add_tail(&msginfo->msglistentry,
0498               &vmbus_connection.chn_msg_list);
0499 
0500     spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
0501 
0502     if (channel->rescind) {
0503         ret = -ENODEV;
0504         goto cleanup;
0505     }
0506 
0507     ret = vmbus_post_msg(gpadlmsg, msginfo->msgsize -
0508                  sizeof(*msginfo), true);
0509 
0510     trace_vmbus_establish_gpadl_header(gpadlmsg, ret);
0511 
0512     if (ret != 0)
0513         goto cleanup;
0514 
0515     list_for_each(curr, &msginfo->submsglist) {
0516         submsginfo = (struct vmbus_channel_msginfo *)curr;
0517         gpadl_body =
0518             (struct vmbus_channel_gpadl_body *)submsginfo->msg;
0519 
0520         gpadl_body->header.msgtype =
0521             CHANNELMSG_GPADL_BODY;
0522         gpadl_body->gpadl = next_gpadl_handle;
0523 
0524         ret = vmbus_post_msg(gpadl_body,
0525                      submsginfo->msgsize - sizeof(*submsginfo),
0526                      true);
0527 
0528         trace_vmbus_establish_gpadl_body(gpadl_body, ret);
0529 
0530         if (ret != 0)
0531             goto cleanup;
0532 
0533     }
0534     wait_for_completion(&msginfo->waitevent);
0535 
0536     if (msginfo->response.gpadl_created.creation_status != 0) {
0537         pr_err("Failed to establish GPADL: err = 0x%x\n",
0538                msginfo->response.gpadl_created.creation_status);
0539 
0540         ret = -EDQUOT;
0541         goto cleanup;
0542     }
0543 
0544     if (channel->rescind) {
0545         ret = -ENODEV;
0546         goto cleanup;
0547     }
0548 
0549     /* At this point, we received the gpadl created msg */
0550     gpadl->gpadl_handle = gpadlmsg->gpadl;
0551     gpadl->buffer = kbuffer;
0552     gpadl->size = size;
0553 
0554 
0555 cleanup:
0556     spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
0557     list_del(&msginfo->msglistentry);
0558     spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
0559     list_for_each_entry_safe(submsginfo, tmp, &msginfo->submsglist,
0560                  msglistentry) {
0561         kfree(submsginfo);
0562     }
0563 
0564     kfree(msginfo);
0565 
0566     if (ret)
0567         set_memory_encrypted((unsigned long)kbuffer,
0568                      PFN_UP(size));
0569 
0570     return ret;
0571 }
0572 
0573 /*
0574  * vmbus_establish_gpadl - Establish a GPADL for the specified buffer
0575  *
0576  * @channel: a channel
0577  * @kbuffer: from kmalloc or vmalloc
0578  * @size: page-size multiple
0579  * @gpadl_handle: some funky thing
0580  */
0581 int vmbus_establish_gpadl(struct vmbus_channel *channel, void *kbuffer,
0582               u32 size, struct vmbus_gpadl *gpadl)
0583 {
0584     return __vmbus_establish_gpadl(channel, HV_GPADL_BUFFER, kbuffer, size,
0585                        0U, gpadl);
0586 }
0587 EXPORT_SYMBOL_GPL(vmbus_establish_gpadl);
0588 
0589 /**
0590  * request_arr_init - Allocates memory for the requestor array. Each slot
0591  * keeps track of the next available slot in the array. Initially, each
0592  * slot points to the next one (as in a Linked List). The last slot
0593  * does not point to anything, so its value is U64_MAX by default.
0594  * @size The size of the array
0595  */
0596 static u64 *request_arr_init(u32 size)
0597 {
0598     int i;
0599     u64 *req_arr;
0600 
0601     req_arr = kcalloc(size, sizeof(u64), GFP_KERNEL);
0602     if (!req_arr)
0603         return NULL;
0604 
0605     for (i = 0; i < size - 1; i++)
0606         req_arr[i] = i + 1;
0607 
0608     /* Last slot (no more available slots) */
0609     req_arr[i] = U64_MAX;
0610 
0611     return req_arr;
0612 }
0613 
0614 /*
0615  * vmbus_alloc_requestor - Initializes @rqstor's fields.
0616  * Index 0 is the first free slot
0617  * @size: Size of the requestor array
0618  */
0619 static int vmbus_alloc_requestor(struct vmbus_requestor *rqstor, u32 size)
0620 {
0621     u64 *rqst_arr;
0622     unsigned long *bitmap;
0623 
0624     rqst_arr = request_arr_init(size);
0625     if (!rqst_arr)
0626         return -ENOMEM;
0627 
0628     bitmap = bitmap_zalloc(size, GFP_KERNEL);
0629     if (!bitmap) {
0630         kfree(rqst_arr);
0631         return -ENOMEM;
0632     }
0633 
0634     rqstor->req_arr = rqst_arr;
0635     rqstor->req_bitmap = bitmap;
0636     rqstor->size = size;
0637     rqstor->next_request_id = 0;
0638     spin_lock_init(&rqstor->req_lock);
0639 
0640     return 0;
0641 }
0642 
0643 /*
0644  * vmbus_free_requestor - Frees memory allocated for @rqstor
0645  * @rqstor: Pointer to the requestor struct
0646  */
0647 static void vmbus_free_requestor(struct vmbus_requestor *rqstor)
0648 {
0649     kfree(rqstor->req_arr);
0650     bitmap_free(rqstor->req_bitmap);
0651 }
0652 
0653 static int __vmbus_open(struct vmbus_channel *newchannel,
0654                void *userdata, u32 userdatalen,
0655                void (*onchannelcallback)(void *context), void *context)
0656 {
0657     struct vmbus_channel_open_channel *open_msg;
0658     struct vmbus_channel_msginfo *open_info = NULL;
0659     struct page *page = newchannel->ringbuffer_page;
0660     u32 send_pages, recv_pages;
0661     unsigned long flags;
0662     int err;
0663 
0664     if (userdatalen > MAX_USER_DEFINED_BYTES)
0665         return -EINVAL;
0666 
0667     send_pages = newchannel->ringbuffer_send_offset;
0668     recv_pages = newchannel->ringbuffer_pagecount - send_pages;
0669 
0670     if (newchannel->state != CHANNEL_OPEN_STATE)
0671         return -EINVAL;
0672 
0673     /* Create and init requestor */
0674     if (newchannel->rqstor_size) {
0675         if (vmbus_alloc_requestor(&newchannel->requestor, newchannel->rqstor_size))
0676             return -ENOMEM;
0677     }
0678 
0679     newchannel->state = CHANNEL_OPENING_STATE;
0680     newchannel->onchannel_callback = onchannelcallback;
0681     newchannel->channel_callback_context = context;
0682 
0683     if (!newchannel->max_pkt_size)
0684         newchannel->max_pkt_size = VMBUS_DEFAULT_MAX_PKT_SIZE;
0685 
0686     /* Establish the gpadl for the ring buffer */
0687     newchannel->ringbuffer_gpadlhandle.gpadl_handle = 0;
0688 
0689     err = __vmbus_establish_gpadl(newchannel, HV_GPADL_RING,
0690                       page_address(newchannel->ringbuffer_page),
0691                       (send_pages + recv_pages) << PAGE_SHIFT,
0692                       newchannel->ringbuffer_send_offset << PAGE_SHIFT,
0693                       &newchannel->ringbuffer_gpadlhandle);
0694     if (err)
0695         goto error_clean_ring;
0696 
0697     err = hv_ringbuffer_init(&newchannel->outbound,
0698                  page, send_pages, 0);
0699     if (err)
0700         goto error_free_gpadl;
0701 
0702     err = hv_ringbuffer_init(&newchannel->inbound, &page[send_pages],
0703                  recv_pages, newchannel->max_pkt_size);
0704     if (err)
0705         goto error_free_gpadl;
0706 
0707     /* Create and init the channel open message */
0708     open_info = kzalloc(sizeof(*open_info) +
0709                sizeof(struct vmbus_channel_open_channel),
0710                GFP_KERNEL);
0711     if (!open_info) {
0712         err = -ENOMEM;
0713         goto error_free_gpadl;
0714     }
0715 
0716     init_completion(&open_info->waitevent);
0717     open_info->waiting_channel = newchannel;
0718 
0719     open_msg = (struct vmbus_channel_open_channel *)open_info->msg;
0720     open_msg->header.msgtype = CHANNELMSG_OPENCHANNEL;
0721     open_msg->openid = newchannel->offermsg.child_relid;
0722     open_msg->child_relid = newchannel->offermsg.child_relid;
0723     open_msg->ringbuffer_gpadlhandle
0724         = newchannel->ringbuffer_gpadlhandle.gpadl_handle;
0725     /*
0726      * The unit of ->downstream_ringbuffer_pageoffset is HV_HYP_PAGE and
0727      * the unit of ->ringbuffer_send_offset (i.e. send_pages) is PAGE, so
0728      * here we calculate it into HV_HYP_PAGE.
0729      */
0730     open_msg->downstream_ringbuffer_pageoffset =
0731         hv_ring_gpadl_send_hvpgoffset(send_pages << PAGE_SHIFT);
0732     open_msg->target_vp = hv_cpu_number_to_vp_number(newchannel->target_cpu);
0733 
0734     if (userdatalen)
0735         memcpy(open_msg->userdata, userdata, userdatalen);
0736 
0737     spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
0738     list_add_tail(&open_info->msglistentry,
0739               &vmbus_connection.chn_msg_list);
0740     spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
0741 
0742     if (newchannel->rescind) {
0743         err = -ENODEV;
0744         goto error_clean_msglist;
0745     }
0746 
0747     err = vmbus_post_msg(open_msg,
0748                  sizeof(struct vmbus_channel_open_channel), true);
0749 
0750     trace_vmbus_open(open_msg, err);
0751 
0752     if (err != 0)
0753         goto error_clean_msglist;
0754 
0755     wait_for_completion(&open_info->waitevent);
0756 
0757     spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
0758     list_del(&open_info->msglistentry);
0759     spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
0760 
0761     if (newchannel->rescind) {
0762         err = -ENODEV;
0763         goto error_free_info;
0764     }
0765 
0766     if (open_info->response.open_result.status) {
0767         err = -EAGAIN;
0768         goto error_free_info;
0769     }
0770 
0771     newchannel->state = CHANNEL_OPENED_STATE;
0772     kfree(open_info);
0773     return 0;
0774 
0775 error_clean_msglist:
0776     spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
0777     list_del(&open_info->msglistentry);
0778     spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
0779 error_free_info:
0780     kfree(open_info);
0781 error_free_gpadl:
0782     vmbus_teardown_gpadl(newchannel, &newchannel->ringbuffer_gpadlhandle);
0783 error_clean_ring:
0784     hv_ringbuffer_cleanup(&newchannel->outbound);
0785     hv_ringbuffer_cleanup(&newchannel->inbound);
0786     vmbus_free_requestor(&newchannel->requestor);
0787     newchannel->state = CHANNEL_OPEN_STATE;
0788     return err;
0789 }
0790 
0791 /*
0792  * vmbus_connect_ring - Open the channel but reuse ring buffer
0793  */
0794 int vmbus_connect_ring(struct vmbus_channel *newchannel,
0795                void (*onchannelcallback)(void *context), void *context)
0796 {
0797     return  __vmbus_open(newchannel, NULL, 0, onchannelcallback, context);
0798 }
0799 EXPORT_SYMBOL_GPL(vmbus_connect_ring);
0800 
0801 /*
0802  * vmbus_open - Open the specified channel.
0803  */
0804 int vmbus_open(struct vmbus_channel *newchannel,
0805            u32 send_ringbuffer_size, u32 recv_ringbuffer_size,
0806            void *userdata, u32 userdatalen,
0807            void (*onchannelcallback)(void *context), void *context)
0808 {
0809     int err;
0810 
0811     err = vmbus_alloc_ring(newchannel, send_ringbuffer_size,
0812                    recv_ringbuffer_size);
0813     if (err)
0814         return err;
0815 
0816     err = __vmbus_open(newchannel, userdata, userdatalen,
0817                onchannelcallback, context);
0818     if (err)
0819         vmbus_free_ring(newchannel);
0820 
0821     return err;
0822 }
0823 EXPORT_SYMBOL_GPL(vmbus_open);
0824 
0825 /*
0826  * vmbus_teardown_gpadl -Teardown the specified GPADL handle
0827  */
0828 int vmbus_teardown_gpadl(struct vmbus_channel *channel, struct vmbus_gpadl *gpadl)
0829 {
0830     struct vmbus_channel_gpadl_teardown *msg;
0831     struct vmbus_channel_msginfo *info;
0832     unsigned long flags;
0833     int ret;
0834 
0835     info = kzalloc(sizeof(*info) +
0836                sizeof(struct vmbus_channel_gpadl_teardown), GFP_KERNEL);
0837     if (!info)
0838         return -ENOMEM;
0839 
0840     init_completion(&info->waitevent);
0841     info->waiting_channel = channel;
0842 
0843     msg = (struct vmbus_channel_gpadl_teardown *)info->msg;
0844 
0845     msg->header.msgtype = CHANNELMSG_GPADL_TEARDOWN;
0846     msg->child_relid = channel->offermsg.child_relid;
0847     msg->gpadl = gpadl->gpadl_handle;
0848 
0849     spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
0850     list_add_tail(&info->msglistentry,
0851               &vmbus_connection.chn_msg_list);
0852     spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
0853 
0854     if (channel->rescind)
0855         goto post_msg_err;
0856 
0857     ret = vmbus_post_msg(msg, sizeof(struct vmbus_channel_gpadl_teardown),
0858                  true);
0859 
0860     trace_vmbus_teardown_gpadl(msg, ret);
0861 
0862     if (ret)
0863         goto post_msg_err;
0864 
0865     wait_for_completion(&info->waitevent);
0866 
0867     gpadl->gpadl_handle = 0;
0868 
0869 post_msg_err:
0870     /*
0871      * If the channel has been rescinded;
0872      * we will be awakened by the rescind
0873      * handler; set the error code to zero so we don't leak memory.
0874      */
0875     if (channel->rescind)
0876         ret = 0;
0877 
0878     spin_lock_irqsave(&vmbus_connection.channelmsg_lock, flags);
0879     list_del(&info->msglistentry);
0880     spin_unlock_irqrestore(&vmbus_connection.channelmsg_lock, flags);
0881 
0882     kfree(info);
0883 
0884     ret = set_memory_encrypted((unsigned long)gpadl->buffer,
0885                    PFN_UP(gpadl->size));
0886     if (ret)
0887         pr_warn("Fail to set mem host visibility in GPADL teardown %d.\n", ret);
0888 
0889     return ret;
0890 }
0891 EXPORT_SYMBOL_GPL(vmbus_teardown_gpadl);
0892 
0893 void vmbus_reset_channel_cb(struct vmbus_channel *channel)
0894 {
0895     unsigned long flags;
0896 
0897     /*
0898      * vmbus_on_event(), running in the per-channel tasklet, can race
0899      * with vmbus_close_internal() in the case of SMP guest, e.g., when
0900      * the former is accessing channel->inbound.ring_buffer, the latter
0901      * could be freeing the ring_buffer pages, so here we must stop it
0902      * first.
0903      *
0904      * vmbus_chan_sched() might call the netvsc driver callback function
0905      * that ends up scheduling NAPI work that accesses the ring buffer.
0906      * At this point, we have to ensure that any such work is completed
0907      * and that the channel ring buffer is no longer being accessed, cf.
0908      * the calls to napi_disable() in netvsc_device_remove().
0909      */
0910     tasklet_disable(&channel->callback_event);
0911 
0912     /* See the inline comments in vmbus_chan_sched(). */
0913     spin_lock_irqsave(&channel->sched_lock, flags);
0914     channel->onchannel_callback = NULL;
0915     spin_unlock_irqrestore(&channel->sched_lock, flags);
0916 
0917     channel->sc_creation_callback = NULL;
0918 
0919     /* Re-enable tasklet for use on re-open */
0920     tasklet_enable(&channel->callback_event);
0921 }
0922 
0923 static int vmbus_close_internal(struct vmbus_channel *channel)
0924 {
0925     struct vmbus_channel_close_channel *msg;
0926     int ret;
0927 
0928     vmbus_reset_channel_cb(channel);
0929 
0930     /*
0931      * In case a device driver's probe() fails (e.g.,
0932      * util_probe() -> vmbus_open() returns -ENOMEM) and the device is
0933      * rescinded later (e.g., we dynamically disable an Integrated Service
0934      * in Hyper-V Manager), the driver's remove() invokes vmbus_close():
0935      * here we should skip most of the below cleanup work.
0936      */
0937     if (channel->state != CHANNEL_OPENED_STATE)
0938         return -EINVAL;
0939 
0940     channel->state = CHANNEL_OPEN_STATE;
0941 
0942     /* Send a closing message */
0943 
0944     msg = &channel->close_msg.msg;
0945 
0946     msg->header.msgtype = CHANNELMSG_CLOSECHANNEL;
0947     msg->child_relid = channel->offermsg.child_relid;
0948 
0949     ret = vmbus_post_msg(msg, sizeof(struct vmbus_channel_close_channel),
0950                  true);
0951 
0952     trace_vmbus_close_internal(msg, ret);
0953 
0954     if (ret) {
0955         pr_err("Close failed: close post msg return is %d\n", ret);
0956         /*
0957          * If we failed to post the close msg,
0958          * it is perhaps better to leak memory.
0959          */
0960     }
0961 
0962     /* Tear down the gpadl for the channel's ring buffer */
0963     else if (channel->ringbuffer_gpadlhandle.gpadl_handle) {
0964         ret = vmbus_teardown_gpadl(channel, &channel->ringbuffer_gpadlhandle);
0965         if (ret) {
0966             pr_err("Close failed: teardown gpadl return %d\n", ret);
0967             /*
0968              * If we failed to teardown gpadl,
0969              * it is perhaps better to leak memory.
0970              */
0971         }
0972     }
0973 
0974     if (!ret)
0975         vmbus_free_requestor(&channel->requestor);
0976 
0977     return ret;
0978 }
0979 
0980 /* disconnect ring - close all channels */
0981 int vmbus_disconnect_ring(struct vmbus_channel *channel)
0982 {
0983     struct vmbus_channel *cur_channel, *tmp;
0984     int ret;
0985 
0986     if (channel->primary_channel != NULL)
0987         return -EINVAL;
0988 
0989     list_for_each_entry_safe(cur_channel, tmp, &channel->sc_list, sc_list) {
0990         if (cur_channel->rescind)
0991             wait_for_completion(&cur_channel->rescind_event);
0992 
0993         mutex_lock(&vmbus_connection.channel_mutex);
0994         if (vmbus_close_internal(cur_channel) == 0) {
0995             vmbus_free_ring(cur_channel);
0996 
0997             if (cur_channel->rescind)
0998                 hv_process_channel_removal(cur_channel);
0999         }
1000         mutex_unlock(&vmbus_connection.channel_mutex);
1001     }
1002 
1003     /*
1004      * Now close the primary.
1005      */
1006     mutex_lock(&vmbus_connection.channel_mutex);
1007     ret = vmbus_close_internal(channel);
1008     mutex_unlock(&vmbus_connection.channel_mutex);
1009 
1010     return ret;
1011 }
1012 EXPORT_SYMBOL_GPL(vmbus_disconnect_ring);
1013 
1014 /*
1015  * vmbus_close - Close the specified channel
1016  */
1017 void vmbus_close(struct vmbus_channel *channel)
1018 {
1019     if (vmbus_disconnect_ring(channel) == 0)
1020         vmbus_free_ring(channel);
1021 }
1022 EXPORT_SYMBOL_GPL(vmbus_close);
1023 
1024 /**
1025  * vmbus_sendpacket_getid() - Send the specified buffer on the given channel
1026  * @channel: Pointer to vmbus_channel structure
1027  * @buffer: Pointer to the buffer you want to send the data from.
1028  * @bufferlen: Maximum size of what the buffer holds.
1029  * @requestid: Identifier of the request
1030  * @trans_id: Identifier of the transaction associated to this request, if
1031  *            the send is successful; undefined, otherwise.
1032  * @type: Type of packet that is being sent e.g. negotiate, time
1033  *    packet etc.
1034  * @flags: 0 or VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED
1035  *
1036  * Sends data in @buffer directly to Hyper-V via the vmbus.
1037  * This will send the data unparsed to Hyper-V.
1038  *
1039  * Mainly used by Hyper-V drivers.
1040  */
1041 int vmbus_sendpacket_getid(struct vmbus_channel *channel, void *buffer,
1042                u32 bufferlen, u64 requestid, u64 *trans_id,
1043                enum vmbus_packet_type type, u32 flags)
1044 {
1045     struct vmpacket_descriptor desc;
1046     u32 packetlen = sizeof(struct vmpacket_descriptor) + bufferlen;
1047     u32 packetlen_aligned = ALIGN(packetlen, sizeof(u64));
1048     struct kvec bufferlist[3];
1049     u64 aligned_data = 0;
1050     int num_vecs = ((bufferlen != 0) ? 3 : 1);
1051 
1052 
1053     /* Setup the descriptor */
1054     desc.type = type; /* VmbusPacketTypeDataInBand; */
1055     desc.flags = flags; /* VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED; */
1056     /* in 8-bytes granularity */
1057     desc.offset8 = sizeof(struct vmpacket_descriptor) >> 3;
1058     desc.len8 = (u16)(packetlen_aligned >> 3);
1059     desc.trans_id = VMBUS_RQST_ERROR; /* will be updated in hv_ringbuffer_write() */
1060 
1061     bufferlist[0].iov_base = &desc;
1062     bufferlist[0].iov_len = sizeof(struct vmpacket_descriptor);
1063     bufferlist[1].iov_base = buffer;
1064     bufferlist[1].iov_len = bufferlen;
1065     bufferlist[2].iov_base = &aligned_data;
1066     bufferlist[2].iov_len = (packetlen_aligned - packetlen);
1067 
1068     return hv_ringbuffer_write(channel, bufferlist, num_vecs, requestid, trans_id);
1069 }
1070 EXPORT_SYMBOL(vmbus_sendpacket_getid);
1071 
1072 /**
1073  * vmbus_sendpacket() - Send the specified buffer on the given channel
1074  * @channel: Pointer to vmbus_channel structure
1075  * @buffer: Pointer to the buffer you want to send the data from.
1076  * @bufferlen: Maximum size of what the buffer holds.
1077  * @requestid: Identifier of the request
1078  * @type: Type of packet that is being sent e.g. negotiate, time
1079  *    packet etc.
1080  * @flags: 0 or VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED
1081  *
1082  * Sends data in @buffer directly to Hyper-V via the vmbus.
1083  * This will send the data unparsed to Hyper-V.
1084  *
1085  * Mainly used by Hyper-V drivers.
1086  */
1087 int vmbus_sendpacket(struct vmbus_channel *channel, void *buffer,
1088              u32 bufferlen, u64 requestid,
1089              enum vmbus_packet_type type, u32 flags)
1090 {
1091     return vmbus_sendpacket_getid(channel, buffer, bufferlen,
1092                       requestid, NULL, type, flags);
1093 }
1094 EXPORT_SYMBOL(vmbus_sendpacket);
1095 
1096 /*
1097  * vmbus_sendpacket_pagebuffer - Send a range of single-page buffer
1098  * packets using a GPADL Direct packet type. This interface allows you
1099  * to control notifying the host. This will be useful for sending
1100  * batched data. Also the sender can control the send flags
1101  * explicitly.
1102  */
1103 int vmbus_sendpacket_pagebuffer(struct vmbus_channel *channel,
1104                 struct hv_page_buffer pagebuffers[],
1105                 u32 pagecount, void *buffer, u32 bufferlen,
1106                 u64 requestid)
1107 {
1108     int i;
1109     struct vmbus_channel_packet_page_buffer desc;
1110     u32 descsize;
1111     u32 packetlen;
1112     u32 packetlen_aligned;
1113     struct kvec bufferlist[3];
1114     u64 aligned_data = 0;
1115 
1116     if (pagecount > MAX_PAGE_BUFFER_COUNT)
1117         return -EINVAL;
1118 
1119     /*
1120      * Adjust the size down since vmbus_channel_packet_page_buffer is the
1121      * largest size we support
1122      */
1123     descsize = sizeof(struct vmbus_channel_packet_page_buffer) -
1124               ((MAX_PAGE_BUFFER_COUNT - pagecount) *
1125               sizeof(struct hv_page_buffer));
1126     packetlen = descsize + bufferlen;
1127     packetlen_aligned = ALIGN(packetlen, sizeof(u64));
1128 
1129     /* Setup the descriptor */
1130     desc.type = VM_PKT_DATA_USING_GPA_DIRECT;
1131     desc.flags = VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED;
1132     desc.dataoffset8 = descsize >> 3; /* in 8-bytes granularity */
1133     desc.length8 = (u16)(packetlen_aligned >> 3);
1134     desc.transactionid = VMBUS_RQST_ERROR; /* will be updated in hv_ringbuffer_write() */
1135     desc.reserved = 0;
1136     desc.rangecount = pagecount;
1137 
1138     for (i = 0; i < pagecount; i++) {
1139         desc.range[i].len = pagebuffers[i].len;
1140         desc.range[i].offset = pagebuffers[i].offset;
1141         desc.range[i].pfn    = pagebuffers[i].pfn;
1142     }
1143 
1144     bufferlist[0].iov_base = &desc;
1145     bufferlist[0].iov_len = descsize;
1146     bufferlist[1].iov_base = buffer;
1147     bufferlist[1].iov_len = bufferlen;
1148     bufferlist[2].iov_base = &aligned_data;
1149     bufferlist[2].iov_len = (packetlen_aligned - packetlen);
1150 
1151     return hv_ringbuffer_write(channel, bufferlist, 3, requestid, NULL);
1152 }
1153 EXPORT_SYMBOL_GPL(vmbus_sendpacket_pagebuffer);
1154 
1155 /*
1156  * vmbus_sendpacket_multipagebuffer - Send a multi-page buffer packet
1157  * using a GPADL Direct packet type.
1158  * The buffer includes the vmbus descriptor.
1159  */
1160 int vmbus_sendpacket_mpb_desc(struct vmbus_channel *channel,
1161                   struct vmbus_packet_mpb_array *desc,
1162                   u32 desc_size,
1163                   void *buffer, u32 bufferlen, u64 requestid)
1164 {
1165     u32 packetlen;
1166     u32 packetlen_aligned;
1167     struct kvec bufferlist[3];
1168     u64 aligned_data = 0;
1169 
1170     packetlen = desc_size + bufferlen;
1171     packetlen_aligned = ALIGN(packetlen, sizeof(u64));
1172 
1173     /* Setup the descriptor */
1174     desc->type = VM_PKT_DATA_USING_GPA_DIRECT;
1175     desc->flags = VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED;
1176     desc->dataoffset8 = desc_size >> 3; /* in 8-bytes granularity */
1177     desc->length8 = (u16)(packetlen_aligned >> 3);
1178     desc->transactionid = VMBUS_RQST_ERROR; /* will be updated in hv_ringbuffer_write() */
1179     desc->reserved = 0;
1180     desc->rangecount = 1;
1181 
1182     bufferlist[0].iov_base = desc;
1183     bufferlist[0].iov_len = desc_size;
1184     bufferlist[1].iov_base = buffer;
1185     bufferlist[1].iov_len = bufferlen;
1186     bufferlist[2].iov_base = &aligned_data;
1187     bufferlist[2].iov_len = (packetlen_aligned - packetlen);
1188 
1189     return hv_ringbuffer_write(channel, bufferlist, 3, requestid, NULL);
1190 }
1191 EXPORT_SYMBOL_GPL(vmbus_sendpacket_mpb_desc);
1192 
1193 /**
1194  * __vmbus_recvpacket() - Retrieve the user packet on the specified channel
1195  * @channel: Pointer to vmbus_channel structure
1196  * @buffer: Pointer to the buffer you want to receive the data into.
1197  * @bufferlen: Maximum size of what the buffer can hold.
1198  * @buffer_actual_len: The actual size of the data after it was received.
1199  * @requestid: Identifier of the request
1200  * @raw: true means keep the vmpacket_descriptor header in the received data.
1201  *
1202  * Receives directly from the hyper-v vmbus and puts the data it received
1203  * into Buffer. This will receive the data unparsed from hyper-v.
1204  *
1205  * Mainly used by Hyper-V drivers.
1206  */
1207 static inline int
1208 __vmbus_recvpacket(struct vmbus_channel *channel, void *buffer,
1209            u32 bufferlen, u32 *buffer_actual_len, u64 *requestid,
1210            bool raw)
1211 {
1212     return hv_ringbuffer_read(channel, buffer, bufferlen,
1213                   buffer_actual_len, requestid, raw);
1214 
1215 }
1216 
1217 int vmbus_recvpacket(struct vmbus_channel *channel, void *buffer,
1218              u32 bufferlen, u32 *buffer_actual_len,
1219              u64 *requestid)
1220 {
1221     return __vmbus_recvpacket(channel, buffer, bufferlen,
1222                   buffer_actual_len, requestid, false);
1223 }
1224 EXPORT_SYMBOL(vmbus_recvpacket);
1225 
1226 /*
1227  * vmbus_recvpacket_raw - Retrieve the raw packet on the specified channel
1228  */
1229 int vmbus_recvpacket_raw(struct vmbus_channel *channel, void *buffer,
1230                   u32 bufferlen, u32 *buffer_actual_len,
1231                   u64 *requestid)
1232 {
1233     return __vmbus_recvpacket(channel, buffer, bufferlen,
1234                   buffer_actual_len, requestid, true);
1235 }
1236 EXPORT_SYMBOL_GPL(vmbus_recvpacket_raw);
1237 
1238 /*
1239  * vmbus_next_request_id - Returns a new request id. It is also
1240  * the index at which the guest memory address is stored.
1241  * Uses a spin lock to avoid race conditions.
1242  * @channel: Pointer to the VMbus channel struct
1243  * @rqst_add: Guest memory address to be stored in the array
1244  */
1245 u64 vmbus_next_request_id(struct vmbus_channel *channel, u64 rqst_addr)
1246 {
1247     struct vmbus_requestor *rqstor = &channel->requestor;
1248     unsigned long flags;
1249     u64 current_id;
1250 
1251     /* Check rqstor has been initialized */
1252     if (!channel->rqstor_size)
1253         return VMBUS_NO_RQSTOR;
1254 
1255     lock_requestor(channel, flags);
1256     current_id = rqstor->next_request_id;
1257 
1258     /* Requestor array is full */
1259     if (current_id >= rqstor->size) {
1260         unlock_requestor(channel, flags);
1261         return VMBUS_RQST_ERROR;
1262     }
1263 
1264     rqstor->next_request_id = rqstor->req_arr[current_id];
1265     rqstor->req_arr[current_id] = rqst_addr;
1266 
1267     /* The already held spin lock provides atomicity */
1268     bitmap_set(rqstor->req_bitmap, current_id, 1);
1269 
1270     unlock_requestor(channel, flags);
1271 
1272     /*
1273      * Cannot return an ID of 0, which is reserved for an unsolicited
1274      * message from Hyper-V; Hyper-V does not acknowledge (respond to)
1275      * VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED requests with ID of
1276      * 0 sent by the guest.
1277      */
1278     return current_id + 1;
1279 }
1280 EXPORT_SYMBOL_GPL(vmbus_next_request_id);
1281 
1282 /* As in vmbus_request_addr_match() but without the requestor lock */
1283 u64 __vmbus_request_addr_match(struct vmbus_channel *channel, u64 trans_id,
1284                    u64 rqst_addr)
1285 {
1286     struct vmbus_requestor *rqstor = &channel->requestor;
1287     u64 req_addr;
1288 
1289     /* Check rqstor has been initialized */
1290     if (!channel->rqstor_size)
1291         return VMBUS_NO_RQSTOR;
1292 
1293     /* Hyper-V can send an unsolicited message with ID of 0 */
1294     if (!trans_id)
1295         return VMBUS_RQST_ERROR;
1296 
1297     /* Data corresponding to trans_id is stored at trans_id - 1 */
1298     trans_id--;
1299 
1300     /* Invalid trans_id */
1301     if (trans_id >= rqstor->size || !test_bit(trans_id, rqstor->req_bitmap))
1302         return VMBUS_RQST_ERROR;
1303 
1304     req_addr = rqstor->req_arr[trans_id];
1305     if (rqst_addr == VMBUS_RQST_ADDR_ANY || req_addr == rqst_addr) {
1306         rqstor->req_arr[trans_id] = rqstor->next_request_id;
1307         rqstor->next_request_id = trans_id;
1308 
1309         /* The already held spin lock provides atomicity */
1310         bitmap_clear(rqstor->req_bitmap, trans_id, 1);
1311     }
1312 
1313     return req_addr;
1314 }
1315 EXPORT_SYMBOL_GPL(__vmbus_request_addr_match);
1316 
1317 /*
1318  * vmbus_request_addr_match - Clears/removes @trans_id from the @channel's
1319  * requestor, provided the memory address stored at @trans_id equals @rqst_addr
1320  * (or provided @rqst_addr matches the sentinel value VMBUS_RQST_ADDR_ANY).
1321  *
1322  * Returns the memory address stored at @trans_id, or VMBUS_RQST_ERROR if
1323  * @trans_id is not contained in the requestor.
1324  *
1325  * Acquires and releases the requestor spin lock.
1326  */
1327 u64 vmbus_request_addr_match(struct vmbus_channel *channel, u64 trans_id,
1328                  u64 rqst_addr)
1329 {
1330     unsigned long flags;
1331     u64 req_addr;
1332 
1333     lock_requestor(channel, flags);
1334     req_addr = __vmbus_request_addr_match(channel, trans_id, rqst_addr);
1335     unlock_requestor(channel, flags);
1336 
1337     return req_addr;
1338 }
1339 EXPORT_SYMBOL_GPL(vmbus_request_addr_match);
1340 
1341 /*
1342  * vmbus_request_addr - Returns the memory address stored at @trans_id
1343  * in @rqstor. Uses a spin lock to avoid race conditions.
1344  * @channel: Pointer to the VMbus channel struct
1345  * @trans_id: Request id sent back from Hyper-V. Becomes the requestor's
1346  * next request id.
1347  */
1348 u64 vmbus_request_addr(struct vmbus_channel *channel, u64 trans_id)
1349 {
1350     return vmbus_request_addr_match(channel, trans_id, VMBUS_RQST_ADDR_ANY);
1351 }
1352 EXPORT_SYMBOL_GPL(vmbus_request_addr);
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