Drivers: hv: vmbus: Support a vmbus API for efficiently sending page arrays

Currently, the API for sending a multi-page buffer over VMBUS is limited to
a maximum pfn array of MAX_MULTIPAGE_BUFFER_COUNT. This limitation is
not imposed by the host and unnecessarily limits the maximum payload
that can be sent. Implement an API that does not have this restriction.

Signed-off-by: K. Y. Srinivasan <kys@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/hv/channel.c b/drivers/hv/channel.c
index c76ffbe59f65539597f5ba0cb5b50265ef2f3b7d..18c4f23dacf1b24d6c0c94f13abcff2ccf769730 100644 (file)
--- a/drivers/hv/channel.c
+++ b/drivers/hv/channel.c
@@ -683,6 +683,50 @@ int vmbus_sendpacket_pagebuffer(struct vmbus_channel *channel,
 }
 EXPORT_SYMBOL_GPL(vmbus_sendpacket_pagebuffer);
 
+/*
+ * vmbus_sendpacket_multipagebuffer - Send a multi-page buffer packet
+ * using a GPADL Direct packet type.
+ * The buffer includes the vmbus descriptor.
+ */
+int vmbus_sendpacket_mpb_desc(struct vmbus_channel *channel,
+                             struct vmbus_packet_mpb_array *desc,
+                             u32 desc_size,
+                             void *buffer, u32 bufferlen, u64 requestid)
+{
+       int ret;
+       u32 packetlen;
+       u32 packetlen_aligned;
+       struct kvec bufferlist[3];
+       u64 aligned_data = 0;
+       bool signal = false;
+
+       packetlen = desc_size + bufferlen;
+       packetlen_aligned = ALIGN(packetlen, sizeof(u64));
+
+       /* Setup the descriptor */
+       desc->type = VM_PKT_DATA_USING_GPA_DIRECT;
+       desc->flags = VMBUS_DATA_PACKET_FLAG_COMPLETION_REQUESTED;
+       desc->dataoffset8 = desc_size >> 3; /* in 8-bytes grandularity */
+       desc->length8 = (u16)(packetlen_aligned >> 3);
+       desc->transactionid = requestid;
+       desc->rangecount = 1;
+
+       bufferlist[0].iov_base = desc;
+       bufferlist[0].iov_len = desc_size;
+       bufferlist[1].iov_base = buffer;
+       bufferlist[1].iov_len = bufferlen;
+       bufferlist[2].iov_base = &aligned_data;
+       bufferlist[2].iov_len = (packetlen_aligned - packetlen);
+
+       ret = hv_ringbuffer_write(&channel->outbound, bufferlist, 3, &signal);
+
+       if (ret == 0 && signal)
+               vmbus_setevent(channel);
+
+       return ret;
+}
+EXPORT_SYMBOL_GPL(vmbus_sendpacket_mpb_desc);
+
 /*
  * vmbus_sendpacket_multipagebuffer - Send a multi-page buffer packet
  * using a GPADL Direct packet type.

diff --git a/include/linux/hyperv.h b/include/linux/hyperv.h
index 476c685ca6f9c5c6447944aee2fa98a85cdd14e4..259023a34becc775fc115a62754851776b935880 100644 (file)
--- a/include/linux/hyperv.h
+++ b/include/linux/hyperv.h
@@ -57,6 +57,18 @@ struct hv_multipage_buffer {
        u64 pfn_array[MAX_MULTIPAGE_BUFFER_COUNT];
 };
 
+/*
+ * Multiple-page buffer array; the pfn array is variable size:
+ * The number of entries in the PFN array is determined by
+ * "len" and "offset".
+ */
+struct hv_mpb_array {
+       /* Length and Offset determines the # of pfns in the array */
+       u32 len;
+       u32 offset;
+       u64 pfn_array[];
+};
+
 /* 0x18 includes the proprietary packet header */
 #define MAX_PAGE_BUFFER_PACKET         (0x18 +                 \
                                        (sizeof(struct hv_page_buffer) * \
@@ -814,6 +826,18 @@ struct vmbus_channel_packet_multipage_buffer {
        struct hv_multipage_buffer range;
 } __packed;
 
+/* The format must be the same as struct vmdata_gpa_direct */
+struct vmbus_packet_mpb_array {
+       u16 type;
+       u16 dataoffset8;
+       u16 length8;
+       u16 flags;
+       u64 transactionid;
+       u32 reserved;
+       u32 rangecount;         /* Always 1 in this case */
+       struct hv_mpb_array range;
+} __packed;
+
 
 extern int vmbus_open(struct vmbus_channel *channel,
                            u32 send_ringbuffersize,
@@ -845,6 +869,13 @@ extern int vmbus_sendpacket_multipagebuffer(struct vmbus_channel *channel,
                                        u32 bufferlen,
                                        u64 requestid);
 
+extern int vmbus_sendpacket_mpb_desc(struct vmbus_channel *channel,
+                                    struct vmbus_packet_mpb_array *mpb,
+                                    u32 desc_size,
+                                    void *buffer,
+                                    u32 bufferlen,
+                                    u64 requestid);
+
 extern int vmbus_establish_gpadl(struct vmbus_channel *channel,
                                      void *kbuffer,
                                      u32 size,