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Intel MIC Host Driver Changes for Virtio Devices.

This patch introduces the host "Virtio over PCIe" interface for Intel MIC. It allows creating user space backends on the host and instantiating virtio devices for them on the Intel MIC card. It uses the existing VRINGH infrastructure in the kernel to access virtio rings from the host. A character device per MIC is exposed with IOCTL, mmap and poll callbacks. This allows the user space backend to: (a) add/remove a virtio device via a device page. (b) map (R/O) virtio rings and device page to user space. (c) poll for availability of data. (d) copy a descriptor or entire descriptor chain to/from the card. (e) modify virtio configuration. (f) handle virtio device reset. The buffers are copied over using CPU copies for this initial patch and host initiated MIC DMA support is planned for future patches. The avail and desc virtio rings are in host memory and the used ring is in card memory to maximize writes across PCIe for performance.

Ashutosh Dixit committed 13 years ago

Commit f69bcbf1 parent aa27bad14 files · +1517 −2Browse files

Showing the changes to include/uapi/linux (3 of 14 files). Show all

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3 files
  1. include/uapi/linux/Kbuild +1 −0
  2. include/uapi/linux/mic_common.h +165 −1
  3. include/uapi/linux/mic_ioctl.h +74 −0
include/uapi/linux/Kbuild+1−0
@@ -242,6 +242,7 @@ header-y += mei.h · 241 unmodified lines
242242 header-y += mempolicy.h
243243 header-y += meye.h
244244 header-y += mic_common.h
245+header-y += mic_ioctl.h
245246 header-y += mii.h
246247 header-y += minix_fs.h
247248 header-y += mman.h
include/uapi/linux/mic_common.h+165−1
@@ -21,7 +21,60 @@ · 20 unmodified lines
2121 #ifndef __MIC_COMMON_H_
2222 #define __MIC_COMMON_H_
2323
24−#include <linux/types.h>
24+#include <linux/virtio_ring.h>
25+
26+#ifndef __KERNEL__
27+#define ALIGN(a, x) (((a) + (x) - 1) & ~((x) - 1))
28+#define __aligned(x) __attribute__ ((aligned(x)))
29+#endif
30+
31+#define mic_aligned_size(x) ALIGN(sizeof(x), 8)
32+
33+/**
34+ * struct mic_device_desc: Virtio device information shared between the
35+ * virtio driver and userspace backend
36+ *
37+ * @type: Device type: console/network/disk etc. Type 0/-1 terminates.
38+ * @num_vq: Number of virtqueues.
39+ * @feature_len: Number of bytes of feature bits. Multiply by 2: one for
40+ host features and one for guest acknowledgements.
41+ * @config_len: Number of bytes of the config array after virtqueues.
42+ * @status: A status byte, written by the Guest.
43+ * @config: Start of the following variable length config.
44+ */
45+struct mic_device_desc {
46+ __s8 type;
47+ __u8 num_vq;
48+ __u8 feature_len;
49+ __u8 config_len;
50+ __u8 status;
51+ __u64 config[0];
52+} __aligned(8);
53+
54+/**
55+ * struct mic_device_ctrl: Per virtio device information in the device page
56+ * used internally by the host and card side drivers.
57+ *
58+ * @vdev: Used for storing MIC vdev information by the guest.
59+ * @config_change: Set to 1 by host when a config change is requested.
60+ * @vdev_reset: Set to 1 by guest to indicate virtio device has been reset.
61+ * @guest_ack: Set to 1 by guest to ack a command.
62+ * @host_ack: Set to 1 by host to ack a command.
63+ * @used_address_updated: Set to 1 by guest when the used address should be
64+ * updated.
65+ * @c2h_vdev_db: The doorbell number to be used by guest. Set by host.
66+ * @h2c_vdev_db: The doorbell number to be used by host. Set by guest.
67+ */
68+struct mic_device_ctrl {
69+ __u64 vdev;
70+ __u8 config_change;
71+ __u8 vdev_reset;
72+ __u8 guest_ack;
73+ __u8 host_ack;
74+ __u8 used_address_updated;
75+ __s8 c2h_vdev_db;
76+ __s8 h2c_vdev_db;
77+} __aligned(8);
2578
2679 /**
2780 * struct mic_bootparam: Virtio device independent information in device page
@@ -42,6 +95,117 @@ struct mic_bootparam { · 14 unmodified lines
4295 __u8 shutdown_card;
4396 } __aligned(8);
4497
98+/**
99+ * struct mic_device_page: High level representation of the device page
100+ *
101+ * @bootparam: The bootparam structure is used for sharing information and
102+ * status updates between MIC host and card drivers.
103+ * @desc: Array of MIC virtio device descriptors.
104+ */
105+struct mic_device_page {
106+ struct mic_bootparam bootparam;
107+ struct mic_device_desc desc[0];
108+};
109+/**
110+ * struct mic_vqconfig: This is how we expect the device configuration field
111+ * for a virtqueue to be laid out in config space.
112+ *
113+ * @address: Guest/MIC physical address of the virtio ring
114+ * (avail and desc rings)
115+ * @used_address: Guest/MIC physical address of the used ring
116+ * @num: The number of entries in the virtio_ring
117+ */
118+struct mic_vqconfig {
119+ __u64 address;
120+ __u64 used_address;
121+ __u16 num;
122+} __aligned(8);
123+
124+/*
125+ * The alignment to use between consumer and producer parts of vring.
126+ * This is pagesize for historical reasons.
127+ */
128+#define MIC_VIRTIO_RING_ALIGN 4096
129+
130+#define MIC_MAX_VRINGS 4
131+#define MIC_VRING_ENTRIES 128
132+
133+/*
134+ * Max vring entries (power of 2) to ensure desc and avail rings
135+ * fit in a single page
136+ */
137+#define MIC_MAX_VRING_ENTRIES 128
138+
139+/**
140+ * Max size of the desc block in bytes: includes:
141+ * - struct mic_device_desc
142+ * - struct mic_vqconfig (num_vq of these)
143+ * - host and guest features
144+ * - virtio device config space
145+ */
146+#define MIC_MAX_DESC_BLK_SIZE 256
147+
148+/**
149+ * struct _mic_vring_info - Host vring info exposed to userspace backend
150+ * for the avail index and magic for the card.
151+ *
152+ * @avail_idx: host avail idx
153+ * @magic: A magic debug cookie.
154+ */
155+struct _mic_vring_info {
156+ __u16 avail_idx;
157+ int magic;
158+};
159+
160+/**
161+ * struct mic_vring - Vring information.
162+ *
163+ * @vr: The virtio ring.
164+ * @info: Host vring information exposed to the userspace backend for the
165+ * avail index and magic for the card.
166+ * @va: The va for the buffer allocated for vr and info.
167+ * @len: The length of the buffer required for allocating vr and info.
168+ */
169+struct mic_vring {
170+ struct vring vr;
171+ struct _mic_vring_info *info;
172+ void *va;
173+ int len;
174+};
175+
176+#define mic_aligned_desc_size(d) ALIGN(mic_desc_size(d), 8)
177+
178+#ifndef INTEL_MIC_CARD
179+static inline unsigned mic_desc_size(const struct mic_device_desc *desc)
180+{
181+ return mic_aligned_size(*desc)
182+ + desc->num_vq * mic_aligned_size(struct mic_vqconfig)
183+ + desc->feature_len * 2
184+ + desc->config_len;
185+}
186+
187+static inline struct mic_vqconfig *
188+mic_vq_config(const struct mic_device_desc *desc)
189+{
190+ return (struct mic_vqconfig *)(desc + 1);
191+}
192+
193+static inline __u8 *mic_vq_features(const struct mic_device_desc *desc)
194+{
195+ return (__u8 *)(mic_vq_config(desc) + desc->num_vq);
196+}
197+
198+static inline __u8 *mic_vq_configspace(const struct mic_device_desc *desc)
199+{
200+ return mic_vq_features(desc) + desc->feature_len * 2;
201+}
202+static inline unsigned mic_total_desc_size(struct mic_device_desc *desc)
203+{
204+ return mic_aligned_desc_size(desc) +
205+ mic_aligned_size(struct mic_device_ctrl);
206+}
207+#endif
208+
45209 /* Device page size */
46210 #define MIC_DP_SIZE 4096
47211
include/uapi/linux/mic_ioctl.h+74−0
@@ -0,0 +1,74 @@
1+/*
2+ * Intel MIC Platform Software Stack (MPSS)
3+ *
4+ * Copyright(c) 2013 Intel Corporation.
5+ *
6+ * This program is free software; you can redistribute it and/or modify
7+ * it under the terms of the GNU General Public License, version 2, as
8+ * published by the Free Software Foundation.
9+ *
10+ * This program is distributed in the hope that it will be useful, but
11+ * WITHOUT ANY WARRANTY; without even the implied warranty of
12+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13+ * General Public License for more details.
14+ *
15+ * The full GNU General Public License is included in this distribution in
16+ * the file called "COPYING".
17+ *
18+ * Intel MIC Host driver.
19+ *
20+ */
21+#ifndef _MIC_IOCTL_H_
22+#define _MIC_IOCTL_H_
23+
24+/*
25+ * mic_copy - MIC virtio descriptor copy.
26+ *
27+ * @iov: An array of IOVEC structures containing user space buffers.
28+ * @iovcnt: Number of IOVEC structures in iov.
29+ * @vr_idx: The vring index.
30+ * @update_used: A non zero value results in used index being updated.
31+ * @out_len: The aggregate of the total length written to or read from
32+ * the virtio device.
33+ */
34+struct mic_copy_desc {
35+#ifdef __KERNEL__
36+ struct iovec __user *iov;
37+#else
38+ struct iovec *iov;
39+#endif
40+ int iovcnt;
41+ __u8 vr_idx;
42+ __u8 update_used;
43+ __u32 out_len;
44+};
45+
46+/*
47+ * Add a new virtio device
48+ * The (struct mic_device_desc *) pointer points to a device page entry
49+ * for the virtio device consisting of:
50+ * - struct mic_device_desc
51+ * - struct mic_vqconfig (num_vq of these)
52+ * - host and guest features
53+ * - virtio device config space
54+ * The total size referenced by the pointer should equal the size returned
55+ * by desc_size() in mic_common.h
56+ */
57+#define MIC_VIRTIO_ADD_DEVICE _IOWR('s', 1, struct mic_device_desc *)
58+
59+/*
60+ * Copy the number of entries in the iovec and update the used index
61+ * if requested by the user.
62+ */
63+#define MIC_VIRTIO_COPY_DESC _IOWR('s', 2, struct mic_copy_desc *)
64+
65+/*
66+ * Notify virtio device of a config change
67+ * The (__u8 *) pointer points to config space values for the device
68+ * as they should be written into the device page. The total size
69+ * referenced by the pointer should equal the config_len field of struct
70+ * mic_device_desc.
71+ */
72+#define MIC_VIRTIO_CONFIG_CHANGE _IOWR('s', 5, __u8 *)
73+
74+#endif