S390: ccw firmware: Add virtio device drivers

In order to boot, we need to be able to access a virtio-blk device through
the CCW bus. Implement support for this.

Signed-off-by: Alexander Graf <agraf@suse.de>

pc-bios/s390-ccw/virtio.h

@@ -0,0 +1,158 @@
+/*
+ * Virtio driver bits
+ *
+ * Copyright (c) 2013 Alexander Graf <agraf@suse.de>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or (at
+ * your option) any later version. See the COPYING file in the top-level
+ * directory.
+ */
+
+#ifndef VIRTIO_H
+#define VIRTIO_H
+
+#include "s390-ccw.h"
+
+/* Status byte for guest to report progress, and synchronize features. */
+/* We have seen device and processed generic fields (VIRTIO_CONFIG_F_VIRTIO) */
+#define VIRTIO_CONFIG_S_ACKNOWLEDGE     1
+/* We have found a driver for the device. */
+#define VIRTIO_CONFIG_S_DRIVER          2
+/* Driver has used its parts of the config, and is happy */
+#define VIRTIO_CONFIG_S_DRIVER_OK       4
+/* We've given up on this device. */
+#define VIRTIO_CONFIG_S_FAILED          0x80
+
+enum virtio_dev_type {
+    VIRTIO_ID_NET = 1,
+    VIRTIO_ID_BLOCK = 2,
+    VIRTIO_ID_CONSOLE = 3,
+    VIRTIO_ID_BALLOON = 5,
+};
+
+struct virtio_dev_header {
+    enum virtio_dev_type type : 8;
+    u8  num_vq;
+    u8  feature_len;
+    u8  config_len;
+    u8  status;
+    u8  vqconfig[];
+} __attribute__((packed));
+
+struct virtio_vqconfig {
+    u64 token;
+    u64 address;
+    u16 num;
+    u8  pad[6];
+} __attribute__((packed));
+
+struct vq_info_block {
+    u64 queue;
+    u32 align;
+    u16 index;
+    u16 num;
+} __attribute__((packed));
+
+struct virtio_dev {
+    struct virtio_dev_header *header;
+    struct virtio_vqconfig *vqconfig;
+    char *host_features;
+    char *guest_features;
+    char *config;
+};
+
+#define KVM_S390_VIRTIO_RING_ALIGN	4096
+
+#define VRING_USED_F_NO_NOTIFY  1
+
+/* This marks a buffer as continuing via the next field. */
+#define VRING_DESC_F_NEXT       1
+/* This marks a buffer as write-only (otherwise read-only). */
+#define VRING_DESC_F_WRITE      2
+/* This means the buffer contains a list of buffer descriptors. */
+#define VRING_DESC_F_INDIRECT   4
+
+/* Internal flag to mark follow-up segments as such */
+#define VRING_HIDDEN_IS_CHAIN   256
+
+/* Virtio ring descriptors: 16 bytes.  These can chain together via "next". */
+struct vring_desc {
+    /* Address (guest-physical). */
+    u64 addr;
+    /* Length. */
+    u32 len;
+    /* The flags as indicated above. */
+    u16 flags;
+    /* We chain unused descriptors via this, too */
+    u16 next;
+} __attribute__((packed));
+
+struct vring_avail {
+    u16 flags;
+    u16 idx;
+    u16 ring[];
+} __attribute__((packed));
+
+/* u32 is used here for ids for padding reasons. */
+struct vring_used_elem {
+    /* Index of start of used descriptor chain. */
+    u32 id;
+    /* Total length of the descriptor chain which was used (written to) */
+    u32 len;
+} __attribute__((packed));
+
+struct vring_used {
+    u16 flags;
+    u16 idx;
+    struct vring_used_elem ring[];
+} __attribute__((packed));
+
+struct vring {
+    unsigned int num;
+    int next_idx;
+    struct vring_desc *desc;
+    struct vring_avail *avail;
+    struct vring_used *used;
+    struct subchannel_id schid;
+};
+
+
+/***********************************************
+ *               Virtio block                  *
+ ***********************************************/
+
+/*
+ * Command types
+ *
+ * Usage is a bit tricky as some bits are used as flags and some are not.
+ *
+ * Rules:
+ *   VIRTIO_BLK_T_OUT may be combined with VIRTIO_BLK_T_SCSI_CMD or
+ *   VIRTIO_BLK_T_BARRIER.  VIRTIO_BLK_T_FLUSH is a command of its own
+ *   and may not be combined with any of the other flags.
+ */
+
+/* These two define direction. */
+#define VIRTIO_BLK_T_IN         0
+#define VIRTIO_BLK_T_OUT        1
+
+/* This bit says it's a scsi command, not an actual read or write. */
+#define VIRTIO_BLK_T_SCSI_CMD   2
+
+/* Cache flush command */
+#define VIRTIO_BLK_T_FLUSH      4
+
+/* Barrier before this op. */
+#define VIRTIO_BLK_T_BARRIER    0x80000000
+
+/* This is the first element of the read scatter-gather list. */
+struct virtio_blk_outhdr {
+        /* VIRTIO_BLK_T* */
+        u32 type;
+        /* io priority. */
+        u32 ioprio;
+        /* Sector (ie. 512 byte offset) */
+        u64 sector;
+};
+
+#endif /* VIRTIO_H */