pc-bios/s390-ccw/virtio.c - third_party/qemu - Git at Google

 /*
  * 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.
  */

 #include "libc.h"
 #include "s390-ccw.h"
 #include "cio.h"
 #include "virtio.h"
 #include "virtio-scsi.h"
 #include "bswap.h"
 #include "helper.h"
 #include "s390-time.h"

 #define VRING_WAIT_REPLY_TIMEOUT 30

 static VRing block[VIRTIO_MAX_VQS];
 static char ring_area[VIRTIO_RING_SIZE * VIRTIO_MAX_VQS]
                      __attribute__((__aligned__(PAGE_SIZE)));

 static VDev vdev = {
     .nr_vqs = 1,
     .vrings = block,
     .cmd_vr_idx = 0,
     .ring_area = ring_area,
     .wait_reply_timeout = VRING_WAIT_REPLY_TIMEOUT,
     .schid = { .one = 1 },
     .scsi_block_size = VIRTIO_SCSI_BLOCK_SIZE,
     .blk_factor = 1,
 };

 VDev *virtio_get_device(void)
 {
     return &vdev;
 }

 VirtioDevType virtio_get_device_type(void)
 {
     return vdev.senseid.cu_model;
 }

 /* virtio spec v1.0 para 4.3.3.2 */
 static long kvm_hypercall(unsigned long nr, unsigned long param1,
                           unsigned long param2, unsigned long param3)
 {
     register ulong r_nr asm("1") = nr;
     register ulong r_param1 asm("2") = param1;
     register ulong r_param2 asm("3") = param2;
     register ulong r_param3 asm("4") = param3;
     register long retval asm("2");

     asm volatile ("diag %%r2,%%r4,0x500"
                   : "=d" (retval)
                   : "d" (r_nr), "0" (r_param1), "r"(r_param2), "d"(r_param3)
                   : "memory", "cc");

     return retval;
 }

 static long virtio_notify(SubChannelId schid, int vq_idx, long cookie)
 {
     return kvm_hypercall(KVM_S390_VIRTIO_CCW_NOTIFY, *(u32 *)&schid,
                          vq_idx, cookie);
 }

 /***********************************************
  *             Virtio functions                *
  ***********************************************/

 int drain_irqs(SubChannelId schid)
 {
     Irb irb = {};
     int r = 0;

     while (1) {
         /* FIXME: make use of TPI, for that enable subchannel and isc */
         if (tsch(schid, &irb)) {
             /* Might want to differentiate error codes later on. */
             if (irb.scsw.cstat) {
                 r = -EIO;
             } else if (irb.scsw.dstat != 0xc) {
                 r = -EIO;
             }
             return r;
         }
     }
 }

 static int run_ccw(VDev *vdev, int cmd, void *ptr, int len, bool sli)
 {
     Ccw1 ccw = {};

     ccw.cmd_code = cmd;
     ccw.cda = (long)ptr;
     ccw.count = len;

     if (sli) {
         ccw.flags |= CCW_FLAG_SLI;
     }

     return do_cio(vdev->schid, vdev->senseid.cu_type, ptr2u32(&ccw), CCW_FMT1);
 }

 static void vring_init(VRing *vr, VqInfo *info)
 {
     void *p = (void *) info->queue;

     debug_print_addr("init p", p);
     vr->id = info->index;
     vr->num = info->num;
     vr->desc = p;
     vr->avail = p + info->num * sizeof(VRingDesc);
     vr->used = (void *)(((unsigned long)&vr->avail->ring[info->num]
                + info->align - 1) & ~(info->align - 1));

     /* Zero out all relevant field */
     vr->avail->flags = 0;
     vr->avail->idx = 0;

     /* We're running with interrupts off anyways, so don't bother */
     vr->used->flags = VRING_USED_F_NO_NOTIFY;
     vr->used->idx = 0;
     vr->used_idx = 0;
     vr->next_idx = 0;
     vr->cookie = 0;

     debug_print_addr("init vr", vr);
 }

 bool vring_notify(VRing *vr)
 {
     vr->cookie = virtio_notify(vr->schid, vr->id, vr->cookie);
     return vr->cookie >= 0;
 }

 void vring_send_buf(VRing *vr, void *p, int len, int flags)
 {
     /* For follow-up chains we need to keep the first entry point */
     if (!(flags & VRING_HIDDEN_IS_CHAIN)) {
         vr->avail->ring[vr->avail->idx % vr->num] = vr->next_idx;
     }

     vr->desc[vr->next_idx].addr = (ulong)p;
     vr->desc[vr->next_idx].len = len;
     vr->desc[vr->next_idx].flags = flags & ~VRING_HIDDEN_IS_CHAIN;
     vr->desc[vr->next_idx].next = vr->next_idx;
     vr->desc[vr->next_idx].next++;
     vr->next_idx++;

     /* Chains only have a single ID */
     if (!(flags & VRING_DESC_F_NEXT)) {
         vr->avail->idx++;
     }
 }

 int vr_poll(VRing *vr)
 {
     if (vr->used->idx == vr->used_idx) {
         vring_notify(vr);
         yield();
         return 0;
     }

     vr->used_idx = vr->used->idx;
     vr->next_idx = 0;
     vr->desc[0].len = 0;
     vr->desc[0].flags = 0;
     return 1; /* vr has been updated */
 }

 /*
  * Wait for the host to reply.
  *
  * timeout is in seconds if > 0.
  *
  * Returns 0 on success, 1 on timeout.
  */
 int vring_wait_reply(void)
 {
     ulong target_second = get_time_seconds() + vdev.wait_reply_timeout;

     /* Wait for any queue to be updated by the host */
     do {
         int i, r = 0;

         for (i = 0; i < vdev.nr_vqs; i++) {
             r += vr_poll(&vdev.vrings[i]);
         }
         yield();
         if (r) {
             return 0;
         }
     } while (!vdev.wait_reply_timeout || (get_time_seconds() < target_second));

     return 1;
 }

 int virtio_run(VDev *vdev, int vqid, VirtioCmd *cmd)
 {
     VRing *vr = &vdev->vrings[vqid];
     int i = 0;

     do {
         vring_send_buf(vr, cmd[i].data, cmd[i].size,
                        cmd[i].flags | (i ? VRING_HIDDEN_IS_CHAIN : 0));
     } while (cmd[i++].flags & VRING_DESC_F_NEXT);

     vring_wait_reply();
     if (drain_irqs(vr->schid)) {
         return -1;
     }
     return 0;
 }

 void virtio_setup_ccw(VDev *vdev)
 {
     int i, rc, cfg_size = 0;
     uint8_t status;
     struct VirtioFeatureDesc {
         uint32_t features;
         uint8_t index;
     } __attribute__((packed)) feats;

     IPL_assert(virtio_is_supported(vdev->schid), "PE");
     /* device ID has been established now */

     vdev->config.blk.blk_size = 0; /* mark "illegal" - setup started... */
     vdev->guessed_disk_nature = VIRTIO_GDN_NONE;

     run_ccw(vdev, CCW_CMD_VDEV_RESET, NULL, 0, false);

     status = VIRTIO_CONFIG_S_ACKNOWLEDGE;
     rc = run_ccw(vdev, CCW_CMD_WRITE_STATUS, &status, sizeof(status), false);
     IPL_assert(rc == 0, "Could not write ACKNOWLEDGE status to host");

     switch (vdev->senseid.cu_model) {
     case VIRTIO_ID_NET:
         vdev->nr_vqs = 2;
         vdev->cmd_vr_idx = 0;
         cfg_size = sizeof(vdev->config.net);
         break;
     case VIRTIO_ID_BLOCK:
         vdev->nr_vqs = 1;
         vdev->cmd_vr_idx = 0;
         cfg_size = sizeof(vdev->config.blk);
         break;
     case VIRTIO_ID_SCSI:
         vdev->nr_vqs = 3;
         vdev->cmd_vr_idx = VR_REQUEST;
         cfg_size = sizeof(vdev->config.scsi);
         break;
     default:
         panic("Unsupported virtio device\n");
     }

     status |= VIRTIO_CONFIG_S_DRIVER;
     rc = run_ccw(vdev, CCW_CMD_WRITE_STATUS, &status, sizeof(status), false);
     IPL_assert(rc == 0, "Could not write DRIVER status to host");

     /* Feature negotiation */
     for (i = 0; i < ARRAY_SIZE(vdev->guest_features); i++) {
         feats.features = 0;
         feats.index = i;
         rc = run_ccw(vdev, CCW_CMD_READ_FEAT, &feats, sizeof(feats), false);
         IPL_assert(rc == 0, "Could not get features bits");
         vdev->guest_features[i] &= bswap32(feats.features);
         feats.features = bswap32(vdev->guest_features[i]);
         rc = run_ccw(vdev, CCW_CMD_WRITE_FEAT, &feats, sizeof(feats), false);
         IPL_assert(rc == 0, "Could not set features bits");
     }

     rc = run_ccw(vdev, CCW_CMD_READ_CONF, &vdev->config, cfg_size, false);
     IPL_assert(rc == 0, "Could not get virtio device configuration");

     for (i = 0; i < vdev->nr_vqs; i++) {
         VqInfo info = {
             .queue = (unsigned long long) ring_area + (i * VIRTIO_RING_SIZE),
             .align = KVM_S390_VIRTIO_RING_ALIGN,
             .index = i,
             .num = 0,
         };
         VqConfig config = {
             .index = i,
             .num = 0,
         };

         rc = run_ccw(vdev, CCW_CMD_READ_VQ_CONF, &config, sizeof(config), false);
         IPL_assert(rc == 0, "Could not get virtio device VQ configuration");
         info.num = config.num;
         vring_init(&vdev->vrings[i], &info);
         vdev->vrings[i].schid = vdev->schid;
         IPL_assert(
             run_ccw(vdev, CCW_CMD_SET_VQ, &info, sizeof(info), false) == 0,
             "Cannot set VQ info");
     }

     status |= VIRTIO_CONFIG_S_DRIVER_OK;
     rc = run_ccw(vdev, CCW_CMD_WRITE_STATUS, &status, sizeof(status), false);
     IPL_assert(rc == 0, "Could not write DRIVER_OK status to host");
 }

 bool virtio_is_supported(SubChannelId schid)
 {
     vdev.schid = schid;
     memset(&vdev.senseid, 0, sizeof(vdev.senseid));

     /*
      * Run sense id command.
      * The size of the senseid data differs between devices (notably,
      * between virtio devices and dasds), so specify the largest possible
      * size and suppress the incorrect length indication for smaller sizes.
      */
     if (run_ccw(&vdev, CCW_CMD_SENSE_ID, &vdev.senseid, sizeof(vdev.senseid),
                 true)) {
         return false;
     }
     if (vdev.senseid.cu_type == 0x3832) {
         switch (vdev.senseid.cu_model) {
         case VIRTIO_ID_BLOCK:
         case VIRTIO_ID_SCSI:
         case VIRTIO_ID_NET:
             return true;
         }
     }
     return false;
 }
	/*
	* 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.
	*/

	#include "libc.h"
	#include "s390-ccw.h"
	#include "cio.h"
	#include "virtio.h"
	#include "virtio-scsi.h"
	#include "bswap.h"
	#include "helper.h"
	#include "s390-time.h"

	#define VRING_WAIT_REPLY_TIMEOUT 30

	static VRing block[VIRTIO_MAX_VQS];
	static char ring_area[VIRTIO_RING_SIZE * VIRTIO_MAX_VQS]
	__attribute__((__aligned__(PAGE_SIZE)));

	static VDev vdev = {
	.nr_vqs = 1,
	.vrings = block,
	.cmd_vr_idx = 0,
	.ring_area = ring_area,
	.wait_reply_timeout = VRING_WAIT_REPLY_TIMEOUT,
	.schid = { .one = 1 },
	.scsi_block_size = VIRTIO_SCSI_BLOCK_SIZE,
	.blk_factor = 1,
	};

	VDev *virtio_get_device(void)
	{
	return &vdev;
	}

	VirtioDevType virtio_get_device_type(void)
	{
	return vdev.senseid.cu_model;
	}

	/* virtio spec v1.0 para 4.3.3.2 */
	static long kvm_hypercall(unsigned long nr, unsigned long param1,
	unsigned long param2, unsigned long param3)
	{
	register ulong r_nr asm("1") = nr;
	register ulong r_param1 asm("2") = param1;
	register ulong r_param2 asm("3") = param2;
	register ulong r_param3 asm("4") = param3;
	register long retval asm("2");

	asm volatile ("diag %%r2,%%r4,0x500"
	: "=d" (retval)
	: "d" (r_nr), "0" (r_param1), "r"(r_param2), "d"(r_param3)
	: "memory", "cc");

	return retval;
	}

	static long virtio_notify(SubChannelId schid, int vq_idx, long cookie)
	{
	return kvm_hypercall(KVM_S390_VIRTIO_CCW_NOTIFY, (u32 )&schid,
	vq_idx, cookie);
	}

	/***********************************************
	* Virtio functions *
	***********************************************/

	int drain_irqs(SubChannelId schid)
	{
	Irb irb = {};
	int r = 0;

	while (1) {
	/* FIXME: make use of TPI, for that enable subchannel and isc */
	if (tsch(schid, &irb)) {
	/* Might want to differentiate error codes later on. */
	if (irb.scsw.cstat) {
	r = -EIO;
	} else if (irb.scsw.dstat != 0xc) {
	r = -EIO;
	}
	return r;
	}
	}
	}

	static int run_ccw(VDev vdev, int cmd, void ptr, int len, bool sli)
	{
	Ccw1 ccw = {};

	ccw.cmd_code = cmd;
	ccw.cda = (long)ptr;
	ccw.count = len;

	if (sli) {
	ccw.flags \|= CCW_FLAG_SLI;
	}

	return do_cio(vdev->schid, vdev->senseid.cu_type, ptr2u32(&ccw), CCW_FMT1);
	}

	static void vring_init(VRing vr, VqInfo info)
	{
	void p = (void ) info->queue;

	debug_print_addr("init p", p);
	vr->id = info->index;
	vr->num = info->num;
	vr->desc = p;
	vr->avail = p + info->num * sizeof(VRingDesc);
	vr->used = (void *)(((unsigned long)&vr->avail->ring[info->num]
	+ info->align - 1) & ~(info->align - 1));

	/* Zero out all relevant field */
	vr->avail->flags = 0;
	vr->avail->idx = 0;

	/* We're running with interrupts off anyways, so don't bother */
	vr->used->flags = VRING_USED_F_NO_NOTIFY;
	vr->used->idx = 0;
	vr->used_idx = 0;
	vr->next_idx = 0;
	vr->cookie = 0;

	debug_print_addr("init vr", vr);
	}

	bool vring_notify(VRing *vr)
	{
	vr->cookie = virtio_notify(vr->schid, vr->id, vr->cookie);
	return vr->cookie >= 0;
	}

	void vring_send_buf(VRing vr, void p, int len, int flags)
	{
	/* For follow-up chains we need to keep the first entry point */
	if (!(flags & VRING_HIDDEN_IS_CHAIN)) {
	vr->avail->ring[vr->avail->idx % vr->num] = vr->next_idx;
	}

	vr->desc[vr->next_idx].addr = (ulong)p;
	vr->desc[vr->next_idx].len = len;
	vr->desc[vr->next_idx].flags = flags & ~VRING_HIDDEN_IS_CHAIN;
	vr->desc[vr->next_idx].next = vr->next_idx;
	vr->desc[vr->next_idx].next++;
	vr->next_idx++;

	/* Chains only have a single ID */
	if (!(flags & VRING_DESC_F_NEXT)) {
	vr->avail->idx++;
	}
	}

	int vr_poll(VRing *vr)
	{
	if (vr->used->idx == vr->used_idx) {
	vring_notify(vr);
	yield();
	return 0;
	}

	vr->used_idx = vr->used->idx;
	vr->next_idx = 0;
	vr->desc[0].len = 0;
	vr->desc[0].flags = 0;
	return 1; /* vr has been updated */
	}

	/*
	* Wait for the host to reply.
	*
	* timeout is in seconds if > 0.
	*
	* Returns 0 on success, 1 on timeout.
	*/
	int vring_wait_reply(void)
	{
	ulong target_second = get_time_seconds() + vdev.wait_reply_timeout;

	/* Wait for any queue to be updated by the host */
	do {
	int i, r = 0;

	for (i = 0; i < vdev.nr_vqs; i++) {
	r += vr_poll(&vdev.vrings[i]);
	}
	yield();
	if (r) {
	return 0;
	}
	} while (!vdev.wait_reply_timeout \|\| (get_time_seconds() < target_second));

	return 1;
	}

	int virtio_run(VDev vdev, int vqid, VirtioCmd cmd)
	{
	VRing *vr = &vdev->vrings[vqid];
	int i = 0;

	do {
	vring_send_buf(vr, cmd[i].data, cmd[i].size,
	cmd[i].flags \| (i ? VRING_HIDDEN_IS_CHAIN : 0));
	} while (cmd[i++].flags & VRING_DESC_F_NEXT);

	vring_wait_reply();
	if (drain_irqs(vr->schid)) {
	return -1;
	}
	return 0;
	}

	void virtio_setup_ccw(VDev *vdev)
	{
	int i, rc, cfg_size = 0;
	uint8_t status;
	struct VirtioFeatureDesc {
	uint32_t features;
	uint8_t index;
	} __attribute__((packed)) feats;

	IPL_assert(virtio_is_supported(vdev->schid), "PE");
	/* device ID has been established now */

	vdev->config.blk.blk_size = 0; /* mark "illegal" - setup started... */
	vdev->guessed_disk_nature = VIRTIO_GDN_NONE;

	run_ccw(vdev, CCW_CMD_VDEV_RESET, NULL, 0, false);

	status = VIRTIO_CONFIG_S_ACKNOWLEDGE;
	rc = run_ccw(vdev, CCW_CMD_WRITE_STATUS, &status, sizeof(status), false);
	IPL_assert(rc == 0, "Could not write ACKNOWLEDGE status to host");

	switch (vdev->senseid.cu_model) {
	case VIRTIO_ID_NET:
	vdev->nr_vqs = 2;
	vdev->cmd_vr_idx = 0;
	cfg_size = sizeof(vdev->config.net);
	break;
	case VIRTIO_ID_BLOCK:
	vdev->nr_vqs = 1;
	vdev->cmd_vr_idx = 0;
	cfg_size = sizeof(vdev->config.blk);
	break;
	case VIRTIO_ID_SCSI:
	vdev->nr_vqs = 3;
	vdev->cmd_vr_idx = VR_REQUEST;
	cfg_size = sizeof(vdev->config.scsi);
	break;
	default:
	panic("Unsupported virtio device\n");
	}

	status \|= VIRTIO_CONFIG_S_DRIVER;
	rc = run_ccw(vdev, CCW_CMD_WRITE_STATUS, &status, sizeof(status), false);
	IPL_assert(rc == 0, "Could not write DRIVER status to host");

	/* Feature negotiation */
	for (i = 0; i < ARRAY_SIZE(vdev->guest_features); i++) {
	feats.features = 0;
	feats.index = i;
	rc = run_ccw(vdev, CCW_CMD_READ_FEAT, &feats, sizeof(feats), false);
	IPL_assert(rc == 0, "Could not get features bits");
	vdev->guest_features[i] &= bswap32(feats.features);
	feats.features = bswap32(vdev->guest_features[i]);
	rc = run_ccw(vdev, CCW_CMD_WRITE_FEAT, &feats, sizeof(feats), false);
	IPL_assert(rc == 0, "Could not set features bits");
	}

	rc = run_ccw(vdev, CCW_CMD_READ_CONF, &vdev->config, cfg_size, false);
	IPL_assert(rc == 0, "Could not get virtio device configuration");

	for (i = 0; i < vdev->nr_vqs; i++) {
	VqInfo info = {
	.queue = (unsigned long long) ring_area + (i * VIRTIO_RING_SIZE),
	.align = KVM_S390_VIRTIO_RING_ALIGN,
	.index = i,
	.num = 0,
	};
	VqConfig config = {
	.index = i,
	.num = 0,
	};

	rc = run_ccw(vdev, CCW_CMD_READ_VQ_CONF, &config, sizeof(config), false);
	IPL_assert(rc == 0, "Could not get virtio device VQ configuration");
	info.num = config.num;
	vring_init(&vdev->vrings[i], &info);
	vdev->vrings[i].schid = vdev->schid;
	IPL_assert(
	run_ccw(vdev, CCW_CMD_SET_VQ, &info, sizeof(info), false) == 0,
	"Cannot set VQ info");
	}

	status \|= VIRTIO_CONFIG_S_DRIVER_OK;
	rc = run_ccw(vdev, CCW_CMD_WRITE_STATUS, &status, sizeof(status), false);
	IPL_assert(rc == 0, "Could not write DRIVER_OK status to host");
	}

	bool virtio_is_supported(SubChannelId schid)
	{
	vdev.schid = schid;
	memset(&vdev.senseid, 0, sizeof(vdev.senseid));

	/*
	* Run sense id command.
	* The size of the senseid data differs between devices (notably,
	* between virtio devices and dasds), so specify the largest possible
	* size and suppress the incorrect length indication for smaller sizes.
	*/
	if (run_ccw(&vdev, CCW_CMD_SENSE_ID, &vdev.senseid, sizeof(vdev.senseid),
	true)) {
	return false;
	}
	if (vdev.senseid.cu_type == 0x3832) {
	switch (vdev.senseid.cu_model) {
	case VIRTIO_ID_BLOCK:
	case VIRTIO_ID_SCSI:
	case VIRTIO_ID_NET:
	return true;
	}
	}
	return false;
	}