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pc-bios/s390-ccw: update virtio implementation to allow up to 3 vrings
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Add ability to work with up to 3 vrings, which is required for
virtio-scsi implementation.
Implement the optional cookie to speed up processing of virtio
notifications.

Reviewed-by: Cornelia Huck <cornelia.huck@de.ibm.com>
Signed-off-by: Eugene (jno) Dvurechenski <jno@linux.vnet.ibm.com>
Signed-off-by: Cornelia Huck <cornelia.huck@de.ibm.com>
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Eugene (jno) Dvurechenski authored and cohuck committed Mar 23, 2016
1 parent b88d7fa commit 8512989
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Showing 4 changed files with 90 additions and 56 deletions.
1 change: 0 additions & 1 deletion pc-bios/s390-ccw/main.c
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Expand Up @@ -12,7 +12,6 @@
#include "virtio.h"

char stack[PAGE_SIZE * 8] __attribute__((__aligned__(PAGE_SIZE)));
char ring_area[PAGE_SIZE * 8] __attribute__((__aligned__(PAGE_SIZE)));
uint64_t boot_value;
static SubChannelId blk_schid = { .one = 1 };

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1 change: 0 additions & 1 deletion pc-bios/s390-ccw/s390-ccw.h
View file
Expand Up @@ -61,7 +61,6 @@ void consume_sclp_int(void);
void panic(const char *string);
void write_subsystem_identification(void);
extern char stack[PAGE_SIZE * 8] __attribute__((__aligned__(PAGE_SIZE)));
extern char ring_area[PAGE_SIZE * 8] __attribute__((__aligned__(PAGE_SIZE)));
extern uint64_t boot_value;

/* sclp-ascii.c */
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140 changes: 86 additions & 54 deletions pc-bios/s390-ccw/virtio.c
View file
Expand Up @@ -11,29 +11,35 @@
#include "s390-ccw.h"
#include "virtio.h"

static VRing block;
static VRing block[VIRTIO_MAX_VQS];
static char ring_area[VIRTIO_RING_SIZE * VIRTIO_MAX_VQS]
__attribute__((__aligned__(PAGE_SIZE)));
static int nr_vqs = 1;

static char chsc_page[PAGE_SIZE] __attribute__((__aligned__(PAGE_SIZE)));

/* virtio spec v1.0 para 4.3.3.2 */
static long kvm_hypercall(unsigned long nr, unsigned long param1,
unsigned long param2)
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 2,4,0x500"
: "=d" (retval)
: "d" (r_nr), "0" (r_param1), "r"(r_param2)
: "d" (r_nr), "0" (r_param1), "r"(r_param2), "d"(r_param3)
: "memory", "cc");

return retval;
}

static void virtio_notify(SubChannelId schid)
static long virtio_notify(SubChannelId schid, int vq_idx, long cookie)
{
kvm_hypercall(KVM_S390_VIRTIO_CCW_NOTIFY, *(u32 *)&schid, 0);
return kvm_hypercall(KVM_S390_VIRTIO_CCW_NOTIFY, *(u32 *)&schid,
vq_idx, cookie);
}

/***********************************************
Expand Down Expand Up @@ -106,15 +112,17 @@ static void virtio_reset(SubChannelId schid)
run_ccw(schid, CCW_CMD_VDEV_RESET, NULL, 0);
}

static void vring_init(VRing *vr, unsigned int num, void *p,
unsigned long align)
static void vring_init(VRing *vr, VqInfo *info)
{
void *p = (void *) info->queue;

debug_print_addr("init p", p);
vr->num = num;
vr->id = info->index;
vr->num = info->num;
vr->desc = p;
vr->avail = p + num * sizeof(VRingDesc);
vr->used = (void *)(((unsigned long)&vr->avail->ring[num] + align-1)
& ~(align - 1));
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;
Expand All @@ -125,13 +133,15 @@ static void vring_init(VRing *vr, unsigned int num, void *p,
vr->used->idx = 0;
vr->used_idx = 0;
vr->next_idx = 0;
vr->cookie = 0;

debug_print_addr("init vr", vr);
}

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

static void vring_send_buf(VRing *vr, void *p, int len, int flags)
Expand Down Expand Up @@ -167,35 +177,46 @@ ulong get_second(void)
return (get_clock() >> 12) / 1000000;
}

static 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.
*/
static int vring_wait_reply(VRing *vr, int timeout)
static int vring_wait_reply(int timeout)
{
ulong target_second = get_second() + timeout;
SubChannelId schid = vr->schid;
int r = 0;

/* Wait until the used index has moved. */
while (vr->used->idx == vr->used_idx) {
vring_notify(schid);
if (timeout && (get_second() >= target_second)) {
r = 1;
break;
/* Wait for any queue to be updated by the host */
do {
int i, r = 0;

for (i = 0; i < nr_vqs; i++) {
r += vr_poll(&block[i]);
}
yield();
}

vr->used_idx = vr->used->idx;
vr->next_idx = 0;
vr->desc[0].len = 0;
vr->desc[0].flags = 0;
if (r) {
return 0;
}
} while (!timeout || (get_second() < target_second));

return r;
return 1;
}

/***********************************************
Expand All @@ -213,21 +234,21 @@ int virtio_read_many(ulong sector, void *load_addr, int sec_num)
out_hdr.ioprio = 99;
out_hdr.sector = virtio_sector_adjust(sector);

vring_send_buf(&block, &out_hdr, sizeof(out_hdr), VRING_DESC_F_NEXT);
vring_send_buf(&block[0], &out_hdr, sizeof(out_hdr), VRING_DESC_F_NEXT);

/* This is where we want to receive data */
vring_send_buf(&block, load_addr, virtio_get_block_size() * sec_num,
vring_send_buf(&block[0], load_addr, virtio_get_block_size() * sec_num,
VRING_DESC_F_WRITE | VRING_HIDDEN_IS_CHAIN |
VRING_DESC_F_NEXT);

/* status field */
vring_send_buf(&block, &status, sizeof(u8), VRING_DESC_F_WRITE |
vring_send_buf(&block[0], &status, sizeof(u8), VRING_DESC_F_WRITE |
VRING_HIDDEN_IS_CHAIN);

/* Now we can tell the host to read */
vring_wait_reply(&block, 0);
vring_wait_reply(0);

r = drain_irqs(block.schid);
r = drain_irqs(block[0].schid);
if (r) {
/* Well, whatever status is supposed to contain... */
status = 1;
Expand Down Expand Up @@ -363,41 +384,52 @@ uint64_t virtio_get_blocks(void)
(virtio_get_block_size() / VIRTIO_SECTOR_SIZE);
}

void virtio_setup_block(SubChannelId schid)
static void virtio_setup_ccw(SubChannelId schid,
int nvr, void *cfg, int cfg_size)
{
VqInfo info;
VqConfig config = {};
int i;

blk_cfg.blk_size = 0; /* mark "illegal" - setup started... */
nr_vqs = nvr;
guessed_disk_nature = false;

virtio_reset(schid);
IPL_assert(run_ccw(schid, CCW_CMD_READ_CONF, cfg, cfg_size) == 0,
"Could not get block device configuration");

/*
* Skipping CCW_CMD_READ_FEAT. We're not doing anything fancy, and
* we'll just stop dead anyway if anything does not work like we
* expect it.
*/

config.index = 0;
if (run_ccw(schid, CCW_CMD_READ_VQ_CONF, &config, sizeof(config))) {
panic("Could not get block device VQ configuration\n");
}
if (run_ccw(schid, CCW_CMD_READ_CONF, &blk_cfg, sizeof(blk_cfg))) {
panic("Could not get block device configuration\n");
for (i = 0; i < 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,
};

IPL_assert(
run_ccw(schid, CCW_CMD_READ_VQ_CONF, &config, sizeof(config)) == 0,
"Could not get block device VQ configuration");
info.num = config.num;
vring_init(&block[i], &info);
block[i].schid = schid;
IPL_assert(run_ccw(schid, CCW_CMD_SET_VQ, &info, sizeof(info)) == 0,
"Cannot set VQ info");
}
vring_init(&block, config.num, ring_area,
KVM_S390_VIRTIO_RING_ALIGN);

info.queue = (unsigned long long) ring_area;
info.align = KVM_S390_VIRTIO_RING_ALIGN;
info.index = 0;
info.num = config.num;
block.schid = schid;
virtio_set_status(schid, VIRTIO_CONFIG_S_DRIVER_OK);
}

if (!run_ccw(schid, CCW_CMD_SET_VQ, &info, sizeof(info))) {
virtio_set_status(schid, VIRTIO_CONFIG_S_DRIVER_OK);
}
void virtio_setup_block(SubChannelId schid)
{
virtio_setup_ccw(schid, 1, &blk_cfg, sizeof(blk_cfg));

if (!virtio_ipl_disk_is_valid()) {
/* make sure all getters but blocksize return 0 for invalid IPL disk */
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4 changes: 4 additions & 0 deletions pc-bios/s390-ccw/virtio.h
View file
Expand Up @@ -72,6 +72,8 @@ struct VirtioDev {
};
typedef struct VirtioDev VirtioDev;

#define VIRTIO_RING_SIZE (PAGE_SIZE * 8)
#define VIRTIO_MAX_VQS 3
#define KVM_S390_VIRTIO_RING_ALIGN 4096

#define VRING_USED_F_NO_NOTIFY 1
Expand Down Expand Up @@ -130,6 +132,8 @@ struct VRing {
VRingAvail *avail;
VRingUsed *used;
SubChannelId schid;
long cookie;
int id;
};
typedef struct VRing VRing;

Expand Down

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