// SPDX-License-Identifier: BSD-3-Clause
/*
* Copyright (c) 2009-2012,2016,2023 Microsoft Corp.
* Copyright (c) 2012 NetApp Inc.
* Copyright (c) 2012 Citrix Inc.
* All rights reserved.
*/
#include <errno.h>
#include <fcntl.h>
#include <emmintrin.h>
#include <linux/limits.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <string.h>
#include <sys/mman.h>
#include <sys/uio.h>
#include <unistd.h>
#include "vmbus_bufring.h"
/**
* Compiler barrier.
*
* Guarantees that operation reordering does not occur at compile time
* for operations directly before and after the barrier.
*/
#define rte_compiler_barrier() ({ asm volatile ("" : : : "memory"); })
#define VMBUS_RQST_ERROR 0xFFFFFFFFFFFFFFFF
#define ALIGN(val, align) ((typeof(val))((val) & (~((typeof(val))((align) - 1)))))
void *vmbus_uio_map(int *fd, int size)
{
void *map;
map = mmap(NULL, 2 * size, PROT_READ | PROT_WRITE, MAP_SHARED, *fd, 0);
if (map == MAP_FAILED)
return NULL;
return map;
}
/* Increase bufring index by inc with wraparound */
static inline uint32_t vmbus_br_idxinc(uint32_t idx, uint32_t inc, uint32_t sz)
{
idx += inc;
if (idx >= sz)
idx -= sz;
return idx;
}
void vmbus_br_setup(struct vmbus_br *br, void *buf, unsigned int blen)
{
br->vbr = buf;
br->windex = br->vbr->windex;
br->dsize = blen - sizeof(struct vmbus_bufring);
}
static inline __always_inline void
rte_smp_mb(void)
{
asm volatile("lock addl $0, -128(%%rsp); " ::: "memory");
}
static inline int
rte_atomic32_cmpset(volatile uint32_t *dst, uint32_t exp, uint32_t src)
{
uint8_t res;
asm volatile("lock ; "
"cmpxchgl %[src], %[dst];"
"sete %[res];"
: [res] "=a" (res), /* output */
[dst] "=m" (*dst)
: [src] "r" (src), /* input */
"a" (exp),
"m" (*dst)
: "memory"); /* no-clobber list */
return res;
}
static inline uint32_t
vmbus_txbr_copyto(const struct vmbus_br *tbr, uint32_t windex,
const void *src0, uint32_t cplen)
{
uint8_t *br_data = tbr->vbr->data;
uint32_t br_dsize = tbr->dsize;
const uint8_t *src = src0;
/* XXX use double mapping like Linux kernel? */
if (cplen > br_dsize - windex) {
uint32_t fraglen = br_dsize - windex;
/* Wrap-around detected */
memcpy(br_data + windex, src, fraglen);
memcpy(br_data, src + fraglen, cplen - fraglen);
} else {
memcpy(br_data + windex, src, cplen);
}
return vmbus_br_idxinc(windex, cplen, br_dsize);
}
/*
* Write scattered channel packet to TX bufring.
*
* The offset of this channel packet is written as a 64bits value
* immediately after this channel packet.
*
* The write goes through three stages:
* 1. Reserve space in ring buffer for the new data.
* Writer atomically moves priv_write_index.
* 2. Copy the new data into the ring.
* 3. Update the tail of the ring (visible to host) that indicates
* next read location. Writer updates write_index
*/
static int
vmbus_txbr_write(struct vmbus_br *tbr, const struct iovec iov[], int iovlen)
{
struct vmbus_bufring *vbr = tbr->vbr;
uint32_t ring_size = tbr->dsize;
uint32_t old_windex, next_windex, windex, total;
uint64_t save_windex;
int i;
total = 0;
for (i = 0; i < iovlen; i++)
total += iov[i].iov_len;
total += sizeof(save_windex);
/* Reserve space in ring */
do {
uint32_t avail;
/* Get current free location */
old_windex = tbr->windex;
/* Prevent compiler reordering this with calculation */
rte_compiler_barrier();
avail = vmbus_br_availwrite(tbr, old_windex);
/* If not enough space in ring, then tell caller. */
if (avail <= total)
return -EAGAIN;
next_windex = vmbus_br_idxinc(old_windex, total, ring_size);
/* Atomic update of next write_index for other threads */
} while (!rte_atomic32_cmpset(&tbr->windex, old_windex, next_windex));
/* Space from old..new is now reserved */
windex = old_windex;
for (i = 0; i < iovlen; i++)
windex = vmbus_txbr_copyto(tbr, windex, iov[i].iov_base, iov[i].iov_len);
/* Set the offset of the current channel packet. */
save_windex = ((uint64_t)old_windex) << 32;
windex = vmbus_txbr_copyto(tbr, windex, &save_windex,
sizeof(save_windex));
/* The region reserved should match region used */
if (windex != next_windex)
return -EINVAL;
/* Ensure that data is available before updating host index */
rte_compiler_barrier();
/* Checkin for our reservation. wait for our turn to update host */
while (!rte_atomic32_cmpset(&vbr->windex, old_windex, next_windex))
_mm_pause();
return 0;
}
int rte_vmbus_chan_send(struct vmbus_br *txbr, uint16_t type, void *data,
uint32_t dlen, uint32_t flags)
{
struct vmbus_chanpkt pkt;
unsigned int pktlen, pad_pktlen;
const uint32_t hlen = sizeof(pkt);
uint64_t pad = 0;
struct iovec iov[3];
int error;
pktlen = hlen + dlen;
pad_pktlen = ALIGN(pktlen, sizeof(uint64_t));
pkt.hdr.type = type;
pkt.hdr.flags = flags;
pkt.hdr.hlen = hlen >> VMBUS_CHANPKT_SIZE_SHIFT;
pkt.hdr.tlen = pad_pktlen >> VMBUS_CHANPKT_SIZE_SHIFT;
pkt.hdr.xactid = VMBUS_RQST_ERROR;
iov[0].iov_base = &pkt;
iov[0].iov_len = hlen;
iov[1].iov_base = data;
iov[1].iov_len = dlen;
iov[2].iov_base = &pad;
iov[2].iov_len = pad_pktlen - pktlen;
error = vmbus_txbr_write(txbr, iov, 3);
return error;
}
static inline uint32_t
vmbus_rxbr_copyfrom(const struct vmbus_br *rbr, uint32_t rindex,
void *dst0, size_t cplen)
{
const uint8_t *br_data = rbr->vbr->data;
uint32_t br_dsize = rbr->dsize;
uint8_t *dst = dst0;
if (cplen > br_dsize - rindex) {
uint32_t fraglen = br_dsize - rindex;
/* Wrap-around detected. */
memcpy(dst, br_data + rindex, fraglen);
memcpy(dst + fraglen, br_data, cplen - fraglen);
} else {
memcpy(dst, br_data + rindex, cplen);
}
return vmbus_br_idxinc(rindex, cplen, br_dsize);
}
/* Copy data from receive ring but don't change index */
static int
vmbus_rxbr_peek(const struct vmbus_br *rbr, void *data, size_t dlen)
{
uint32_t avail;
/*
* The requested data and the 64bits channel packet
* offset should be there at least.
*/
avail = vmbus_br_availread(rbr);
if (avail < dlen + sizeof(uint64_t))
return -EAGAIN;
vmbus_rxbr_copyfrom(rbr, rbr->vbr->rindex, data, dlen);
return 0;
}
/*
* Copy data from receive ring and change index
* NOTE:
* We assume (dlen + skip) == sizeof(channel packet).
*/
static int
vmbus_rxbr_read(struct vmbus_br *rbr, void *data, size_t dlen, size_t skip)
{
struct vmbus_bufring *vbr = rbr->vbr;
uint32_t br_dsize = rbr->dsize;
uint32_t rindex;
if (vmbus_br_availread(rbr) < dlen + skip + sizeof(uint64_t))
return -EAGAIN;
/* Record where host was when we started read (for debug) */
rbr->windex = rbr->vbr->windex;
/*
* Copy channel packet from RX bufring.
*/
rindex = vmbus_br_idxinc(rbr->vbr->rindex, skip, br_dsize);
rindex = vmbus_rxbr_copyfrom(rbr, rindex, data, dlen);
/*
* Discard this channel packet's 64bits offset, which is useless to us.
*/
rindex = vmbus_br_idxinc(rindex, sizeof(uint64_t), br_dsize);
/* Update the read index _after_ the channel packet is fetched. */
rte_compiler_barrier();
vbr->rindex = rindex;
return 0;
}
int rte_vmbus_chan_recv_raw(struct vmbus_br *rxbr,
void *data, uint32_t *len)
{
struct vmbus_chanpkt_hdr pkt;
uint32_t dlen, bufferlen = *len;
int error;
error = vmbus_rxbr_peek(rxbr, &pkt, sizeof(pkt));
if (error)
return error;
if (unlikely(pkt.hlen < VMBUS_CHANPKT_HLEN_MIN))
/* XXX this channel is dead actually. */
return -EIO;
if (unlikely(pkt.hlen > pkt.tlen))
return -EIO;
/* Length are in quad words */
dlen = pkt.tlen << VMBUS_CHANPKT_SIZE_SHIFT;
*len = dlen;
/* If caller buffer is not large enough */
if (unlikely(dlen > bufferlen))
return -ENOBUFS;
/* Read data and skip packet header */
error = vmbus_rxbr_read(rxbr, data, dlen, 0);
if (error)
return error;
/* Return the number of bytes read */
return dlen + sizeof(uint64_t);
}
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