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* Copyright (c) 2015 Oracle. All rights reserved.
* Copyright (c) 2003-2007 Network Appliance, Inc. All rights reserved.
*/
/* Lightweight memory registration using Fast Memory Regions (FMR).
* Referred to sometimes as MTHCAFMR mode.
*
* FMR uses synchronous memory registration and deregistration.
* FMR registration is known to be fast, but FMR deregistration
* can take tens of usecs to complete.
*/
/* Normal operation
*
* A Memory Region is prepared for RDMA READ or WRITE using the
* ib_map_phys_fmr verb (fmr_op_map). When the RDMA operation is
* finished, the Memory Region is unmapped using the ib_unmap_fmr
* verb (fmr_op_unmap).
*/
#include "xprt_rdma.h"
#if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
# define RPCDBG_FACILITY RPCDBG_TRANS
#endif
/* Maximum scatter/gather per FMR */
#define RPCRDMA_MAX_FMR_SGES (64)
/* Access mode of externally registered pages */
enum {
RPCRDMA_FMR_ACCESS_FLAGS = IB_ACCESS_REMOTE_WRITE |
IB_ACCESS_REMOTE_READ,
};
bool
fmr_is_supported(struct rpcrdma_ia *ia)
{
if (!ia->ri_device->alloc_fmr) {
pr_info("rpcrdma: 'fmr' mode is not supported by device %s\n",
ia->ri_device->name);
return false;
}
return true;
}
static int
fmr_op_init_mr(struct rpcrdma_ia *ia, struct rpcrdma_mw *mw)
{
static struct ib_fmr_attr fmr_attr = {
.max_pages = RPCRDMA_MAX_FMR_SGES,
.max_maps = 1,
.page_shift = PAGE_SHIFT
};
mw->fmr.fm_physaddrs = kcalloc(RPCRDMA_MAX_FMR_SGES,
sizeof(u64), GFP_KERNEL);
if (!mw->fmr.fm_physaddrs)
goto out_free;
mw->mw_sg = kcalloc(RPCRDMA_MAX_FMR_SGES,
sizeof(*mw->mw_sg), GFP_KERNEL);
if (!mw->mw_sg)
goto out_free;
sg_init_table(mw->mw_sg, RPCRDMA_MAX_FMR_SGES);
mw->fmr.fm_mr = ib_alloc_fmr(ia->ri_pd, RPCRDMA_FMR_ACCESS_FLAGS,
&fmr_attr);
if (IS_ERR(mw->fmr.fm_mr))
goto out_fmr_err;
return 0;
out_fmr_err:
dprintk("RPC: %s: ib_alloc_fmr returned %ld\n", __func__,
PTR_ERR(mw->fmr.fm_mr));
out_free:
kfree(mw->mw_sg);
kfree(mw->fmr.fm_physaddrs);
return -ENOMEM;
}
static int
__fmr_unmap(struct rpcrdma_mw *mw)
{
LIST_HEAD(l);
int rc;
list_add(&mw->fmr.fm_mr->list, &l);
rc = ib_unmap_fmr(&l);
list_del_init(&mw->fmr.fm_mr->list);
return rc;
}
static void
fmr_op_release_mr(struct rpcrdma_mw *r)
{
LIST_HEAD(unmap_list);
int rc;
/* Ensure MW is not on any rl_registered list */
if (!list_empty(&r->mw_list))
list_del(&r->mw_list);
kfree(r->fmr.fm_physaddrs);
kfree(r->mw_sg);
/* In case this one was left mapped, try to unmap it
* to prevent dealloc_fmr from failing with EBUSY
*/
rc = __fmr_unmap(r);
if (rc)
pr_err("rpcrdma: final ib_unmap_fmr for %p failed %i\n",
r, rc);
rc = ib_dealloc_fmr(r->fmr.fm_mr);
if (rc)
pr_err("rpcrdma: final ib_dealloc_fmr for %p returned %i\n",
r, rc);
kfree(r);
}
/* Reset of a single FMR.
*/
static void
fmr_op_recover_mr(struct rpcrdma_mw *mw)
{
struct rpcrdma_xprt *r_xprt = mw->mw_xprt;
int rc;
/* ORDER: invalidate first */
rc = __fmr_unmap(mw);
/* ORDER: then DMA unmap */
ib_dma_unmap_sg(r_xprt->rx_ia.ri_device,
mw->mw_sg, mw->mw_nents, mw->mw_dir);
if (rc)
goto out_release;
rpcrdma_put_mw(r_xprt, mw);
r_xprt->rx_stats.mrs_recovered++;
return;
out_release:
pr_err("rpcrdma: FMR reset failed (%d), %p released\n", rc, mw);
r_xprt->rx_stats.mrs_orphaned++;
spin_lock(&r_xprt->rx_buf.rb_mwlock);
list_del(&mw->mw_all);
spin_unlock(&r_xprt->rx_buf.rb_mwlock);
fmr_op_release_mr(mw);
}
static int
fmr_op_open(struct rpcrdma_ia *ia, struct rpcrdma_ep *ep,
struct rpcrdma_create_data_internal *cdata)
{
ia->ri_max_segs = max_t(unsigned int, 1, RPCRDMA_MAX_DATA_SEGS /
RPCRDMA_MAX_FMR_SGES);
return 0;
}
/* FMR mode conveys up to 64 pages of payload per chunk segment.
*/
static size_t
fmr_op_maxpages(struct rpcrdma_xprt *r_xprt)
{
return min_t(unsigned int, RPCRDMA_MAX_DATA_SEGS,
RPCRDMA_MAX_HDR_SEGS * RPCRDMA_MAX_FMR_SGES);
}
/* Use the ib_map_phys_fmr() verb to register a memory region
* for remote access via RDMA READ or RDMA WRITE.
*/
static int
fmr_op_map(struct rpcrdma_xprt *r_xprt, struct rpcrdma_mr_seg *seg,
int nsegs, bool writing, struct rpcrdma_mw **out)
{
struct rpcrdma_mr_seg *seg1 = seg;
int len, pageoff, i, rc;
struct rpcrdma_mw *mw;
u64 *dma_pages;
mw = rpcrdma_get_mw(r_xprt);
if (!mw)
return -ENOBUFS;
pageoff = offset_in_page(seg1->mr_offset);
seg1->mr_offset -= pageoff; /* start of page */
seg1->mr_len += pageoff;
len = -pageoff;
if (nsegs > RPCRDMA_MAX_FMR_SGES)
nsegs = RPCRDMA_MAX_FMR_SGES;
for (i = 0; i < nsegs;) {
if (seg->mr_page)
sg_set_page(&mw->mw_sg[i],
seg->mr_page,
seg->mr_len,
offset_in_page(seg->mr_offset));
else
sg_set_buf(&mw->mw_sg[i], seg->mr_offset,
seg->mr_len);
len += seg->mr_len;
++seg;
++i;
/* Check for holes */
if ((i < nsegs && offset_in_page(seg->mr_offset)) ||
offset_in_page((seg-1)->mr_offset + (seg-1)->mr_len))
break;
}
mw->mw_nents = i;
mw->mw_dir = rpcrdma_data_dir(writing);
if (i == 0)
goto out_dmamap_err;
if (!ib_dma_map_sg(r_xprt->rx_ia.ri_device,
mw->mw_sg, mw->mw_nents, mw->mw_dir))
goto out_dmamap_err;
for (i = 0, dma_pages = mw->fmr.fm_physaddrs; i < mw->mw_nents; i++)
dma_pages[i] = sg_dma_address(&mw->mw_sg[i]);
rc = ib_map_phys_fmr(mw->fmr.fm_mr, dma_pages, mw->mw_nents,
dma_pages[0]);
if (rc)
goto out_maperr;
mw->mw_handle = mw->fmr.fm_mr->rkey;
mw->mw_length = len;
mw->mw_offset = dma_pages[0] + pageoff;
*out = mw;
return mw->mw_nents;
out_dmamap_err:
pr_err("rpcrdma: failed to dma map sg %p sg_nents %u\n",
mw->mw_sg, mw->mw_nents);
rpcrdma_defer_mr_recovery(mw);
return -EIO;
out_maperr:
pr_err("rpcrdma: ib_map_phys_fmr %u@0x%llx+%i (%d) status %i\n",
len, (unsigned long long)dma_pages[0],
pageoff, mw->mw_nents, rc);
rpcrdma_defer_mr_recovery(mw);
return -EIO;
}
/* Invalidate all memory regions that were registered for "req".
*
* Sleeps until it is safe for the host CPU to access the
* previously mapped memory regions.
*
* Caller ensures that req->rl_registered is not empty.
*/
static void
fmr_op_unmap_sync(struct rpcrdma_xprt *r_xprt, struct rpcrdma_req *req)
{
struct rpcrdma_mw *mw, *tmp;
LIST_HEAD(unmap_list);
int rc;
dprintk("RPC: %s: req %p\n", __func__, req);
/* ORDER: Invalidate all of the req's MRs first
*
* ib_unmap_fmr() is slow, so use a single call instead
* of one call per mapped FMR.
*/
list_for_each_entry(mw, &req->rl_registered, mw_list)
list_add_tail(&mw->fmr.fm_mr->list, &unmap_list);
r_xprt->rx_stats.local_inv_needed++;
rc = ib_unmap_fmr(&unmap_list);
if (rc)
goto out_reset;
/* ORDER: Now DMA unmap all of the req's MRs, and return
* them to the free MW list.
*/
list_for_each_entry_safe(mw, tmp, &req->rl_registered, mw_list) {
list_del_init(&mw->mw_list);
list_del_init(&mw->fmr.fm_mr->list);
ib_dma_unmap_sg(r_xprt->rx_ia.ri_device,
mw->mw_sg, mw->mw_nents, mw->mw_dir);
rpcrdma_put_mw(r_xprt, mw);
}
return;
out_reset:
pr_err("rpcrdma: ib_unmap_fmr failed (%i)\n", rc);
list_for_each_entry_safe(mw, tmp, &req->rl_registered, mw_list) {
list_del_init(&mw->fmr.fm_mr->list);
fmr_op_recover_mr(mw);
}
}
/* Use a slow, safe mechanism to invalidate all memory regions
* that were registered for "req".
*/
static void
fmr_op_unmap_safe(struct rpcrdma_xprt *r_xprt, struct rpcrdma_req *req,
bool sync)
{
struct rpcrdma_mw *mw;
while (!list_empty(&req->rl_registered)) {
mw = list_first_entry(&req->rl_registered,
struct rpcrdma_mw, mw_list);
list_del_init(&mw->mw_list);
if (sync)
fmr_op_recover_mr(mw);
else
rpcrdma_defer_mr_recovery(mw);
}
}
const struct rpcrdma_memreg_ops rpcrdma_fmr_memreg_ops = {
.ro_map = fmr_op_map,
.ro_unmap_sync = fmr_op_unmap_sync,
.ro_unmap_safe = fmr_op_unmap_safe,
.ro_recover_mr = fmr_op_recover_mr,
.ro_open = fmr_op_open,
.ro_maxpages = fmr_op_maxpages,
.ro_init_mr = fmr_op_init_mr,
.ro_release_mr = fmr_op_release_mr,
.ro_displayname = "fmr",
.ro_send_w_inv_ok = 0,
};
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