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// SPDX-License-Identifier: GPL-2.0
/*
* Copyright (c) 2015, 2017 Oracle. All rights reserved.
* Copyright (c) 2003-2007 Network Appliance, Inc. All rights reserved.
*/
/* Lightweight memory registration using Fast Registration Work
* Requests (FRWR).
*
* FRWR features ordered asynchronous registration and deregistration
* of arbitrarily sized memory regions. This is the fastest and safest
* but most complex memory registration mode.
*/
/* Normal operation
*
* A Memory Region is prepared for RDMA READ or WRITE using a FAST_REG
* Work Request (frwr_map). When the RDMA operation is finished, this
* Memory Region is invalidated using a LOCAL_INV Work Request
* (frwr_unmap_sync).
*
* Typically these Work Requests are not signaled, and neither are RDMA
* SEND Work Requests (with the exception of signaling occasionally to
* prevent provider work queue overflows). This greatly reduces HCA
* interrupt workload.
*
* As an optimization, frwr_unmap marks MRs INVALID before the
* LOCAL_INV WR is posted. If posting succeeds, the MR is placed on
* rb_mrs immediately so that no work (like managing a linked list
* under a spinlock) is needed in the completion upcall.
*
* But this means that frwr_map() can occasionally encounter an MR
* that is INVALID but the LOCAL_INV WR has not completed. Work Queue
* ordering prevents a subsequent FAST_REG WR from executing against
* that MR while it is still being invalidated.
*/
/* Transport recovery
*
* ->op_map and the transport connect worker cannot run at the same
* time, but ->op_unmap can fire while the transport connect worker
* is running. Thus MR recovery is handled in ->op_map, to guarantee
* that recovered MRs are owned by a sending RPC, and not one where
* ->op_unmap could fire at the same time transport reconnect is
* being done.
*
* When the underlying transport disconnects, MRs are left in one of
* four states:
*
* INVALID: The MR was not in use before the QP entered ERROR state.
*
* VALID: The MR was registered before the QP entered ERROR state.
*
* FLUSHED_FR: The MR was being registered when the QP entered ERROR
* state, and the pending WR was flushed.
*
* FLUSHED_LI: The MR was being invalidated when the QP entered ERROR
* state, and the pending WR was flushed.
*
* When frwr_map encounters FLUSHED and VALID MRs, they are recovered
* with ib_dereg_mr and then are re-initialized. Because MR recovery
* allocates fresh resources, it is deferred to a workqueue, and the
* recovered MRs are placed back on the rb_mrs list when recovery is
* complete. frwr_map allocates another MR for the current RPC while
* the broken MR is reset.
*
* To ensure that frwr_map doesn't encounter an MR that is marked
* INVALID but that is about to be flushed due to a previous transport
* disconnect, the transport connect worker attempts to drain all
* pending send queue WRs before the transport is reconnected.
*/
#include <linux/sunrpc/rpc_rdma.h>
#include <linux/sunrpc/svc_rdma.h>
#include "xprt_rdma.h"
#include <trace/events/rpcrdma.h>
#if IS_ENABLED(CONFIG_SUNRPC_DEBUG)
# define RPCDBG_FACILITY RPCDBG_TRANS
#endif
/**
* frwr_is_supported - Check if device supports FRWR
* @ia: interface adapter to check
*
* Returns true if device supports FRWR, otherwise false
*/
bool frwr_is_supported(struct rpcrdma_ia *ia)
{
struct ib_device_attr *attrs = &ia->ri_device->attrs;
if (!(attrs->device_cap_flags & IB_DEVICE_MEM_MGT_EXTENSIONS))
goto out_not_supported;
if (attrs->max_fast_reg_page_list_len == 0)
goto out_not_supported;
return true;
out_not_supported:
pr_info("rpcrdma: 'frwr' mode is not supported by device %s\n",
ia->ri_device->name);
return false;
}
/**
* frwr_release_mr - Destroy one MR
* @mr: MR allocated by frwr_init_mr
*
*/
void frwr_release_mr(struct rpcrdma_mr *mr)
{
int rc;
rc = ib_dereg_mr(mr->frwr.fr_mr);
if (rc)
trace_xprtrdma_frwr_dereg(mr, rc);
kfree(mr->mr_sg);
kfree(mr);
}
/* MRs are dynamically allocated, so simply clean up and release the MR.
* A replacement MR will subsequently be allocated on demand.
*/
static void
frwr_mr_recycle_worker(struct work_struct *work)
{
struct rpcrdma_mr *mr = container_of(work, struct rpcrdma_mr, mr_recycle);
struct rpcrdma_xprt *r_xprt = mr->mr_xprt;
trace_xprtrdma_mr_recycle(mr);
if (mr->mr_dir != DMA_NONE) {
trace_xprtrdma_mr_unmap(mr);
ib_dma_unmap_sg(r_xprt->rx_ia.ri_device,
mr->mr_sg, mr->mr_nents, mr->mr_dir);
mr->mr_dir = DMA_NONE;
}
spin_lock(&r_xprt->rx_buf.rb_mrlock);
list_del(&mr->mr_all);
r_xprt->rx_stats.mrs_recycled++;
spin_unlock(&r_xprt->rx_buf.rb_mrlock);
frwr_release_mr(mr);
}
/**
* frwr_init_mr - Initialize one MR
* @ia: interface adapter
* @mr: generic MR to prepare for FRWR
*
* Returns zero if successful. Otherwise a negative errno
* is returned.
*/
int frwr_init_mr(struct rpcrdma_ia *ia, struct rpcrdma_mr *mr)
{
unsigned int depth = ia->ri_max_frwr_depth;
struct scatterlist *sg;
struct ib_mr *frmr;
int rc;
frmr = ib_alloc_mr(ia->ri_pd, ia->ri_mrtype, depth);
if (IS_ERR(frmr))
goto out_mr_err;
sg = kcalloc(depth, sizeof(*sg), GFP_KERNEL);
if (!sg)
goto out_list_err;
mr->frwr.fr_mr = frmr;
mr->frwr.fr_state = FRWR_IS_INVALID;
mr->mr_dir = DMA_NONE;
INIT_LIST_HEAD(&mr->mr_list);
INIT_WORK(&mr->mr_recycle, frwr_mr_recycle_worker);
init_completion(&mr->frwr.fr_linv_done);
sg_init_table(sg, depth);
mr->mr_sg = sg;
return 0;
out_mr_err:
rc = PTR_ERR(frmr);
trace_xprtrdma_frwr_alloc(mr, rc);
return rc;
out_list_err:
dprintk("RPC: %s: sg allocation failure\n",
__func__);
ib_dereg_mr(frmr);
return -ENOMEM;
}
/**
* frwr_open - Prepare an endpoint for use with FRWR
* @ia: interface adapter this endpoint will use
* @ep: endpoint to prepare
* @cdata: transport parameters
*
* On success, sets:
* ep->rep_attr.cap.max_send_wr
* ep->rep_attr.cap.max_recv_wr
* cdata->max_requests
* ia->ri_max_segs
*
* And these FRWR-related fields:
* ia->ri_max_frwr_depth
* ia->ri_mrtype
*
* On failure, a negative errno is returned.
*/
int frwr_open(struct rpcrdma_ia *ia, struct rpcrdma_ep *ep,
struct rpcrdma_create_data_internal *cdata)
{
struct ib_device_attr *attrs = &ia->ri_device->attrs;
int max_qp_wr, depth, delta;
ia->ri_mrtype = IB_MR_TYPE_MEM_REG;
if (attrs->device_cap_flags & IB_DEVICE_SG_GAPS_REG)
ia->ri_mrtype = IB_MR_TYPE_SG_GAPS;
/* Quirk: Some devices advertise a large max_fast_reg_page_list_len
* capability, but perform optimally when the MRs are not larger
* than a page.
*/
if (attrs->max_sge_rd > 1)
ia->ri_max_frwr_depth = attrs->max_sge_rd;
else
ia->ri_max_frwr_depth = attrs->max_fast_reg_page_list_len;
if (ia->ri_max_frwr_depth > RPCRDMA_MAX_DATA_SEGS)
ia->ri_max_frwr_depth = RPCRDMA_MAX_DATA_SEGS;
dprintk("RPC: %s: max FR page list depth = %u\n",
__func__, ia->ri_max_frwr_depth);
/* Add room for frwr register and invalidate WRs.
* 1. FRWR reg WR for head
* 2. FRWR invalidate WR for head
* 3. N FRWR reg WRs for pagelist
* 4. N FRWR invalidate WRs for pagelist
* 5. FRWR reg WR for tail
* 6. FRWR invalidate WR for tail
* 7. The RDMA_SEND WR
*/
depth = 7;
/* Calculate N if the device max FRWR depth is smaller than
* RPCRDMA_MAX_DATA_SEGS.
*/
if (ia->ri_max_frwr_depth < RPCRDMA_MAX_DATA_SEGS) {
delta = RPCRDMA_MAX_DATA_SEGS - ia->ri_max_frwr_depth;
do {
depth += 2; /* FRWR reg + invalidate */
delta -= ia->ri_max_frwr_depth;
} while (delta > 0);
}
max_qp_wr = ia->ri_device->attrs.max_qp_wr;
max_qp_wr -= RPCRDMA_BACKWARD_WRS;
max_qp_wr -= 1;
if (max_qp_wr < RPCRDMA_MIN_SLOT_TABLE)
return -ENOMEM;
if (cdata->max_requests > max_qp_wr)
cdata->max_requests = max_qp_wr;
ep->rep_attr.cap.max_send_wr = cdata->max_requests * depth;
if (ep->rep_attr.cap.max_send_wr > max_qp_wr) {
cdata->max_requests = max_qp_wr / depth;
if (!cdata->max_requests)
return -EINVAL;
ep->rep_attr.cap.max_send_wr = cdata->max_requests *
depth;
}
ep->rep_attr.cap.max_send_wr += RPCRDMA_BACKWARD_WRS;
ep->rep_attr.cap.max_send_wr += 1; /* for ib_drain_sq */
ep->rep_attr.cap.max_recv_wr = cdata->max_requests;
ep->rep_attr.cap.max_recv_wr += RPCRDMA_BACKWARD_WRS;
ep->rep_attr.cap.max_recv_wr += 1; /* for ib_drain_rq */
ia->ri_max_segs = max_t(unsigned int, 1, RPCRDMA_MAX_DATA_SEGS /
ia->ri_max_frwr_depth);
/* Reply chunks require segments for head and tail buffers */
ia->ri_max_segs += 2;
if (ia->ri_max_segs > RPCRDMA_MAX_HDR_SEGS)
ia->ri_max_segs = RPCRDMA_MAX_HDR_SEGS;
return 0;
}
/**
* frwr_maxpages - Compute size of largest payload
* @r_xprt: transport
*
* Returns maximum size of an RPC message, in pages.
*
* FRWR mode conveys a list of pages per chunk segment. The
* maximum length of that list is the FRWR page list depth.
*/
size_t frwr_maxpages(struct rpcrdma_xprt *r_xprt)
{
struct rpcrdma_ia *ia = &r_xprt->rx_ia;
return min_t(unsigned int, RPCRDMA_MAX_DATA_SEGS,
(ia->ri_max_segs - 2) * ia->ri_max_frwr_depth);
}
static void
__frwr_sendcompletion_flush(struct ib_wc *wc, const char *wr)
{
if (wc->status != IB_WC_WR_FLUSH_ERR)
pr_err("rpcrdma: %s: %s (%u/0x%x)\n",
wr, ib_wc_status_msg(wc->status),
wc->status, wc->vendor_err);
}
/**
* frwr_wc_fastreg - Invoked by RDMA provider for a flushed FastReg WC
* @cq: completion queue (ignored)
* @wc: completed WR
*
*/
static void
frwr_wc_fastreg(struct ib_cq *cq, struct ib_wc *wc)
{
struct ib_cqe *cqe = wc->wr_cqe;
struct rpcrdma_frwr *frwr =
container_of(cqe, struct rpcrdma_frwr, fr_cqe);
/* WARNING: Only wr_cqe and status are reliable at this point */
if (wc->status != IB_WC_SUCCESS) {
frwr->fr_state = FRWR_FLUSHED_FR;
__frwr_sendcompletion_flush(wc, "fastreg");
}
trace_xprtrdma_wc_fastreg(wc, frwr);
}
/**
* frwr_wc_localinv - Invoked by RDMA provider for a flushed LocalInv WC
* @cq: completion queue (ignored)
* @wc: completed WR
*
*/
static void
frwr_wc_localinv(struct ib_cq *cq, struct ib_wc *wc)
{
struct ib_cqe *cqe = wc->wr_cqe;
struct rpcrdma_frwr *frwr = container_of(cqe, struct rpcrdma_frwr,
fr_cqe);
/* WARNING: Only wr_cqe and status are reliable at this point */
if (wc->status != IB_WC_SUCCESS) {
frwr->fr_state = FRWR_FLUSHED_LI;
__frwr_sendcompletion_flush(wc, "localinv");
}
trace_xprtrdma_wc_li(wc, frwr);
}
/**
* frwr_wc_localinv_wake - Invoked by RDMA provider for a signaled LocalInv WC
* @cq: completion queue (ignored)
* @wc: completed WR
*
* Awaken anyone waiting for an MR to finish being fenced.
*/
static void
frwr_wc_localinv_wake(struct ib_cq *cq, struct ib_wc *wc)
{
struct ib_cqe *cqe = wc->wr_cqe;
struct rpcrdma_frwr *frwr = container_of(cqe, struct rpcrdma_frwr,
fr_cqe);
/* WARNING: Only wr_cqe and status are reliable at this point */
if (wc->status != IB_WC_SUCCESS) {
frwr->fr_state = FRWR_FLUSHED_LI;
__frwr_sendcompletion_flush(wc, "localinv");
}
complete(&frwr->fr_linv_done);
trace_xprtrdma_wc_li_wake(wc, frwr);
}
/**
* frwr_map - Register a memory region
* @r_xprt: controlling transport
* @seg: memory region co-ordinates
* @nsegs: number of segments remaining
* @writing: true when RDMA Write will be used
* @xid: XID of RPC using the registered memory
* @out: initialized MR
*
* Prepare a REG_MR Work Request to register a memory region
* for remote access via RDMA READ or RDMA WRITE.
*
* Returns the next segment or a negative errno pointer.
* On success, the prepared MR is planted in @out.
*/
struct rpcrdma_mr_seg *frwr_map(struct rpcrdma_xprt *r_xprt,
struct rpcrdma_mr_seg *seg,
int nsegs, bool writing, __be32 xid,
struct rpcrdma_mr **out)
{
struct rpcrdma_ia *ia = &r_xprt->rx_ia;
bool holes_ok = ia->ri_mrtype == IB_MR_TYPE_SG_GAPS;
struct rpcrdma_frwr *frwr;
struct rpcrdma_mr *mr;
struct ib_mr *ibmr;
struct ib_reg_wr *reg_wr;
int i, n;
u8 key;
mr = NULL;
do {
if (mr)
rpcrdma_mr_recycle(mr);
mr = rpcrdma_mr_get(r_xprt);
if (!mr)
return ERR_PTR(-EAGAIN);
} while (mr->frwr.fr_state != FRWR_IS_INVALID);
frwr = &mr->frwr;
frwr->fr_state = FRWR_IS_VALID;
if (nsegs > ia->ri_max_frwr_depth)
nsegs = ia->ri_max_frwr_depth;
for (i = 0; i < nsegs;) {
if (seg->mr_page)
sg_set_page(&mr->mr_sg[i],
seg->mr_page,
seg->mr_len,
offset_in_page(seg->mr_offset));
else
sg_set_buf(&mr->mr_sg[i], seg->mr_offset,
seg->mr_len);
++seg;
++i;
if (holes_ok)
continue;
if ((i < nsegs && offset_in_page(seg->mr_offset)) ||
offset_in_page((seg-1)->mr_offset + (seg-1)->mr_len))
break;
}
mr->mr_dir = rpcrdma_data_dir(writing);
mr->mr_nents = ib_dma_map_sg(ia->ri_device, mr->mr_sg, i, mr->mr_dir);
if (!mr->mr_nents)
goto out_dmamap_err;
ibmr = frwr->fr_mr;
n = ib_map_mr_sg(ibmr, mr->mr_sg, mr->mr_nents, NULL, PAGE_SIZE);
if (unlikely(n != mr->mr_nents))
goto out_mapmr_err;
ibmr->iova &= 0x00000000ffffffff;
ibmr->iova |= ((u64)be32_to_cpu(xid)) << 32;
key = (u8)(ibmr->rkey & 0x000000FF);
ib_update_fast_reg_key(ibmr, ++key);
reg_wr = &frwr->fr_regwr;
reg_wr->mr = ibmr;
reg_wr->key = ibmr->rkey;
reg_wr->access = writing ?
IB_ACCESS_REMOTE_WRITE | IB_ACCESS_LOCAL_WRITE :
IB_ACCESS_REMOTE_READ;
mr->mr_handle = ibmr->rkey;
mr->mr_length = ibmr->length;
mr->mr_offset = ibmr->iova;
trace_xprtrdma_mr_map(mr);
*out = mr;
return seg;
out_dmamap_err:
frwr->fr_state = FRWR_IS_INVALID;
trace_xprtrdma_frwr_sgerr(mr, i);
rpcrdma_mr_put(mr);
return ERR_PTR(-EIO);
out_mapmr_err:
trace_xprtrdma_frwr_maperr(mr, n);
rpcrdma_mr_recycle(mr);
return ERR_PTR(-EIO);
}
/**
* frwr_send - post Send WR containing the RPC Call message
* @ia: interface adapter
* @req: Prepared RPC Call
*
* For FRWR, chain any FastReg WRs to the Send WR. Only a
* single ib_post_send call is needed to register memory
* and then post the Send WR.
*
* Returns the result of ib_post_send.
*/
int frwr_send(struct rpcrdma_ia *ia, struct rpcrdma_req *req)
{
struct ib_send_wr *post_wr;
struct rpcrdma_mr *mr;
post_wr = &req->rl_sendctx->sc_wr;
list_for_each_entry(mr, &req->rl_registered, mr_list) {
struct rpcrdma_frwr *frwr;
frwr = &mr->frwr;
frwr->fr_cqe.done = frwr_wc_fastreg;
frwr->fr_regwr.wr.next = post_wr;
frwr->fr_regwr.wr.wr_cqe = &frwr->fr_cqe;
frwr->fr_regwr.wr.num_sge = 0;
frwr->fr_regwr.wr.opcode = IB_WR_REG_MR;
frwr->fr_regwr.wr.send_flags = 0;
post_wr = &frwr->fr_regwr.wr;
}
/* If ib_post_send fails, the next ->send_request for
* @req will queue these MRs for recovery.
*/
return ib_post_send(ia->ri_id->qp, post_wr, NULL);
}
/**
* frwr_reminv - handle a remotely invalidated mr on the @mrs list
* @rep: Received reply
* @mrs: list of MRs to check
*
*/
void frwr_reminv(struct rpcrdma_rep *rep, struct list_head *mrs)
{
struct rpcrdma_mr *mr;
list_for_each_entry(mr, mrs, mr_list)
if (mr->mr_handle == rep->rr_inv_rkey) {
list_del_init(&mr->mr_list);
trace_xprtrdma_mr_remoteinv(mr);
mr->frwr.fr_state = FRWR_IS_INVALID;
rpcrdma_mr_unmap_and_put(mr);
break; /* only one invalidated MR per RPC */
}
}
/**
* frwr_unmap_sync - invalidate memory regions that were registered for @req
* @r_xprt: controlling transport
* @mrs: list of MRs to process
*
* Sleeps until it is safe for the host CPU to access the
* previously mapped memory regions.
*
* Caller ensures that @mrs is not empty before the call. This
* function empties the list.
*/
void frwr_unmap_sync(struct rpcrdma_xprt *r_xprt, struct list_head *mrs)
{
struct ib_send_wr *first, **prev, *last;
const struct ib_send_wr *bad_wr;
struct rpcrdma_ia *ia = &r_xprt->rx_ia;
struct rpcrdma_frwr *frwr;
struct rpcrdma_mr *mr;
int count, rc;
/* ORDER: Invalidate all of the MRs first
*
* Chain the LOCAL_INV Work Requests and post them with
* a single ib_post_send() call.
*/
frwr = NULL;
count = 0;
prev = &first;
list_for_each_entry(mr, mrs, mr_list) {
mr->frwr.fr_state = FRWR_IS_INVALID;
frwr = &mr->frwr;
trace_xprtrdma_mr_localinv(mr);
frwr->fr_cqe.done = frwr_wc_localinv;
last = &frwr->fr_invwr;
memset(last, 0, sizeof(*last));
last->wr_cqe = &frwr->fr_cqe;
last->opcode = IB_WR_LOCAL_INV;
last->ex.invalidate_rkey = mr->mr_handle;
count++;
*prev = last;
prev = &last->next;
}
if (!frwr)
goto unmap;
/* Strong send queue ordering guarantees that when the
* last WR in the chain completes, all WRs in the chain
* are complete.
*/
last->send_flags = IB_SEND_SIGNALED;
frwr->fr_cqe.done = frwr_wc_localinv_wake;
reinit_completion(&frwr->fr_linv_done);
/* Transport disconnect drains the receive CQ before it
* replaces the QP. The RPC reply handler won't call us
* unless ri_id->qp is a valid pointer.
*/
r_xprt->rx_stats.local_inv_needed++;
bad_wr = NULL;
rc = ib_post_send(ia->ri_id->qp, first, &bad_wr);
if (bad_wr != first)
wait_for_completion(&frwr->fr_linv_done);
if (rc)
goto out_release;
/* ORDER: Now DMA unmap all of the MRs, and return
* them to the free MR list.
*/
unmap:
while (!list_empty(mrs)) {
mr = rpcrdma_mr_pop(mrs);
rpcrdma_mr_unmap_and_put(mr);
}
return;
out_release:
pr_err("rpcrdma: FRWR invalidate ib_post_send returned %i\n", rc);
/* Unmap and release the MRs in the LOCAL_INV WRs that did not
* get posted.
*/
while (bad_wr) {
frwr = container_of(bad_wr, struct rpcrdma_frwr,
fr_invwr);
mr = container_of(frwr, struct rpcrdma_mr, frwr);
bad_wr = bad_wr->next;
list_del_init(&mr->mr_list);
rpcrdma_mr_recycle(mr);
}
}