| Message ID | f2dd21a3d0f2005e02c34c793325317f1c326ce1.1662461897.git.matsuda-daisuke@fujitsu.com (mailing list archive) |
|---|---|
| State | RFC |
| Headers | show |
| Series | RDMA/rxe: On-Demand Paging on SoftRoCE | expand |
On Wed, Sep 07, 2022 at 11:43:04AM +0900, Daisuke Matsuda wrote: > rxe_mr_copy() is used widely to copy data to/from a user MR. requester uses > it to load payloads of requesting packets; responder uses it to process > Send, Write, and Read operaetions; completer uses it to copy data from > response packets of Read and Atomic operations to a user MR. > > Allow these operations to be used with ODP by adding a counterpart function > rxe_odp_mr_copy(). It is comprised of the following steps: > 1. Check the driver page table(umem_odp->dma_list) to see if pages being > accessed are present with appropriate permission. > 2. If necessary, trigger page fault to map the pages. > 3. Convert their user space addresses to kernel logical addresses using > PFNs in the driver page table(umem_odp->pfn_list). > 4. Execute data copy fo/from the pages. > > umem_mutex is used to ensure that dma_list (an array of addresses of an MR) > is not changed while it is checked and that mapped pages are not > invalidated before data copy completes. > > Signed-off-by: Daisuke Matsuda <matsuda-daisuke@fujitsu.com> > --- > drivers/infiniband/sw/rxe/rxe.c | 10 ++ > drivers/infiniband/sw/rxe/rxe_loc.h | 2 + > drivers/infiniband/sw/rxe/rxe_mr.c | 2 +- > drivers/infiniband/sw/rxe/rxe_odp.c | 173 +++++++++++++++++++++++++++ > drivers/infiniband/sw/rxe/rxe_resp.c | 6 +- > 5 files changed, 190 insertions(+), 3 deletions(-) <...> > +/* umem mutex is always locked when returning from this function. */ > +static int rxe_odp_map_range(struct rxe_mr *mr, u64 iova, int length, u32 flags) > +{ > + struct ib_umem_odp *umem_odp = to_ib_umem_odp(mr->umem); > + const int max_tries = 3; > + int cnt = 0; > + > + int err; > + u64 perm; > + bool need_fault; > + > + if (unlikely(length < 1)) > + return -EINVAL; > + > + perm = ODP_READ_ALLOWED_BIT; > + if (!(flags & RXE_PAGEFAULT_RDONLY)) > + perm |= ODP_WRITE_ALLOWED_BIT; > + > + mutex_lock(&umem_odp->umem_mutex); > + > + /* > + * A successful return from rxe_odp_do_pagefault() does not guarantee > + * that all pages in the range became present. Recheck the DMA address > + * array, allowing max 3 tries for pagefault. > + */ > + while ((need_fault = rxe_is_pagefault_neccesary(umem_odp, > + iova, length, perm))) { > + > + if (cnt >= max_tries) > + break; > + > + mutex_unlock(&umem_odp->umem_mutex); > + > + /* rxe_odp_do_pagefault() locks the umem mutex. */ Maybe it is correct and safe to release lock in the middle, but it is not clear. The whole pattern of taking lock in one function and later releasing it in another doesn't look right to me. Thanks
On Thu, Sep 8, 2022 5:30 PM Leon Romanovsky wrote: > On Wed, Sep 07, 2022 at 11:43:04AM +0900, Daisuke Matsuda wrote: > > rxe_mr_copy() is used widely to copy data to/from a user MR. requester uses > > it to load payloads of requesting packets; responder uses it to process > > Send, Write, and Read operaetions; completer uses it to copy data from > > response packets of Read and Atomic operations to a user MR. > > > > Allow these operations to be used with ODP by adding a counterpart function > > rxe_odp_mr_copy(). It is comprised of the following steps: > > 1. Check the driver page table(umem_odp->dma_list) to see if pages being > > accessed are present with appropriate permission. > > 2. If necessary, trigger page fault to map the pages. > > 3. Convert their user space addresses to kernel logical addresses using > > PFNs in the driver page table(umem_odp->pfn_list). > > 4. Execute data copy fo/from the pages. > > > > umem_mutex is used to ensure that dma_list (an array of addresses of an MR) > > is not changed while it is checked and that mapped pages are not > > invalidated before data copy completes. > > > > Signed-off-by: Daisuke Matsuda <matsuda-daisuke@fujitsu.com> > > --- > > drivers/infiniband/sw/rxe/rxe.c | 10 ++ > > drivers/infiniband/sw/rxe/rxe_loc.h | 2 + > > drivers/infiniband/sw/rxe/rxe_mr.c | 2 +- > > drivers/infiniband/sw/rxe/rxe_odp.c | 173 +++++++++++++++++++++++++++ > > drivers/infiniband/sw/rxe/rxe_resp.c | 6 +- > > 5 files changed, 190 insertions(+), 3 deletions(-) > > <...> > > > +/* umem mutex is always locked when returning from this function. */ > > +static int rxe_odp_map_range(struct rxe_mr *mr, u64 iova, int length, u32 flags) > > +{ > > + struct ib_umem_odp *umem_odp = to_ib_umem_odp(mr->umem); > > + const int max_tries = 3; > > + int cnt = 0; > > + > > + int err; > > + u64 perm; > > + bool need_fault; > > + > > + if (unlikely(length < 1)) > > + return -EINVAL; > > + > > + perm = ODP_READ_ALLOWED_BIT; > > + if (!(flags & RXE_PAGEFAULT_RDONLY)) > > + perm |= ODP_WRITE_ALLOWED_BIT; > > + > > + mutex_lock(&umem_odp->umem_mutex); > > + > > + /* > > + * A successful return from rxe_odp_do_pagefault() does not guarantee > > + * that all pages in the range became present. Recheck the DMA address > > + * array, allowing max 3 tries for pagefault. > > + */ > > + while ((need_fault = rxe_is_pagefault_neccesary(umem_odp, > > + iova, length, perm))) { > > + > > + if (cnt >= max_tries) > > + break; > > + > > + mutex_unlock(&umem_odp->umem_mutex); > > + > > + /* rxe_odp_do_pagefault() locks the umem mutex. */ > > Maybe it is correct and safe to release lock in the middle, but it is > not clear. The whole pattern of taking lock in one function and later > releasing it in another doesn't look right to me. When the driver finds the pages are not mapped in rxe_is_pagefault_neccesary(), it releases the lock to let the kernel execute page invalidation meantime, and takes the lock again to do page fault in ib_umem_odp_map_dma_and_lock(). Then, it proceed to rxe_is_pagefault_neccesary() again with the lock taken. I admit the usage of the lock is quite confusing. It is locked before making it clear that the target pages are present. It is released when the target pages are missing and page fault is required, or when access to the target pages in a MR is done. I will move some lock taking/releasing operations to rxe_odp_mr_copy() and rxe_odp_atomic_ops() so that people can understand the situation easier. Also, I will rethink the way I explain it in comments and the patch description. Thank you, Daisuke Matsuda > > Thanks
diff --git a/drivers/infiniband/sw/rxe/rxe.c b/drivers/infiniband/sw/rxe/rxe.c index 0719f451253c..dd287fc60e9d 100644 --- a/drivers/infiniband/sw/rxe/rxe.c +++ b/drivers/infiniband/sw/rxe/rxe.c @@ -79,6 +79,16 @@ static void rxe_init_device_param(struct rxe_dev *rxe) /* IB_ODP_SUPPORT_IMPLICIT is not supported right now. */ rxe->attr.odp_caps.general_caps |= IB_ODP_SUPPORT; + + rxe->attr.odp_caps.per_transport_caps.ud_odp_caps |= IB_ODP_SUPPORT_SEND; + rxe->attr.odp_caps.per_transport_caps.ud_odp_caps |= IB_ODP_SUPPORT_RECV; + rxe->attr.odp_caps.per_transport_caps.ud_odp_caps |= IB_ODP_SUPPORT_SRQ_RECV; + + rxe->attr.odp_caps.per_transport_caps.rc_odp_caps |= IB_ODP_SUPPORT_SEND; + rxe->attr.odp_caps.per_transport_caps.rc_odp_caps |= IB_ODP_SUPPORT_RECV; + rxe->attr.odp_caps.per_transport_caps.rc_odp_caps |= IB_ODP_SUPPORT_WRITE; + rxe->attr.odp_caps.per_transport_caps.rc_odp_caps |= IB_ODP_SUPPORT_READ; + rxe->attr.odp_caps.per_transport_caps.rc_odp_caps |= IB_ODP_SUPPORT_SRQ_RECV; } } diff --git a/drivers/infiniband/sw/rxe/rxe_loc.h b/drivers/infiniband/sw/rxe/rxe_loc.h index 03b4078b90a3..91982b5a690c 100644 --- a/drivers/infiniband/sw/rxe/rxe_loc.h +++ b/drivers/infiniband/sw/rxe/rxe_loc.h @@ -192,5 +192,7 @@ static inline unsigned int wr_opcode_mask(int opcode, struct rxe_qp *qp) /* rxe_odp.c */ int rxe_create_user_odp_mr(struct ib_pd *pd, u64 start, u64 length, u64 iova, int access_flags, struct rxe_mr *mr); +int rxe_odp_mr_copy(struct rxe_mr *mr, u64 iova, void *addr, int length, + enum rxe_mr_copy_dir dir); #endif /* RXE_LOC_H */ diff --git a/drivers/infiniband/sw/rxe/rxe_mr.c b/drivers/infiniband/sw/rxe/rxe_mr.c index 0ae72a4516be..2091e865dd8f 100644 --- a/drivers/infiniband/sw/rxe/rxe_mr.c +++ b/drivers/infiniband/sw/rxe/rxe_mr.c @@ -439,7 +439,7 @@ int copy_data( iova = sge->addr + offset; if (mr->odp_enabled) - err = -EOPNOTSUPP; + err = rxe_odp_mr_copy(mr, iova, addr, bytes, dir); else err = rxe_mr_copy(mr, iova, addr, bytes, dir); if (err) diff --git a/drivers/infiniband/sw/rxe/rxe_odp.c b/drivers/infiniband/sw/rxe/rxe_odp.c index 1f6930ba714c..85c34995c704 100644 --- a/drivers/infiniband/sw/rxe/rxe_odp.c +++ b/drivers/infiniband/sw/rxe/rxe_odp.c @@ -3,6 +3,8 @@ * Copyright (c) 2022 Fujitsu Ltd. All rights reserved. */ +#include <linux/hmm.h> + #include <rdma/ib_umem_odp.h> #include "rxe.h" @@ -112,3 +114,174 @@ int rxe_create_user_odp_mr(struct ib_pd *pd, u64 start, u64 length, u64 iova, return err; } + +static inline bool rxe_is_pagefault_neccesary(struct ib_umem_odp *umem_odp, + u64 iova, int length, u32 perm) +{ + int idx; + u64 addr; + bool need_fault = false; + + addr = iova & (~(BIT(umem_odp->page_shift) - 1)); + + /* Skim through all pages that are to be accessed. */ + while (addr < iova + length) { + idx = (addr - ib_umem_start(umem_odp)) >> umem_odp->page_shift; + + if (!(umem_odp->dma_list[idx] & perm)) { + need_fault = true; + break; + } + + addr += BIT(umem_odp->page_shift); + } + return need_fault; +} + +/* umem mutex is always locked when returning from this function. */ +static int rxe_odp_map_range(struct rxe_mr *mr, u64 iova, int length, u32 flags) +{ + struct ib_umem_odp *umem_odp = to_ib_umem_odp(mr->umem); + const int max_tries = 3; + int cnt = 0; + + int err; + u64 perm; + bool need_fault; + + if (unlikely(length < 1)) + return -EINVAL; + + perm = ODP_READ_ALLOWED_BIT; + if (!(flags & RXE_PAGEFAULT_RDONLY)) + perm |= ODP_WRITE_ALLOWED_BIT; + + mutex_lock(&umem_odp->umem_mutex); + + /* + * A successful return from rxe_odp_do_pagefault() does not guarantee + * that all pages in the range became present. Recheck the DMA address + * array, allowing max 3 tries for pagefault. + */ + while ((need_fault = rxe_is_pagefault_neccesary(umem_odp, + iova, length, perm))) { + + if (cnt >= max_tries) + break; + + mutex_unlock(&umem_odp->umem_mutex); + + /* rxe_odp_do_pagefault() locks the umem mutex. */ + err = rxe_odp_do_pagefault(mr, iova, length, flags); + if (err < 0) + return err; + + cnt++; + } + + if (need_fault) + return -EFAULT; + + return 0; +} + +static inline void *rxe_odp_get_virt(struct ib_umem_odp *umem_odp, int umem_idx, + size_t offset) +{ + struct page *page; + void *virt; + + /* + * Step 1. Get page struct from the pfn array. + * Step 2. Convert page struct to kernel logical address. + * Step 3. Add offset in the page to the address. + */ + page = hmm_pfn_to_page(umem_odp->pfn_list[umem_idx]); + virt = page_address(page); + + if (!virt) + return NULL; + + virt += offset; + + return virt; +} + +static int __rxe_odp_mr_copy(struct rxe_mr *mr, u64 iova, void *addr, + int length, enum rxe_mr_copy_dir dir) +{ + struct ib_umem_odp *umem_odp = to_ib_umem_odp(mr->umem); + + int idx, bytes; + u8 *user_va; + size_t offset; + + idx = (iova - ib_umem_start(umem_odp)) >> umem_odp->page_shift; + offset = iova & (BIT(umem_odp->page_shift) - 1); + + while (length > 0) { + u8 *src, *dest; + + user_va = (u8 *)rxe_odp_get_virt(umem_odp, idx, offset); + if (!user_va) + return -EFAULT; + + src = (dir == RXE_TO_MR_OBJ) ? addr : user_va; + dest = (dir == RXE_TO_MR_OBJ) ? user_va : addr; + + bytes = BIT(umem_odp->page_shift) - offset; + + if (bytes > length) + bytes = length; + + memcpy(dest, src, bytes); + + length -= bytes; + idx++; + offset = 0; + } + + /* The mutex was locked in rxe_odp_map_range(). + * Now it is safe to invalidate the MR, so unlock it + */ + mutex_unlock(&umem_odp->umem_mutex); + + return 0; +} + +int rxe_odp_mr_copy(struct rxe_mr *mr, u64 iova, void *addr, int length, + enum rxe_mr_copy_dir dir) +{ + struct ib_umem_odp *umem_odp = to_ib_umem_odp(mr->umem); + u32 flags = 0; + + int err; + + if (length == 0) + return 0; + + WARN_ON_ONCE(!mr->odp_enabled); + + switch (dir) { + case RXE_TO_MR_OBJ: + break; + + case RXE_FROM_MR_OBJ: + flags = RXE_PAGEFAULT_RDONLY; + break; + + default: + return -EINVAL; + } + + /* umem mutex is locked here to prevent MR invalidation before data copy + * completes; On success, it is unlocked in __rxe_odp_mr_copy() + */ + err = rxe_odp_map_range(mr, iova, length, flags); + if (err) { + mutex_unlock(&umem_odp->umem_mutex); + return err; + } + + return __rxe_odp_mr_copy(mr, iova, addr, length, dir); +} diff --git a/drivers/infiniband/sw/rxe/rxe_resp.c b/drivers/infiniband/sw/rxe/rxe_resp.c index dd8632e783f6..bf439004c378 100644 --- a/drivers/infiniband/sw/rxe/rxe_resp.c +++ b/drivers/infiniband/sw/rxe/rxe_resp.c @@ -536,7 +536,8 @@ static enum resp_states write_data_in(struct rxe_qp *qp, int data_len = payload_size(pkt); if (qp->resp.mr->odp_enabled) - err = -EOPNOTSUPP; + err = rxe_odp_mr_copy(qp->resp.mr, qp->resp.va + qp->resp.offset, + payload_addr(pkt), data_len, RXE_TO_MR_OBJ); else err = rxe_mr_copy(qp->resp.mr, qp->resp.va + qp->resp.offset, payload_addr(pkt), data_len, RXE_TO_MR_OBJ); @@ -839,7 +840,8 @@ static enum resp_states read_reply(struct rxe_qp *qp, return RESPST_ERR_RNR; if (mr->odp_enabled) - err = -EOPNOTSUPP; + err = rxe_odp_mr_copy(mr, res->read.va, payload_addr(&ack_pkt), + payload, RXE_FROM_MR_OBJ); else err = rxe_mr_copy(mr, res->read.va, payload_addr(&ack_pkt), payload, RXE_FROM_MR_OBJ);
rxe_mr_copy() is used widely to copy data to/from a user MR. requester uses it to load payloads of requesting packets; responder uses it to process Send, Write, and Read operaetions; completer uses it to copy data from response packets of Read and Atomic operations to a user MR. Allow these operations to be used with ODP by adding a counterpart function rxe_odp_mr_copy(). It is comprised of the following steps: 1. Check the driver page table(umem_odp->dma_list) to see if pages being accessed are present with appropriate permission. 2. If necessary, trigger page fault to map the pages. 3. Convert their user space addresses to kernel logical addresses using PFNs in the driver page table(umem_odp->pfn_list). 4. Execute data copy fo/from the pages. umem_mutex is used to ensure that dma_list (an array of addresses of an MR) is not changed while it is checked and that mapped pages are not invalidated before data copy completes. Signed-off-by: Daisuke Matsuda <matsuda-daisuke@fujitsu.com> --- drivers/infiniband/sw/rxe/rxe.c | 10 ++ drivers/infiniband/sw/rxe/rxe_loc.h | 2 + drivers/infiniband/sw/rxe/rxe_mr.c | 2 +- drivers/infiniband/sw/rxe/rxe_odp.c | 173 +++++++++++++++++++++++++++ drivers/infiniband/sw/rxe/rxe_resp.c | 6 +- 5 files changed, 190 insertions(+), 3 deletions(-)