Re: [PATCH 02/17] hw/block/nvme: handle dma errors

["Philippe Mathieu-Daudé" <philmd@redhat.com>]

Hi Klaus,

On 9/4/20 4:19 PM, Klaus Jensen wrote:
> From: Klaus Jensen <k.jensen@samsung.com>
> 
> Handling DMA errors gracefully is required for the device to pass the
> block/011 test ("disable PCI device while doing I/O") in the blktests
> suite.
> 
> With this patch the device passes the test by retrying "critical"
> transfers (posting of completion entries and processing of submission
> queue entries).
> 
> If DMA errors occur at any other point in the execution of the command
> (say, while mapping the PRPs), the command is aborted with a Data
> Transfer Error status code.
> 
> Signed-off-by: Klaus Jensen <k.jensen@samsung.com>
> Acked-by: Keith Busch <kbusch@kernel.org>
> Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
> ---
>  hw/block/nvme.c       | 43 ++++++++++++++++++++++++++++++++-----------
>  hw/block/trace-events |  2 ++
>  include/block/nvme.h  |  2 +-
>  3 files changed, 35 insertions(+), 12 deletions(-)
> 
> diff --git a/hw/block/nvme.c b/hw/block/nvme.c
> index 63078f600920..49bcdf31ced6 100644
> --- a/hw/block/nvme.c
> +++ b/hw/block/nvme.c
> @@ -140,14 +140,14 @@ static inline void *nvme_addr_to_cmb(NvmeCtrl *n, hwaddr addr)
>      return &n->cmbuf[addr - n->ctrl_mem.addr];
>  }
>  
> -static void nvme_addr_read(NvmeCtrl *n, hwaddr addr, void *buf, int size)
> +static int nvme_addr_read(NvmeCtrl *n, hwaddr addr, void *buf, int size)

If this get merged first:
https://www.mail-archive.com/qemu-devel@nongnu.org/msg737483.html
then please return MemTxResult, ...

>  {
>      if (n->bar.cmbsz && nvme_addr_is_cmb(n, addr)) {
>          memcpy(buf, nvme_addr_to_cmb(n, addr), size);
> -        return;
> +        return 0;
>      }
>  
> -    pci_dma_read(&n->parent_obj, addr, buf, size);
> +    return pci_dma_read(&n->parent_obj, addr, buf, size);
>  }
>  
>  static int nvme_check_sqid(NvmeCtrl *n, uint16_t sqid)
> @@ -253,7 +253,7 @@ static uint16_t nvme_map_addr_cmb(NvmeCtrl *n, QEMUIOVector *iov, hwaddr addr,
>      trace_pci_nvme_map_addr_cmb(addr, len);
>  
>      if (!nvme_addr_is_cmb(n, addr) || !nvme_addr_is_cmb(n, addr + len - 1)) {
> -        return NVME_DATA_TRAS_ERROR;
> +        return NVME_DATA_TRANSFER_ERROR;
>      }
>  
>      qemu_iovec_add(iov, nvme_addr_to_cmb(n, addr), len);
> @@ -307,6 +307,7 @@ static uint16_t nvme_map_prp(NvmeCtrl *n, uint64_t prp1, uint64_t prp2,
>      int num_prps = (len >> n->page_bits) + 1;
>      uint16_t status;
>      bool prp_list_in_cmb = false;
> +    int ret;
>  
>      QEMUSGList *qsg = &req->qsg;
>      QEMUIOVector *iov = &req->iov;
> @@ -347,7 +348,11 @@ static uint16_t nvme_map_prp(NvmeCtrl *n, uint64_t prp1, uint64_t prp2,
>  
>              nents = (len + n->page_size - 1) >> n->page_bits;
>              prp_trans = MIN(n->max_prp_ents, nents) * sizeof(uint64_t);
> -            nvme_addr_read(n, prp2, (void *)prp_list, prp_trans);
> +            ret = nvme_addr_read(n, prp2, (void *)prp_list, prp_trans);
> +            if (ret) {

... and check it (other cases following).

> +                trace_pci_nvme_err_addr_read(prp2);
> +                return NVME_DATA_TRANSFER_ERROR;
> +            }
>              while (len != 0) {
>                  uint64_t prp_ent = le64_to_cpu(prp_list[i]);
>  
> @@ -364,8 +369,12 @@ static uint16_t nvme_map_prp(NvmeCtrl *n, uint64_t prp1, uint64_t prp2,
>                      i = 0;
>                      nents = (len + n->page_size - 1) >> n->page_bits;
>                      prp_trans = MIN(n->max_prp_ents, nents) * sizeof(uint64_t);
> -                    nvme_addr_read(n, prp_ent, (void *)prp_list,
> -                        prp_trans);
> +                    ret = nvme_addr_read(n, prp_ent, (void *)prp_list,
> +                                         prp_trans);
> +                    if (ret) {
> +                        trace_pci_nvme_err_addr_read(prp_ent);
> +                        return NVME_DATA_TRANSFER_ERROR;
> +                    }
>                      prp_ent = le64_to_cpu(prp_list[i]);
>                  }
>  
> @@ -457,6 +466,7 @@ static void nvme_post_cqes(void *opaque)
>      NvmeCQueue *cq = opaque;
>      NvmeCtrl *n = cq->ctrl;
>      NvmeRequest *req, *next;
> +    int ret;
>  
>      QTAILQ_FOREACH_SAFE(req, &cq->req_list, entry, next) {
>          NvmeSQueue *sq;
> @@ -466,15 +476,21 @@ static void nvme_post_cqes(void *opaque)
>              break;
>          }
>  
> -        QTAILQ_REMOVE(&cq->req_list, req, entry);
>          sq = req->sq;
>          req->cqe.status = cpu_to_le16((req->status << 1) | cq->phase);
>          req->cqe.sq_id = cpu_to_le16(sq->sqid);
>          req->cqe.sq_head = cpu_to_le16(sq->head);
>          addr = cq->dma_addr + cq->tail * n->cqe_size;
> +        ret = pci_dma_write(&n->parent_obj, addr, (void *)&req->cqe,
> +                            sizeof(req->cqe));
> +        if (ret) {
> +            trace_pci_nvme_err_addr_write(addr);
> +            timer_mod(cq->timer, qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) +
> +                      500 * SCALE_MS);
> +            break;
> +        }
> +        QTAILQ_REMOVE(&cq->req_list, req, entry);
>          nvme_inc_cq_tail(cq);
> -        pci_dma_write(&n->parent_obj, addr, (void *)&req->cqe,
> -            sizeof(req->cqe));
>          nvme_req_exit(req);
>          QTAILQ_INSERT_TAIL(&sq->req_list, req, entry);
>      }
> @@ -1611,7 +1627,12 @@ static void nvme_process_sq(void *opaque)
>  
>      while (!(nvme_sq_empty(sq) || QTAILQ_EMPTY(&sq->req_list))) {
>          addr = sq->dma_addr + sq->head * n->sqe_size;
> -        nvme_addr_read(n, addr, (void *)&cmd, sizeof(cmd));
> +        if (nvme_addr_read(n, addr, (void *)&cmd, sizeof(cmd))) {
> +            trace_pci_nvme_err_addr_read(addr);
> +            timer_mod(sq->timer, qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) +
> +                      500 * SCALE_MS);
> +            break;
> +        }
>          nvme_inc_sq_head(sq);
>  
>          req = QTAILQ_FIRST(&sq->req_list);
> diff --git a/hw/block/trace-events b/hw/block/trace-events
> index 72cf2d15cb8e..50d5702e6b80 100644
> --- a/hw/block/trace-events
> +++ b/hw/block/trace-events
> @@ -86,6 +86,8 @@ pci_nvme_mmio_shutdown_cleared(void) "shutdown bit cleared"
>  
>  # nvme traces for error conditions
>  pci_nvme_err_mdts(uint16_t cid, size_t len) "cid %"PRIu16" len %zu"
> +pci_nvme_err_addr_read(uint64_t addr) "addr 0x%"PRIx64""
> +pci_nvme_err_addr_write(uint64_t addr) "addr 0x%"PRIx64""
>  pci_nvme_err_invalid_dma(void) "PRP/SGL is too small for transfer size"
>  pci_nvme_err_invalid_prplist_ent(uint64_t prplist) "PRP list entry is null or not page aligned: 0x%"PRIx64""
>  pci_nvme_err_invalid_prp2_align(uint64_t prp2) "PRP2 is not page aligned: 0x%"PRIx64""
> diff --git a/include/block/nvme.h b/include/block/nvme.h
> index 65e68a82c897..c8d0a3473f0d 100644
> --- a/include/block/nvme.h
> +++ b/include/block/nvme.h
> @@ -630,7 +630,7 @@ enum NvmeStatusCodes {
>      NVME_INVALID_OPCODE         = 0x0001,
>      NVME_INVALID_FIELD          = 0x0002,
>      NVME_CID_CONFLICT           = 0x0003,
> -    NVME_DATA_TRAS_ERROR        = 0x0004,
> +    NVME_DATA_TRANSFER_ERROR    = 0x0004,
>      NVME_POWER_LOSS_ABORT       = 0x0005,
>      NVME_INTERNAL_DEV_ERROR     = 0x0006,
>      NVME_CMD_ABORT_REQ          = 0x0007,
>