[PATCH v2 20/20] nvme: handle dma errors

[Klaus Jensen <its@irrelevant.dk>]

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 or SGLs), the command is aborted with a
Data Transfer Error status code.

Signed-off-by: Klaus Jensen <k.jensen@samsung.com>
---
 hw/block/nvme.c       | 63 +++++++++++++++++++++++++++++++++----------
 hw/block/trace-events |  2 ++
 include/block/nvme.h  |  2 +-
 3 files changed, 52 insertions(+), 15 deletions(-)

diff --git a/hw/block/nvme.c b/hw/block/nvme.c
index d0103c16cfe9..00c5b843295b 100644
--- a/hw/block/nvme.c
+++ b/hw/block/nvme.c
@@ -71,26 +71,26 @@ static inline bool nvme_addr_is_cmb(NvmeCtrl *n, hwaddr addr)
     return addr >= low && addr < hi;
 }
 
-static inline void nvme_addr_read(NvmeCtrl *n, hwaddr addr, void *buf,
+static inline int nvme_addr_read(NvmeCtrl *n, hwaddr addr, void *buf,
     int size)
 {
     if (n->cmbsz && nvme_addr_is_cmb(n, addr)) {
         memcpy(buf, (void *) &n->cmbuf[addr - n->ctrl_mem.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 inline void nvme_addr_write(NvmeCtrl *n, hwaddr addr, void *buf,
+static inline int nvme_addr_write(NvmeCtrl *n, hwaddr addr, void *buf,
     int size)
 {
     if (n->cmbsz && nvme_addr_is_cmb(n, addr)) {
         memcpy((void *) &n->cmbuf[addr - n->ctrl_mem.addr], buf, size);
-        return;
+        return 0;
     }
 
-    pci_dma_write(&n->parent_obj, addr, buf, size);
+    return pci_dma_write(&n->parent_obj, addr, buf, size);
 }
 
 static int nvme_check_sqid(NvmeCtrl *n, uint16_t sqid)
@@ -228,7 +228,11 @@ static uint16_t nvme_map_prp(NvmeCtrl *n, QEMUSGList *qsg, uint64_t prp1,
 
             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);
+            if (nvme_addr_read(n, prp2, (void *) prp_list, prp_trans)) {
+                trace_nvme_err_addr_read((void *) prp2);
+                status = NVME_DATA_TRANSFER_ERROR;
+                goto unmap;
+            }
             while (len != 0) {
                 bool addr_is_cmb;
                 uint64_t prp_ent = le64_to_cpu(prp_list[i]);
@@ -250,7 +254,11 @@ static uint16_t nvme_map_prp(NvmeCtrl *n, QEMUSGList *qsg, uint64_t prp1,
                     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);
+                    if (nvme_addr_read(n, prp_ent, (void *) prp_list, prp_trans)) {
+                        trace_nvme_err_addr_read((void *) prp_ent);
+                        status = NVME_DATA_TRANSFER_ERROR;
+                        goto unmap;
+                    }
                     prp_ent = le64_to_cpu(prp_list[i]);
                 }
 
@@ -402,7 +410,11 @@ static uint16_t nvme_map_sgl(NvmeCtrl *n, QEMUSGList *qsg,
 
         /* read the segment in chunks of 256 descriptors (4k) */
         while (nsgld > MAX_NSGLD) {
-            nvme_addr_read(n, addr, segment, sizeof(segment));
+            if (nvme_addr_read(n, addr, segment, sizeof(segment))) {
+                trace_nvme_err_addr_read((void *) addr);
+                status = NVME_DATA_TRANSFER_ERROR;
+                goto unmap;
+            }
 
             status = nvme_map_sgl_data(n, qsg, segment, MAX_NSGLD, &len, req);
             if (status) {
@@ -413,7 +425,11 @@ static uint16_t nvme_map_sgl(NvmeCtrl *n, QEMUSGList *qsg,
             addr += MAX_NSGLD * sizeof(NvmeSglDescriptor);
         }
 
-        nvme_addr_read(n, addr, segment, nsgld * sizeof(NvmeSglDescriptor));
+        if (nvme_addr_read(n, addr, segment, nsgld * sizeof(NvmeSglDescriptor))) {
+            trace_nvme_err_addr_read((void *) addr);
+            status = NVME_DATA_TRANSFER_ERROR;
+            goto unmap;
+        }
 
         sgl = segment[nsgld - 1];
         addr = le64_to_cpu(sgl.addr);
@@ -458,7 +474,11 @@ static uint16_t nvme_map_sgl(NvmeCtrl *n, QEMUSGList *qsg,
     nsgld = le64_to_cpu(sgl.len) / sizeof(NvmeSglDescriptor);
 
     while (nsgld > MAX_NSGLD) {
-        nvme_addr_read(n, addr, segment, sizeof(segment));
+        if (nvme_addr_read(n, addr, segment, sizeof(segment))) {
+            trace_nvme_err_addr_read((void *) addr);
+            status = NVME_DATA_TRANSFER_ERROR;
+            goto unmap;
+        }
 
         status = nvme_map_sgl_data(n, qsg, segment, MAX_NSGLD, &len, req);
         if (status) {
@@ -469,7 +489,11 @@ static uint16_t nvme_map_sgl(NvmeCtrl *n, QEMUSGList *qsg,
         addr += MAX_NSGLD * sizeof(NvmeSglDescriptor);
     }
 
-    nvme_addr_read(n, addr, segment, nsgld * sizeof(NvmeSglDescriptor));
+    if (nvme_addr_read(n, addr, segment, nsgld * sizeof(NvmeSglDescriptor))) {
+        trace_nvme_err_addr_read((void *) addr);
+        status = NVME_DATA_TRANSFER_ERROR;
+        goto unmap;
+    }
 
     status = nvme_map_sgl_data(n, qsg, segment, nsgld, &len, req);
     if (status) {
@@ -819,8 +843,14 @@ static void nvme_post_cqes(void *opaque)
         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;
+        if (nvme_addr_write(n, addr, (void *) cqe, sizeof(*cqe))) {
+            trace_nvme_err_addr_write((void *) addr);
+            QTAILQ_INSERT_TAIL(&cq->req_list, req, entry);
+            timer_mod(cq->timer, qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) +
+                100 * SCALE_MS);
+            break;
+        }
         nvme_inc_cq_tail(cq);
-        nvme_addr_write(n, addr, (void *) cqe, sizeof(*cqe));
         QTAILQ_INSERT_TAIL(&sq->req_list, req, entry);
     }
     if (cq->tail != cq->head) {
@@ -1937,7 +1967,12 @@ 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(NvmeCmd));
+        if (nvme_addr_read(n, addr, (void *)&cmd, sizeof(NvmeCmd))) {
+            trace_nvme_err_addr_read((void *) addr);
+            timer_mod(sq->timer, qemu_clock_get_ns(QEMU_CLOCK_VIRTUAL) +
+                100 * 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 95c24f514754..54aa001bf52d 100644
--- a/hw/block/trace-events
+++ b/hw/block/trace-events
@@ -84,6 +84,8 @@ nvme_mmio_shutdown_cleared(void) "shutdown bit cleared"
 nvme_err_mdts(uint16_t cid, size_t mdts, size_t len) "cid %"PRIu16" mdts %"PRIu64" len %"PRIu64""
 nvme_err_prinfo(uint16_t cid, uint16_t ctrl) "cid %"PRIu16" ctrl %"PRIu16""
 nvme_err_aio(uint16_t cid, void *aio, const char *blkname, uint64_t offset, const char *opc, void *req, uint16_t status) "cid %"PRIu16" aio %p blk \"%s\" offset %"PRIu64" opc \"%s\" req %p status 0x%"PRIx16""
+nvme_err_addr_read(void *addr) "addr %p"
+nvme_err_addr_write(void *addr) "addr %p"
 nvme_err_invalid_sgl_descriptor(uint16_t cid, uint8_t typ) "cid %"PRIu16" type 0x%"PRIx8""
 nvme_err_invalid_sgl_excess_length(uint16_t cid) "cid %"PRIu16""
 nvme_err_invalid_dma(void) "PRP/SGL is too small for transfer size"
diff --git a/include/block/nvme.h b/include/block/nvme.h
index ba0a9d4e328f..5a2075e739ee 100644
--- a/include/block/nvme.h
+++ b/include/block/nvme.h
@@ -459,7 +459,7 @@ 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,
-- 
2.23.0