[PATCH 4/4] nvme-pci: implement host memory buffer support
Christoph Hellwig
hch at lst.de
Sat May 20 06:13:57 PDT 2017
If a controller supports the host memory buffer we try to provide
it with the requested size up to an upper cap set as a module
parameter. We try to give as few as possible descriptors, eventually
working our way down.
Signed-off-by: Christoph Hellwig <hch at lst.de>
---
drivers/nvme/host/pci.c | 187 +++++++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 185 insertions(+), 2 deletions(-)
diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
index fed803232edc..93868b9750cd 100644
--- a/drivers/nvme/host/pci.c
+++ b/drivers/nvme/host/pci.c
@@ -66,6 +66,11 @@ static bool use_cmb_sqes = true;
module_param(use_cmb_sqes, bool, 0644);
MODULE_PARM_DESC(use_cmb_sqes, "use controller's memory buffer for I/O SQes");
+static unsigned int max_host_mem_size_mb = 128;
+module_param(max_host_mem_size_mb, uint, 0444);
+MODULE_PARM_DESC(max_host_mem_size_mb,
+ "Maximum Host Memory Buffer (HMB) size per controller (in MiB)");
+
static struct workqueue_struct *nvme_workq;
struct nvme_dev;
@@ -104,10 +109,18 @@ struct nvme_dev {
u32 cmbloc;
struct nvme_ctrl ctrl;
struct completion ioq_wait;
+
+ /* shadow doorbell buffer support: */
u32 *dbbuf_dbs;
dma_addr_t dbbuf_dbs_dma_addr;
u32 *dbbuf_eis;
dma_addr_t dbbuf_eis_dma_addr;
+
+ /* host memory buffer support: */
+ u64 host_mem_size;
+ u32 nr_host_mem_descs;
+ struct nvme_host_mem_buf_desc *host_mem_descs;
+ void **host_mem_desc_bufs;
};
static inline unsigned int sq_idx(unsigned int qid, u32 stride)
@@ -1509,6 +1522,160 @@ static inline void nvme_release_cmb(struct nvme_dev *dev)
}
}
+static int nvme_set_host_mem(struct nvme_dev *dev, u32 bits)
+{
+ size_t len = dev->nr_host_mem_descs * sizeof(*dev->host_mem_descs);
+ struct nvme_command c;
+ u64 dma_addr;
+ int ret;
+
+ dma_addr = dma_map_single(dev->dev, dev->host_mem_descs, len,
+ DMA_TO_DEVICE);
+ if (dma_mapping_error(dev->dev, dma_addr))
+ return -ENOMEM;
+
+ memset(&c, 0, sizeof(c));
+ c.features.opcode = nvme_admin_set_features;
+ c.features.fid = cpu_to_le32(NVME_FEAT_HOST_MEM_BUF);
+ c.features.dword11 = cpu_to_le32(bits);
+ c.features.dword12 = cpu_to_le32(dev->host_mem_size /
+ dev->ctrl.page_size);
+ c.features.dword13 = cpu_to_le32(lower_32_bits(dma_addr));
+ c.features.dword14 = cpu_to_le32(upper_32_bits(dma_addr));
+ c.features.dword15 = cpu_to_le32(dev->nr_host_mem_descs);
+
+ ret = nvme_submit_sync_cmd(dev->ctrl.admin_q, &c, NULL, 0);
+ if (ret) {
+ dev_warn(dev->ctrl.device,
+ "failed to set host mem (err %d, flags %#x).\n",
+ ret, bits);
+ }
+ dma_unmap_single(dev->dev, dma_addr, len, DMA_TO_DEVICE);
+ return ret;
+}
+
+static void nvme_free_host_mem(struct nvme_dev *dev)
+{
+ int i;
+
+ for (i = 0; i < dev->nr_host_mem_descs; i++) {
+ struct nvme_host_mem_buf_desc *desc = &dev->host_mem_descs[i];
+ size_t size = le32_to_cpu(desc->size) * dev->ctrl.page_size;
+
+ dma_free_coherent(dev->dev, size, dev->host_mem_desc_bufs[i],
+ le64_to_cpu(desc->addr));
+ }
+
+ kfree(dev->host_mem_desc_bufs);
+ dev->host_mem_desc_bufs = NULL;
+ kfree(dev->host_mem_descs);
+ dev->host_mem_descs = NULL;
+}
+
+static int nvme_alloc_host_mem(struct nvme_dev *dev, u64 min, u64 preferred)
+{
+ struct nvme_host_mem_buf_desc *descs;
+ u32 chunk_size, max_entries, i = 0;
+ void **bufs;
+ u64 size;
+
+ /* start big and work our way down */
+ chunk_size = min(preferred, (u64)PAGE_SIZE << MAX_ORDER);
+retry:
+ max_entries = DIV_ROUND_UP(preferred, chunk_size);
+ descs = kcalloc(max_entries, sizeof(*descs), GFP_KERNEL);
+ if (!descs)
+ goto out;
+
+ bufs = kcalloc(max_entries, sizeof(*bufs), GFP_KERNEL);
+ if (!bufs)
+ goto out_free_descs;
+
+ for (size = 0; size < preferred; size += chunk_size) {
+ u32 len = min_t(u64, chunk_size, preferred - size);
+ dma_addr_t dma_addr;
+
+ bufs[i] = dma_alloc_attrs(dev->dev, len, &dma_addr, GFP_KERNEL,
+ DMA_ATTR_NO_KERNEL_MAPPING | DMA_ATTR_NO_WARN);
+ if (!bufs[i])
+ break;
+
+ descs[i].addr = cpu_to_le64(dma_addr);
+ descs[i].size = cpu_to_le32(len / dev->ctrl.page_size);
+ i++;
+ }
+
+ if (!size || (min && size < min)) {
+ dev_warn(dev->ctrl.device,
+ "failed to allocate host memory buffer.\n");
+ goto out_free_bufs;
+ }
+
+ dev_info(dev->ctrl.device,
+ "allocated %lld MiB host memory buffer.\n", size / 1024 / 1024);
+ dev->nr_host_mem_descs = i;
+ dev->host_mem_size = size;
+ dev->host_mem_descs = descs;
+ dev->host_mem_desc_bufs = bufs;
+ return 0;
+
+out_free_bufs:
+ while (--i >= 0) {
+ struct nvme_host_mem_buf_desc *desc = &dev->host_mem_descs[i];
+ size_t size = le32_to_cpu(desc->size) * dev->ctrl.page_size;
+
+ dma_free_coherent(dev->dev, size, dev->host_mem_desc_bufs[i],
+ le64_to_cpu(desc->addr));
+ }
+
+ kfree(bufs);
+out_free_descs:
+ kfree(descs);
+out:
+ /* try a smaller chunk size if we failed early */
+ if (chunk_size >= PAGE_SIZE * 2 && (i == 0 || size < min)) {
+ chunk_size /= 2;
+ goto retry;
+ }
+ dev->host_mem_descs = NULL;
+ return -ENOMEM;
+}
+
+static void nvme_setup_host_mem(struct nvme_dev *dev)
+{
+ u64 max = (u64)max_host_mem_size_mb * 1024 * 1024;
+ u64 preferred = (u64)dev->ctrl.hmpre * 4096;
+ u64 min = (u64)dev->ctrl.hmmin * 4096;
+ u32 enable_bits = NVME_HOST_MEM_ENABLE;
+
+ preferred = min(preferred, max);
+ if (min > max) {
+ dev_warn(dev->ctrl.device,
+ "min host memory (%lld MiB) above limit (%d MiB).\n",
+ preferred / 1024 / 1024, max_host_mem_size_mb);
+ nvme_free_host_mem(dev);
+ return;
+ }
+
+ /*
+ * If we already have a buffer allocated check if we can reuse it.
+ */
+ if (dev->host_mem_descs) {
+ if (dev->host_mem_size >= min)
+ enable_bits |= NVME_HOST_MEM_RETURN;
+ else
+ nvme_free_host_mem(dev);
+ }
+
+ if (!dev->host_mem_descs) {
+ if (nvme_alloc_host_mem(dev, min, preferred))
+ return;
+ }
+
+ if (nvme_set_host_mem(dev, enable_bits))
+ nvme_free_host_mem(dev);
+}
+
static size_t db_bar_size(struct nvme_dev *dev, unsigned nr_io_queues)
{
return 4096 + ((nr_io_queues + 1) * 8 * dev->db_stride);
@@ -1809,8 +1976,20 @@ static void nvme_dev_disable(struct nvme_dev *dev, bool shutdown)
* Give the controller a chance to complete all entered requests if
* doing a safe shutdown.
*/
- if (!dead && shutdown)
- nvme_wait_freeze_timeout(&dev->ctrl, NVME_IO_TIMEOUT);
+ if (!dead) {
+ if (shutdown)
+ nvme_wait_freeze_timeout(&dev->ctrl, NVME_IO_TIMEOUT);
+
+ /*
+ * If the controller is still alive tell it to stop using the
+ * host memory buffer. In theory the shutdown / reset should
+ * make sure that it doesn't access the host memoery anymore,
+ * but I'd rather be safe than sorry..
+ */
+ if (dev->host_mem_descs)
+ nvme_set_host_mem(dev, 0);
+
+ }
nvme_stop_queues(&dev->ctrl);
queues = dev->online_queues - 1;
@@ -1945,6 +2124,9 @@ static void nvme_reset_work(struct work_struct *work)
"unable to allocate dma for dbbuf\n");
}
+ if (dev->ctrl.hmpre)
+ nvme_setup_host_mem(dev);
+
result = nvme_setup_io_queues(dev);
if (result)
goto out;
@@ -2182,6 +2364,7 @@ static void nvme_remove(struct pci_dev *pdev)
flush_work(&dev->reset_work);
nvme_uninit_ctrl(&dev->ctrl);
nvme_dev_disable(dev, true);
+ nvme_free_host_mem(dev);
nvme_dev_remove_admin(dev);
nvme_free_queues(dev, 0);
nvme_release_cmb(dev);
--
2.11.0
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