nvme-pci: do not directly handle subsys reset fallout

Scheduling reset_work after a nvme subsystem reset is expected to fail
on pcie, but this also prevents potential handling the platform's pcie
services may provide that might successfully recovering the link without
re-enumeration. Such examples include AER, DPC, and power's EEH.

Provide a pci specific operation that safely initiates a subsystem
reset, and instead of scheduling reset work, read back the status
register to trigger a pcie read error.

Since this only affects pci, the other fabrics drivers subscribe to a
generic nvmf subsystem reset that is exactly the same as before. The
loop fabric doesn't use it because nvmet doesn't support setting that
property anyway.

And since we're using the magic NSSR value in two places now, provide a
symbolic define for it.

Reported-by: Nilay Shroff <nilay@linux.ibm.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Keith Busch <kbusch@kernel.org>

diff --git a/drivers/nvme/host/fabrics.c b/drivers/nvme/host/fabrics.c
index b5a4b5fd573e0d6c330d977de1cae1fd92c276e0..44e342a46f39f9d1f7ae985e73ae9289cb134da0 100644 (file)
--- a/drivers/nvme/host/fabrics.c
+++ b/drivers/nvme/host/fabrics.c
@@ -280,6 +280,21 @@ int nvmf_reg_write32(struct nvme_ctrl *ctrl, u32 off, u32 val)
 }
 EXPORT_SYMBOL_GPL(nvmf_reg_write32);
 
+int nvmf_subsystem_reset(struct nvme_ctrl *ctrl)
+{
+       int ret;
+
+       if (!nvme_wait_reset(ctrl))
+               return -EBUSY;
+
+       ret = ctrl->ops->reg_write32(ctrl, NVME_REG_NSSR, NVME_SUBSYS_RESET);
+       if (ret)
+               return ret;
+
+       return nvme_try_sched_reset(ctrl);
+}
+EXPORT_SYMBOL_GPL(nvmf_subsystem_reset);
+
 /**
  * nvmf_log_connect_error() - Error-parsing-diagnostic print out function for
  *                             connect() errors.

diff --git a/drivers/nvme/host/fabrics.h b/drivers/nvme/host/fabrics.h
index 602135910ae9cc40f9ae24fa6204314f978fdbfe..21d75dc4a3a09126e4a58ed0f9e3fefae692053d 100644 (file)
--- a/drivers/nvme/host/fabrics.h
+++ b/drivers/nvme/host/fabrics.h
@@ -217,6 +217,7 @@ static inline unsigned int nvmf_nr_io_queues(struct nvmf_ctrl_options *opts)
 int nvmf_reg_read32(struct nvme_ctrl *ctrl, u32 off, u32 *val);
 int nvmf_reg_read64(struct nvme_ctrl *ctrl, u32 off, u64 *val);
 int nvmf_reg_write32(struct nvme_ctrl *ctrl, u32 off, u32 val);
+int nvmf_subsystem_reset(struct nvme_ctrl *ctrl);
 int nvmf_connect_admin_queue(struct nvme_ctrl *ctrl);
 int nvmf_connect_io_queue(struct nvme_ctrl *ctrl, u16 qid);
 int nvmf_register_transport(struct nvmf_transport_ops *ops);

diff --git a/drivers/nvme/host/fc.c b/drivers/nvme/host/fc.c
index fee84b0055d07d006395150b4eeaf9e704e33f98..b81af7919e94c421387033bf8361a9cf8a867486 100644 (file)
--- a/drivers/nvme/host/fc.c
+++ b/drivers/nvme/host/fc.c
@@ -3382,6 +3382,7 @@ static const struct nvme_ctrl_ops nvme_fc_ctrl_ops = {
        .reg_read32             = nvmf_reg_read32,
        .reg_read64             = nvmf_reg_read64,
        .reg_write32            = nvmf_reg_write32,
+       .subsystem_reset        = nvmf_subsystem_reset,
        .free_ctrl              = nvme_fc_free_ctrl,
        .submit_async_event     = nvme_fc_submit_async_event,
        .delete_ctrl            = nvme_fc_delete_ctrl,

diff --git a/drivers/nvme/host/nvme.h b/drivers/nvme/host/nvme.h
index 73442d3f504b46501843ce33712c6acf4cd18342..c63f2b4523691477d6d2b1640d82f7df7a11a551 100644 (file)
--- a/drivers/nvme/host/nvme.h
+++ b/drivers/nvme/host/nvme.h
@@ -551,6 +551,7 @@ struct nvme_ctrl_ops {
        int (*reg_read64)(struct nvme_ctrl *ctrl, u32 off, u64 *val);
        void (*free_ctrl)(struct nvme_ctrl *ctrl);
        void (*submit_async_event)(struct nvme_ctrl *ctrl);
+       int (*subsystem_reset)(struct nvme_ctrl *ctrl);
        void (*delete_ctrl)(struct nvme_ctrl *ctrl);
        void (*stop_ctrl)(struct nvme_ctrl *ctrl);
        int (*get_address)(struct nvme_ctrl *ctrl, char *buf, int size);
@@ -649,18 +650,9 @@ int nvme_try_sched_reset(struct nvme_ctrl *ctrl);
 
 static inline int nvme_reset_subsystem(struct nvme_ctrl *ctrl)
 {
-       int ret;
-
-       if (!ctrl->subsystem)
+       if (!ctrl->subsystem || !ctrl->ops->subsystem_reset)
                return -ENOTTY;
-       if (!nvme_wait_reset(ctrl))
-               return -EBUSY;
-
-       ret = ctrl->ops->reg_write32(ctrl, NVME_REG_NSSR, 0x4E564D65);
-       if (ret)
-               return ret;
-
-       return nvme_try_sched_reset(ctrl);
+       return ctrl->ops->subsystem_reset(ctrl);
 }
 
 /*

diff --git a/drivers/nvme/host/pci.c b/drivers/nvme/host/pci.c
index c92125b0238d480432cd728cf66044fd7bb81fcc..c1e1ecd0f1dff770910fca57147699d239ed6ebc 100644 (file)
--- a/drivers/nvme/host/pci.c
+++ b/drivers/nvme/host/pci.c
@@ -1143,6 +1143,41 @@ static void nvme_pci_submit_async_event(struct nvme_ctrl *ctrl)
        spin_unlock(&nvmeq->sq_lock);
 }
 
+static int nvme_pci_subsystem_reset(struct nvme_ctrl *ctrl)
+{
+       struct nvme_dev *dev = to_nvme_dev(ctrl);
+       int ret = 0;
+
+       /*
+        * Taking the shutdown_lock ensures the BAR mapping is not being
+        * altered by reset_work. Holding this lock before the RESETTING state
+        * change, if successful, also ensures nvme_remove won't be able to
+        * proceed to iounmap until we're done.
+        */
+       mutex_lock(&dev->shutdown_lock);
+       if (!dev->bar_mapped_size) {
+               ret = -ENODEV;
+               goto unlock;
+       }
+
+       if (!nvme_change_ctrl_state(ctrl, NVME_CTRL_RESETTING)) {
+               ret = -EBUSY;
+               goto unlock;
+       }
+
+       writel(NVME_SUBSYS_RESET, dev->bar + NVME_REG_NSSR);
+       nvme_change_ctrl_state(ctrl, NVME_CTRL_LIVE);
+
+       /*
+        * Read controller status to flush the previous write and trigger a
+        * pcie read error.
+        */
+       readl(dev->bar + NVME_REG_CSTS);
+unlock:
+       mutex_unlock(&dev->shutdown_lock);
+       return ret;
+}
+
 static int adapter_delete_queue(struct nvme_dev *dev, u8 opcode, u16 id)
 {
        struct nvme_command c = { };
@@ -2859,6 +2894,7 @@ static const struct nvme_ctrl_ops nvme_pci_ctrl_ops = {
        .reg_read64             = nvme_pci_reg_read64,
        .free_ctrl              = nvme_pci_free_ctrl,
        .submit_async_event     = nvme_pci_submit_async_event,
+       .subsystem_reset        = nvme_pci_subsystem_reset,
        .get_address            = nvme_pci_get_address,
        .print_device_info      = nvme_pci_print_device_info,
        .supports_pci_p2pdma    = nvme_pci_supports_pci_p2pdma,

diff --git a/drivers/nvme/host/rdma.c b/drivers/nvme/host/rdma.c
index 5c44c7c5c688c2bd31aab60355f5d37616549b9e..2eb33842f9711a997123cb24c14fd2e7d1cffd02 100644 (file)
--- a/drivers/nvme/host/rdma.c
+++ b/drivers/nvme/host/rdma.c
@@ -2201,6 +2201,7 @@ static const struct nvme_ctrl_ops nvme_rdma_ctrl_ops = {
        .reg_read32             = nvmf_reg_read32,
        .reg_read64             = nvmf_reg_read64,
        .reg_write32            = nvmf_reg_write32,
+       .subsystem_reset        = nvmf_subsystem_reset,
        .free_ctrl              = nvme_rdma_free_ctrl,
        .submit_async_event     = nvme_rdma_submit_async_event,
        .delete_ctrl            = nvme_rdma_delete_ctrl,

diff --git a/drivers/nvme/host/tcp.c b/drivers/nvme/host/tcp.c
index 3be67c98c906e6eda180c5d5f888f1a381ad9215..a2a47d3ab99f0d0b25bf1a1221945e1dcc92db10 100644 (file)
--- a/drivers/nvme/host/tcp.c
+++ b/drivers/nvme/host/tcp.c
@@ -2662,6 +2662,7 @@ static const struct nvme_ctrl_ops nvme_tcp_ctrl_ops = {
        .reg_read32             = nvmf_reg_read32,
        .reg_read64             = nvmf_reg_read64,
        .reg_write32            = nvmf_reg_write32,
+       .subsystem_reset        = nvmf_subsystem_reset,
        .free_ctrl              = nvme_tcp_free_ctrl,
        .submit_async_event     = nvme_tcp_submit_async_event,
        .delete_ctrl            = nvme_tcp_delete_ctrl,

diff --git a/include/linux/nvme.h b/include/linux/nvme.h
index 27faae34245d71ae07976eb29ccc8d9178af44c6..57e27e48c9131da94ccb506e9f2de0fb5bf24cca 100644 (file)
--- a/include/linux/nvme.h
+++ b/include/linux/nvme.h
@@ -25,6 +25,9 @@
 
 #define NVME_NSID_ALL          0xffffffff
 
+/* Special NSSR value, 'NVMe' */
+#define NVME_SUBSYS_RESET      0x4E564D65
+
 enum nvme_subsys_type {
        /* Referral to another discovery type target subsystem */
        NVME_NQN_DISC   = 1,