cxl: Adapter failure handling

Check the AFU state whenever an API is called. The hypervisor may
issue a reset of the adapter when it detects a fault. When it happens,
it launches an error recovery which will either move the AFU to a
permanent failure state, or in the disabled state.
If the AFU is found to be disabled, detach all existing contexts from
it before issuing a AFU reset to re-enable it.

Before detaching contexts, notify any kernel driver through the EEH
callbacks of the AFU pci device.

Co-authored-by: Frederic Barrat <fbarrat@linux.vnet.ibm.com>
Signed-off-by: Frederic Barrat <fbarrat@linux.vnet.ibm.com>
Signed-off-by: Christophe Lombard <clombard@linux.vnet.ibm.com>
Reviewed-by: Manoj Kumar <manoj@linux.vnet.ibm.com>
Acked-by: Ian Munsie <imunsie@au1.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

7 files changed, 198 insertions, 35 deletions

diff --git a/drivers/misc/cxl/context.c b/drivers/misc/cxl/context.c
index 180c85a32825..10370f280500 100644
--- a/drivers/misc/cxl/context.c
+++ b/drivers/misc/cxl/context.c
@@ -220,7 +220,7 @@ int __detach_context(struct cxl_context *ctx)
          * If detach fails when hw is down, we don't care.
          */
         WARN_ON(cxl_ops->detach_process(ctx) &&
-                cxl_ops->link_ok(ctx->afu->adapter));
+                cxl_ops->link_ok(ctx->afu->adapter, ctx->afu));
         flush_work(&ctx->fault_work); /* Only needed for dedicated process */
 
         /* release the reference to the group leader and mm handling pid */
diff --git a/drivers/misc/cxl/cxl.h b/drivers/misc/cxl/cxl.h
index b388c971810f..e345860c25eb 100644
--- a/drivers/misc/cxl/cxl.h
+++ b/drivers/misc/cxl/cxl.h
@@ -379,6 +379,8 @@ struct cxl_afu_guest {
         phys_addr_t p2n_phys;
         u64 p2n_size;
         int max_ints;
+        struct mutex recovery_lock;
+        int previous_state;
 };
 
 struct cxl_afu {
@@ -617,7 +619,7 @@ struct cxl_process_element {
         __be32 software_state;
 } __packed;
 
-static inline bool cxl_adapter_link_ok(struct cxl *cxl)
+static inline bool cxl_adapter_link_ok(struct cxl *cxl, struct cxl_afu *afu)
 {
         struct pci_dev *pdev;
 
@@ -636,13 +638,13 @@ static inline void __iomem *_cxl_p1_addr(struct cxl *cxl, cxl_p1_reg_t reg)
 
 static inline void cxl_p1_write(struct cxl *cxl, cxl_p1_reg_t reg, u64 val)
 {
-        if (likely(cxl_adapter_link_ok(cxl)))
+        if (likely(cxl_adapter_link_ok(cxl, NULL)))
                 out_be64(_cxl_p1_addr(cxl, reg), val);
 }
 
 static inline u64 cxl_p1_read(struct cxl *cxl, cxl_p1_reg_t reg)
 {
-        if (likely(cxl_adapter_link_ok(cxl)))
+        if (likely(cxl_adapter_link_ok(cxl, NULL)))
                 return in_be64(_cxl_p1_addr(cxl, reg));
         else
                 return ~0ULL;
@@ -656,13 +658,13 @@ static inline void __iomem *_cxl_p1n_addr(struct cxl_afu *afu, cxl_p1n_reg_t reg
 
 static inline void cxl_p1n_write(struct cxl_afu *afu, cxl_p1n_reg_t reg, u64 val)
 {
-        if (likely(cxl_adapter_link_ok(afu->adapter)))
+        if (likely(cxl_adapter_link_ok(afu->adapter, afu)))
                 out_be64(_cxl_p1n_addr(afu, reg), val);
 }
 
 static inline u64 cxl_p1n_read(struct cxl_afu *afu, cxl_p1n_reg_t reg)
 {
-        if (likely(cxl_adapter_link_ok(afu->adapter)))
+        if (likely(cxl_adapter_link_ok(afu->adapter, afu)))
                 return in_be64(_cxl_p1n_addr(afu, reg));
         else
                 return ~0ULL;
@@ -675,13 +677,13 @@ static inline void __iomem *_cxl_p2n_addr(struct cxl_afu *afu, cxl_p2n_reg_t reg
 
 static inline void cxl_p2n_write(struct cxl_afu *afu, cxl_p2n_reg_t reg, u64 val)
 {
-        if (likely(cxl_adapter_link_ok(afu->adapter)))
+        if (likely(cxl_adapter_link_ok(afu->adapter, afu)))
                 out_be64(_cxl_p2n_addr(afu, reg), val);
 }
 
 static inline u64 cxl_p2n_read(struct cxl_afu *afu, cxl_p2n_reg_t reg)
 {
-        if (likely(cxl_adapter_link_ok(afu->adapter)))
+        if (likely(cxl_adapter_link_ok(afu->adapter, afu)))
                 return in_be64(_cxl_p2n_addr(afu, reg));
         else
                 return ~0ULL;
@@ -857,7 +859,7 @@ struct cxl_backend_ops {
                         u64 wed, u64 amr);
         int (*detach_process)(struct cxl_context *ctx);
         bool (*support_attributes)(const char *attr_name, enum cxl_attrs type);
-        bool (*link_ok)(struct cxl *cxl);
+        bool (*link_ok)(struct cxl *cxl, struct cxl_afu *afu);
         void (*release_afu)(struct device *dev);
         ssize_t (*afu_read_err_buffer)(struct cxl_afu *afu, char *buf,
                                 loff_t off, size_t count);
diff --git a/drivers/misc/cxl/file.c b/drivers/misc/cxl/file.c
index e16046292dd6..eec468f1612f 100644
--- a/drivers/misc/cxl/file.c
+++ b/drivers/misc/cxl/file.c
@@ -76,7 +76,7 @@ static int __afu_open(struct inode *inode, struct file *file, bool master)
         if (!afu->current_mode)
                 goto err_put_afu;
 
-        if (!cxl_ops->link_ok(adapter)) {
+        if (!cxl_ops->link_ok(adapter, afu)) {
                 rc = -EIO;
                 goto err_put_afu;
         }
@@ -257,7 +257,7 @@ long afu_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
         if (ctx->status == CLOSED)
                 return -EIO;
 
-        if (!cxl_ops->link_ok(ctx->afu->adapter))
+        if (!cxl_ops->link_ok(ctx->afu->adapter, ctx->afu))
                 return -EIO;
 
         pr_devel("afu_ioctl\n");
@@ -287,7 +287,7 @@ int afu_mmap(struct file *file, struct vm_area_struct *vm)
         if (ctx->status != STARTED)
                 return -EIO;
 
-        if (!cxl_ops->link_ok(ctx->afu->adapter))
+        if (!cxl_ops->link_ok(ctx->afu->adapter, ctx->afu))
                 return -EIO;
 
         return cxl_context_iomap(ctx, vm);
@@ -334,7 +334,7 @@ ssize_t afu_read(struct file *file, char __user *buf, size_t count,
         int rc;
         DEFINE_WAIT(wait);
 
-        if (!cxl_ops->link_ok(ctx->afu->adapter))
+        if (!cxl_ops->link_ok(ctx->afu->adapter, ctx->afu))
                 return -EIO;
 
         if (count < CXL_READ_MIN_SIZE)
@@ -347,7 +347,7 @@ ssize_t afu_read(struct file *file, char __user *buf, size_t count,
                 if (ctx_event_pending(ctx))
                         break;
 
-                if (!cxl_ops->link_ok(ctx->afu->adapter)) {
+                if (!cxl_ops->link_ok(ctx->afu->adapter, ctx->afu)) {
                         rc = -EIO;
                         goto out;
                 }
diff --git a/drivers/misc/cxl/guest.c b/drivers/misc/cxl/guest.c
index 2b07ebd2b429..8213372de2b7 100644
--- a/drivers/misc/cxl/guest.c
+++ b/drivers/misc/cxl/guest.c
@@ -15,6 +15,46 @@
 #include "hcalls.h"
 #include "trace.h"
 
+#define CXL_ERROR_DETECTED_EVENT        1
+#define CXL_SLOT_RESET_EVENT            2
+#define CXL_RESUME_EVENT                3
+
+static void pci_error_handlers(struct cxl_afu *afu,
+                                int bus_error_event,
+                                pci_channel_state_t state)
+{
+        struct pci_dev *afu_dev;
+
+        if (afu->phb == NULL)
+                return;
+
+        list_for_each_entry(afu_dev, &afu->phb->bus->devices, bus_list) {
+                if (!afu_dev->driver)
+                        continue;
+
+                switch (bus_error_event) {
+                case CXL_ERROR_DETECTED_EVENT:
+                        afu_dev->error_state = state;
+
+                        if (afu_dev->driver->err_handler &&
+                            afu_dev->driver->err_handler->error_detected)
+                                afu_dev->driver->err_handler->error_detected(afu_dev, state);
+                break;
+                case CXL_SLOT_RESET_EVENT:
+                        afu_dev->error_state = state;
+
+                        if (afu_dev->driver->err_handler &&
+                            afu_dev->driver->err_handler->slot_reset)
+                                afu_dev->driver->err_handler->slot_reset(afu_dev);
+                break;
+                case CXL_RESUME_EVENT:
+                        if (afu_dev->driver->err_handler &&
+                            afu_dev->driver->err_handler->resume)
+                                afu_dev->driver->err_handler->resume(afu_dev);
+                break;
+                }
+        }
+}
 
 static irqreturn_t guest_handle_psl_slice_error(struct cxl_context *ctx, u64 dsisr,
                                         u64 errstat)
@@ -133,6 +173,22 @@ static irqreturn_t guest_psl_irq(int irq, void *data)
         return rc;
 }
 
+static int afu_read_error_state(struct cxl_afu *afu, int *state_out)
+{
+        u64 state;
+        int rc = 0;
+
+        rc = cxl_h_read_error_state(afu->guest->handle, &state);
+        if (!rc) {
+                WARN_ON(state != H_STATE_NORMAL &&
+                        state != H_STATE_DISABLE &&
+                        state != H_STATE_TEMP_UNAVAILABLE &&
+                        state != H_STATE_PERM_UNAVAILABLE);
+                *state_out = state & 0xffffffff;
+        }
+        return rc;
+}
+
 static irqreturn_t guest_slice_irq_err(int irq, void *data)
 {
         struct cxl_afu *afu = data;
@@ -201,10 +257,26 @@ static int irq_free_range(struct cxl *adapter, int irq, int len)
 
 static int guest_reset(struct cxl *adapter)
 {
-        int rc;
+        struct cxl_afu *afu = NULL;
+        int i, rc;
 
         pr_devel("Adapter reset request\n");
+        for (i = 0; i < adapter->slices; i++) {
+                if ((afu = adapter->afu[i])) {
+                        pci_error_handlers(afu, CXL_ERROR_DETECTED_EVENT,
+                                        pci_channel_io_frozen);
+                        cxl_context_detach_all(afu);
+                }
+        }
+
         rc = cxl_h_reset_adapter(adapter->guest->handle);
+        for (i = 0; i < adapter->slices; i++) {
+                if (!rc && (afu = adapter->afu[i])) {
+                        pci_error_handlers(afu, CXL_SLOT_RESET_EVENT,
+                                        pci_channel_io_normal);
+                        pci_error_handlers(afu, CXL_RESUME_EVENT, 0);
+                }
+        }
         return rc;
 }
 
@@ -556,7 +628,7 @@ static int guest_detach_process(struct cxl_context *ctx)
         pr_devel("in %s\n", __func__);
         trace_cxl_detach(ctx);
 
-        if (!cxl_ops->link_ok(ctx->afu->adapter))
+        if (!cxl_ops->link_ok(ctx->afu->adapter, ctx->afu))
                 return -EIO;
 
         if (ctx->afu->current_mode == CXL_MODE_DIRECTED)
@@ -730,8 +802,95 @@ static void guest_unmap_slice_regs(struct cxl_afu *afu)
                 iounmap(afu->p2n_mmio);
 }
 
-static bool guest_link_ok(struct cxl *cxl)
+static int afu_update_state(struct cxl_afu *afu)
 {
+        int rc, cur_state;
+
+        rc = afu_read_error_state(afu, &cur_state);
+        if (rc)
+                return rc;
+
+        if (afu->guest->previous_state == cur_state)
+                return 0;
+
+        pr_devel("AFU(%d) update state to %#x\n", afu->slice, cur_state);
+
+        switch (cur_state) {
+        case H_STATE_NORMAL:
+                afu->guest->previous_state = cur_state;
+                rc = 1;
+                break;
+
+        case H_STATE_DISABLE:
+                pci_error_handlers(afu, CXL_ERROR_DETECTED_EVENT,
+                                pci_channel_io_frozen);
+
+                cxl_context_detach_all(afu);
+                if ((rc = cxl_ops->afu_reset(afu)))
+                        pr_devel("reset hcall failed %d\n", rc);
+
+                rc = afu_read_error_state(afu, &cur_state);
+                if (!rc && cur_state == H_STATE_NORMAL) {
+                        pci_error_handlers(afu, CXL_SLOT_RESET_EVENT,
+                                        pci_channel_io_normal);
+                        pci_error_handlers(afu, CXL_RESUME_EVENT, 0);
+                        rc = 1;
+                }
+                afu->guest->previous_state = 0;
+                break;
+
+        case H_STATE_TEMP_UNAVAILABLE:
+                afu->guest->previous_state = cur_state;
+                break;
+
+        case H_STATE_PERM_UNAVAILABLE:
+                dev_err(&afu->dev, "AFU is in permanent error state\n");
+                pci_error_handlers(afu, CXL_ERROR_DETECTED_EVENT,
+                                pci_channel_io_perm_failure);
+                afu->guest->previous_state = cur_state;
+                break;
+
+        default:
+                pr_err("Unexpected AFU(%d) error state: %#x\n",
+                       afu->slice, cur_state);
+                return -EINVAL;
+        }
+
+        return rc;
+}
+
+static int afu_do_recovery(struct cxl_afu *afu)
+{
+        int rc;
+
+        /* many threads can arrive here, in case of detach_all for example.
+         * Only one needs to drive the recovery
+         */
+        if (mutex_trylock(&afu->guest->recovery_lock)) {
+                rc = afu_update_state(afu);
+                mutex_unlock(&afu->guest->recovery_lock);
+                return rc;
+        }
+        return 0;
+}
+
+static bool guest_link_ok(struct cxl *cxl, struct cxl_afu *afu)
+{
+        int state;
+
+        if (afu) {
+                if (afu_read_error_state(afu, &state) ||
+                        state != H_STATE_NORMAL) {
+                        if (afu_do_recovery(afu) > 0) {
+                                /* check again in case we've just fixed it */
+                                if (!afu_read_error_state(afu, &state) &&
+                                        state == H_STATE_NORMAL)
+                                        return true;
+                        }
+                        return false;
+                }
+        }
+
         return true;
 }
 
@@ -770,6 +929,8 @@ int cxl_guest_init_afu(struct cxl *adapter, int slice, struct device_node *afu_n
                 return -ENOMEM;
         }
 
+        mutex_init(&afu->guest->recovery_lock);
+
         if ((rc = dev_set_name(&afu->dev, "afu%i.%i",
                                           adapter->adapter_num,
                                           slice)))
diff --git a/drivers/misc/cxl/main.c b/drivers/misc/cxl/main.c
index 14b15835dc4a..ae68c3201156 100644
--- a/drivers/misc/cxl/main.c
+++ b/drivers/misc/cxl/main.c
@@ -48,7 +48,7 @@ int cxl_afu_slbia(struct cxl_afu *afu)
                 /* If the adapter has gone down, we can assume that we
                  * will PERST it and that will invalidate everything.
                  */
-                if (!cxl_ops->link_ok(afu->adapter))
+                if (!cxl_ops->link_ok(afu->adapter, afu))
                         return -EIO;
                 cpu_relax();
         }
diff --git a/drivers/misc/cxl/native.c b/drivers/misc/cxl/native.c
index e564ae657584..387fcbdf9793 100644
--- a/drivers/misc/cxl/native.c
+++ b/drivers/misc/cxl/native.c
@@ -42,7 +42,7 @@ static int afu_control(struct cxl_afu *afu, u64 command,
                         goto out;
                 }
 
-                if (!cxl_ops->link_ok(afu->adapter)) {
+                if (!cxl_ops->link_ok(afu->adapter, afu)) {
                         afu->enabled = enabled;
                         rc = -EIO;
                         goto out;
@@ -92,7 +92,7 @@ static int native_afu_reset(struct cxl_afu *afu)
 
 static int native_afu_check_and_enable(struct cxl_afu *afu)
 {
-        if (!cxl_ops->link_ok(afu->adapter)) {
+        if (!cxl_ops->link_ok(afu->adapter, afu)) {
                 WARN(1, "Refusing to enable afu while link down!\n");
                 return -EIO;
         }
@@ -114,7 +114,7 @@ int cxl_psl_purge(struct cxl_afu *afu)
 
         pr_devel("PSL purge request\n");
 
-        if (!cxl_ops->link_ok(afu->adapter)) {
+        if (!cxl_ops->link_ok(afu->adapter, afu)) {
                 dev_warn(&afu->dev, "PSL Purge called with link down, ignoring\n");
                 rc = -EIO;
                 goto out;
@@ -136,7 +136,7 @@ int cxl_psl_purge(struct cxl_afu *afu)
                         rc = -EBUSY;
                         goto out;
                 }
-                if (!cxl_ops->link_ok(afu->adapter)) {
+                if (!cxl_ops->link_ok(afu->adapter, afu)) {
                         rc = -EIO;
                         goto out;
                 }
@@ -250,7 +250,7 @@ int cxl_tlb_slb_invalidate(struct cxl *adapter)
                         dev_warn(&adapter->dev, "WARNING: CXL adapter wide TLBIA timed out!\n");
                         return -EBUSY;
                 }
-                if (!cxl_ops->link_ok(adapter))
+                if (!cxl_ops->link_ok(adapter, NULL))
                         return -EIO;
                 cpu_relax();
         }
@@ -261,7 +261,7 @@ int cxl_tlb_slb_invalidate(struct cxl *adapter)
                         dev_warn(&adapter->dev, "WARNING: CXL adapter wide SLBIA timed out!\n");
                         return -EBUSY;
                 }
-                if (!cxl_ops->link_ok(adapter))
+                if (!cxl_ops->link_ok(adapter, NULL))
                         return -EIO;
                 cpu_relax();
         }
@@ -302,7 +302,7 @@ static void slb_invalid(struct cxl_context *ctx)
         cxl_p1_write(adapter, CXL_PSL_SLBIA, CXL_TLB_SLB_IQ_LPIDPID);
 
         while (1) {
-                if (!cxl_ops->link_ok(adapter))
+                if (!cxl_ops->link_ok(adapter, NULL))
                         break;
                 slbia = cxl_p1_read(adapter, CXL_PSL_SLBIA);
                 if (!(slbia & CXL_TLB_SLB_P))
@@ -333,7 +333,7 @@ static int do_process_element_cmd(struct cxl_context *ctx,
                         rc = -EBUSY;
                         goto out;
                 }
-                if (!cxl_ops->link_ok(ctx->afu->adapter)) {
+                if (!cxl_ops->link_ok(ctx->afu->adapter, ctx->afu)) {
                         dev_warn(&ctx->afu->dev, "WARNING: Device link down, aborting Process Element Command!\n");
                         rc = -EIO;
                         goto out;
@@ -389,7 +389,7 @@ static int terminate_process_element(struct cxl_context *ctx)
          * should always succeed: it's not running if the hw has gone
          * away and is being reset.
          */
-        if (cxl_ops->link_ok(ctx->afu->adapter))
+        if (cxl_ops->link_ok(ctx->afu->adapter, ctx->afu))
                 rc = do_process_element_cmd(ctx, CXL_SPA_SW_CMD_TERMINATE,
                                             CXL_PE_SOFTWARE_STATE_V | CXL_PE_SOFTWARE_STATE_T);
         ctx->elem->software_state = 0;  /* Remove Valid bit */
@@ -408,7 +408,7 @@ static int remove_process_element(struct cxl_context *ctx)
         /* We could be asked to remove when the hw is down. Again, if
          * the hw is down, the PE is gone, so we succeed.
          */
-        if (cxl_ops->link_ok(ctx->afu->adapter))
+        if (cxl_ops->link_ok(ctx->afu->adapter, ctx->afu))
                 rc = do_process_element_cmd(ctx, CXL_SPA_SW_CMD_REMOVE, 0);
 
         if (!rc)
@@ -650,7 +650,7 @@ static int native_afu_activate_mode(struct cxl_afu *afu, int mode)
         if (!(mode & afu->modes_supported))
                 return -EINVAL;
 
-        if (!cxl_ops->link_ok(afu->adapter)) {
+        if (!cxl_ops->link_ok(afu->adapter, afu)) {
                 WARN(1, "Device link is down, refusing to activate!\n");
                 return -EIO;
         }
@@ -666,7 +666,7 @@ static int native_afu_activate_mode(struct cxl_afu *afu, int mode)
 static int native_attach_process(struct cxl_context *ctx, bool kernel,
                                 u64 wed, u64 amr)
 {
-        if (!cxl_ops->link_ok(ctx->afu->adapter)) {
+        if (!cxl_ops->link_ok(ctx->afu->adapter, ctx->afu)) {
                 WARN(1, "Device link is down, refusing to attach process!\n");
                 return -EIO;
         }
@@ -718,7 +718,7 @@ static int native_get_irq_info(struct cxl_afu *afu, struct cxl_irq_info *info)
         /* If the adapter has gone away, we can't get any meaningful
          * information.
          */
-        if (!cxl_ops->link_ok(afu->adapter))
+        if (!cxl_ops->link_ok(afu->adapter, afu))
                 return -EIO;
 
         info->dsisr = cxl_p2n_read(afu, CXL_PSL_DSISR_An);
@@ -975,7 +975,7 @@ static bool native_support_attributes(const char *attr_name,
 
 static int native_afu_cr_read64(struct cxl_afu *afu, int cr, u64 off, u64 *out)
 {
-        if (unlikely(!cxl_ops->link_ok(afu->adapter)))
+        if (unlikely(!cxl_ops->link_ok(afu->adapter, afu)))
                 return -EIO;
         if (unlikely(off >= afu->crs_len))
                 return -ERANGE;
@@ -986,7 +986,7 @@ static int native_afu_cr_read64(struct cxl_afu *afu, int cr, u64 off, u64 *out)
 
 static int native_afu_cr_read32(struct cxl_afu *afu, int cr, u64 off, u32 *out)
 {
-        if (unlikely(!cxl_ops->link_ok(afu->adapter)))
+        if (unlikely(!cxl_ops->link_ok(afu->adapter, afu)))
                 return -EIO;
         if (unlikely(off >= afu->crs_len))
                 return -ERANGE;
@@ -1021,7 +1021,7 @@ static int native_afu_cr_read8(struct cxl_afu *afu, int cr, u64 off, u8 *out)
 
 static int native_afu_cr_write32(struct cxl_afu *afu, int cr, u64 off, u32 in)
 {
-        if (unlikely(!cxl_ops->link_ok(afu->adapter)))
+        if (unlikely(!cxl_ops->link_ok(afu->adapter, afu)))
                 return -EIO;
         if (unlikely(off >= afu->crs_len))
                 return -ERANGE;
diff --git a/drivers/misc/cxl/vphb.c b/drivers/misc/cxl/vphb.c
index c960a09a4232..490b93486451 100644
--- a/drivers/misc/cxl/vphb.c
+++ b/drivers/misc/cxl/vphb.c
@@ -49,7 +49,7 @@ static bool cxl_pci_enable_device_hook(struct pci_dev *dev)
         phb = pci_bus_to_host(dev->bus);
         afu = (struct cxl_afu *)phb->private_data;
 
-        if (!cxl_ops->link_ok(afu->adapter)) {
+        if (!cxl_ops->link_ok(afu->adapter, afu)) {
                 dev_warn(&dev->dev, "%s: Device link is down, refusing to enable AFU\n", __func__);
                 return false;
         }