cxl: Add support for ASB_Notify on POWER9

The POWER9 core supports a new feature: ASB_Notify which requires the
support of the Special Purpose Register: TIDR.

The ASB_Notify command, generated by the AFU, will attempt to
wake-up the host thread identified by the particular LPID:PID:TID.

This patch assign a unique TIDR (thread id) for the current thread which
will be used in the process element entry.

Signed-off-by: Christophe Lombard <clombard@linux.vnet.ibm.com>
Reviewed-by: Philippe Bergheaud <felix@linux.vnet.ibm.com>
Acked-by: Frederic Barrat <fbarrat@linux.vnet.ibm.com>
Reviewed-by: Vaibhav Jain <vaibhav@linux.vnet.ibm.com>
Acked-by: Andrew Donnellan <andrew.donnellan@au1.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

5 files changed, 32 insertions, 4 deletions

diff --git a/drivers/misc/cxl/context.c b/drivers/misc/cxl/context.c
index 12a41b2753f0..7ff315ad3692 100644
--- a/drivers/misc/cxl/context.c
+++ b/drivers/misc/cxl/context.c
@@ -45,6 +45,8 @@ int cxl_context_init(struct cxl_context *ctx, struct cxl_afu *afu, bool master)
         ctx->pid = NULL; /* Set in start work ioctl */
         mutex_init(&ctx->mapping_lock);
         ctx->mapping = NULL;
+        ctx->tidr = 0;
+        ctx->assign_tidr = false;
 
         if (cxl_is_power8()) {
                 spin_lock_init(&ctx->sste_lock);
diff --git a/drivers/misc/cxl/cxl.h b/drivers/misc/cxl/cxl.h
index e46a4062904a..53149fbd780e 100644
--- a/drivers/misc/cxl/cxl.h
+++ b/drivers/misc/cxl/cxl.h
@@ -630,6 +630,9 @@ struct cxl_context {
         struct list_head extra_irq_contexts;
 
         struct mm_struct *mm;
+
+        u16 tidr;
+        bool assign_tidr;
 };
 
 struct cxl_irq_info;
diff --git a/drivers/misc/cxl/cxllib.c b/drivers/misc/cxl/cxllib.c
index dc9bc1807fdf..30ccba436b3b 100644
--- a/drivers/misc/cxl/cxllib.c
+++ b/drivers/misc/cxl/cxllib.c
@@ -199,10 +199,11 @@ int cxllib_get_PE_attributes(struct task_struct *task,
                  */
                 attr->pid = mm->context.id;
                 mmput(mm);
+                attr->tid = task->thread.tidr;
         } else {
                 attr->pid = 0;
+                attr->tid = 0;
         }
-        attr->tid = 0;
         return 0;
 }
 EXPORT_SYMBOL_GPL(cxllib_get_PE_attributes);
diff --git a/drivers/misc/cxl/file.c b/drivers/misc/cxl/file.c
index 76c0b0ca9388..93fd381f6484 100644
--- a/drivers/misc/cxl/file.c
+++ b/drivers/misc/cxl/file.c
@@ -173,7 +173,7 @@ static long afu_ioctl_start_work(struct cxl_context *ctx,
          * flags are set it's invalid
          */
         if (work.reserved1 || work.reserved2 || work.reserved3 ||
-            work.reserved4 || work.reserved5 || work.reserved6 ||
+            work.reserved4 || work.reserved5 ||
             (work.flags & ~CXL_START_WORK_ALL)) {
                 rc = -EINVAL;
                 goto out;
@@ -186,12 +186,16 @@ static long afu_ioctl_start_work(struct cxl_context *ctx,
                 rc =  -EINVAL;
                 goto out;
         }
+
         if ((rc = afu_register_irqs(ctx, work.num_interrupts)))
                 goto out;
 
         if (work.flags & CXL_START_WORK_AMR)
                 amr = work.amr & mfspr(SPRN_UAMOR);
 
+        if (work.flags & CXL_START_WORK_TID)
+                ctx->assign_tidr = true;
+
         ctx->mmio_err_ff = !!(work.flags & CXL_START_WORK_ERR_FF);
 
         /*
@@ -263,8 +267,15 @@ static long afu_ioctl_start_work(struct cxl_context *ctx,
                 goto out;
         }
 
-        ctx->status = STARTED;
         rc = 0;
+        if (work.flags & CXL_START_WORK_TID) {
+                work.tid = ctx->tidr;
+                if (copy_to_user(uwork, &work, sizeof(work)))
+                        rc = -EFAULT;
+        }
+
+        ctx->status = STARTED;
+
 out:
         mutex_unlock(&ctx->status_mutex);
         return rc;
diff --git a/drivers/misc/cxl/native.c b/drivers/misc/cxl/native.c
index 02b6b45b4c20..1b3d7c65ea3f 100644
--- a/drivers/misc/cxl/native.c
+++ b/drivers/misc/cxl/native.c
@@ -16,6 +16,7 @@
 #include <linux/uaccess.h>
 #include <linux/delay.h>
 #include <asm/synch.h>
+#include <asm/switch_to.h>
 #include <misc/cxl-base.h>
 
 #include "cxl.h"
@@ -655,6 +656,7 @@ static void update_ivtes_directed(struct cxl_context *ctx)
 static int process_element_entry_psl9(struct cxl_context *ctx, u64 wed, u64 amr)
 {
         u32 pid;
+        int rc;
 
         cxl_assign_psn_space(ctx);
 
@@ -673,7 +675,16 @@ static int process_element_entry_psl9(struct cxl_context *ctx, u64 wed, u64 amr)
                 pid = ctx->mm->context.id;
         }
 
-        ctx->elem->common.tid = 0;
+        /* Assign a unique TIDR (thread id) for the current thread */
+        if (!(ctx->tidr) && (ctx->assign_tidr)) {
+                rc = set_thread_tidr(current);
+                if (rc)
+                        return -ENODEV;
+                ctx->tidr = current->thread.tidr;
+                pr_devel("%s: current tidr: %d\n", __func__, ctx->tidr);
+        }
+
+        ctx->elem->common.tid = cpu_to_be32(ctx->tidr);
         ctx->elem->common.pid = cpu_to_be32(pid);
 
         ctx->elem->sr = cpu_to_be64(calculate_sr(ctx));