cxl: Only check pid for userspace contexts

We only need to check the pid attached to this context for userspace contexts.
Kernel contexts can skip this check.
Signed-off-by: Michael Neuling <mikey@neuling.org>
Acked-by: Ian Munsie <imunsie@au1.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

drivers/misc/cxl/fault.c

@@ -172,8 +172,8 @@ void cxl_handle_fault(struct work_struct *fault_work)
 		container_of(fault_work, struct cxl_context, fault_work);
 	u64 dsisr = ctx->dsisr;
 	u64 dar = ctx->dar;
-	struct task_struct *task;
-	struct mm_struct *mm;
+	struct task_struct *task = NULL;
+	struct mm_struct *mm = NULL;
 
 	if (cxl_p2n_read(ctx->afu, CXL_PSL_DSISR_An) != dsisr ||
 	    cxl_p2n_read(ctx->afu, CXL_PSL_DAR_An) != dar ||
@@ -194,6 +194,7 @@ void cxl_handle_fault(struct work_struct *fault_work)
 	pr_devel("CXL BOTTOM HALF handling fault for afu pe: %i. "
 		"DSISR: %#llx DAR: %#llx\n", ctx->pe, dsisr, dar);
 
+	if (!ctx->kernel) {
 		if (!(task = get_pid_task(ctx->pid, PIDTYPE_PID))) {
 			pr_devel("cxl_handle_fault unable to get task %i\n",
 				 pid_nr(ctx->pid));
@@ -206,6 +207,7 @@ void cxl_handle_fault(struct work_struct *fault_work)
 			cxl_ack_ae(ctx);
 			goto out;
 		}
+	}
 
 	if (dsisr & CXL_PSL_DSISR_An_DS)
 		cxl_handle_segment_miss(ctx, mm, dar);
@@ -214,8 +216,10 @@ void cxl_handle_fault(struct work_struct *fault_work)
 	else
 		WARN(1, "cxl_handle_fault has nothing to handle\n");
 
+	if (mm)
 		mmput(mm);
 out:
+	if (task)
 		put_task_struct(task);
 }