cxl: Export library to support IBM XSL

This patch exports a in-kernel 'library' API which can be called by
other drivers to help interacting with an IBM XSL on a POWER9 system.

The XSL (Translation Service Layer) is a stripped down version of the
PSL (Power Service Layer) used in some cards such as the Mellanox CX5.
Like the PSL, it implements the CAIA architecture, but has a number
of differences, mostly in it's implementation dependent registers.

The XSL also uses a special DMA cxl mode, which uses a slightly
different init sequence for the CAPP and PHB.

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

1 files changed, 19 insertions, 10 deletions

diff --git a/drivers/misc/cxl/fault.c b/drivers/misc/cxl/fault.c
index c79e39bad7a4..6eed7d03e2b5 100644
--- a/drivers/misc/cxl/fault.c
+++ b/drivers/misc/cxl/fault.c
@@ -132,18 +132,15 @@ static int cxl_handle_segment_miss(struct cxl_context *ctx,
         return IRQ_HANDLED;
 }
 
-static void cxl_handle_page_fault(struct cxl_context *ctx,
-                                  struct mm_struct *mm, u64 dsisr, u64 dar)
+int cxl_handle_mm_fault(struct mm_struct *mm, u64 dsisr, u64 dar)
 {
         unsigned flt = 0;
         int result;
         unsigned long access, flags, inv_flags = 0;
 
-        trace_cxl_pte_miss(ctx, dsisr, dar);
-
         if ((result = copro_handle_mm_fault(mm, dar, dsisr, &flt))) {
                 pr_devel("copro_handle_mm_fault failed: %#x\n", result);
-                return cxl_ack_ae(ctx);
+                return result;
         }
 
         if (!radix_enabled()) {
@@ -155,9 +152,8 @@ static void cxl_handle_page_fault(struct cxl_context *ctx,
                 if (dsisr & CXL_PSL_DSISR_An_S)
                         access |= _PAGE_WRITE;
 
-                access |= _PAGE_PRIVILEGED;
-                if ((!ctx->kernel) || (REGION_ID(dar) == USER_REGION_ID))
-                        access &= ~_PAGE_PRIVILEGED;
+                if (!mm && (REGION_ID(dar) != USER_REGION_ID))
+                        access |= _PAGE_PRIVILEGED;
 
                 if (dsisr & DSISR_NOHPTE)
                         inv_flags |= HPTE_NOHPTE_UPDATE;
@@ -166,8 +162,21 @@ static void cxl_handle_page_fault(struct cxl_context *ctx,
                 hash_page_mm(mm, dar, access, 0x300, inv_flags);
                 local_irq_restore(flags);
         }
-        pr_devel("Page fault successfully handled for pe: %i!\n", ctx->pe);
-        cxl_ops->ack_irq(ctx, CXL_PSL_TFC_An_R, 0);
+        return 0;
+}
+
+static void cxl_handle_page_fault(struct cxl_context *ctx,
+                                  struct mm_struct *mm,
+                                  u64 dsisr, u64 dar)
+{
+        trace_cxl_pte_miss(ctx, dsisr, dar);
+
+        if (cxl_handle_mm_fault(mm, dsisr, dar)) {
+                cxl_ack_ae(ctx);
+        } else {
+                pr_devel("Page fault successfully handled for pe: %i!\n", ctx->pe);
+                cxl_ops->ack_irq(ctx, CXL_PSL_TFC_An_R, 0);
+        }
 }
 
 /*