tile: support new Tilera hypervisor

The Tilera hypervisor shipped in releases up through MDE 4.1 launches
the client operating system (i.e. Linux) at privilege level 1 (PL1).
Starting with MDE 4.2, as part of the work to enable KVM, the
Tilera hypervisor launches Linux at PL2 instead.

This commit makes the KERNEL_PL option default to 2 for tilegx, while
still saying at 1 for tilepro, which doesn't have an updated hypervisor.
It also explains how and when you might want to choose another value.
In addition, we change a small buglet in the on-chip Ethernet driver,
where we were failing to use the KERNEL_PL constant in an API call.

To make the transition cleaner, this change also provides the updated
hv_init() API for the new hypervisor that supports announcing Linux's
compiled-in PL, so the hypervisor can generate a suitable error in the
case of a mismatched hypervisor and Linux binary.

Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>
Cc: stable@vger.linux.org

1 files changed, 9 insertions, 3 deletions

diff --git a/arch/tile/kernel/head_64.S b/arch/tile/kernel/head_64.S
index f9a2734f7b82..6093964fa5c7 100644
--- a/arch/tile/kernel/head_64.S
+++ b/arch/tile/kernel/head_64.S
@@ -34,13 +34,19 @@
 ENTRY(_start)
         /* Notify the hypervisor of what version of the API we want */
         {
+#if KERNEL_PL == 1 && _HV_VERSION == 13
+          /* Support older hypervisors by asking for API version 12. */
+          movei r0, _HV_VERSION_OLD_HV_INIT
+#else
+          movei r0, _HV_VERSION
+#endif
           movei r1, TILE_CHIP
-          movei r2, TILE_CHIP_REV
         }
         {
-          moveli r0, _HV_VERSION
-          jal hv_init
+          movei r2, TILE_CHIP_REV
+          movei r3, KERNEL_PL
         }
+        jal hv_init
         /* Get a reasonable default ASID in r0 */
         {
           move r0, zero