[PATCH v2] powerpc/powernv: Tell OPAL about our MMU mode on POWER9

[Michael Neuling]

From: Benjamin Herrenschmidt <b...@kernel.crashing.org>

That will allow OPAL to configure the CPU in an optimal way.

Signed-off-by: Benjamin Herrenschmidt <b...@kernel.crashing.org>
Signed-off-by: Michael Neuling <mi...@neuling.org>
---
v2:
  - Always set the hash bit since we always need hash for KVM guests.
  - Gate with ARCH_300 since this can break P8.
---
 arch/powerpc/include/asm/opal-api.h    |  9 +++++++++
 arch/powerpc/platforms/powernv/opal.c  | 19 +++++++++++++++++--
 arch/powerpc/platforms/powernv/setup.c | 11 ++++++++++-
 3 files changed, 36 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/include/asm/opal-api.h 
b/arch/powerpc/include/asm/opal-api.h
index 0b543f0f54..b3111c14f8 100644
--- a/arch/powerpc/include/asm/opal-api.h
+++ b/arch/powerpc/include/asm/opal-api.h
@@ -876,6 +876,15 @@ struct OpalIoPhb4ErrorData {
 enum {
        OPAL_REINIT_CPUS_HILE_BE        = (1 << 0),
        OPAL_REINIT_CPUS_HILE_LE        = (1 << 1),
+
+       /* These two define the base MMU mode of the host on P9
+        *
+        * On P9 Nimbus DD2.0 and Cumlus (and later), KVM can still
+        * create hash guests in "radix" mode with care (full core
+        * switch only).
+        */
+       OPAL_REINIT_CPUS_MMU_HASH       = (1 << 2),
+       OPAL_REINIT_CPUS_MMU_RADIX      = (1 << 3),
 };
 
 typedef struct oppanel_line {
diff --git a/arch/powerpc/platforms/powernv/opal.c 
b/arch/powerpc/platforms/powernv/opal.c
index 59684b4af4..eaefae10bd 100644
--- a/arch/powerpc/platforms/powernv/opal.c
+++ b/arch/powerpc/platforms/powernv/opal.c
@@ -59,6 +59,8 @@ static struct task_struct *kopald_tsk;
 
 void opal_configure_cores(void)
 {
+       uint64_t reinit_flags = 0;
+
        /* Do the actual re-init, This will clobber all FPRs, VRs, etc...
         *
         * It will preserve non volatile GPRs and HSPRG0/1. It will
@@ -66,11 +68,24 @@ void opal_configure_cores(void)
         * but it might clobber a bunch.
         */
 #ifdef __BIG_ENDIAN__
-       opal_reinit_cpus(OPAL_REINIT_CPUS_HILE_BE);
+       reinit_flags |= OPAL_REINIT_CPUS_HILE_BE;
 #else
-       opal_reinit_cpus(OPAL_REINIT_CPUS_HILE_LE);
+       reinit_flags |= OPAL_REINIT_CPUS_HILE_LE;
 #endif
 
+       /*
+        * POWER9 always support running hash:
+        *  ie. Host hash  supports  hash guests
+        *      Host radix supports  hash/radix guests
+        */
+       if (cpu_has_feature(CPU_FTR_ARCH_300)) {
+               reinit_flags |= OPAL_REINIT_CPUS_MMU_HASH;
+               if (early_radix_enabled())
+                       reinit_flags |= OPAL_REINIT_CPUS_MMU_RADIX;
+       }
+
+       opal_reinit_cpus(reinit_flags);
+
        /* Restore some bits */
        if (cur_cpu_spec->cpu_restore)
                cur_cpu_spec->cpu_restore();
diff --git a/arch/powerpc/platforms/powernv/setup.c 
b/arch/powerpc/platforms/powernv/setup.c
index 2dc7e5fb86..7d2723429d 100644
--- a/arch/powerpc/platforms/powernv/setup.c
+++ b/arch/powerpc/platforms/powernv/setup.c
@@ -225,6 +225,8 @@ static void pnv_kexec_wait_secondaries_down(void)
 
 static void pnv_kexec_cpu_down(int crash_shutdown, int secondary)
 {
+       uint64_t reinit_flags;
+
        if (xive_enabled())
                xive_kexec_teardown_cpu(secondary);
        else
@@ -254,8 +256,15 @@ static void pnv_kexec_cpu_down(int crash_shutdown, int 
secondary)
                 * We might be running as little-endian - now that interrupts
                 * are disabled, reset the HILE bit to big-endian so we don't
                 * take interrupts in the wrong endian later
+                *
+                * We reinit to enable both radix and hash on P9 to ensure
+                * the mode used by the next kernel is always supported.
                 */
-               opal_reinit_cpus(OPAL_REINIT_CPUS_HILE_BE);
+               reinit_flags = OPAL_REINIT_CPUS_HILE_BE;
+               if (cpu_has_feature(CPU_FTR_ARCH_300))
+                       reinit_flags |= OPAL_REINIT_CPUS_MMU_RADIX |
+                               OPAL_REINIT_CPUS_MMU_HASH;
+               opal_reinit_cpus(reinit_flags);
        }
 }
 #endif /* CONFIG_KEXEC_CORE */
-- 
2.11.0