[POWERPC] Implement SLB shadow buffer

This adds a shadow buffer for the SLBs and regsiters it with PHYP.
Only the bolted SLB entries (top 3) are shadowed.

The SLB shadow buffer tells the hypervisor what the kernel needs to
have in the SLB for the kernel to be able to function.  The hypervisor
can use this information to speed up partition context switches.

Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>

1 files changed, 20 insertions, 4 deletions

diff --git a/arch/powerpc/platforms/pseries/lpar.c b/arch/powerpc/platforms/pseries/lpar.c
index 6cbf14266d5e..1820a0b0a8c6 100644
--- a/arch/powerpc/platforms/pseries/lpar.c
+++ b/arch/powerpc/platforms/pseries/lpar.c
@@ -252,18 +252,34 @@ out:
 void vpa_init(int cpu)
 {
         int hwcpu = get_hard_smp_processor_id(cpu);
-        unsigned long vpa = __pa(&lppaca[cpu]);
+        unsigned long addr;
         long ret;
 
         if (cpu_has_feature(CPU_FTR_ALTIVEC))
                 lppaca[cpu].vmxregs_in_use = 1;
 
-        ret = register_vpa(hwcpu, vpa);
+        addr = __pa(&lppaca[cpu]);
+        ret = register_vpa(hwcpu, addr);
 
-        if (ret)
+        if (ret) {
                 printk(KERN_ERR "WARNING: vpa_init: VPA registration for "
                                 "cpu %d (hw %d) of area %lx returns %ld\n",
-                                cpu, hwcpu, vpa, ret);
+                                cpu, hwcpu, addr, ret);
+                return;
+        }
+        /*
+         * PAPR says this feature is SLB-Buffer but firmware never
+         * reports that.  All SPLPAR support SLB shadow buffer.
+         */
+        addr = __pa(&slb_shadow[cpu]);
+        if (firmware_has_feature(FW_FEATURE_SPLPAR)) {
+                ret = register_slb_shadow(hwcpu, addr);
+                if (ret)
+                        printk(KERN_ERR
+                               "WARNING: vpa_init: SLB shadow buffer "
+                               "registration for cpu %d (hw %d) of area %lx "
+                               "returns %ld\n", cpu, hwcpu, addr, ret);
+        }
 }
 
 long pSeries_lpar_hpte_insert(unsigned long hpte_group,