powerpc/64: Call H_REGISTER_PROC_TBL when running as a HPT guest on POWER9

On POWER9, since commit cc3d2940 ("powerpc/64: Enable use of radix
MMU under hypervisor on POWER9", 2017-01-30), we set both the radix and
HPT bits in the client-architecture-support (CAS) vector, which tells
the hypervisor that we can do either radix or HPT.  According to PAPR,
if we use this combination we are promising to do a H_REGISTER_PROC_TBL
hcall later on to let the hypervisor know whether we are doing radix
or HPT.  We currently do this call if we are doing radix but not if
we are doing HPT.  If the hypervisor is able to support both radix
and HPT guests, it would be entitled to defer allocation of the HPT
until the H_REGISTER_PROC_TBL call, and to fail any attempts to create
HPTEs until the H_REGISTER_PROC_TBL call.  Thus we need to do a
H_REGISTER_PROC_TBL call when we are doing HPT; otherwise we may
crash at boot time.

This adds the code to call H_REGISTER_PROC_TBL in this case, before
we attempt to create any HPT entries using H_ENTER.

Fixes: cc3d2940 ("powerpc/64: Enable use of radix MMU under hypervisor on POWER9")
Cc: stable@vger.kernel.org # v4.11+
Signed-off-by: Paul Mackerras <paulus@ozlabs.org>
Reviewed-by: Suraj Jitindar Singh <sjitindarsingh@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

arch/powerpc/mm/hash_utils_64.c

@@ -875,6 +875,12 @@ static void __init htab_initialize(void)
 		/* Using a hypervisor which owns the htab */
 		htab_address = NULL;
 		_SDR1 = 0; 
+		/*
+		 * On POWER9, we need to do a H_REGISTER_PROC_TBL hcall
+		 * to inform the hypervisor that we wish to use the HPT.
+		 */
+		if (cpu_has_feature(CPU_FTR_ARCH_300))
+			register_process_table(0, 0, 0);
 #ifdef CONFIG_FA_DUMP
 		/*
 		 * If firmware assisted dump is active firmware preserves

arch/powerpc/platforms/pseries/lpar.c

@@ -726,15 +726,18 @@ static int pseries_lpar_resize_hpt(unsigned long shift)
 	return 0;
 }
 
-/* Actually only used for radix, so far */
 static int pseries_lpar_register_process_table(unsigned long base,
 			unsigned long page_size, unsigned long table_size)
 {
 	long rc;
-	unsigned long flags = PROC_TABLE_NEW;
+	unsigned long flags = 0;
 
+	if (table_size)
+		flags |= PROC_TABLE_NEW;
 	if (radix_enabled())
 		flags |= PROC_TABLE_RADIX | PROC_TABLE_GTSE;
+	else
+		flags |= PROC_TABLE_HPT_SLB;
 	for (;;) {
 		rc = plpar_hcall_norets(H_REGISTER_PROC_TBL, flags, base,
 					page_size, table_size);
@@ -760,6 +763,7 @@ void __init hpte_init_pseries(void)
 	mmu_hash_ops.flush_hash_range	 = pSeries_lpar_flush_hash_range;
 	mmu_hash_ops.hpte_clear_all      = pseries_hpte_clear_all;
 	mmu_hash_ops.hugepage_invalidate = pSeries_lpar_hugepage_invalidate;
+	register_process_table		 = pseries_lpar_register_process_table;
 
 	if (firmware_has_feature(FW_FEATURE_HPT_RESIZE))
 		mmu_hash_ops.resize_hpt = pseries_lpar_resize_hpt;