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

Paul Mackerras paulus at ozlabs.org
Thu Feb 16 16:03:39 AEDT 2017

On POWER9, since commit cc3d2940133d ("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: cc3d2940133d ("powerpc/64: Enable use of radix MMU under hypervisor on POWER9")
Signed-off-by: Paul Mackerras <paulus at ozlabs.org>
This needs to go in after the topic/ppc-kvm branch.

arch/powerpc/mm/hash_utils_64.c       | 6 ++++++
 arch/powerpc/platforms/pseries/lpar.c | 8 ++++++--
 2 files changed, 12 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/mm/hash_utils_64.c b/arch/powerpc/mm/hash_utils_64.c
index 8033493..b0ed96e 100644
--- a/arch/powerpc/mm/hash_utils_64.c
+++ b/arch/powerpc/mm/hash_utils_64.c
@@ -839,6 +839,12 @@ 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);
 		 * If firmware assisted dump is active firmware preserves
diff --git a/arch/powerpc/platforms/pseries/lpar.c b/arch/powerpc/platforms/pseries/lpar.c
index 0587655..5b47026 100644
--- a/arch/powerpc/platforms/pseries/lpar.c
+++ b/arch/powerpc/platforms/pseries/lpar.c
@@ -609,15 +609,18 @@ static int __init disable_bulk_remove(char *str)
 __setup("bulk_remove=", disable_bulk_remove);
-/* 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())
+	else
+		flags |= PROC_TABLE_HPT_SLB;
 	for (;;) {
 		rc = plpar_hcall_norets(H_REGISTER_PROC_TBL, flags, base,
 					page_size, table_size);
@@ -643,6 +646,7 @@ 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;
 void radix_init_pseries(void)

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