Subject: [PATCH 8/9] powerpc/mm: Wire up hpte_removebolted for powernv

From: Oliver O'Halloran <[email-masked]>
Date: Wed, 12 Apr 2017 03:42:32 +1000

From: Rashmica Gupta <[email-masked]>

Adds support for removing bolted (i.e kernel linear mapping) mappings on
powernv. This is needed to support memory hot unplug operations which
are required for the teardown of DAX/PMEM devices.

Cc: Rashmica Gupta <[email-masked]>
Cc: Anton Blanchard <[email-masked]>
Signed-off-by: Oliver O'Halloran <[email-masked]>
---
Could the original author of this add their S-o-b? I pulled it out of
Rashmica's memtrace patch, but I remember someone saying Anton wrote
it originally.
---
 arch/powerpc/mm/hash_native_64.c | 31 +++++++++++++++++++++++++++++++
 1 file changed, 31 insertions(+)

diff --git a/arch/powerpc/mm/hash_native_64.c b/arch/powerpc/mm/hash_native_64.c
index 65bb8f33b399..9ba91d4905a4 100644
--- a/arch/powerpc/mm/hash_native_64.c
+++ b/arch/powerpc/mm/hash_native_64.c
@@ -407,6 +407,36 @@ static void native_hpte_updateboltedpp(unsigned long newpp, unsigned long ea,
 	tlbie(vpn, psize, psize, ssize, 0);
 }
 
+/*
+ * Remove a bolted kernel entry. Memory hotplug uses this.
+ *
+ * No need to lock here because we should be the only user.
+ */
+static int native_hpte_removebolted(unsigned long ea, int psize, int ssize)
+{
+	unsigned long vpn;
+	unsigned long vsid;
+	long slot;
+	struct hash_pte *hptep;
+
+	vsid = get_kernel_vsid(ea, ssize);
+	vpn = hpt_vpn(ea, vsid, ssize);
+
+	slot = native_hpte_find(vpn, psize, ssize);
+	if (slot == -1)
+		return -ENOENT;
+
+	hptep = htab_address + slot;
+
+	/* Invalidate the hpte */
+	hptep->v = 0;
+
+	/* Invalidate the TLB */
+	tlbie(vpn, psize, psize, ssize, 0);
+	return 0;
+}
+
+
 static void native_hpte_invalidate(unsigned long slot, unsigned long vpn,
 				   int bpsize, int apsize, int ssize, int local)
 {
@@ -725,6 +755,7 @@ void __init hpte_init_native(void)
 	mmu_hash_ops.hpte_invalidate	= native_hpte_invalidate;
 	mmu_hash_ops.hpte_updatepp	= native_hpte_updatepp;
 	mmu_hash_ops.hpte_updateboltedpp = native_hpte_updateboltedpp;
+	mmu_hash_ops.hpte_removebolted = native_hpte_removebolted;
 	mmu_hash_ops.hpte_insert	= native_hpte_insert;
 	mmu_hash_ops.hpte_remove	= native_hpte_remove;
 	mmu_hash_ops.hpte_clear_all	= native_hpte_clear;
-- 
2.9.3