From 79b123cdf9cf0d4a1620baa8c611962626323a08 Mon Sep 17 00:00:00 2001
From: "Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>
Date: Mon, 7 Sep 2020 12:55:39 +0530
Subject: [PATCH] powerepc/book3s64/hash: Align start/end address correctly
 with bolt mapping

References: bsc#1184957
Patch-mainline: v5.10-rc1
Git-commit: 79b123cdf9cf0d4a1620baa8c611962626323a08

This ensures we don't do a partial mapping of memory. With nvdimm, when
creating namespaces with size not aligned to 16MB, the kernel ends up partially
mapping the pages. This can result in kernel adding multiple hash page table
entries for the same range. A new namespace will result in
create_section_mapping() with start and end overlapping an already existing
bolted hash page table entry.

commit: 6acd7d5ef264 ("libnvdimm/namespace: Enforce memremap_compat_align()")
made sure that we always create namespaces aligned to 16MB. But we can do
better by avoiding mapping pages that are not aligned. This helps to catch
access to these partially mapped pages early.

Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200907072539.67310-1-aneesh.kumar@linux.ibm.com
Acked-by: Michal Suchanek <msuchanek@suse.de>
---
 arch/powerpc/mm/hash_utils_64.c    | 12 +++++++++---
 arch/powerpc/mm/pgtable-radix.c |  1 +
 2 files changed, 10 insertions(+), 3 deletions(-)

diff --git a/arch/powerpc/mm/hash_utils_64.c b/arch/powerpc/mm/hash_utils_64.c
index c663e7ba801f..7185bc43b24f 100644
--- a/arch/powerpc/mm/hash_utils_64.c
+++ b/arch/powerpc/mm/hash_utils_64.c
@@ -260,8 +260,12 @@ int htab_bolt_mapping(unsigned long vstart, unsigned long vend,
 	DBG("htab_bolt_mapping(%lx..%lx -> %lx (%lx,%d,%d)\n",
 	    vstart, vend, pstart, prot, psize, ssize);
 
-	for (vaddr = vstart, paddr = pstart; vaddr < vend;
-	     vaddr += step, paddr += step) {
+	/* Carefully map only the possible range */
+	vaddr = ALIGN(vstart, step);
+	paddr = ALIGN(pstart, step);
+	vend  = ALIGN_DOWN(vend, step);
+
+	for (; vaddr < vend; vaddr += step, paddr += step) {
 		unsigned long hash, hpteg;
 		unsigned long vsid = get_kernel_vsid(vaddr, ssize);
 		unsigned long vpn  = hpt_vpn(vaddr, vsid, ssize);
@@ -343,7 +347,9 @@ int htab_remove_mapping(unsigned long vstart, unsigned long vend,
 	if (!mmu_hash_ops.hpte_removebolted)
 		return -ENODEV;
 
-	for (vaddr = vstart; vaddr < vend; vaddr += step) {
+	/* Unmap the full range specificied */
+	vaddr = ALIGN_DOWN(vstart, step);
+	for (;vaddr < vend; vaddr += step) {
 		rc = mmu_hash_ops.hpte_removebolted(vaddr, psize, ssize);
 		if (rc == -ENOENT) {
 			ret = -ENOENT;
diff --git a/arch/powerpc/mm/pgtable-radix.c b/arch/powerpc/mm/pgtable-radix.c
--- a/arch/powerpc/mm/pgtable-radix.c
+++ b/arch/powerpc/mm/pgtable-radix.c
@@ -276,6 +276,7 @@ static int __meminit create_physical_mapping(unsigned long start,
 #endif
 
 	start = _ALIGN_UP(start, PAGE_SIZE);
+	end   = ALIGN_DOWN(end, PAGE_SIZE);
 	for (addr = start; addr < end; addr += mapping_size) {
 		unsigned long gap, previous_size;
 		int rc;
-- 
2.26.2