[PATCH 0/4] powerpc: Memory hotplug cleanups

[PATCH 0/4] powerpc: Memory hotplug cleanups

[David Gibson]

These are some fairly straightforward cleanups to the memory hotplug
paths on powerpc.  Mostly it deals with more graceful handling of
failure cases.

This series is a soft prerequisite for my patches for HPT resizing on
pseries.

David Gibson (4):
  arch/powerpc: Clean up error handling for htab_remove_mapping
  arch/powerpc: Handle removing maybe-present bolted HPTEs
  arch/powerpc: Clean up memory hotplug failure paths
  arch/powerpc: Split hash page table sizing heuristic into a helper

 arch/powerpc/include/asm/machdep.h    |  2 +-
 arch/powerpc/include/asm/mmu-hash64.h |  3 ++
 arch/powerpc/mm/hash_utils_64.c       | 66 +++++++++++++++++++++--------------
 arch/powerpc/mm/init_64.c             | 47 ++++++++++++++++---------
 arch/powerpc/mm/mem.c                 | 10 ++++--
 arch/powerpc/platforms/pseries/lpar.c |  7 ++--
 6 files changed, 88 insertions(+), 47 deletions(-)

-- 
2.5.0

[PATCH 1/4] arch/powerpc: Clean up error handling for htab_remove_mapping

[David Gibson]

Currently, the only error that htab_remove_mapping() can report is -EINVAL,
if removal of bolted HPTEs isn't implemeted for this platform.  We make
a few clean ups to the handling of this:

 * EINVAL isn't really the right code - there's nothing wrong with the
   function's arguments - use ENODEV instead
 * We were also printing a warning message, but that's a decision better
   left up to the callers, so remove it
 * One caller is vmemmap_remove_mapping(), which will just BUG_ON() on
   error, making the warning message irrelevant, so no change is needed
   there.
 * The other caller is remove_section_mapping().  This is called in the
   memory hot remove path at a point after vmemmap_remove_mapping() so
   if hpte_removebolted isn't implemented, we'd expect to have already
   BUG()ed anyway.  Put a WARN_ON() here, in lieu of a printk() since this
   really shouldn't be happening.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
---
 arch/powerpc/mm/hash_utils_64.c | 13 ++++++-------
 1 file changed, 6 insertions(+), 7 deletions(-)

diff --git a/arch/powerpc/mm/hash_utils_64.c b/arch/powerpc/mm/hash_utils_64.c
index ba59d59..9f7d727 100644
--- a/arch/powerpc/mm/hash_utils_64.c
+++ b/arch/powerpc/mm/hash_utils_64.c
@@ -273,11 +273,8 @@ int htab_remove_mapping(unsigned long vstart, unsigned long vend,
 	shift = mmu_psize_defs[psize].shift;
 	step = 1 << shift;
 
-	if (!ppc_md.hpte_removebolted) {
-		printk(KERN_WARNING "Platform doesn't implement "
-				"hpte_removebolted\n");
-		return -EINVAL;
-	}
+	if (!ppc_md.hpte_removebolted)
+		return -ENODEV;
 
 	for (vaddr = vstart; vaddr < vend; vaddr += step)
 		ppc_md.hpte_removebolted(vaddr, psize, ssize);
@@ -641,8 +638,10 @@ int create_section_mapping(unsigned long start, unsigned long end)
 
 int remove_section_mapping(unsigned long start, unsigned long end)
 {
-	return htab_remove_mapping(start, end, mmu_linear_psize,
-			mmu_kernel_ssize);
+	int rc = htab_remove_mapping(start, end, mmu_linear_psize,
+				     mmu_kernel_ssize);
+	WARN_ON(rc < 0);
+	return rc;
 }
 #endif /* CONFIG_MEMORY_HOTPLUG */
 
-- 
2.5.0

[PATCH 2/4] arch/powerpc: Handle removing maybe-present bolted HPTEs

[David Gibson]

At the moment the hpte_removebolted callback in ppc_md returns void and
will BUG_ON() if the hpte it's asked to remove doesn't exist in the first
place.  This is awkward for the case of cleaning up a mapping which was
partially made before failing.

So, we add a return value to hpte_removebolted, and have it reutrn ENOENT
in the case that the HPTE to remove didn't exist in the first place.

In the (sole) caller, we propagate errors in hpte_removebolted to its
caller to handle.  However, we handle ENOENT specially, continuing to
complete the unmapping over the specified range before returning the error
to the caller.

This means that htab_remove_mapping() will work sanely on a partially
present mapping, removing any HPTEs which are present, while also returning
ENOENT to its caller in case it's important there.

There are two callers of htab_remove_mapping():
   - In remove_section_mapping() we already WARN_ON() any error return,
     which is reasonable - in this case the mapping should be fully
     present
   - In vmemmap_remove_mapping() we BUG_ON() any error.  We change that to
     just a WARN_ON() in the case of ENOENT, since failing to remove a
     mapping that wasn't there in the first place probably shouldn't be
     fatal.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
---
 arch/powerpc/include/asm/machdep.h    |  2 +-
 arch/powerpc/mm/hash_utils_64.c       | 10 +++++++---
 arch/powerpc/mm/init_64.c             |  9 +++++----
 arch/powerpc/platforms/pseries/lpar.c |  7 +++++--
 4 files changed, 18 insertions(+), 10 deletions(-)

diff --git a/arch/powerpc/include/asm/machdep.h b/arch/powerpc/include/asm/machdep.h
index 3f191f5..a7d3f66 100644
--- a/arch/powerpc/include/asm/machdep.h
+++ b/arch/powerpc/include/asm/machdep.h
@@ -54,7 +54,7 @@ struct machdep_calls {
 				       int psize, int apsize,
 				       int ssize);
 	long		(*hpte_remove)(unsigned long hpte_group);
-	void            (*hpte_removebolted)(unsigned long ea,
+	long            (*hpte_removebolted)(unsigned long ea,
 					     int psize, int ssize);
 	void		(*flush_hash_range)(unsigned long number, int local);
 	void		(*hugepage_invalidate)(unsigned long vsid,
diff --git a/arch/powerpc/mm/hash_utils_64.c b/arch/powerpc/mm/hash_utils_64.c
index 9f7d727..0737eae 100644
--- a/arch/powerpc/mm/hash_utils_64.c
+++ b/arch/powerpc/mm/hash_utils_64.c
@@ -269,6 +269,7 @@ int htab_remove_mapping(unsigned long vstart, unsigned long vend,
 {
 	unsigned long vaddr;
 	unsigned int step, shift;
+	int rc = 0;
 
 	shift = mmu_psize_defs[psize].shift;
 	step = 1 << shift;
@@ -276,10 +277,13 @@ int htab_remove_mapping(unsigned long vstart, unsigned long vend,
 	if (!ppc_md.hpte_removebolted)
 		return -ENODEV;
 
-	for (vaddr = vstart; vaddr < vend; vaddr += step)
-		ppc_md.hpte_removebolted(vaddr, psize, ssize);
+	for (vaddr = vstart; vaddr < vend; vaddr += step) {
+		rc = ppc_md.hpte_removebolted(vaddr, psize, ssize);
+		if ((rc < 0) && (rc != -ENOENT))
+			return rc;
+	}
 
-	return 0;
+	return rc;
 }
 #endif /* CONFIG_MEMORY_HOTPLUG */
 
diff --git a/arch/powerpc/mm/init_64.c b/arch/powerpc/mm/init_64.c
index 379a6a9..baa1a23 100644
--- a/arch/powerpc/mm/init_64.c
+++ b/arch/powerpc/mm/init_64.c
@@ -232,10 +232,11 @@ static void __meminit vmemmap_create_mapping(unsigned long start,
 static void vmemmap_remove_mapping(unsigned long start,
 				   unsigned long page_size)
 {
-	int mapped = htab_remove_mapping(start, start + page_size,
-					 mmu_vmemmap_psize,
-					 mmu_kernel_ssize);
-	BUG_ON(mapped < 0);
+	int rc = htab_remove_mapping(start, start + page_size,
+				     mmu_vmemmap_psize,
+				     mmu_kernel_ssize);
+	BUG_ON((rc < 0) && (rc != -ENOENT));
+	WARN_ON(rc == -ENOENT);
 }
 #endif
 
diff --git a/arch/powerpc/platforms/pseries/lpar.c b/arch/powerpc/platforms/pseries/lpar.c
index 477290a..92d472d 100644
--- a/arch/powerpc/platforms/pseries/lpar.c
+++ b/arch/powerpc/platforms/pseries/lpar.c
@@ -505,7 +505,7 @@ static void pSeries_lpar_hugepage_invalidate(unsigned long vsid,
 }
 #endif
 
-static void pSeries_lpar_hpte_removebolted(unsigned long ea,
+static long pSeries_lpar_hpte_removebolted(unsigned long ea,
 					   int psize, int ssize)
 {
 	unsigned long vpn;
@@ -515,11 +515,14 @@ static void pSeries_lpar_hpte_removebolted(unsigned long ea,
 	vpn = hpt_vpn(ea, vsid, ssize);
 
 	slot = pSeries_lpar_hpte_find(vpn, psize, ssize);
-	BUG_ON(slot == -1);
+	if (slot == -1)
+		return -ENOENT;
+
 	/*
 	 * lpar doesn't use the passed actual page size
 	 */
 	pSeries_lpar_hpte_invalidate(slot, vpn, psize, 0, ssize, 0);
+	return 0;
 }
 
 /*
-- 
2.5.0

[PATCH 3/4] arch/powerpc: Clean up memory hotplug failure paths

[David Gibson]

This makes a number of cleanups to handling of mapping failures during
memory hotplug on Power:

For errors creating the linear mapping for the hot-added region:
  * This is now reported with EFAULT which is more appropriate than the
    previous EINVAL (the failure is unlikely to be related to the
    function's parameters)
  * An error in this path now prints a warning message, rather than just
    silently failing to add the extra memory.
  * Previously a failure here could result in the region being partially
    mapped.  We now clean up any partial mapping before failing.

For errors creating the vmemmap for the hot-added region:
   * This is now reported with EFAULT instead of causing a BUG() - this
     could happen for external reason (e.g. full hash table) so it's better
     to handle this non-fatally
   * An error message is also printed, so the failure won't be silent
   * As above a failure could cause a partially mapped region, we now
     clean this up.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
---
 arch/powerpc/mm/hash_utils_64.c | 13 ++++++++++---
 arch/powerpc/mm/init_64.c       | 38 ++++++++++++++++++++++++++------------
 arch/powerpc/mm/mem.c           | 10 ++++++++--
 3 files changed, 44 insertions(+), 17 deletions(-)

diff --git a/arch/powerpc/mm/hash_utils_64.c b/arch/powerpc/mm/hash_utils_64.c
index 0737eae..e88a86e 100644
--- a/arch/powerpc/mm/hash_utils_64.c
+++ b/arch/powerpc/mm/hash_utils_64.c
@@ -635,9 +635,16 @@ static unsigned long __init htab_get_table_size(void)
 #ifdef CONFIG_MEMORY_HOTPLUG
 int create_section_mapping(unsigned long start, unsigned long end)
 {
-	return htab_bolt_mapping(start, end, __pa(start),
-				 pgprot_val(PAGE_KERNEL), mmu_linear_psize,
-				 mmu_kernel_ssize);
+	int rc = htab_bolt_mapping(start, end, __pa(start),
+				   pgprot_val(PAGE_KERNEL), mmu_linear_psize,
+				   mmu_kernel_ssize);
+
+	if (rc < 0) {
+		int rc2 = htab_remove_mapping(start, end, mmu_linear_psize,
+					      mmu_kernel_ssize);
+		BUG_ON(rc2 && (rc2 != -ENOENT));
+	}
+	return rc;
 }
 
 int remove_section_mapping(unsigned long start, unsigned long end)
diff --git a/arch/powerpc/mm/init_64.c b/arch/powerpc/mm/init_64.c
index baa1a23..0cc944b 100644
--- a/arch/powerpc/mm/init_64.c
+++ b/arch/powerpc/mm/init_64.c
@@ -188,9 +188,9 @@ static int __meminit vmemmap_populated(unsigned long start, int page_size)
  */
 
 #ifdef CONFIG_PPC_BOOK3E
-static void __meminit vmemmap_create_mapping(unsigned long start,
-					     unsigned long page_size,
-					     unsigned long phys)
+static int __meminit vmemmap_create_mapping(unsigned long start,
+					    unsigned long page_size,
+					    unsigned long phys)
 {
 	/* Create a PTE encoding without page size */
 	unsigned long i, flags = _PAGE_PRESENT | _PAGE_ACCESSED |
@@ -208,6 +208,8 @@ static void __meminit vmemmap_create_mapping(unsigned long start,
 	 */
 	for (i = 0; i < page_size; i += PAGE_SIZE)
 		BUG_ON(map_kernel_page(start + i, phys, flags));
+
+	return 0;
 }
 
 #ifdef CONFIG_MEMORY_HOTPLUG
@@ -217,15 +219,20 @@ static void vmemmap_remove_mapping(unsigned long start,
 }
 #endif
 #else /* CONFIG_PPC_BOOK3E */
-static void __meminit vmemmap_create_mapping(unsigned long start,
-					     unsigned long page_size,
-					     unsigned long phys)
+static int __meminit vmemmap_create_mapping(unsigned long start,
+					    unsigned long page_size,
+					    unsigned long phys)
 {
-	int  mapped = htab_bolt_mapping(start, start + page_size, phys,
-					pgprot_val(PAGE_KERNEL),
-					mmu_vmemmap_psize,
-					mmu_kernel_ssize);
-	BUG_ON(mapped < 0);
+	int rc = htab_bolt_mapping(start, start + page_size, phys,
+				   pgprot_val(PAGE_KERNEL),
+				   mmu_vmemmap_psize, mmu_kernel_ssize);
+	if (rc < 0) {
+		int rc2 = htab_remove_mapping(start, start + page_size,
+					      mmu_vmemmap_psize,
+					      mmu_kernel_ssize);
+		BUG_ON(rc2 && (rc2 != -ENOENT));
+	}
+	return rc;
 }
 
 #ifdef CONFIG_MEMORY_HOTPLUG
@@ -304,6 +311,7 @@ int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node)
 
 	for (; start < end; start += page_size) {
 		void *p;
+		int rc;
 
 		if (vmemmap_populated(start, page_size))
 			continue;
@@ -317,7 +325,13 @@ int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node)
 		pr_debug("      * %016lx..%016lx allocated at %p\n",
 			 start, start + page_size, p);
 
-		vmemmap_create_mapping(start, page_size, __pa(p));
+		rc = vmemmap_create_mapping(start, page_size, __pa(p));
+		if (rc < 0) {
+			pr_warning(
+				"vmemmap_populate: Unable to create vmemmap mapping: %d",
+				rc);
+			return -EFAULT;
+		}
 	}
 
 	return 0;
diff --git a/arch/powerpc/mm/mem.c b/arch/powerpc/mm/mem.c
index 22d94c3..1593f89 100644
--- a/arch/powerpc/mm/mem.c
+++ b/arch/powerpc/mm/mem.c
@@ -119,12 +119,18 @@ int arch_add_memory(int nid, u64 start, u64 size, bool for_device)
 	struct zone *zone;
 	unsigned long start_pfn = start >> PAGE_SHIFT;
 	unsigned long nr_pages = size >> PAGE_SHIFT;
+	int rc;
 
 	pgdata = NODE_DATA(nid);
 
 	start = (unsigned long)__va(start);
-	if (create_section_mapping(start, start + size))
-		return -EINVAL;
+	rc = create_section_mapping(start, start + size);
+	if (rc) {
+		pr_warning(
+			"Unable to crate mapping for hot added memory 0x%llx..0x%llx: %d",
+			start, start + size, rc);
+		return -EFAULT;
+	}
 
 	/* this should work for most non-highmem platforms */
 	zone = pgdata->node_zones +
-- 
2.5.0

[PATCH 4/4] arch/powerpc: Split hash page table sizing heuristic into a helper

[David Gibson]

htab_get_table_size() either retrieve the size of the hash page table (HPT)
from the device tree - if the HPT size is determined by firmware - or
uses a heuristic to determine a good size based on RAM size if the kernel
is responsible for allocating the HPT.

To support a PAPR extension allowing resizing of the HPT, we're going to
want the memory size -> HPT size logic elsewhere, so split it out into a
helper function.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
---
 arch/powerpc/include/asm/mmu-hash64.h |  3 +++
 arch/powerpc/mm/hash_utils_64.c       | 30 +++++++++++++++++-------------
 2 files changed, 20 insertions(+), 13 deletions(-)

diff --git a/arch/powerpc/include/asm/mmu-hash64.h b/arch/powerpc/include/asm/mmu-hash64.h
index 7352d3f..cf070fd 100644
--- a/arch/powerpc/include/asm/mmu-hash64.h
+++ b/arch/powerpc/include/asm/mmu-hash64.h
@@ -607,6 +607,9 @@ static inline unsigned long get_kernel_vsid(unsigned long ea, int ssize)
 	context = (MAX_USER_CONTEXT) + ((ea >> 60) - 0xc) + 1;
 	return get_vsid(context, ea, ssize);
 }
+
+unsigned htab_shift_for_mem_size(unsigned long mem_size);
+
 #endif /* __ASSEMBLY__ */
 
 #endif /* _ASM_POWERPC_MMU_HASH64_H_ */
diff --git a/arch/powerpc/mm/hash_utils_64.c b/arch/powerpc/mm/hash_utils_64.c
index e88a86e..d63f7dc 100644
--- a/arch/powerpc/mm/hash_utils_64.c
+++ b/arch/powerpc/mm/hash_utils_64.c
@@ -606,10 +606,24 @@ static int __init htab_dt_scan_pftsize(unsigned long node,
 	return 0;
 }
 
-static unsigned long __init htab_get_table_size(void)
+unsigned htab_shift_for_mem_size(unsigned long mem_size)
 {
-	unsigned long mem_size, rnd_mem_size, pteg_count, psize;
+	unsigned memshift = __ilog2(mem_size);
+	unsigned pshift = mmu_psize_defs[mmu_virtual_psize].shift;
+	unsigned pteg_shift;
+
+	/* round mem_size up to next power of 2 */
+	if ((1UL << memshift) < mem_size)
+		memshift += 1;
+
+	/* aim for 2 pages / pteg */
+	pteg_shift = memshift - (pshift + 1);
+
+	return max(pteg_shift + 7, 18U);
+}
 
+static unsigned long __init htab_get_table_size(void)
+{
 	/* If hash size isn't already provided by the platform, we try to
 	 * retrieve it from the device-tree. If it's not there neither, we
 	 * calculate it now based on the total RAM size
@@ -619,17 +633,7 @@ static unsigned long __init htab_get_table_size(void)
 	if (ppc64_pft_size)
 		return 1UL << ppc64_pft_size;
 
-	/* round mem_size up to next power of 2 */
-	mem_size = memblock_phys_mem_size();
-	rnd_mem_size = 1UL << __ilog2(mem_size);
-	if (rnd_mem_size < mem_size)
-		rnd_mem_size <<= 1;
-
-	/* # pages / 2 */
-	psize = mmu_psize_defs[mmu_virtual_psize].shift;
-	pteg_count = max(rnd_mem_size >> (psize + 1), 1UL << 11);
-
-	return pteg_count << 7;
+	return htab_shift_for_mem_size(memblock_phys_mem_size());
 }
 
 #ifdef CONFIG_MEMORY_HOTPLUG
-- 
2.5.0