ZONE_DEVICE and pmem API support for powerpc

PATCH Applied Oliver O'Halloran 10 participants 31 messages Apr 11, 2017 – Apr 23, 2017 1 message not in the archive

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Memory management PowerPC MM core libnvdimm: non-volatile memory device +1 more subsystems

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Oliver O'Halloran

author

2017-04-11 17:42 UTC #0 lore raw

Hi all,

This series adds support for ZONE_DEVICE and the pmem api on powerpc. Namely, support for altmaps and the various bits and pieces required for DAX PMD faults. The first two patches touch generic mm/ code, but otherwise this is fairly well contained in arch/powerpc.

If the nvdimm folks could sanity check this series I'd appreciate it.

Series is based on next-20170411, but it should apply elsewhere with minor fixups to arch_{add|remove}_memory due to conflicts with HMM. For those interested in testing this, there is a driver and matching firmware that carves out some system memory for use as an emulated Con Tutto memory card.

Driver: https://github.com/oohal/linux/tree/contutto-next
Firmware: https://github.com/oohal/skiboot/tree/fake-contutto

Edit core/init.c:686 to control the amount of memory borrowed for the emulated device. I'm keeping the driver out of tree for a until 4.13 since I plan on reworking the firmware interface anyway and There's at least one showstopper bug.

Thanks,
Oliver

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Oliver O'Halloran

author

2017-04-11 17:42 UTC #1 lore raw

PATCH 1/9 mm/huge_memory: Use zap_deposited_table() more

Depending flags of the PMD being zapped there may or may not be a deposited pgtable to be freed. In two of the three cases this is open coded while the third uses the zap_deposited_table() helper. This patch converts the others to use the helper to clean things up a bit.

Cc "Aneesh Kumar K.V" <[email protected]>

Cc "Kirill A. Shutemov" <[email protected]>

Cc [email protected]

Signed-off-by Oliver O'Halloran <[email protected]>

---
For reference:

void zap_deposited_table(struct mm_struct *mm, pmd_t *pmd)

{
        pgtable_t pgtable;

        pgtable = pgtable_trans_huge_withdraw(mm, pmd);
        pte_free(mm, pgtable);
        atomic_long_dec(&mm->nr_ptes);
}
---
 mm/huge_memory.c | 8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

mm/huge_memory.c +2 -6

index b787c4cfda0e..aa01dd47cc65 100644
@@ -1615,8 +1615,7 @@ int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
 		if (is_huge_zero_pmd(orig_pmd))
 			tlb_remove_page_size(tlb, pmd_page(orig_pmd), HPAGE_PMD_SIZE);
 	} else if (is_huge_zero_pmd(orig_pmd)) {
-		pte_free(tlb->mm, pgtable_trans_huge_withdraw(tlb->mm, pmd));
-		atomic_long_dec(&tlb->mm->nr_ptes);
+		zap_deposited_table(tlb->mm, pmd);
 		spin_unlock(ptl);
 		tlb_remove_page_size(tlb, pmd_page(orig_pmd), HPAGE_PMD_SIZE);
 	} else {

@@ -1625,10 +1624,7 @@ int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
 		VM_BUG_ON_PAGE(page_mapcount(page) < 0, page);
 		VM_BUG_ON_PAGE(!PageHead(page), page);
 		if (PageAnon(page)) {
-			pgtable_t pgtable;
-			pgtable = pgtable_trans_huge_withdraw(tlb->mm, pmd);
-			pte_free(tlb->mm, pgtable);
-			atomic_long_dec(&tlb->mm->nr_ptes);
+			zap_deposited_table(tlb->mm, pmd);
 			add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR);
 		} else {
 			if (arch_needs_pgtable_deposit())

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Aneesh Kumar K.V

Reviewed-by on v1 1/9

2017-04-12 05:44 UTC #2 lore raw

Re: [PATCH 1/9] mm/huge_memory: Use zap_deposited_table() more

Quoted 9 lines · Oliver O'Halloran

Depending flags of the PMD being zapped there may or may not be a deposited pgtable to be freed. In two of the three cases this is open coded while the third uses the zap_deposited_table() helper. This patch converts the others to use the helper to clean things up a bit.
Cc "Aneesh Kumar K.V" <[email protected]>
Cc "Kirill A. Shutemov" <[email protected]>
Cc [email protected]
Signed-off-by Oliver O'Halloran <[email protected]>

Reviewed-by Aneesh Kumar K.V <[email protected]>

Quoted 43 lines

---
For reference:

void zap_deposited_table(struct mm_struct *mm, pmd_t *pmd)

{
        pgtable_t pgtable;

        pgtable = pgtable_trans_huge_withdraw(mm, pmd);
        pte_free(mm, pgtable);
        atomic_long_dec(&mm->nr_ptes);
}
---
 mm/huge_memory.c | 8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

mm/huge_memory.c +2 -6

index b787c4cfda0e..aa01dd47cc65 100644
@@ -1615,8 +1615,7 @@ int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
 		if (is_huge_zero_pmd(orig_pmd))
 			tlb_remove_page_size(tlb, pmd_page(orig_pmd), HPAGE_PMD_SIZE);
 	} else if (is_huge_zero_pmd(orig_pmd)) {
-		pte_free(tlb->mm, pgtable_trans_huge_withdraw(tlb->mm, pmd));
-		atomic_long_dec(&tlb->mm->nr_ptes);
+		zap_deposited_table(tlb->mm, pmd);
 		spin_unlock(ptl);
 		tlb_remove_page_size(tlb, pmd_page(orig_pmd), HPAGE_PMD_SIZE);
 	} else {

@@ -1625,10 +1624,7 @@ int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
 		VM_BUG_ON_PAGE(page_mapcount(page) < 0, page);
 		VM_BUG_ON_PAGE(!PageHead(page), page);
 		if (PageAnon(page)) {
-			pgtable_t pgtable;
-			pgtable = pgtable_trans_huge_withdraw(tlb->mm, pmd);
-			pte_free(tlb->mm, pgtable);
-			atomic_long_dec(&tlb->mm->nr_ptes);
+			zap_deposited_table(tlb->mm, pmd);
 			add_mm_counter(tlb->mm, MM_ANONPAGES, -HPAGE_PMD_NR);
 		} else {
 			if (arch_needs_pgtable_deposit())

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David Rientjes

Acked-by on v1 1/9

2017-04-18 21:35 UTC #3 lore raw

Re: [PATCH 1/9] mm/huge_memory: Use zap_deposited_table() more

In reply to Oliver O'Halloran

Quoted 9 lines · Oliver O'Halloran

Depending flags of the PMD being zapped there may or may not be a deposited pgtable to be freed. In two of the three cases this is open coded while the third uses the zap_deposited_table() helper. This patch converts the others to use the helper to clean things up a bit.
Cc "Aneesh Kumar K.V" <[email protected]>
Cc "Kirill A. Shutemov" <[email protected]>
Cc [email protected]
Signed-off-by Oliver O'Halloran <[email protected]>

Acked-by David Rientjes <[email protected]>

Oliver O'Halloran

author

2017-04-11 17:42 UTC #4 lore raw

PATCH 2/9 mm/huge_memory: Deposit a pgtable for DAX PMD faults when required

In reply to Oliver O'Halloran

Although all architectures use a deposited page table for THP on anonymous VMAs some architectures (s390 and powerpc) require the deposited storage even for file backed VMAs due to quirks of their MMUs. This patch adds support for depositing a table in DAX PMD fault handling path for archs that require it. Other architectures should see no functional changes.

Cc "Aneesh Kumar K.V" <[email protected]>

Cc [email protected]

Signed-off-by Oliver O'Halloran <[email protected]>

---
 mm/huge_memory.c | 20 ++++++++++++++++++--
 1 file changed, 18 insertions(+), 2 deletions(-)

mm/huge_memory.c +18 -2

index aa01dd47cc65..a84909cf20d3 100644
@@ -715,7 +715,8 @@ int do_huge_pmd_anonymous_page(struct vm_fault *vmf)
 }
 
 static void insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr,
-		pmd_t *pmd, pfn_t pfn, pgprot_t prot, bool write)
+		pmd_t *pmd, pfn_t pfn, pgprot_t prot, bool write,
+		pgtable_t pgtable)
 {
 	struct mm_struct *mm = vma->vm_mm;
 	pmd_t entry;

@@ -729,6 +730,12 @@ static void insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr,
 		entry = pmd_mkyoung(pmd_mkdirty(entry));
 		entry = maybe_pmd_mkwrite(entry, vma);
 	}
+
+	if (pgtable) {
+		pgtable_trans_huge_deposit(mm, pmd, pgtable);
+		atomic_long_inc(&mm->nr_ptes);
+	}
+
 	set_pmd_at(mm, addr, pmd, entry);
 	update_mmu_cache_pmd(vma, addr, pmd);
 	spin_unlock(ptl);

@@ -738,6 +745,7 @@ int vmf_insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr,
 			pmd_t *pmd, pfn_t pfn, bool write)
 {
 	pgprot_t pgprot = vma->vm_page_prot;
+	pgtable_t pgtable = NULL;
 	/*
 	 * If we had pmd_special, we could avoid all these restrictions,
 	 * but we need to be consistent with PTEs and architectures that

@@ -752,9 +760,15 @@ int vmf_insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr,
 	if (addr < vma->vm_start || addr >= vma->vm_end)
 		return VM_FAULT_SIGBUS;
 
+	if (arch_needs_pgtable_deposit()) {
+		pgtable = pte_alloc_one(vma->vm_mm, addr);
+		if (!pgtable)
+			return VM_FAULT_OOM;
+	}
+
 	track_pfn_insert(vma, &pgprot, pfn);
 
-	insert_pfn_pmd(vma, addr, pmd, pfn, pgprot, write);
+	insert_pfn_pmd(vma, addr, pmd, pfn, pgprot, write, pgtable);
 	return VM_FAULT_NOPAGE;
 }
 EXPORT_SYMBOL_GPL(vmf_insert_pfn_pmd);

@@ -1611,6 +1625,8 @@ int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
 			tlb->fullmm);
 	tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
 	if (vma_is_dax(vma)) {
+		if (arch_needs_pgtable_deposit())
+			zap_deposited_table(tlb->mm, pmd);
 		spin_unlock(ptl);
 		if (is_huge_zero_pmd(orig_pmd))
 			tlb_remove_page_size(tlb, pmd_page(orig_pmd), HPAGE_PMD_SIZE);

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Aneesh Kumar K.V

Reviewed-by on v1 2/9

2017-04-12 05:51 UTC #5 lore raw

Re: [PATCH 2/9] mm/huge_memory: Deposit a pgtable for DAX PMD faults when required

Quoted 9 lines · Oliver O'Halloran

Although all architectures use a deposited page table for THP on anonymous VMAs some architectures (s390 and powerpc) require the deposited storage even for file backed VMAs due to quirks of their MMUs. This patch adds support for depositing a table in DAX PMD fault handling path for archs that require it. Other architectures should see no functional changes.
Cc "Aneesh Kumar K.V" <[email protected]>
Cc [email protected]
Signed-off-by Oliver O'Halloran <[email protected]>

Reviewed-by Aneesh Kumar K.V <[email protected]>

Quoted 67 lines

---
 mm/huge_memory.c | 20 ++++++++++++++++++--
 1 file changed, 18 insertions(+), 2 deletions(-)

mm/huge_memory.c +18 -2

index aa01dd47cc65..a84909cf20d3 100644
@@ -715,7 +715,8 @@ int do_huge_pmd_anonymous_page(struct vm_fault *vmf)
 }
 
 static void insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr,
-		pmd_t *pmd, pfn_t pfn, pgprot_t prot, bool write)
+		pmd_t *pmd, pfn_t pfn, pgprot_t prot, bool write,
+		pgtable_t pgtable)
 {
 	struct mm_struct *mm = vma->vm_mm;
 	pmd_t entry;

@@ -729,6 +730,12 @@ static void insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr,
 		entry = pmd_mkyoung(pmd_mkdirty(entry));
 		entry = maybe_pmd_mkwrite(entry, vma);
 	}
+
+	if (pgtable) {
+		pgtable_trans_huge_deposit(mm, pmd, pgtable);
+		atomic_long_inc(&mm->nr_ptes);
+	}
+
 	set_pmd_at(mm, addr, pmd, entry);
 	update_mmu_cache_pmd(vma, addr, pmd);
 	spin_unlock(ptl);

@@ -738,6 +745,7 @@ int vmf_insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr,
 			pmd_t *pmd, pfn_t pfn, bool write)
 {
 	pgprot_t pgprot = vma->vm_page_prot;
+	pgtable_t pgtable = NULL;
 	/*
 	 * If we had pmd_special, we could avoid all these restrictions,
 	 * but we need to be consistent with PTEs and architectures that

@@ -752,9 +760,15 @@ int vmf_insert_pfn_pmd(struct vm_area_struct *vma, unsigned long addr,
 	if (addr < vma->vm_start || addr >= vma->vm_end)
 		return VM_FAULT_SIGBUS;
 
+	if (arch_needs_pgtable_deposit()) {
+		pgtable = pte_alloc_one(vma->vm_mm, addr);
+		if (!pgtable)
+			return VM_FAULT_OOM;
+	}
+
 	track_pfn_insert(vma, &pgprot, pfn);
 
-	insert_pfn_pmd(vma, addr, pmd, pfn, pgprot, write);
+	insert_pfn_pmd(vma, addr, pmd, pfn, pgprot, write, pgtable);
 	return VM_FAULT_NOPAGE;
 }
 EXPORT_SYMBOL_GPL(vmf_insert_pfn_pmd);

@@ -1611,6 +1625,8 @@ int zap_huge_pmd(struct mmu_gather *tlb, struct vm_area_struct *vma,
 			tlb->fullmm);
 	tlb_remove_pmd_tlb_entry(tlb, pmd, addr);
 	if (vma_is_dax(vma)) {
+		if (arch_needs_pgtable_deposit())
+			zap_deposited_table(tlb->mm, pmd);
 		spin_unlock(ptl);
 		if (is_huge_zero_pmd(orig_pmd))
 			tlb_remove_page_size(tlb, pmd_page(orig_pmd), HPAGE_PMD_SIZE);

Signature · 1 line

2.9.3

Oliver O'Halloran

author

2017-04-11 17:43 UTC #6 lore raw

PATCH 3/9 powerpc/mm: Add _PAGE_DEVMAP for ppc64.

In reply to Oliver O'Halloran

From: "Aneesh Kumar K.V" <[email protected]>

Add a _PAGE_DEVMAP bit for PTE and DAX PMD entires. PowerPC doesn't currently support PUD faults so we haven't extended it to the PUD level.

Cc Aneesh Kumar K.V <[email protected]>

Signed-off-by Oliver O'Halloran <[email protected]>

---
 arch/powerpc/include/asm/book3s/64/pgtable.h | 37 +++++++++++++++++++++++++++-
 1 file changed, 36 insertions(+), 1 deletion(-)

arch/powerpc/include/asm/book3s/64/pgtable.h +36 -1

index fb72ff6b98e6..b5fc6337649e 100644
@@ -78,6 +78,9 @@
 
 #define _PAGE_SOFT_DIRTY	_RPAGE_SW3 /* software: software dirty tracking */
 #define _PAGE_SPECIAL		_RPAGE_SW2 /* software: special page */
+#define _PAGE_DEVMAP		_RPAGE_SW1
+#define __HAVE_ARCH_PTE_DEVMAP
+
 /*
  * Drivers request for cache inhibited pte mapping using _PAGE_NO_CACHE
  * Instead of fixing all of them, add an alternate define which

@@ -602,6 +605,16 @@ static inline pte_t pte_mkhuge(pte_t pte)
 	return pte;
 }
 
+static inline pte_t pte_mkdevmap(pte_t pte)
+{
+	return __pte(pte_val(pte) | _PAGE_SPECIAL|_PAGE_DEVMAP);
+}
+
+static inline int pte_devmap(pte_t pte)
+{
+	return !!(pte_raw(pte) & cpu_to_be64(_PAGE_DEVMAP));
+}
+
 static inline pte_t pte_modify(pte_t pte, pgprot_t newprot)
 {
 	/* FIXME!! check whether this need to be a conditional */

@@ -966,6 +979,9 @@ static inline pte_t *pmdp_ptep(pmd_t *pmd)
 #define pmd_mk_savedwrite(pmd)	pte_pmd(pte_mk_savedwrite(pmd_pte(pmd)))
 #define pmd_clear_savedwrite(pmd)	pte_pmd(pte_clear_savedwrite(pmd_pte(pmd)))
 
+#define pud_pfn(...) (0)
+#define pgd_pfn(...) (0)
+
 #ifdef CONFIG_HAVE_ARCH_SOFT_DIRTY
 #define pmd_soft_dirty(pmd)    pte_soft_dirty(pmd_pte(pmd))
 #define pmd_mksoft_dirty(pmd)  pte_pmd(pte_mksoft_dirty(pmd_pte(pmd)))

@@ -1140,7 +1156,6 @@ static inline int pmd_move_must_withdraw(struct spinlock *new_pmd_ptl,
 	return true;
 }
 
-
 #define arch_needs_pgtable_deposit arch_needs_pgtable_deposit
 static inline bool arch_needs_pgtable_deposit(void)
 {

@@ -1149,6 +1164,26 @@ static inline bool arch_needs_pgtable_deposit(void)
 	return true;
 }
 
+static inline pmd_t pmd_mkdevmap(pmd_t pmd)
+{
+	return pte_pmd(pte_mkdevmap(pmd_pte(pmd)));
+}
+
+static inline int pmd_devmap(pmd_t pmd)
+{
+	return pte_devmap(pmd_pte(pmd));
+}
+
+static inline int pud_devmap(pud_t pud)
+{
+	return 0;
+}
+
+static inline int pgd_devmap(pgd_t pgd)
+{
+	return 0;
+}
+
 #endif /* CONFIG_TRANSPARENT_HUGEPAGE */
 #endif /* __ASSEMBLY__ */
 #endif /* _ASM_POWERPC_BOOK3S_64_PGTABLE_H_ */

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Stephen Rothwell

2017-04-12 00:19 UTC #7 lore raw

Re: [PATCH 3/9] powerpc/mm: Add _PAGE_DEVMAP for ppc64.

Hi Oliver,

Quoted 9 lines · On Wed, 12 Apr 2017 03:42:27 +1000 Oliver O'Halloran <[email protected]> wrote:

From: "Aneesh Kumar K.V" <[email protected]>
Add a _PAGE_DEVMAP bit for PTE and DAX PMD entires. PowerPC doesn't currently support PUD faults so we haven't extended it to the PUD level.
Cc Aneesh Kumar K.V <[email protected]>
Signed-off-by Oliver O'Halloran <[email protected]>

This needs Aneesh's Signed-off-by.

Signature · 2 lines

Cheers,
Stephen Rothwell

Aneesh Kumar K.V

2017-04-12 03:07 UTC #8 lore raw

Re: [PATCH 3/9] powerpc/mm: Add _PAGE_DEVMAP for ppc64.

Quoted 6 lines · Stephen Rothwell

Hi Oliver,
Quoted 3 lines · On Wed, 12 Apr 2017 03:42:27 +1000 Oliver O'Halloran <[email protected]> wrote:
From: "Aneesh Kumar K.V" <[email protected]>

Quoted 9 lines

Quoted 6 lines
Add a _PAGE_DEVMAP bit for PTE and DAX PMD entires. PowerPC doesn't currently support PUD faults so we haven't extended it to the PUD level.
Cc Aneesh Kumar K.V <[email protected]>
Signed-off-by Oliver O'Halloran <[email protected]>
This needs Aneesh's Signed-off-by.

Signed-off-by Aneesh Kumar K.V <[email protected]>

-aneesh

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Aneesh Kumar K.V

2017-04-13 05:21 UTC #9 lore raw

Re: [PATCH 3/9] powerpc/mm: Add _PAGE_DEVMAP for ppc64.

In reply to Oliver O'Halloran

Quoted 8 lines · Oliver O'Halloran

From: "Aneesh Kumar K.V" <[email protected]>
Add a _PAGE_DEVMAP bit for PTE and DAX PMD entires. PowerPC doesn't currently support PUD faults so we haven't extended it to the PUD level.
Cc Aneesh Kumar K.V <[email protected]>
Signed-off-by Oliver O'Halloran <[email protected]>

Few changes we would need. We will now need to make sure a devmap pmd entry is not confused with THP. ie,

we should compare against _PAGE_PTE and _PAGE_DEVMAP in pmd_trans_huge(). hash already has one bit we use to differentiate between hugetlb and THP. May be we can genarlize this and come up with a way to differentiate THP, HUGETLB,pmd DEVMAP entries ?

also I don't see you handing get_user_pages_fast() ?

-aneesh

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Oliver O'Halloran

author

2017-04-11 17:43 UTC #10 lore raw

PATCH 4/9 powerpc/mm: Reshuffle vmemmap_free()

In reply to Oliver O'Halloran

Removes an indentation level and shuffles some code around to make the following patch cleaner. No functional changes.

Signed-off-by Oliver O'Halloran <[email protected]>

---
 arch/powerpc/mm/init_64.c | 47 +++++++++++++++++++++++++----------------------
 1 file changed, 25 insertions(+), 22 deletions(-)

arch/powerpc/mm/init_64.c +25 ~~-22~~

index ec84b31c6c86..f8124edb6ffa 100644
@@ -234,12 +234,15 @@ static unsigned long vmemmap_list_free(unsigned long start)
 void __ref vmemmap_free(unsigned long start, unsigned long end)
 {
 	unsigned long page_size = 1 << mmu_psize_defs[mmu_vmemmap_psize].shift;
+	unsigned long page_order = get_order(page_size);
 
 	start = _ALIGN_DOWN(start, page_size);
 
 	pr_debug("vmemmap_free %lx...%lx\n", start, end);
 
 	for (; start < end; start += page_size) {
+		struct page *page = pfn_to_page(addr >> PAGE_SHIFT);
+		unsigned int nr_pages;
 		unsigned long addr;
 
 		/*

@@ -251,29 +254,29 @@ void __ref vmemmap_free(unsigned long start, unsigned long end)
 			continue;
 
 		addr = vmemmap_list_free(start);
-		if (addr) {
-			struct page *page = pfn_to_page(addr >> PAGE_SHIFT);
-
-			if (PageReserved(page)) {
-				/* allocated from bootmem */
-				if (page_size < PAGE_SIZE) {
-					/*
-					 * this shouldn't happen, but if it is
-					 * the case, leave the memory there
-					 */
-					WARN_ON_ONCE(1);
-				} else {
-					unsigned int nr_pages =
-						1 << get_order(page_size);
-					while (nr_pages--)
-						free_reserved_page(page++);
-				}
-			} else
-				free_pages((unsigned long)(__va(addr)),
-							get_order(page_size));
-
-			vmemmap_remove_mapping(start, page_size);
+		if (!addr)
+			continue;
+
+		page = pfn_to_page(addr >> PAGE_SHIFT);
+		nr_pages = 1 << page_order;
+
+		if (PageReserved(page)) {
+			/* allocated from bootmem */
+			if (page_size < PAGE_SIZE) {
+				/*
+				 * this shouldn't happen, but if it is
+				 * the case, leave the memory there
+				 */
+				WARN_ON_ONCE(1);
+			} else {
+				while (nr_pages--)
+					free_reserved_page(page++);
+			}
+		} else {
+			free_pages((unsigned long)(__va(addr)), page_order);
 		}
+
+		vmemmap_remove_mapping(start, page_size);
 	}
 }
 #endif

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Stephen Rothwell

2017-04-12 00:33 UTC #11 lore raw

Re: [PATCH 4/9] powerpc/mm: Reshuffle vmemmap_free()

Hi Oliver,

Quoted 7 lines · On Wed, 12 Apr 2017 03:42:28 +1000 Oliver O'Halloran <[email protected]> wrote:

arch/powerpc/mm/init_64.c +0 -0

index ec84b31c6c86..f8124edb6ffa 100644
@@ -234,12 +234,15 @@ static unsigned long vmemmap_list_free(unsigned long start)
 void __ref vmemmap_free(unsigned long start, unsigned long end)

arch/powerpc/mm/init_64.c static unsigned long vmemmap_list_free(unsigned long start) · line 244

Quoted 10 lines

arch/powerpc/mm/init_64.c +2 -0

 {
 	unsigned long page_size = 1 << mmu_psize_defs[mmu_vmemmap_psize].shift;
+	unsigned long page_order = get_order(page_size);
 
 	start = _ALIGN_DOWN(start, page_size);
 
 	pr_debug("vmemmap_free %lx...%lx\n", start, end);
 
 	for (; start < end; start += page_size) {
+		struct page *page = pfn_to_page(addr >> PAGE_SHIFT);

The declaration of addr is below here and, even so, it would be uninitialised ...

Quoted 2 lines

arch/powerpc/mm/init_64.c +1 -0

+		unsigned int nr_pages;
 		unsigned long addr;

Signature · 2 lines

Cheers,
Stephen Rothwell

Oliver O'Halloran

author

2017-04-11 17:43 UTC #12 lore raw

PATCH 5/9 powerpc/vmemmap: Add altmap support

In reply to Oliver O'Halloran

Adds support to powerpc for the altmap feature of ZONE_DEVICE memory. An altmap is a driver provided region that is used to provide the backing storage for the struct pages of ZONE_DEVICE memory. In situations where large amount of ZONE_DEVICE memory is being added to the system the altmap reduces pressure on main system memory by allowing the mm/ metadata to be stored on the device itself rather in main memory.

Signed-off-by Oliver O'Halloran <[email protected]>

---
 arch/powerpc/mm/init_64.c | 20 +++++++++++++++-----
 arch/powerpc/mm/mem.c     | 16 +++++++++++++---
 2 files changed, 28 insertions(+), 8 deletions(-)

arch/powerpc/mm/init_64.c +15 -5

index f8124edb6ffa..225fbb8034e6 100644
@@ -44,6 +44,7 @@
 #include <linux/slab.h>
 #include <linux/of_fdt.h>
 #include <linux/libfdt.h>
+#include <linux/memremap.h>
 
 #include <asm/pgalloc.h>
 #include <asm/page.h>

@@ -171,13 +172,17 @@ int __meminit vmemmap_populate(unsigned long start, unsigned long end, int node)
 	pr_debug("vmemmap_populate %lx..%lx, node %d\n", start, end, node);
 
 	for (; start < end; start += page_size) {
+		struct vmem_altmap *altmap;
 		void *p;
 		int rc;
 
 		if (vmemmap_populated(start, page_size))
 			continue;
 
-		p = vmemmap_alloc_block(page_size, node);
+		/* altmap lookups only work at section boundaries */
+		altmap = to_vmem_altmap(SECTION_ALIGN_DOWN(start));
+
+		p =  __vmemmap_alloc_block_buf(page_size, node, altmap);
 		if (!p)
 			return -ENOMEM;

@@ -241,9 +246,10 @@ void __ref vmemmap_free(unsigned long start, unsigned long end)
 	pr_debug("vmemmap_free %lx...%lx\n", start, end);
 
 	for (; start < end; start += page_size) {
-		struct page *page = pfn_to_page(addr >> PAGE_SHIFT);
-		unsigned int nr_pages;
-		unsigned long addr;
+		unsigned long nr_pages, addr;
+		struct vmem_altmap *altmap;
+		struct page *section_base;
+		struct page *page;
 
 		/*
 		 * the section has already be marked as invalid, so

@@ -258,9 +264,13 @@ void __ref vmemmap_free(unsigned long start, unsigned long end)
 			continue;
 
 		page = pfn_to_page(addr >> PAGE_SHIFT);
+		section_base = pfn_to_page(vmemmap_section_start(start));
 		nr_pages = 1 << page_order;
 
-		if (PageReserved(page)) {
+		altmap = to_vmem_altmap((unsigned long) section_base);
+		if (altmap) {
+			vmem_altmap_free(altmap, nr_pages);
+		} else if (PageReserved(page)) {
 			/* allocated from bootmem */
 			if (page_size < PAGE_SIZE) {
 				/*

arch/powerpc/mm/mem.c +13 -3

index 3bbba178b464..6f7b64eaa9d8 100644
@@ -36,6 +36,7 @@
 #include <linux/hugetlb.h>
 #include <linux/slab.h>
 #include <linux/vmalloc.h>
+#include <linux/memremap.h>
 
 #include <asm/pgalloc.h>
 #include <asm/prom.h>

@@ -176,7 +177,8 @@ int arch_remove_memory(u64 start, u64 size, enum memory_type type)
 {
 	unsigned long start_pfn = start >> PAGE_SHIFT;
 	unsigned long nr_pages = size >> PAGE_SHIFT;
-	struct zone *zone;
+	struct vmem_altmap *altmap;
+	struct page *page;
 	int ret;
 
 	/*

@@ -193,8 +195,16 @@ int arch_remove_memory(u64 start, u64 size, enum memory_type type)
 		return -EINVAL;
 	}
 
-	zone = page_zone(pfn_to_page(start_pfn));
-	ret = __remove_pages(zone, start_pfn, nr_pages);
+	/*
+	 * If we have an altmap then we need to skip over any reserved PFNs
+	 * when querying the zone.
+	 */
+	page = pfn_to_page(start_pfn);
+	altmap = to_vmem_altmap((unsigned long) page);
+	if (altmap)
+		page += vmem_altmap_offset(altmap);
+
+	ret = __remove_pages(page_zone(page), start_pfn, nr_pages);
 	if (ret)
 		return ret;

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Balbir Singh

Reviewed-by on v1 5/9

2017-04-12 00:24 UTC #13 lore raw

Re: [PATCH 5/9] powerpc/vmemmap: Add altmap support

Quoted 9 lines · Oliver O'Halloran

Adds support to powerpc for the altmap feature of ZONE_DEVICE memory. An altmap is a driver provided region that is used to provide the backing storage for the struct pages of ZONE_DEVICE memory. In situations where large amount of ZONE_DEVICE memory is being added to the system the altmap reduces pressure on main system memory by allowing the mm/ metadata to be stored on the device itself rather in main memory.
Signed-off-by Oliver O'Halloran <[email protected]>
---

Reviewed-by Balbir Singh <[email protected]>

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Oliver O'Halloran

author

2017-04-11 17:43 UTC #14 lore raw

PATCH 6/9 powerpc, mm: Enable ZONE_DEVICE on powerpc

In reply to Oliver O'Halloran

Flip the switch. Running around and screaming "IT'S ALIVE" is optional, but recommended.

Signed-off-by Oliver O'Halloran <[email protected]>

---
 mm/Kconfig | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

mm/Kconfig +1 -1

index 43d000e44424..d696af58f97f 100644
@@ -724,7 +724,7 @@ config ZONE_DEVICE
 	depends on MEMORY_HOTPLUG
 	depends on MEMORY_HOTREMOVE
 	depends on SPARSEMEM_VMEMMAP
-	depends on X86_64 #arch_add_memory() comprehends device memory
+	depends on (X86_64 || PPC_BOOK3S_64)  #arch_add_memory() comprehends device memory
 
 	help
 	  Device memory hotplug support allows for establishing pmem,

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Balbir Singh

Reviewed-by on v1 6/9

2017-04-12 00:25 UTC #15 lore raw

Re: [PATCH 6/9] powerpc, mm: Enable ZONE_DEVICE on powerpc

Quoted 13 lines · Oliver O'Halloran

Flip the switch. Running around and screaming "IT'S ALIVE" is optional, but recommended.
Signed-off-by Oliver O'Halloran <[email protected]>
---
 mm/Kconfig | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
mm/Kconfig +0 -0
index 43d000e44424..d696af58f97f 100644

mm/Kconfig config ZONE_DEVICE · line 727

Quoted 5 lines

mm/Kconfig +1 -1

@@ -724,7 +724,7 @@ config ZONE_DEVICE
 	depends on MEMORY_HOTPLUG
 	depends on MEMORY_HOTREMOVE
 	depends on SPARSEMEM_VMEMMAP
-	depends on X86_64 #arch_add_memory() comprehends device memory
+	depends on (X86_64 || PPC_BOOK3S_64)  #arch_add_memory() comprehends device memory

Reviewed-by Balbir Singh <[email protected]>

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Stephen Rothwell

2017-04-12 00:43 UTC #16 lore raw

Re: [PATCH 6/9] powerpc, mm: Enable ZONE_DEVICE on powerpc

In reply to Oliver O'Halloran

Hi Oliver,

Quoted 14 lines · On Wed, 12 Apr 2017 03:42:30 +1000 Oliver O'Halloran <[email protected]> wrote:

Flip the switch. Running around and screaming "IT'S ALIVE" is optional, but recommended.
Signed-off-by Oliver O'Halloran <[email protected]>
---
 mm/Kconfig | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)
mm/Kconfig +0 -0
index 43d000e44424..d696af58f97f 100644

mm/Kconfig config ZONE_DEVICE · line 728

Quoted 6 lines

mm/Kconfig +1 -1

@@ -724,7 +724,7 @@ config ZONE_DEVICE
 	depends on MEMORY_HOTPLUG
 	depends on MEMORY_HOTREMOVE
 	depends on SPARSEMEM_VMEMMAP
-	depends on X86_64 #arch_add_memory() comprehends device memory
+	depends on (X86_64 || PPC_BOOK3S_64)  #arch_add_memory() comprehends device memory

That's fine, but at what point do we create CONFIG_ARCH_HAVE_ZONE_DEVICE, replace the "depends on <archs/platforms>" above with "depends on ARCH_HAVE_ZONE_DEVICE" and select that from the appropriate places?

Signature · 2 lines

Cheers,
Stephen Rothwell

Michael Ellerman

reviewer

2017-04-12 02:03 UTC #17 lore raw

Re: [PATCH 6/9] powerpc, mm: Enable ZONE_DEVICE on powerpc

Quoted 12 lines · Stephen Rothwell

Hi Oliver,
Quoted 9 lines · On Wed, 12 Apr 2017 03:42:30 +1000 Oliver O'Halloran <[email protected]> wrote:
Flip the switch. Running around and screaming "IT'S ALIVE" is optional, but recommended.
Signed-off-by Oliver O'Halloran <[email protected]>
---
 mm/Kconfig | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

Quoted 16 lines

mm/Kconfig config ZONE_DEVICE · line 728
Quoted 11 lines
mm/Kconfig +1 -1
index 43d000e44424..d696af58f97f 100644
@@ -724,7 +724,7 @@ config ZONE_DEVICE
 	depends on MEMORY_HOTPLUG
 	depends on MEMORY_HOTREMOVE
 	depends on SPARSEMEM_VMEMMAP
-	depends on X86_64 #arch_add_memory() comprehends device memory
+	depends on (X86_64 || PPC_BOOK3S_64)  #arch_add_memory() comprehends device memory
 
That's fine, but at what point do we create CONFIG_ARCH_HAVE_ZONE_DEVICE, replace the "depends on <archs/platforms>" above with "depends on ARCH_HAVE_ZONE_DEVICE" and select that from the appropriate places?

You mean CONFIG_HAVE_ZONE_DEVICE :)

A patch to do that, and update x86, would be a good precursor to this series. It could probably go in right now, and be in place for when this series lands.

cheers

Oliver O'Halloran

author

2017-04-11 17:43 UTC #18 lore raw

PATCH 7/9 powerpc/mm: Wire up ioremap_cache

In reply to Oliver O'Halloran

The default implementation of ioremap_cache() is aliased to ioremap(). On powerpc ioremap() creates cache-inhibited mappings by default which is almost certainly not what you wanted.

Signed-off-by Oliver O'Halloran <[email protected]>

---
 arch/powerpc/include/asm/io.h | 2 ++
 1 file changed, 2 insertions(+)

arch/powerpc/include/asm/io.h +2 -0

index 5ed292431b5b..839eb031857f 100644
@@ -757,6 +757,8 @@ extern void __iomem *ioremap_prot(phys_addr_t address, unsigned long size,
 extern void __iomem *ioremap_wc(phys_addr_t address, unsigned long size);
 #define ioremap_nocache(addr, size)	ioremap((addr), (size))
 #define ioremap_uc(addr, size)		ioremap((addr), (size))
+#define ioremap_cache(addr, size) \
+	ioremap_prot((addr), (size), pgprot_val(PAGE_KERNEL))
 
 extern void iounmap(volatile void __iomem *addr);

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Michael Ellerman

Applied

2017-04-23 11:53 UTC #19 lore raw

Re: [7/9] powerpc/mm: Wire up ioremap_cache

Quoted 5 lines · Oliver O'Halloran

The default implementation of ioremap_cache() is aliased to ioremap(). On powerpc ioremap() creates cache-inhibited mappings by default which is almost certainly not what you wanted.
Signed-off-by Oliver O'Halloran <[email protected]>

Applied to powerpc next, thanks.

https://git.kernel.org/powerpc/c/f855b2f544d664cfa3055edb7ffd20

cheers

Oliver O'Halloran

author

2017-04-11 17:43 UTC #20 lore raw

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

In reply to Oliver O'Halloran

From: Rashmica Gupta <[email protected]>

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 protected]>

Cc Anton Blanchard <[email protected]>

Signed-off-by Oliver O'Halloran <[email protected]>

---
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(+)

arch/powerpc/mm/hash_native_64.c +31 -0

index 65bb8f33b399..9ba91d4905a4 100644
@@ -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;

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A message that is not in the archive (sent off-list or not yet received): 20170411174233.21902-9-oohall-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org

Anton Blanchard

2017-04-11 22:50 UTC #22 lore raw

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

Hi Oliver,

Quoted 6 lines

From: Rashmica Gupta <[email protected]>
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.

Quoted 7 lines

Cc Rashmica Gupta <[email protected]>
Cc Anton Blanchard <[email protected]>
Signed-off-by Oliver O'Halloran <[email protected]>
---
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.

I did.

Signed-off-by Anton Blanchard <[email protected]>

Anton

Quoted 54 lines

---
 arch/powerpc/mm/hash_native_64.c | 31 +++++++++++++++++++++++++++++++
 1 file changed, 31 insertions(+)

(quoted diff) +0 -0

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

arch/powerpc/mm/hash_native_64.c +30 -0

@@ -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;

Stephen Rothwell

2017-04-12 00:18 UTC #23 lore raw

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

Hi Oliver,

Quoted 15 lines · On Wed, 12 Apr 2017 08:50:56 +1000 Anton Blanchard <[email protected]> wrote:

Quoted 7 lines
From: Rashmica Gupta <[email protected]>
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.
Quoted 7 lines
Cc Rashmica Gupta <[email protected]>
Cc Anton Blanchard <[email protected]>
Signed-off-by Oliver O'Halloran <[email protected]>
---
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.

Quoted 3 lines

I did.
Signed-off-by Anton Blanchard <[email protected]>

If you are going to claim that Rashmica authored this patch (and you do with the From: line above), then you need her Signed-off-by as well.

Signature · 2 lines

Cheers,
Stephen Rothwell

Rashmica Gupta

2017-04-12 03:30 UTC #24 lore raw

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

Quoted 16 lines · Stephen Rothwell

Hi Oliver,
Quoted 13 lines · On Wed, 12 Apr 2017 08:50:56 +1000 Anton Blanchard <[email protected]> wrote:
Quoted 13 lines
From: Rashmica Gupta <[email protected]>
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 protected]>
Cc Anton Blanchard <[email protected]>
Signed-off-by Oliver O'Halloran <[email protected]>
---
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.

Quoted 6 lines

Quoted 3 lines
I did.
Signed-off-by Anton Blanchard <[email protected]>
If you are going to claim that Rashmica authored this patch (and you do with the From: line above), then you need her Signed-off-by as well.

Oliver, can you change the 'From' to a 'Reviewed By'?
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Balbir Singh

2017-04-12 01:53 UTC #25 lore raw

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

In reply to Oliver O'Halloran

Quoted 22 lines · Oliver O'Halloran

From: Rashmica Gupta <[email protected]>
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 protected]>
Cc Anton Blanchard <[email protected]>
Signed-off-by Oliver O'Halloran <[email protected]>
---
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(+)
arch/powerpc/mm/hash_native_64.c +0 -0
index 65bb8f33b399..9ba91d4905a4 100644

arch/powerpc/mm/hash_native_64.c static void native_hpte_updateboltedpp(unsigned long newpp, unsigned long ea, · line 413

Quoted 7 lines

arch/powerpc/mm/hash_native_64.c +4 -0

@@ -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.

As long as this is after the necessary isolation and is called from arch_remove_memory(), I think we should be fine

Quoted 4 lines

arch/powerpc/mm/hash_native_64.c +4 -0

+ */
+static int native_hpte_removebolted(unsigned long ea, int psize, int ssize)
+{
+	unsigned long vpn;

arch/powerpc/mm/hash_native_64.c static void native_hpte_updateboltedpp(unsigned long newpp, unsigned long ea, · line 427

Quoted 10 lines

arch/powerpc/mm/hash_native_64.c +10 -0

+	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;

If slot == -1, it means someone else removed the HPTE entry? Are we racing? I suspect we should never hit this situation during hotunplug, specifically since this is bolted.

arch/powerpc/mm/hash_native_64.c static void native_hpte_updateboltedpp(unsigned long newpp, unsigned long ea, · line 432

Quoted 5 lines

arch/powerpc/mm/hash_native_64.c +5 -0

+
+	hptep = htab_address + slot;
+
+	/* Invalidate the hpte */
+	hptep->v = 0;

Under DEBUG or otherwise, I would add more checks like

1. was hpte_v & HPTE_V_VALID and BOLTED set? If not, we've already invalidated that hpte and we can skip the tlbie. Since this was bolted you might be right that it is always valid and bolted

arch/powerpc/mm/hash_native_64.c static void native_hpte_updateboltedpp(unsigned long newpp, unsigned long ea, · line 435

Quoted 3 lines

arch/powerpc/mm/hash_native_64.c +3 -0
+
+	/* Invalidate the TLB */
+	tlbie(vpn, psize, psize, ssize, 0);

The API also does not clear linear_map_hash_slots[] under DEBUG_PAGEALLOC

arch/powerpc/mm/hash_native_64.c static void native_hpte_updateboltedpp(unsigned long newpp, unsigned long ea, · line 439

Quoted 4 lines

arch/powerpc/mm/hash_native_64.c +4 -0
+	return 0;
+}
+
+

Balbir Singh.
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Oliver O'Halloran

author

2017-04-13 04:21 UTC #26 lore raw

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

Quoted 44 lines · Balbir Singh

Quoted 22 lines · Oliver O'Halloran
From: Rashmica Gupta <[email protected]>
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 protected]>
Cc Anton Blanchard <[email protected]>
Signed-off-by Oliver O'Halloran <[email protected]>
---
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(+)
arch/powerpc/mm/hash_native_64.c +0 -0
index 65bb8f33b399..9ba91d4905a4 100644
arch/powerpc/mm/hash_native_64.c static void native_hpte_updateboltedpp(unsigned long newpp, unsigned long ea, · line 413
Quoted 7 lines
arch/powerpc/mm/hash_native_64.c +4 -0
@@ -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.
As long as this is after the necessary isolation and is called from arch_remove_memory(), I think we should be fine
Quoted 10 lines
arch/powerpc/mm/hash_native_64.c +10 -0
+ */
+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);

Quoted 8 lines

arch/powerpc/mm/hash_native_64.c static void native_hpte_updateboltedpp(unsigned long newpp, unsigned long ea, · line 427
Quoted 4 lines
arch/powerpc/mm/hash_native_64.c +4 -0
+
+     slot = native_hpte_find(vpn, psize, ssize);
+     if (slot == -1)
+             return -ENOENT;
If slot == -1, it means someone else removed the HPTE entry? Are we racing? I suspect we should never hit this situation during hotunplug, specifically since this is bolted.

Or the slot was never populated in the first place. I'd rather keep the current behaviour since it aligns with the behaviour of pSeries_lpar_hpte_removebolted and we might hit these situations in the future if the sub-section hotplug patches are merged (big if...).

Quoted 9 lines

arch/powerpc/mm/hash_native_64.c static void native_hpte_updateboltedpp(unsigned long newpp, unsigned long ea, · line 432
Quoted 6 lines
arch/powerpc/mm/hash_native_64.c +5 -0
+
+     hptep = htab_address + slot;
+
+     /* Invalidate the hpte */
+     hptep->v = 0;
Under DEBUG or otherwise, I would add more checks like

Quoted 3 lines

1. was hpte_v & HPTE_V_VALID and BOLTED set? If not, we've already invalidated that hpte and we can skip the tlbie. Since this was bolted you might be right that it is always valid and bolted

A VM_WARN_ON() if the bolted bit is clear might be appropriate. We don't need to check the valid bit since hpte_native_find() will fail if it's cleared.

Quoted 6 lines

arch/powerpc/mm/hash_native_64.c static void native_hpte_updateboltedpp(unsigned long newpp, unsigned long ea, · line 435
Quoted 4 lines
arch/powerpc/mm/hash_native_64.c +3 -0
+
+     /* Invalidate the TLB */
+     tlbie(vpn, psize, psize, ssize, 0);
The API also does not clear linear_map_hash_slots[] under DEBUG_PAGEALLOC

I'm not sure what API you're referring to here. The tracking for linear_map_hash_slots[] is agnostic of mmu_hash_ops so we shouldn't be touching it here. It also looks like DEBUG_PAGEALLOC is a bit broken with hotplugged memory anyway so I think that's a fix for a different patch.

Quoted 7 lines

arch/powerpc/mm/hash_native_64.c static void native_hpte_updateboltedpp(unsigned long newpp, unsigned long ea, · line 439
Quoted 5 lines
arch/powerpc/mm/hash_native_64.c +4 -0
+     return 0;
+}
+
+
Balbir Singh.

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Michael Ellerman

reviewer

2017-04-13 10:10 UTC #27 lore raw

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

Quoted 9 lines · Oliver O'Halloran

Quoted 2 lines · Balbir Singh
The API also does not clear linear_map_hash_slots[] under DEBUG_PAGEALLOC
I'm not sure what API you're referring to here. The tracking for linear_map_hash_slots[] is agnostic of mmu_hash_ops so we shouldn't be touching it here. It also looks like DEBUG_PAGEALLOC is a bit broken with hotplugged memory anyway so I think that's a fix for a different patch.

It's old and has probably bit-rotted, so I'm happy for it to be fixed up later if necessary.

cheers

Oliver O'Halloran

author

2017-04-11 17:43 UTC #28 lore raw

PATCH 9/9 powerpc: Add pmem API support

In reply to Oliver O'Halloran

Initial powerpc support for the arch-specific bit of the persistent memory API. Nothing fancy here.

Signed-off-by Oliver O'Halloran <[email protected]>

---
 arch/powerpc/Kconfig            |   1 +
 arch/powerpc/include/asm/pmem.h | 109 ++++++++++++++++++++++++++++++++++++++++
 arch/powerpc/kernel/misc_64.S   |   2 +-
 3 files changed, 111 insertions(+), 1 deletion(-)
 create mode 100644 arch/powerpc/include/asm/pmem.h

arch/powerpc/Kconfig +1 -0

index d7413ed700b8..cf84d0db49ab 100644
@@ -87,6 +87,7 @@ config PPC
 	select ARCH_HAS_DMA_SET_COHERENT_MASK
 	select ARCH_HAS_ELF_RANDOMIZE
 	select ARCH_HAS_GCOV_PROFILE_ALL
+	select ARCH_HAS_PMEM_API
 	select ARCH_HAS_SCALED_CPUTIME		if VIRT_CPU_ACCOUNTING_NATIVE
 	select ARCH_HAS_SG_CHAIN
 	select ARCH_HAS_TICK_BROADCAST		if GENERIC_CLOCKEVENTS_BROADCAST

arch/powerpc/include/asm/pmem.h new file +109 -0

109 lines not on this page · raw message

arch/powerpc/kernel/misc_64.S +1 -1

index c119044cad0d..1378a8d61faf 100644
@@ -182,7 +182,7 @@ _GLOBAL(flush_dcache_phys_range)
 	isync
 	blr
 
-_GLOBAL(flush_inval_dcache_range)
+_GLOBAL_TOC(flush_inval_dcache_range)
  	ld	r10,PPC64_CACHES@toc(r2)
 	lwz	r7,DCACHEL1BLOCKSIZE(r10)	/* Get dcache block size */
 	addi	r5,r7,-1

Signature · 6 lines

2.9.3

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Dan Williams

2017-04-11 18:22 UTC #29 lore raw

In reply to Oliver O'Halloran

Quoted 8 lines · Oliver O'Halloran

Hi all,
This series adds support for ZONE_DEVICE and the pmem api on powerpc. Namely, support for altmaps and the various bits and pieces required for DAX PMD faults. The first two patches touch generic mm/ code, but otherwise this is fairly well contained in arch/powerpc.
If the nvdimm folks could sanity check this series I'd appreciate it.

Quick feedback: I'm in the process of cleaning up and resubmitting my patch set to push the pmem api down into the driver directly.

    https://lwn.net/Articles/713064/

I'm also reworking memory hotplug to allow sub-section allocations which has collided with Michal Hocko's hotplug reworks. It will be good to have some more eyes on that work to understand the cross-arch implications.

    https://lkml.org/lkml/2017/3/19/146

Quoted 5 lines

Series is based on next-20170411, but it should apply elsewhere with minor fixups to arch_{add|remove}_memory due to conflicts with HMM. For those interested in testing this, there is a driver and matching firmware that carves out some system memory for use as an emulated Con Tutto memory card.

Quoted 7 lines

Driver: https://github.com/oohal/linux/tree/contutto-next
Firmware: https://github.com/oohal/skiboot/tree/fake-contutto
Edit core/init.c:686 to control the amount of memory borrowed for the emulated device. I'm keeping the driver out of tree for a until 4.13 since I plan on reworking the firmware interface anyway and There's at least one showstopper bug.

Is this memory card I/O-cache coherent? I.e. existing dma mapping api can hand out mappings to it? Just trying to figure out if this the existing pmem-definition of ZONE_DEVICE or a new one.
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Oliver O'Halloran

author

2017-04-12 09:14 UTC #30 lore raw

Quoted 8 lines · Dan Williams

Quoted 7 lines · Oliver O'Halloran
Hi all,
This series adds support for ZONE_DEVICE and the pmem api on powerpc. Namely, support for altmaps and the various bits and pieces required for DAX PMD faults. The first two patches touch generic mm/ code, but otherwise this is fairly well contained in arch/powerpc.

Quoted 6 lines

Quoted 1 line
If the nvdimm folks could sanity check this series I'd appreciate it.
Quick feedback: I'm in the process of cleaning up and resubmitting my patch set to push the pmem api down into the driver directly.
    https://lwn.net/Articles/713064/

That's been on my radar for a while and I was hoping it would be in 4.12. Moving operations into the driver makes a lot of sense from a design perspective and it should make supporting some of the contutto's eccentricities a bit easier.

Quoted 6 lines

I'm also reworking memory hotplug to allow sub-section allocations which has collided with Michal Hocko's hotplug reworks. It will be good to have some more eyes on that work to understand the cross-arch implications.
    https://lkml.org/lkml/2017/3/19/146

I'd been putting off looking at this since I figured it would clash with the hotplug rework and HMM, but I'll see if I can get it working on ppc.

Quoted 8 lines

Quoted 8 lines
Series is based on next-20170411, but it should apply elsewhere with minor fixups to arch_{add|remove}_memory due to conflicts with HMM. For those interested in testing this, there is a driver and matching firmware that carves out some system memory for use as an emulated Con Tutto memory card.
Driver: https://github.com/oohal/linux/tree/contutto-next
Firmware: https://github.com/oohal/skiboot/tree/fake-contutto

Quoted 8 lines

Quoted 4 lines
Edit core/init.c:686 to control the amount of memory borrowed for the emulated device. I'm keeping the driver out of tree for a until 4.13 since I plan on reworking the firmware interface anyway and There's at least one showstopper bug.
Is this memory card I/O-cache coherent? I.e. existing dma mapping api can hand out mappings to it? Just trying to figure out if this the existing pmem-definition of ZONE_DEVICE or a new one.

As far as the rest of the system is concerned Con Tutto memory is identical to normal system memory. All accesses to the card's memory is mediated by a memory controller which participates in the memory coherency protocol. That said, the link between the card and the system is non-coherent so logic on the FPGA can access memory incoherently. I'm primarily interested in using the card as a memory platform so I haven't spent a lot of time thinking about the latter use case, but a different concept of device memory might be required there.

Oliver
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Stephen Rothwell

2017-04-12 01:10 UTC #31 lore raw

In reply to Oliver O'Halloran

Hi Oliver,

Quoted 3 lines · On Wed, 12 Apr 2017 03:42:24 +1000 Oliver O'Halloran <[email protected]> wrote:

Series is based on next-20170411, but it should apply elsewhere with minor fixups to arch_{add|remove}_memory due to conflicts with HMM. For those

Just to make life fun for you, Andrew has dropped the HMM patches from his quilt series today (and so they will not be in next-20170412).

Signature · 2 lines

Cheers,
Stephen Rothwell