[PATCH kernel 0/4] vfio/spapr_tce: Reworks for NVIDIA V100 + P9 passthrough (part 1)

[PATCH kernel 0/4] vfio/spapr_tce: Reworks for NVIDIA V100 + P9 passthrough (part 1)

[Alexey Kardashevskiy]

This is a first set of patches required for passing through NVIDIA V100
with coherent memory. The full patchset is here:
https://github.com/aik/linux/tree/nv2
The matching QEMU is here:
https://github.com/aik/qemu/tree/nv2

This particular patchset prepares for having device memory which is not
backed with page structs.

Does 4/4 really need splitting?


Please comment. Thanks.



Alexey Kardashevskiy (4):
  powerpc/mm/iommu: Rename mm_iommu_get
  powerpc/mm/iommu/vfio_spapr_tce: Change mm_iommu_get to reference a
    region
  powerpc/mm/iommu: Make mm_iommu_new() fail on existing regions
  powerpc/vfio/iommu/kvm: Do not pin device memory

 arch/powerpc/include/asm/iommu.h       |  5 +-
 arch/powerpc/include/asm/mmu_context.h |  9 +++-
 arch/powerpc/kernel/iommu.c            |  9 ++--
 arch/powerpc/kvm/book3s_64_vio.c       | 18 ++++---
 arch/powerpc/mm/mmu_context_iommu.c    | 97 +++++++++++++++++++++++++++++-----
 drivers/vfio/vfio_iommu_spapr_tce.c    | 65 +++++++++++++++--------
 6 files changed, 151 insertions(+), 52 deletions(-)

-- 
2.11.0

[PATCH kernel 1/4] powerpc/mm/iommu: Rename mm_iommu_get

[Alexey Kardashevskiy]

Normally mm_iommu_get() is supposed to add a reference and
mm_iommu_put() to remove it. However historically mm_iommu_find() does
the referencing and mm_iommu_get() is doing allocation and referencing.

This is step 1 towards simpler mm_iommu_get().

This renames:
- mm_iommu_get to mm_iommu_new;
- mm_iommu_find to mm_iommu_get.

This should cause no behavioural change.

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
---
 arch/powerpc/include/asm/mmu_context.h | 4 ++--
 arch/powerpc/mm/mmu_context_iommu.c    | 8 ++++----
 drivers/vfio/vfio_iommu_spapr_tce.c    | 6 +++---
 3 files changed, 9 insertions(+), 9 deletions(-)

diff --git a/arch/powerpc/include/asm/mmu_context.h b/arch/powerpc/include/asm/mmu_context.h
index b694d6a..59d4941 100644
--- a/arch/powerpc/include/asm/mmu_context.h
+++ b/arch/powerpc/include/asm/mmu_context.h
@@ -21,7 +21,7 @@ struct mm_iommu_table_group_mem_t;
 
 extern int isolate_lru_page(struct page *page);	/* from internal.h */
 extern bool mm_iommu_preregistered(struct mm_struct *mm);
-extern long mm_iommu_get(struct mm_struct *mm,
+extern long mm_iommu_new(struct mm_struct *mm,
 		unsigned long ua, unsigned long entries,
 		struct mm_iommu_table_group_mem_t **pmem);
 extern long mm_iommu_put(struct mm_struct *mm,
@@ -32,7 +32,7 @@ extern struct mm_iommu_table_group_mem_t *mm_iommu_lookup(struct mm_struct *mm,
 		unsigned long ua, unsigned long size);
 extern struct mm_iommu_table_group_mem_t *mm_iommu_lookup_rm(
 		struct mm_struct *mm, unsigned long ua, unsigned long size);
-extern struct mm_iommu_table_group_mem_t *mm_iommu_find(struct mm_struct *mm,
+extern struct mm_iommu_table_group_mem_t *mm_iommu_get(struct mm_struct *mm,
 		unsigned long ua, unsigned long entries);
 extern long mm_iommu_ua_to_hpa(struct mm_iommu_table_group_mem_t *mem,
 		unsigned long ua, unsigned int pageshift, unsigned long *hpa);
diff --git a/arch/powerpc/mm/mmu_context_iommu.c b/arch/powerpc/mm/mmu_context_iommu.c
index 56c2234..8eeb99d 100644
--- a/arch/powerpc/mm/mmu_context_iommu.c
+++ b/arch/powerpc/mm/mmu_context_iommu.c
@@ -126,7 +126,7 @@ static int mm_iommu_move_page_from_cma(struct page *page)
 	return 0;
 }
 
-long mm_iommu_get(struct mm_struct *mm, unsigned long ua, unsigned long entries,
+long mm_iommu_new(struct mm_struct *mm, unsigned long ua, unsigned long entries,
 		struct mm_iommu_table_group_mem_t **pmem)
 {
 	struct mm_iommu_table_group_mem_t *mem;
@@ -252,7 +252,7 @@ long mm_iommu_get(struct mm_struct *mm, unsigned long ua, unsigned long entries,
 
 	return ret;
 }
-EXPORT_SYMBOL_GPL(mm_iommu_get);
+EXPORT_SYMBOL_GPL(mm_iommu_new);
 
 static void mm_iommu_unpin(struct mm_iommu_table_group_mem_t *mem)
 {
@@ -368,7 +368,7 @@ struct mm_iommu_table_group_mem_t *mm_iommu_lookup_rm(struct mm_struct *mm,
 	return ret;
 }
 
-struct mm_iommu_table_group_mem_t *mm_iommu_find(struct mm_struct *mm,
+struct mm_iommu_table_group_mem_t *mm_iommu_get(struct mm_struct *mm,
 		unsigned long ua, unsigned long entries)
 {
 	struct mm_iommu_table_group_mem_t *mem, *ret = NULL;
@@ -382,7 +382,7 @@ struct mm_iommu_table_group_mem_t *mm_iommu_find(struct mm_struct *mm,
 
 	return ret;
 }
-EXPORT_SYMBOL_GPL(mm_iommu_find);
+EXPORT_SYMBOL_GPL(mm_iommu_get);
 
 long mm_iommu_ua_to_hpa(struct mm_iommu_table_group_mem_t *mem,
 		unsigned long ua, unsigned int pageshift, unsigned long *hpa)
diff --git a/drivers/vfio/vfio_iommu_spapr_tce.c b/drivers/vfio/vfio_iommu_spapr_tce.c
index ad63725..1701798 100644
--- a/drivers/vfio/vfio_iommu_spapr_tce.c
+++ b/drivers/vfio/vfio_iommu_spapr_tce.c
@@ -156,7 +156,7 @@ static long tce_iommu_unregister_pages(struct tce_container *container,
 	if ((vaddr & ~PAGE_MASK) || (size & ~PAGE_MASK))
 		return -EINVAL;
 
-	mem = mm_iommu_find(container->mm, vaddr, size >> PAGE_SHIFT);
+	mem = mm_iommu_get(container->mm, vaddr, size >> PAGE_SHIFT);
 	if (!mem)
 		return -ENOENT;
 
@@ -185,7 +185,7 @@ static long tce_iommu_register_pages(struct tce_container *container,
 			((vaddr + size) < vaddr))
 		return -EINVAL;
 
-	mem = mm_iommu_find(container->mm, vaddr, entries);
+	mem = mm_iommu_get(container->mm, vaddr, entries);
 	if (mem) {
 		list_for_each_entry(tcemem, &container->prereg_list, next) {
 			if (tcemem->mem == mem)
@@ -193,7 +193,7 @@ static long tce_iommu_register_pages(struct tce_container *container,
 		}
 	}
 
-	ret = mm_iommu_get(container->mm, vaddr, entries, &mem);
+	ret = mm_iommu_new(container->mm, vaddr, entries, &mem);
 	if (ret)
 		return ret;
 
-- 
2.11.0

[PATCH kernel 2/4] powerpc/mm/iommu/vfio_spapr_tce: Change mm_iommu_get to reference a region

[Alexey Kardashevskiy]

We are going to add another helper to preregister device memory so
instead of having mm_iommu_new() which pre-registers the normal memory
and references the region, we need separate helpers for pre-registerign
and referencing.

To make the mm_iommu_get name reflect what it is supposed to do, this
changes mm_iommu_get() to reference the region so from now on for every
mm_iommu_get() we need a matching mm_iommu_put().

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
---
 arch/powerpc/mm/mmu_context_iommu.c |  5 +++++
 drivers/vfio/vfio_iommu_spapr_tce.c | 33 ++++++++++++++++++++++-----------
 2 files changed, 27 insertions(+), 11 deletions(-)

diff --git a/arch/powerpc/mm/mmu_context_iommu.c b/arch/powerpc/mm/mmu_context_iommu.c
index 8eeb99d..a8c4a3c 100644
--- a/arch/powerpc/mm/mmu_context_iommu.c
+++ b/arch/powerpc/mm/mmu_context_iommu.c
@@ -373,13 +373,18 @@ struct mm_iommu_table_group_mem_t *mm_iommu_get(struct mm_struct *mm,
 {
 	struct mm_iommu_table_group_mem_t *mem, *ret = NULL;
 
+	mutex_lock(&mem_list_mutex);
+
 	list_for_each_entry_rcu(mem, &mm->context.iommu_group_mem_list, next) {
 		if ((mem->ua == ua) && (mem->entries == entries)) {
 			ret = mem;
+			++mem->used;
 			break;
 		}
 	}
 
+	mutex_unlock(&mem_list_mutex);
+
 	return ret;
 }
 EXPORT_SYMBOL_GPL(mm_iommu_get);
diff --git a/drivers/vfio/vfio_iommu_spapr_tce.c b/drivers/vfio/vfio_iommu_spapr_tce.c
index 1701798..56db071 100644
--- a/drivers/vfio/vfio_iommu_spapr_tce.c
+++ b/drivers/vfio/vfio_iommu_spapr_tce.c
@@ -151,7 +151,8 @@ static long tce_iommu_unregister_pages(struct tce_container *container,
 {
 	struct mm_iommu_table_group_mem_t *mem;
 	struct tce_iommu_prereg *tcemem;
-	bool found = false;
+	bool found;
+	long ret;
 
 	if ((vaddr & ~PAGE_MASK) || (size & ~PAGE_MASK))
 		return -EINVAL;
@@ -168,9 +169,13 @@ static long tce_iommu_unregister_pages(struct tce_container *container,
 	}
 
 	if (!found)
-		return -ENOENT;
+		ret = -ENOENT;
+	else
+		ret = tce_iommu_prereg_free(container, tcemem);
 
-	return tce_iommu_prereg_free(container, tcemem);
+	mm_iommu_put(container->mm, mem);
+
+	return ret;
 }
 
 static long tce_iommu_register_pages(struct tce_container *container,
@@ -188,19 +193,21 @@ static long tce_iommu_register_pages(struct tce_container *container,
 	mem = mm_iommu_get(container->mm, vaddr, entries);
 	if (mem) {
 		list_for_each_entry(tcemem, &container->prereg_list, next) {
-			if (tcemem->mem == mem)
-				return -EBUSY;
+			if (tcemem->mem == mem) {
+				ret = -EBUSY;
+				goto put_exit;
+			}
 		}
+	} else {
+		ret = mm_iommu_new(container->mm, vaddr, entries, &mem);
+		if (ret)
+			return ret;
 	}
 
-	ret = mm_iommu_new(container->mm, vaddr, entries, &mem);
-	if (ret)
-		return ret;
-
 	tcemem = kzalloc(sizeof(*tcemem), GFP_KERNEL);
 	if (!tcemem) {
-		mm_iommu_put(container->mm, mem);
-		return -ENOMEM;
+		ret = -ENOMEM;
+		goto put_exit;
 	}
 
 	tcemem->mem = mem;
@@ -209,6 +216,10 @@ static long tce_iommu_register_pages(struct tce_container *container,
 	container->enabled = true;
 
 	return 0;
+
+put_exit:
+	mm_iommu_put(container->mm, mem);
+	return ret;
 }
 
 static bool tce_page_is_contained(struct page *page, unsigned page_shift)
-- 
2.11.0

[PATCH kernel 3/4] powerpc/mm/iommu: Make mm_iommu_new() fail on existing regions

[Alexey Kardashevskiy]

Since we are going to have 2 different preregistering helpers, let's
make it clear that mm_iommu_new() is only for the normal (i.e. not device)
memory and for existing areas mm_iommu_get() should be used instead.

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
---
 arch/powerpc/mm/mmu_context_iommu.c | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/arch/powerpc/mm/mmu_context_iommu.c b/arch/powerpc/mm/mmu_context_iommu.c
index a8c4a3c..839dbce 100644
--- a/arch/powerpc/mm/mmu_context_iommu.c
+++ b/arch/powerpc/mm/mmu_context_iommu.c
@@ -141,8 +141,7 @@ long mm_iommu_new(struct mm_struct *mm, unsigned long ua, unsigned long entries,
 	list_for_each_entry_rcu(mem, &mm->context.iommu_group_mem_list,
 			next) {
 		if ((mem->ua == ua) && (mem->entries == entries)) {
-			++mem->used;
-			*pmem = mem;
+			ret = -EBUSY;
 			goto unlock_exit;
 		}
 
-- 
2.11.0

[PATCH kernel 4/4] powerpc/vfio/iommu/kvm: Do not pin device memory

[Alexey Kardashevskiy]

This new memory does not have page structs as it is not plugged to
the host so gup() will fail anyway.

This adds 2 helpers:
- mm_iommu_newdev() to preregister the "memory device" memory so
the rest of API can still be used;
- mm_iommu_is_devmem() to know if the physical address is one of thise
new regions which we must avoid unpinning of.

This adds @mm to tce_page_is_contained() and iommu_tce_xchg() to test
if the memory is device memory to avoid pfn_to_page().

Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
---
 arch/powerpc/include/asm/iommu.h       |  5 +-
 arch/powerpc/include/asm/mmu_context.h |  5 ++
 arch/powerpc/kernel/iommu.c            |  9 ++--
 arch/powerpc/kvm/book3s_64_vio.c       | 18 ++++----
 arch/powerpc/mm/mmu_context_iommu.c    | 83 ++++++++++++++++++++++++++++++----
 drivers/vfio/vfio_iommu_spapr_tce.c    | 28 ++++++++----
 6 files changed, 116 insertions(+), 32 deletions(-)

diff --git a/arch/powerpc/include/asm/iommu.h b/arch/powerpc/include/asm/iommu.h
index 35db0cb..a8aeac0 100644
--- a/arch/powerpc/include/asm/iommu.h
+++ b/arch/powerpc/include/asm/iommu.h
@@ -218,8 +218,9 @@ extern void iommu_register_group(struct iommu_table_group *table_group,
 extern int iommu_add_device(struct device *dev);
 extern void iommu_del_device(struct device *dev);
 extern int __init tce_iommu_bus_notifier_init(void);
-extern long iommu_tce_xchg(struct iommu_table *tbl, unsigned long entry,
-		unsigned long *hpa, enum dma_data_direction *direction);
+extern long iommu_tce_xchg(struct mm_struct *mm, struct iommu_table *tbl,
+		unsigned long entry, unsigned long *hpa,
+		enum dma_data_direction *direction);
 #else
 static inline void iommu_register_group(struct iommu_table_group *table_group,
 					int pci_domain_number,
diff --git a/arch/powerpc/include/asm/mmu_context.h b/arch/powerpc/include/asm/mmu_context.h
index 59d4941..45330ff 100644
--- a/arch/powerpc/include/asm/mmu_context.h
+++ b/arch/powerpc/include/asm/mmu_context.h
@@ -24,6 +24,9 @@ extern bool mm_iommu_preregistered(struct mm_struct *mm);
 extern long mm_iommu_new(struct mm_struct *mm,
 		unsigned long ua, unsigned long entries,
 		struct mm_iommu_table_group_mem_t **pmem);
+extern long mm_iommu_newdev(struct mm_struct *mm, unsigned long ua,
+		unsigned long entries, unsigned long dev_hpa,
+		struct mm_iommu_table_group_mem_t **pmem);
 extern long mm_iommu_put(struct mm_struct *mm,
 		struct mm_iommu_table_group_mem_t *mem);
 extern void mm_iommu_init(struct mm_struct *mm);
@@ -39,6 +42,8 @@ extern long mm_iommu_ua_to_hpa(struct mm_iommu_table_group_mem_t *mem,
 extern long mm_iommu_ua_to_hpa_rm(struct mm_iommu_table_group_mem_t *mem,
 		unsigned long ua, unsigned int pageshift, unsigned long *hpa);
 extern void mm_iommu_ua_mark_dirty_rm(struct mm_struct *mm, unsigned long ua);
+extern bool mm_iommu_is_devmem(struct mm_struct *mm, unsigned long hpa,
+		unsigned int pageshift);
 extern long mm_iommu_mapped_inc(struct mm_iommu_table_group_mem_t *mem);
 extern void mm_iommu_mapped_dec(struct mm_iommu_table_group_mem_t *mem);
 #endif
diff --git a/arch/powerpc/kernel/iommu.c b/arch/powerpc/kernel/iommu.c
index 19b4c62..ab88b0f 100644
--- a/arch/powerpc/kernel/iommu.c
+++ b/arch/powerpc/kernel/iommu.c
@@ -47,6 +47,7 @@
 #include <asm/fadump.h>
 #include <asm/vio.h>
 #include <asm/tce.h>
+#include <asm/mmu_context.h>
 
 #define DBG(...)
 
@@ -993,15 +994,17 @@ int iommu_tce_check_gpa(unsigned long page_shift, unsigned long gpa)
 }
 EXPORT_SYMBOL_GPL(iommu_tce_check_gpa);
 
-long iommu_tce_xchg(struct iommu_table *tbl, unsigned long entry,
-		unsigned long *hpa, enum dma_data_direction *direction)
+long iommu_tce_xchg(struct mm_struct *mm, struct iommu_table *tbl,
+		unsigned long entry, unsigned long *hpa,
+		enum dma_data_direction *direction)
 {
 	long ret;
 
 	ret = tbl->it_ops->exchange(tbl, entry, hpa, direction);
 
 	if (!ret && ((*direction == DMA_FROM_DEVICE) ||
-			(*direction == DMA_BIDIRECTIONAL)))
+			(*direction == DMA_BIDIRECTIONAL)) &&
+			!mm_iommu_is_devmem(mm, *hpa, tbl->it_page_shift))
 		SetPageDirty(pfn_to_page(*hpa >> PAGE_SHIFT));
 
 	/* if (unlikely(ret))
diff --git a/arch/powerpc/kvm/book3s_64_vio.c b/arch/powerpc/kvm/book3s_64_vio.c
index 62a8d03..532ab797 100644
--- a/arch/powerpc/kvm/book3s_64_vio.c
+++ b/arch/powerpc/kvm/book3s_64_vio.c
@@ -397,12 +397,13 @@ static long kvmppc_tce_validate(struct kvmppc_spapr_tce_table *stt,
 	return H_SUCCESS;
 }
 
-static void kvmppc_clear_tce(struct iommu_table *tbl, unsigned long entry)
+static void kvmppc_clear_tce(struct mm_struct *mm, struct iommu_table *tbl,
+		unsigned long entry)
 {
 	unsigned long hpa = 0;
 	enum dma_data_direction dir = DMA_NONE;
 
-	iommu_tce_xchg(tbl, entry, &hpa, &dir);
+	iommu_tce_xchg(mm, tbl, entry, &hpa, &dir);
 }
 
 static long kvmppc_tce_iommu_mapped_dec(struct kvm *kvm,
@@ -433,7 +434,7 @@ static long kvmppc_tce_iommu_do_unmap(struct kvm *kvm,
 	unsigned long hpa = 0;
 	long ret;
 
-	if (WARN_ON_ONCE(iommu_tce_xchg(tbl, entry, &hpa, &dir)))
+	if (WARN_ON_ONCE(iommu_tce_xchg(kvm->mm, tbl, entry, &hpa, &dir)))
 		return H_TOO_HARD;
 
 	if (dir == DMA_NONE)
@@ -441,7 +442,7 @@ static long kvmppc_tce_iommu_do_unmap(struct kvm *kvm,
 
 	ret = kvmppc_tce_iommu_mapped_dec(kvm, tbl, entry);
 	if (ret != H_SUCCESS)
-		iommu_tce_xchg(tbl, entry, &hpa, &dir);
+		iommu_tce_xchg(kvm->mm, tbl, entry, &hpa, &dir);
 
 	return ret;
 }
@@ -487,7 +488,7 @@ long kvmppc_tce_iommu_do_map(struct kvm *kvm, struct iommu_table *tbl,
 	if (mm_iommu_mapped_inc(mem))
 		return H_TOO_HARD;
 
-	ret = iommu_tce_xchg(tbl, entry, &hpa, &dir);
+	ret = iommu_tce_xchg(kvm->mm, tbl, entry, &hpa, &dir);
 	if (WARN_ON_ONCE(ret)) {
 		mm_iommu_mapped_dec(mem);
 		return H_TOO_HARD;
@@ -566,7 +567,7 @@ long kvmppc_h_put_tce(struct kvm_vcpu *vcpu, unsigned long liobn,
 					entry, ua, dir);
 
 		if (ret != H_SUCCESS) {
-			kvmppc_clear_tce(stit->tbl, entry);
+			kvmppc_clear_tce(vcpu->kvm->mm, stit->tbl, entry);
 			goto unlock_exit;
 		}
 	}
@@ -655,7 +656,8 @@ long kvmppc_h_put_tce_indirect(struct kvm_vcpu *vcpu,
 					iommu_tce_direction(tce));
 
 			if (ret != H_SUCCESS) {
-				kvmppc_clear_tce(stit->tbl, entry);
+				kvmppc_clear_tce(vcpu->kvm->mm, stit->tbl,
+						entry);
 				goto unlock_exit;
 			}
 		}
@@ -704,7 +706,7 @@ long kvmppc_h_stuff_tce(struct kvm_vcpu *vcpu,
 				return ret;
 
 			WARN_ON_ONCE(1);
-			kvmppc_clear_tce(stit->tbl, entry);
+			kvmppc_clear_tce(vcpu->kvm->mm, stit->tbl, entry);
 		}
 	}
 
diff --git a/arch/powerpc/mm/mmu_context_iommu.c b/arch/powerpc/mm/mmu_context_iommu.c
index 839dbce..4835b4e 100644
--- a/arch/powerpc/mm/mmu_context_iommu.c
+++ b/arch/powerpc/mm/mmu_context_iommu.c
@@ -36,6 +36,8 @@ struct mm_iommu_table_group_mem_t {
 	u64 ua;			/* userspace address */
 	u64 entries;		/* number of entries in hpas[] */
 	u64 *hpas;		/* vmalloc'ed */
+#define MM_IOMMU_TABLE_INVALID_HPA	((uint64_t)-1)
+	u64 dev_hpa;		/* Device memory base address */
 };
 
 static long mm_iommu_adjust_locked_vm(struct mm_struct *mm,
@@ -126,7 +128,8 @@ static int mm_iommu_move_page_from_cma(struct page *page)
 	return 0;
 }
 
-long mm_iommu_new(struct mm_struct *mm, unsigned long ua, unsigned long entries,
+static long mm_iommu_do_alloc(struct mm_struct *mm, unsigned long ua,
+		unsigned long entries, unsigned long dev_hpa,
 		struct mm_iommu_table_group_mem_t **pmem)
 {
 	struct mm_iommu_table_group_mem_t *mem;
@@ -155,11 +158,13 @@ long mm_iommu_new(struct mm_struct *mm, unsigned long ua, unsigned long entries,
 
 	}
 
-	ret = mm_iommu_adjust_locked_vm(mm, entries, true);
-	if (ret)
-		goto unlock_exit;
+	if (dev_hpa == MM_IOMMU_TABLE_INVALID_HPA) {
+		ret = mm_iommu_adjust_locked_vm(mm, entries, true);
+		if (ret)
+			goto unlock_exit;
 
-	locked_entries = entries;
+		locked_entries = entries;
+	}
 
 	mem = kzalloc(sizeof(*mem), GFP_KERNEL);
 	if (!mem) {
@@ -167,6 +172,13 @@ long mm_iommu_new(struct mm_struct *mm, unsigned long ua, unsigned long entries,
 		goto unlock_exit;
 	}
 
+	if (dev_hpa != MM_IOMMU_TABLE_INVALID_HPA) {
+		mem->pageshift = __ffs(dev_hpa | (entries << PAGE_SHIFT));
+		mem->dev_hpa = dev_hpa;
+		goto good_exit;
+	}
+	mem->dev_hpa = MM_IOMMU_TABLE_INVALID_HPA;
+
 	/*
 	 * For a starting point for a maximum page size calculation
 	 * we use @ua and @entries natural alignment to allow IOMMU pages
@@ -235,6 +247,7 @@ long mm_iommu_new(struct mm_struct *mm, unsigned long ua, unsigned long entries,
 		mem->hpas[i] = page_to_pfn(page) << PAGE_SHIFT;
 	}
 
+good_exit:
 	atomic64_set(&mem->mapped, 1);
 	mem->used = 1;
 	mem->ua = ua;
@@ -251,13 +264,31 @@ long mm_iommu_new(struct mm_struct *mm, unsigned long ua, unsigned long entries,
 
 	return ret;
 }
+
+long mm_iommu_new(struct mm_struct *mm, unsigned long ua, unsigned long entries,
+		struct mm_iommu_table_group_mem_t **pmem)
+{
+	return mm_iommu_do_alloc(mm, ua, entries, MM_IOMMU_TABLE_INVALID_HPA,
+			pmem);
+}
 EXPORT_SYMBOL_GPL(mm_iommu_new);
 
+long mm_iommu_newdev(struct mm_struct *mm, unsigned long ua,
+		unsigned long entries, unsigned long dev_hpa,
+		struct mm_iommu_table_group_mem_t **pmem)
+{
+	return mm_iommu_do_alloc(mm, ua, entries, dev_hpa, pmem);
+}
+EXPORT_SYMBOL_GPL(mm_iommu_newdev);
+
 static void mm_iommu_unpin(struct mm_iommu_table_group_mem_t *mem)
 {
 	long i;
 	struct page *page = NULL;
 
+	if (!mem->hpas)
+		return;
+
 	for (i = 0; i < mem->entries; ++i) {
 		if (!mem->hpas[i])
 			continue;
@@ -299,6 +330,7 @@ static void mm_iommu_release(struct mm_iommu_table_group_mem_t *mem)
 long mm_iommu_put(struct mm_struct *mm, struct mm_iommu_table_group_mem_t *mem)
 {
 	long ret = 0;
+	unsigned long entries, dev_hpa;
 
 	mutex_lock(&mem_list_mutex);
 
@@ -320,9 +352,12 @@ long mm_iommu_put(struct mm_struct *mm, struct mm_iommu_table_group_mem_t *mem)
 	}
 
 	/* @mapped became 0 so now mappings are disabled, release the region */
+	entries = mem->entries;
+	dev_hpa = mem->dev_hpa;
 	mm_iommu_release(mem);
 
-	mm_iommu_adjust_locked_vm(mm, mem->entries, false);
+	if (dev_hpa == MM_IOMMU_TABLE_INVALID_HPA)
+		mm_iommu_adjust_locked_vm(mm, entries, false);
 
 unlock_exit:
 	mutex_unlock(&mem_list_mutex);
@@ -392,7 +427,7 @@ long mm_iommu_ua_to_hpa(struct mm_iommu_table_group_mem_t *mem,
 		unsigned long ua, unsigned int pageshift, unsigned long *hpa)
 {
 	const long entry = (ua - mem->ua) >> PAGE_SHIFT;
-	u64 *va = &mem->hpas[entry];
+	u64 *va;
 
 	if (entry >= mem->entries)
 		return -EFAULT;
@@ -400,6 +435,12 @@ long mm_iommu_ua_to_hpa(struct mm_iommu_table_group_mem_t *mem,
 	if (pageshift > mem->pageshift)
 		return -EFAULT;
 
+	if (!mem->hpas) {
+		*hpa = mem->dev_hpa + (ua - mem->ua);
+		return 0;
+	}
+
+	va = &mem->hpas[entry];
 	*hpa = (*va & MM_IOMMU_TABLE_GROUP_PAGE_MASK) | (ua & ~PAGE_MASK);
 
 	return 0;
@@ -410,7 +451,6 @@ long mm_iommu_ua_to_hpa_rm(struct mm_iommu_table_group_mem_t *mem,
 		unsigned long ua, unsigned int pageshift, unsigned long *hpa)
 {
 	const long entry = (ua - mem->ua) >> PAGE_SHIFT;
-	void *va = &mem->hpas[entry];
 	unsigned long *pa;
 
 	if (entry >= mem->entries)
@@ -419,7 +459,12 @@ long mm_iommu_ua_to_hpa_rm(struct mm_iommu_table_group_mem_t *mem,
 	if (pageshift > mem->pageshift)
 		return -EFAULT;
 
-	pa = (void *) vmalloc_to_phys(va);
+	if (!mem->hpas) {
+		*hpa = mem->dev_hpa + (ua - mem->ua);
+		return 0;
+	}
+
+	pa = (void *) vmalloc_to_phys(&mem->hpas[entry]);
 	if (!pa)
 		return -EFAULT;
 
@@ -449,6 +494,26 @@ extern void mm_iommu_ua_mark_dirty_rm(struct mm_struct *mm, unsigned long ua)
 	*pa |= MM_IOMMU_TABLE_GROUP_PAGE_DIRTY;
 }
 
+extern bool mm_iommu_is_devmem(struct mm_struct *mm, unsigned long hpa,
+		unsigned int pageshift)
+{
+	struct mm_iommu_table_group_mem_t *mem;
+	const unsigned long pagesize = 1UL << pageshift;
+
+	list_for_each_entry_rcu(mem, &mm->context.iommu_group_mem_list, next) {
+		if (mem->dev_hpa == MM_IOMMU_TABLE_INVALID_HPA)
+			continue;
+
+		if ((mem->dev_hpa <= hpa) &&
+				(hpa + pagesize <= mem->dev_hpa +
+				 (mem->entries << PAGE_SHIFT)))
+			return true;
+	}
+
+	return false;
+}
+EXPORT_SYMBOL_GPL(mm_iommu_is_devmem);
+
 long mm_iommu_mapped_inc(struct mm_iommu_table_group_mem_t *mem)
 {
 	if (atomic64_inc_not_zero(&mem->mapped))
diff --git a/drivers/vfio/vfio_iommu_spapr_tce.c b/drivers/vfio/vfio_iommu_spapr_tce.c
index 56db071..ed89137 100644
--- a/drivers/vfio/vfio_iommu_spapr_tce.c
+++ b/drivers/vfio/vfio_iommu_spapr_tce.c
@@ -222,8 +222,15 @@ static long tce_iommu_register_pages(struct tce_container *container,
 	return ret;
 }
 
-static bool tce_page_is_contained(struct page *page, unsigned page_shift)
+static bool tce_page_is_contained(struct mm_struct *mm, unsigned long hpa,
+		unsigned int page_shift)
 {
+	struct page *page;
+
+	if (mm_iommu_is_devmem(mm, hpa, page_shift))
+		return true;
+
+	page = pfn_to_page(hpa >> PAGE_SHIFT);
 	/*
 	 * Check that the TCE table granularity is not bigger than the size of
 	 * a page we just found. Otherwise the hardware can get access to
@@ -499,7 +506,8 @@ static int tce_iommu_clear(struct tce_container *container,
 
 		direction = DMA_NONE;
 		oldhpa = 0;
-		ret = iommu_tce_xchg(tbl, entry, &oldhpa, &direction);
+		ret = iommu_tce_xchg(container->mm, tbl, entry, &oldhpa,
+				&direction);
 		if (ret)
 			continue;
 
@@ -537,7 +545,6 @@ static long tce_iommu_build(struct tce_container *container,
 		enum dma_data_direction direction)
 {
 	long i, ret = 0;
-	struct page *page;
 	unsigned long hpa;
 	enum dma_data_direction dirtmp;
 
@@ -548,15 +555,16 @@ static long tce_iommu_build(struct tce_container *container,
 		if (ret)
 			break;
 
-		page = pfn_to_page(hpa >> PAGE_SHIFT);
-		if (!tce_page_is_contained(page, tbl->it_page_shift)) {
+		if (!tce_page_is_contained(container->mm, hpa,
+				tbl->it_page_shift)) {
 			ret = -EPERM;
 			break;
 		}
 
 		hpa |= offset;
 		dirtmp = direction;
-		ret = iommu_tce_xchg(tbl, entry + i, &hpa, &dirtmp);
+		ret = iommu_tce_xchg(container->mm, tbl, entry + i, &hpa,
+				&dirtmp);
 		if (ret) {
 			tce_iommu_unuse_page(container, hpa);
 			pr_err("iommu_tce: %s failed ioba=%lx, tce=%lx, ret=%ld\n",
@@ -583,7 +591,6 @@ static long tce_iommu_build_v2(struct tce_container *container,
 		enum dma_data_direction direction)
 {
 	long i, ret = 0;
-	struct page *page;
 	unsigned long hpa;
 	enum dma_data_direction dirtmp;
 
@@ -596,8 +603,8 @@ static long tce_iommu_build_v2(struct tce_container *container,
 		if (ret)
 			break;
 
-		page = pfn_to_page(hpa >> PAGE_SHIFT);
-		if (!tce_page_is_contained(page, tbl->it_page_shift)) {
+		if (!tce_page_is_contained(container->mm, hpa,
+				tbl->it_page_shift)) {
 			ret = -EPERM;
 			break;
 		}
@@ -610,7 +617,8 @@ static long tce_iommu_build_v2(struct tce_container *container,
 		if (mm_iommu_mapped_inc(mem))
 			break;
 
-		ret = iommu_tce_xchg(tbl, entry + i, &hpa, &dirtmp);
+		ret = iommu_tce_xchg(container->mm, tbl, entry + i, &hpa,
+				&dirtmp);
 		if (ret) {
 			/* dirtmp cannot be DMA_NONE here */
 			tce_iommu_unuse_page_v2(container, tbl, entry + i);
-- 
2.11.0

Re: [PATCH kernel 1/4] powerpc/mm/iommu: Rename mm_iommu_get

[David Gibson]

[-- Attachment #1: Type: text/plain, Size: 5232 bytes --]

On Mon, Oct 15, 2018 at 08:24:13PM +1100, Alexey Kardashevskiy wrote:
> Normally mm_iommu_get() is supposed to add a reference and
> mm_iommu_put() to remove it. However historically mm_iommu_find() does
> the referencing and mm_iommu_get() is doing allocation and referencing.
> 
> This is step 1 towards simpler mm_iommu_get().
> 
> This renames:
> - mm_iommu_get to mm_iommu_new;
> - mm_iommu_find to mm_iommu_get.
> 
> This should cause no behavioural change.
> 
> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>

Erm.. as far as I can tell, mm_iommu_find() doesn't adjust any
reference counts, so renaming it to mm_iommu_get() doesn't really make
sense.

> ---
>  arch/powerpc/include/asm/mmu_context.h | 4 ++--
>  arch/powerpc/mm/mmu_context_iommu.c    | 8 ++++----
>  drivers/vfio/vfio_iommu_spapr_tce.c    | 6 +++---
>  3 files changed, 9 insertions(+), 9 deletions(-)
> 
> diff --git a/arch/powerpc/include/asm/mmu_context.h b/arch/powerpc/include/asm/mmu_context.h
> index b694d6a..59d4941 100644
> --- a/arch/powerpc/include/asm/mmu_context.h
> +++ b/arch/powerpc/include/asm/mmu_context.h
> @@ -21,7 +21,7 @@ struct mm_iommu_table_group_mem_t;
>  
>  extern int isolate_lru_page(struct page *page);	/* from internal.h */
>  extern bool mm_iommu_preregistered(struct mm_struct *mm);
> -extern long mm_iommu_get(struct mm_struct *mm,
> +extern long mm_iommu_new(struct mm_struct *mm,
>  		unsigned long ua, unsigned long entries,
>  		struct mm_iommu_table_group_mem_t **pmem);
>  extern long mm_iommu_put(struct mm_struct *mm,
> @@ -32,7 +32,7 @@ extern struct mm_iommu_table_group_mem_t *mm_iommu_lookup(struct mm_struct *mm,
>  		unsigned long ua, unsigned long size);
>  extern struct mm_iommu_table_group_mem_t *mm_iommu_lookup_rm(
>  		struct mm_struct *mm, unsigned long ua, unsigned long size);
> -extern struct mm_iommu_table_group_mem_t *mm_iommu_find(struct mm_struct *mm,
> +extern struct mm_iommu_table_group_mem_t *mm_iommu_get(struct mm_struct *mm,
>  		unsigned long ua, unsigned long entries);
>  extern long mm_iommu_ua_to_hpa(struct mm_iommu_table_group_mem_t *mem,
>  		unsigned long ua, unsigned int pageshift, unsigned long *hpa);
> diff --git a/arch/powerpc/mm/mmu_context_iommu.c b/arch/powerpc/mm/mmu_context_iommu.c
> index 56c2234..8eeb99d 100644
> --- a/arch/powerpc/mm/mmu_context_iommu.c
> +++ b/arch/powerpc/mm/mmu_context_iommu.c
> @@ -126,7 +126,7 @@ static int mm_iommu_move_page_from_cma(struct page *page)
>  	return 0;
>  }
>  
> -long mm_iommu_get(struct mm_struct *mm, unsigned long ua, unsigned long entries,
> +long mm_iommu_new(struct mm_struct *mm, unsigned long ua, unsigned long entries,
>  		struct mm_iommu_table_group_mem_t **pmem)
>  {
>  	struct mm_iommu_table_group_mem_t *mem;
> @@ -252,7 +252,7 @@ long mm_iommu_get(struct mm_struct *mm, unsigned long ua, unsigned long entries,
>  
>  	return ret;
>  }
> -EXPORT_SYMBOL_GPL(mm_iommu_get);
> +EXPORT_SYMBOL_GPL(mm_iommu_new);
>  
>  static void mm_iommu_unpin(struct mm_iommu_table_group_mem_t *mem)
>  {
> @@ -368,7 +368,7 @@ struct mm_iommu_table_group_mem_t *mm_iommu_lookup_rm(struct mm_struct *mm,
>  	return ret;
>  }
>  
> -struct mm_iommu_table_group_mem_t *mm_iommu_find(struct mm_struct *mm,
> +struct mm_iommu_table_group_mem_t *mm_iommu_get(struct mm_struct *mm,
>  		unsigned long ua, unsigned long entries)
>  {
>  	struct mm_iommu_table_group_mem_t *mem, *ret = NULL;
> @@ -382,7 +382,7 @@ struct mm_iommu_table_group_mem_t *mm_iommu_find(struct mm_struct *mm,
>  
>  	return ret;
>  }
> -EXPORT_SYMBOL_GPL(mm_iommu_find);
> +EXPORT_SYMBOL_GPL(mm_iommu_get);
>  
>  long mm_iommu_ua_to_hpa(struct mm_iommu_table_group_mem_t *mem,
>  		unsigned long ua, unsigned int pageshift, unsigned long *hpa)
> diff --git a/drivers/vfio/vfio_iommu_spapr_tce.c b/drivers/vfio/vfio_iommu_spapr_tce.c
> index ad63725..1701798 100644
> --- a/drivers/vfio/vfio_iommu_spapr_tce.c
> +++ b/drivers/vfio/vfio_iommu_spapr_tce.c
> @@ -156,7 +156,7 @@ static long tce_iommu_unregister_pages(struct tce_container *container,
>  	if ((vaddr & ~PAGE_MASK) || (size & ~PAGE_MASK))
>  		return -EINVAL;
>  
> -	mem = mm_iommu_find(container->mm, vaddr, size >> PAGE_SHIFT);
> +	mem = mm_iommu_get(container->mm, vaddr, size >> PAGE_SHIFT);
>  	if (!mem)
>  		return -ENOENT;
>  
> @@ -185,7 +185,7 @@ static long tce_iommu_register_pages(struct tce_container *container,
>  			((vaddr + size) < vaddr))
>  		return -EINVAL;
>  
> -	mem = mm_iommu_find(container->mm, vaddr, entries);
> +	mem = mm_iommu_get(container->mm, vaddr, entries);
>  	if (mem) {
>  		list_for_each_entry(tcemem, &container->prereg_list, next) {
>  			if (tcemem->mem == mem)
> @@ -193,7 +193,7 @@ static long tce_iommu_register_pages(struct tce_container *container,
>  		}
>  	}
>  
> -	ret = mm_iommu_get(container->mm, vaddr, entries, &mem);
> +	ret = mm_iommu_new(container->mm, vaddr, entries, &mem);
>  	if (ret)
>  		return ret;
>  

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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Re: [PATCH kernel 2/4] powerpc/mm/iommu/vfio_spapr_tce: Change mm_iommu_get to reference a region

[David Gibson]

[-- Attachment #1: Type: text/plain, Size: 3941 bytes --]

On Mon, Oct 15, 2018 at 08:24:14PM +1100, Alexey Kardashevskiy wrote:
> We are going to add another helper to preregister device memory so
> instead of having mm_iommu_new() which pre-registers the normal memory
> and references the region, we need separate helpers for pre-registerign
> and referencing.
> 
> To make the mm_iommu_get name reflect what it is supposed to do, this
> changes mm_iommu_get() to reference the region so from now on for every
> mm_iommu_get() we need a matching mm_iommu_put().
> 
> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>

.. ah, I see.

I think this should be folded with the first patch, so we don't have
an interim step where mm_iommu_get() has a misleading name.

> ---
>  arch/powerpc/mm/mmu_context_iommu.c |  5 +++++
>  drivers/vfio/vfio_iommu_spapr_tce.c | 33 ++++++++++++++++++++++-----------
>  2 files changed, 27 insertions(+), 11 deletions(-)
> 
> diff --git a/arch/powerpc/mm/mmu_context_iommu.c b/arch/powerpc/mm/mmu_context_iommu.c
> index 8eeb99d..a8c4a3c 100644
> --- a/arch/powerpc/mm/mmu_context_iommu.c
> +++ b/arch/powerpc/mm/mmu_context_iommu.c
> @@ -373,13 +373,18 @@ struct mm_iommu_table_group_mem_t *mm_iommu_get(struct mm_struct *mm,
>  {
>  	struct mm_iommu_table_group_mem_t *mem, *ret = NULL;
>  
> +	mutex_lock(&mem_list_mutex);
> +
>  	list_for_each_entry_rcu(mem, &mm->context.iommu_group_mem_list, next) {
>  		if ((mem->ua == ua) && (mem->entries == entries)) {
>  			ret = mem;
> +			++mem->used;
>  			break;
>  		}
>  	}
>  
> +	mutex_unlock(&mem_list_mutex);
> +
>  	return ret;
>  }
>  EXPORT_SYMBOL_GPL(mm_iommu_get);
> diff --git a/drivers/vfio/vfio_iommu_spapr_tce.c b/drivers/vfio/vfio_iommu_spapr_tce.c
> index 1701798..56db071 100644
> --- a/drivers/vfio/vfio_iommu_spapr_tce.c
> +++ b/drivers/vfio/vfio_iommu_spapr_tce.c
> @@ -151,7 +151,8 @@ static long tce_iommu_unregister_pages(struct tce_container *container,
>  {
>  	struct mm_iommu_table_group_mem_t *mem;
>  	struct tce_iommu_prereg *tcemem;
> -	bool found = false;
> +	bool found;
> +	long ret;
>  
>  	if ((vaddr & ~PAGE_MASK) || (size & ~PAGE_MASK))
>  		return -EINVAL;
> @@ -168,9 +169,13 @@ static long tce_iommu_unregister_pages(struct tce_container *container,
>  	}
>  
>  	if (!found)
> -		return -ENOENT;
> +		ret = -ENOENT;
> +	else
> +		ret = tce_iommu_prereg_free(container, tcemem);
>  
> -	return tce_iommu_prereg_free(container, tcemem);
> +	mm_iommu_put(container->mm, mem);
> +
> +	return ret;
>  }
>  
>  static long tce_iommu_register_pages(struct tce_container *container,
> @@ -188,19 +193,21 @@ static long tce_iommu_register_pages(struct tce_container *container,
>  	mem = mm_iommu_get(container->mm, vaddr, entries);
>  	if (mem) {
>  		list_for_each_entry(tcemem, &container->prereg_list, next) {
> -			if (tcemem->mem == mem)
> -				return -EBUSY;
> +			if (tcemem->mem == mem) {
> +				ret = -EBUSY;
> +				goto put_exit;
> +			}
>  		}
> +	} else {
> +		ret = mm_iommu_new(container->mm, vaddr, entries, &mem);
> +		if (ret)
> +			return ret;
>  	}
>  
> -	ret = mm_iommu_new(container->mm, vaddr, entries, &mem);
> -	if (ret)
> -		return ret;
> -
>  	tcemem = kzalloc(sizeof(*tcemem), GFP_KERNEL);
>  	if (!tcemem) {
> -		mm_iommu_put(container->mm, mem);
> -		return -ENOMEM;
> +		ret = -ENOMEM;
> +		goto put_exit;
>  	}
>  
>  	tcemem->mem = mem;
> @@ -209,6 +216,10 @@ static long tce_iommu_register_pages(struct tce_container *container,
>  	container->enabled = true;
>  
>  	return 0;
> +
> +put_exit:
> +	mm_iommu_put(container->mm, mem);
> +	return ret;
>  }
>  
>  static bool tce_page_is_contained(struct page *page, unsigned page_shift)

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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Re: [PATCH kernel 3/4] powerpc/mm/iommu: Make mm_iommu_new() fail on existing regions

[David Gibson]

[-- Attachment #1: Type: text/plain, Size: 1429 bytes --]

On Mon, Oct 15, 2018 at 08:24:15PM +1100, Alexey Kardashevskiy wrote:
> Since we are going to have 2 different preregistering helpers, let's
> make it clear that mm_iommu_new() is only for the normal (i.e. not device)
> memory and for existing areas mm_iommu_get() should be used instead.
> 
> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>

I think the idea is sensible.  However (and, yes, this is really an
existing bug) - shouldn't we check for a request to add anything
overlapping with an existing region, not just one that exactly
matches?

> ---
>  arch/powerpc/mm/mmu_context_iommu.c | 3 +--
>  1 file changed, 1 insertion(+), 2 deletions(-)
> 
> diff --git a/arch/powerpc/mm/mmu_context_iommu.c b/arch/powerpc/mm/mmu_context_iommu.c
> index a8c4a3c..839dbce 100644
> --- a/arch/powerpc/mm/mmu_context_iommu.c
> +++ b/arch/powerpc/mm/mmu_context_iommu.c
> @@ -141,8 +141,7 @@ long mm_iommu_new(struct mm_struct *mm, unsigned long ua, unsigned long entries,
>  	list_for_each_entry_rcu(mem, &mm->context.iommu_group_mem_list,
>  			next) {
>  		if ((mem->ua == ua) && (mem->entries == entries)) {
> -			++mem->used;
> -			*pmem = mem;
> +			ret = -EBUSY;
>  			goto unlock_exit;
>  		}
>  

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

[-- Attachment #2: signature.asc --]
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Re: [PATCH kernel 3/4] powerpc/mm/iommu: Make mm_iommu_new() fail on existing regions

[Alexey Kardashevskiy]

On 17/10/2018 12:00, David Gibson wrote:
> On Mon, Oct 15, 2018 at 08:24:15PM +1100, Alexey Kardashevskiy wrote:
>> Since we are going to have 2 different preregistering helpers, let's
>> make it clear that mm_iommu_new() is only for the normal (i.e. not device)
>> memory and for existing areas mm_iommu_get() should be used instead.
>>
>> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
> 
> I think the idea is sensible.  However (and, yes, this is really an
> existing bug) - shouldn't we check for a request to add anything
> overlapping with an existing region, not just one that exactly
> matches?

The overlap check is below the changed hunk:

https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/powerpc/mm/mmu_context_iommu.c#n150


> 
>> ---
>>  arch/powerpc/mm/mmu_context_iommu.c | 3 +--
>>  1 file changed, 1 insertion(+), 2 deletions(-)
>>
>> diff --git a/arch/powerpc/mm/mmu_context_iommu.c b/arch/powerpc/mm/mmu_context_iommu.c
>> index a8c4a3c..839dbce 100644
>> --- a/arch/powerpc/mm/mmu_context_iommu.c
>> +++ b/arch/powerpc/mm/mmu_context_iommu.c
>> @@ -141,8 +141,7 @@ long mm_iommu_new(struct mm_struct *mm, unsigned long ua, unsigned long entries,
>>  	list_for_each_entry_rcu(mem, &mm->context.iommu_group_mem_list,
>>  			next) {
>>  		if ((mem->ua == ua) && (mem->entries == entries)) {
>> -			++mem->used;
>> -			*pmem = mem;
>> +			ret = -EBUSY;
>>  			goto unlock_exit;
>>  		}
>>  
> 

-- 
Alexey

Re: [PATCH kernel 3/4] powerpc/mm/iommu: Make mm_iommu_new() fail on existing regions

[David Gibson]

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On Wed, Oct 17, 2018 at 02:34:32PM +1100, Alexey Kardashevskiy wrote:
> 
> 
> On 17/10/2018 12:00, David Gibson wrote:
> > On Mon, Oct 15, 2018 at 08:24:15PM +1100, Alexey Kardashevskiy wrote:
> >> Since we are going to have 2 different preregistering helpers, let's
> >> make it clear that mm_iommu_new() is only for the normal (i.e. not device)
> >> memory and for existing areas mm_iommu_get() should be used instead.
> >>
> >> Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
> > 
> > I think the idea is sensible.  However (and, yes, this is really an
> > existing bug) - shouldn't we check for a request to add anything
> > overlapping with an existing region, not just one that exactly
> > matches?
> 
> The overlap check is below the changed hunk:
> 
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/arch/powerpc/mm/mmu_context_iommu.c#n150

Ah, right.

In that case can't you just drop this whole if.  I don't see that
there's any use in giving different error codes for "tried to register
exactly a region you registered before" and "tried to register a
region overlapping one you registered before.


> 
> 
> > 
> >> ---
> >>  arch/powerpc/mm/mmu_context_iommu.c | 3 +--
> >>  1 file changed, 1 insertion(+), 2 deletions(-)
> >>
> >> diff --git a/arch/powerpc/mm/mmu_context_iommu.c b/arch/powerpc/mm/mmu_context_iommu.c
> >> index a8c4a3c..839dbce 100644
> >> --- a/arch/powerpc/mm/mmu_context_iommu.c
> >> +++ b/arch/powerpc/mm/mmu_context_iommu.c
> >> @@ -141,8 +141,7 @@ long mm_iommu_new(struct mm_struct *mm, unsigned long ua, unsigned long entries,
> >>  	list_for_each_entry_rcu(mem, &mm->context.iommu_group_mem_list,
> >>  			next) {
> >>  		if ((mem->ua == ua) && (mem->entries == entries)) {
> >> -			++mem->used;
> >> -			*pmem = mem;
> >> +			ret = -EBUSY;
> >>  			goto unlock_exit;
> >>  		}
> >>  
> > 
> 

-- 
David Gibson			| I'll have my music baroque, and my code
david AT gibson.dropbear.id.au	| minimalist, thank you.  NOT _the_ _other_
				| _way_ _around_!
http://www.ozlabs.org/~dgibson

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