Inter-revision diff: patch 18

Comparing v6 (message) to v10 (message)

--- v6
+++ v10
@@ -1,427 +1,335 @@
-At the moment writing new TCE value to the IOMMU table fails with EBUSY
-if there is a valid entry already. However PAPR specification allows
-the guest to write new TCE value without clearing it first.
-
-Another problem this patch is addressing is the use of pool locks for
-external IOMMU users such as VFIO. The pool locks are to protect
-DMA page allocator rather than entries and since the host kernel does
-not control what pages are in use, there is no point in pool locks and
-exchange()+put_page(oldtce) is sufficient to avoid possible races.
-
-This adds an exchange() callback to iommu_table_ops which does the same
-thing as set() plus it returns replaced TCE and DMA direction so
-the caller can release the pages afterwards.
-
-The returned old TCE value is a virtual address as the new TCE value.
-This is different from tce_clear() which returns a physical address.
-
-This implements exchange() for P5IOC2/IODA/IODA2. This adds a requirement
-for a platform to have exchange() implemented in order to support VFIO.
-
-This replaces iommu_tce_build() and iommu_clear_tce() with
-a single iommu_tce_xchg().
-
-This makes sure that TCE permission bits are not set in TCE passed to
-IOMMU API as those are to be calculated by platform code from DMA direction.
-
-This moves SetPageDirty() to the IOMMU code to make it work for both
-VFIO ioctl interface in in-kernel TCE acceleration (when it becomes
-available later).
+This adds tce_iommu_take_ownership() and tce_iommu_release_ownership
+which call in a loop iommu_take_ownership()/iommu_release_ownership()
+for every table on the group. As there is just one now, no change in
+behaviour is expected.
+
+At the moment the iommu_table struct has a set_bypass() which enables/
+disables DMA bypass on IODA2 PHB. This is exposed to POWERPC IOMMU code
+which calls this callback when external IOMMU users such as VFIO are
+about to get over a PHB.
+
+The set_bypass() callback is not really an iommu_table function but
+IOMMU/PE function. This introduces a iommu_table_group_ops struct and
+adds take_ownership()/release_ownership() callbacks to it which are
+called when an external user takes/releases control over the IOMMU.
+
+This replaces set_bypass() with ownership callbacks as it is not
+necessarily just bypass enabling, it can be something else/more
+so let's give it more generic name.
+
+The callbacks is implemented for IODA2 only. Other platforms (P5IOC2,
+IODA1) will use the old iommu_take_ownership/iommu_release_ownership API.
+The following patches will replace iommu_take_ownership/
+iommu_release_ownership calls in IODA2 with full IOMMU table release/
+create.
+
+As we here and touching bypass control, this removes
+pnv_pci_ioda2_setup_bypass_pe() as it does not do much
+more compared to pnv_pci_ioda2_set_bypass. This moves tce_bypass_base
+initialization to pnv_pci_ioda2_setup_dma_pe.
 
 Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
+[aw: for the vfio related changes]
+Acked-by: Alex Williamson <alex.williamson@redhat.com>
 ---
- arch/powerpc/include/asm/iommu.h            | 15 +++++--
- arch/powerpc/kernel/iommu.c                 | 54 ++++++++++---------------
- arch/powerpc/platforms/powernv/pci-ioda.c   | 26 ++++++++++++
- arch/powerpc/platforms/powernv/pci-p5ioc2.c |  1 +
- arch/powerpc/platforms/powernv/pci.c        | 15 +++++++
- arch/powerpc/platforms/powernv/pci.h        |  2 +
- drivers/vfio/vfio_iommu_spapr_tce.c         | 62 ++++++++++++++++++-----------
- 7 files changed, 113 insertions(+), 62 deletions(-)
+Changes:
+v10:
+* fixed comments around take_ownership/release_ownership in iommu_table_group_ops
+
+v9:
+* squashed "vfio: powerpc/spapr: powerpc/iommu: Rework IOMMU ownership control"
+and "vfio: powerpc/spapr: powerpc/powernv/ioda2: Rework IOMMU ownership control"
+into a single patch
+* moved helpers with a loop through tables in a group
+to vfio_iommu_spapr_tce.c to keep the platform code free of IOMMU table
+groups as much as possible
+* added missing tce_iommu_clear() to tce_iommu_release_ownership()
+* replaced the set_ownership(enable) callback with take_ownership() and
+release_ownership()
+---
+ arch/powerpc/include/asm/iommu.h          | 11 ++++-
+ arch/powerpc/kernel/iommu.c               | 12 -----
+ arch/powerpc/platforms/powernv/pci-ioda.c | 73 ++++++++++++++++++-------------
+ drivers/vfio/vfio_iommu_spapr_tce.c       | 70 ++++++++++++++++++++++++++---
+ 4 files changed, 116 insertions(+), 50 deletions(-)
 
 diff --git a/arch/powerpc/include/asm/iommu.h b/arch/powerpc/include/asm/iommu.h
-index d1f8c6c..6af22a4 100644
+index 664beeb..c5375c5 100644
 --- a/arch/powerpc/include/asm/iommu.h
 +++ b/arch/powerpc/include/asm/iommu.h
-@@ -44,11 +44,20 @@ extern int iommu_is_off;
- extern int iommu_force_on;
- 
- struct iommu_table_ops {
-+	/* When called with direction==DMA_NONE, it is equal to clear() */
- 	int (*set)(struct iommu_table *tbl,
- 			long index, long npages,
- 			unsigned long uaddr,
- 			enum dma_data_direction direction,
- 			struct dma_attrs *attrs);
-+	/*
-+	 * Exchanges existing TCE with new TCE plus direction bits;
-+	 * returns old TCE and DMA direction mask
-+	 */
-+	int (*exchange)(struct iommu_table *tbl,
-+			long index,
-+			unsigned long *tce,
-+			enum dma_data_direction *direction);
- 	void (*clear)(struct iommu_table *tbl,
- 			long index, long npages);
- 	unsigned long (*get)(struct iommu_table *tbl, long index);
-@@ -231,10 +240,8 @@ extern int iommu_tce_clear_param_check(struct iommu_table *tbl,
- 		unsigned long npages);
- extern int iommu_tce_put_param_check(struct iommu_table *tbl,
- 		unsigned long ioba, unsigned long tce);
--extern int iommu_tce_build(struct iommu_table *tbl, unsigned long entry,
--		unsigned long hwaddr, enum dma_data_direction direction);
--extern unsigned long iommu_clear_tce(struct iommu_table *tbl,
--		unsigned long entry);
-+extern long iommu_tce_xchg(struct iommu_table *tbl, unsigned long entry,
-+		unsigned long *tce, enum dma_data_direction *direction);
- 
- extern void iommu_flush_tce(struct iommu_table *tbl);
- extern int iommu_take_ownership(struct iommu_table_group *table_group);
+@@ -95,7 +95,6 @@ struct iommu_table {
+ 	struct list_head it_group_list;/* List of iommu_table_group_link */
+ #endif
+ 	struct iommu_table_ops *it_ops;
+-	void (*set_bypass)(struct iommu_table *tbl, bool enable);
+ };
+ 
+ /* Pure 2^n version of get_order */
+@@ -130,6 +129,15 @@ extern struct iommu_table *iommu_init_table(struct iommu_table * tbl,
+ 
+ #define IOMMU_TABLE_GROUP_MAX_TABLES	1
+ 
++struct iommu_table_group;
++
++struct iommu_table_group_ops {
++	/* Switch ownership from platform code to external user (e.g. VFIO) */
++	void (*take_ownership)(struct iommu_table_group *table_group);
++	/* Switch ownership from external user (e.g. VFIO) back to core */
++	void (*release_ownership)(struct iommu_table_group *table_group);
++};
++
+ struct iommu_table_group_link {
+ 	struct list_head next;
+ 	struct rcu_head rcu;
+@@ -139,6 +147,7 @@ struct iommu_table_group_link {
+ struct iommu_table_group {
+ 	struct iommu_group *group;
+ 	struct iommu_table *tables[IOMMU_TABLE_GROUP_MAX_TABLES];
++	struct iommu_table_group_ops *ops;
+ };
+ 
+ extern void iommu_register_group(struct iommu_table_group *table_group,
 diff --git a/arch/powerpc/kernel/iommu.c b/arch/powerpc/kernel/iommu.c
-index df888a7..2856a4a 100644
+index bdf19c6..7e54714 100644
 --- a/arch/powerpc/kernel/iommu.c
 +++ b/arch/powerpc/kernel/iommu.c
-@@ -982,9 +982,6 @@ EXPORT_SYMBOL_GPL(iommu_tce_clear_param_check);
- int iommu_tce_put_param_check(struct iommu_table *tbl,
- 		unsigned long ioba, unsigned long tce)
- {
--	if (!(tce & (TCE_PCI_WRITE | TCE_PCI_READ)))
--		return -EINVAL;
--
- 	if (tce & ~(IOMMU_PAGE_MASK(tbl) | TCE_PCI_WRITE | TCE_PCI_READ))
- 		return -EINVAL;
- 
-@@ -1002,44 +999,23 @@ int iommu_tce_put_param_check(struct iommu_table *tbl,
- }
- EXPORT_SYMBOL_GPL(iommu_tce_put_param_check);
- 
--unsigned long iommu_clear_tce(struct iommu_table *tbl, unsigned long entry)
--{
--	unsigned long oldtce;
--	struct iommu_pool *pool = get_pool(tbl, entry);
--
--	spin_lock(&(pool->lock));
--
--	oldtce = tbl->it_ops->get(tbl, entry);
--	if (oldtce & (TCE_PCI_WRITE | TCE_PCI_READ))
--		tbl->it_ops->clear(tbl, entry, 1);
--	else
--		oldtce = 0;
--
--	spin_unlock(&(pool->lock));
--
--	return oldtce;
--}
--EXPORT_SYMBOL_GPL(iommu_clear_tce);
--
- /*
-  * hwaddr is a kernel virtual address here (0xc... bazillion),
-  * tce_build converts it to a physical address.
-  */
--int iommu_tce_build(struct iommu_table *tbl, unsigned long entry,
--		unsigned long hwaddr, enum dma_data_direction direction)
-+long iommu_tce_xchg(struct iommu_table *tbl, unsigned long entry,
-+		unsigned long *tce, enum dma_data_direction *direction)
- {
--	int ret = -EBUSY;
--	unsigned long oldtce;
--	struct iommu_pool *pool = get_pool(tbl, entry);
-+	long ret;
- 
--	spin_lock(&(pool->lock));
-+	if (*tce & ~IOMMU_PAGE_MASK(tbl))
-+		return -EINVAL;
- 
--	oldtce = tbl->it_ops->get(tbl, entry);
--	/* Add new entry if it is not busy */
--	if (!(oldtce & (TCE_PCI_WRITE | TCE_PCI_READ)))
--		ret = tbl->it_ops->set(tbl, entry, 1, hwaddr, direction, NULL);
-+	ret = tbl->it_ops->exchange(tbl, entry, tce, direction);
- 
--	spin_unlock(&(pool->lock));
-+	if (!ret && ((*direction == DMA_FROM_DEVICE) ||
-+			(*direction == DMA_BIDIRECTIONAL)))
-+		SetPageDirty(pfn_to_page(__pa(tce) >> PAGE_SHIFT));
- 
- 	/* if (unlikely(ret))
- 		pr_err("iommu_tce: %s failed on hwaddr=%lx ioba=%lx kva=%lx ret=%d\n",
-@@ -1048,13 +1024,23 @@ int iommu_tce_build(struct iommu_table *tbl, unsigned long entry,
- 
- 	return ret;
- }
--EXPORT_SYMBOL_GPL(iommu_tce_build);
-+EXPORT_SYMBOL_GPL(iommu_tce_xchg);
- 
- static int iommu_table_take_ownership(struct iommu_table *tbl)
- {
- 	unsigned long flags, i, sz = (tbl->it_size + 7) >> 3;
- 	int ret = 0;
- 
-+	/*
-+	 * VFIO does not control TCE entries allocation and the guest
-+	 * can write new TCEs on top of existing ones so iommu_tce_build()
-+	 * must be able to release old pages. This functionality
-+	 * requires exchange() callback defined so if it is not
-+	 * implemented, we disallow taking ownership over the table.
-+	 */
-+	if (!tbl->it_ops->exchange)
-+		return -EINVAL;
-+
- 	spin_lock_irqsave(&tbl->large_pool.lock, flags);
- 	for (i = 0; i < tbl->nr_pools; i++)
- 		spin_lock(&tbl->pools[i].lock);
+@@ -1044,14 +1044,6 @@ int iommu_take_ownership(struct iommu_table *tbl)
+ 
+ 	memset(tbl->it_map, 0xff, sz);
+ 
+-	/*
+-	 * Disable iommu bypass, otherwise the user can DMA to all of
+-	 * our physical memory via the bypass window instead of just
+-	 * the pages that has been explicitly mapped into the iommu
+-	 */
+-	if (tbl->set_bypass)
+-		tbl->set_bypass(tbl, false);
+-
+ 	return 0;
+ }
+ EXPORT_SYMBOL_GPL(iommu_take_ownership);
+@@ -1065,10 +1057,6 @@ void iommu_release_ownership(struct iommu_table *tbl)
+ 	/* Restore bit#0 set by iommu_init_table() */
+ 	if (tbl->it_offset == 0)
+ 		set_bit(0, tbl->it_map);
+-
+-	/* The kernel owns the device now, we can restore the iommu bypass */
+-	if (tbl->set_bypass)
+-		tbl->set_bypass(tbl, true);
+ }
+ EXPORT_SYMBOL_GPL(iommu_release_ownership);
+ 
 diff --git a/arch/powerpc/platforms/powernv/pci-ioda.c b/arch/powerpc/platforms/powernv/pci-ioda.c
-index fd993bc..9691b3a 100644
+index 53bf242b..35ab19c8 100644
 --- a/arch/powerpc/platforms/powernv/pci-ioda.c
 +++ b/arch/powerpc/platforms/powernv/pci-ioda.c
-@@ -1128,6 +1128,18 @@ static int pnv_ioda1_tce_build_vm(struct iommu_table *tbl, long index,
- 	return ret;
- }
- 
-+static int pnv_ioda1_tce_xchg_vm(struct iommu_table *tbl, long index,
-+		unsigned long *tce, enum dma_data_direction *direction)
+@@ -1918,13 +1918,8 @@ static void pnv_pci_ioda_setup_dma_pe(struct pnv_phb *phb,
+ 	}
+ }
+ 
+-static void pnv_pci_ioda2_set_bypass(struct iommu_table *tbl, bool enable)
++static void pnv_pci_ioda2_set_bypass(struct pnv_ioda_pe *pe, bool enable)
+ {
+-	struct iommu_table_group_link *tgl = list_first_entry_or_null(
+-			&tbl->it_group_list, struct iommu_table_group_link,
+-			next);
+-	struct pnv_ioda_pe *pe = container_of(tgl->table_group,
+-			struct pnv_ioda_pe, table_group);
+ 	uint16_t window_id = (pe->pe_number << 1 ) + 1;
+ 	int64_t rc;
+ 
+@@ -1951,33 +1946,48 @@ static void pnv_pci_ioda2_set_bypass(struct iommu_table *tbl, bool enable)
+ 		pe->tce_bypass_enabled = enable;
+ }
+ 
+-static void pnv_pci_ioda2_setup_bypass_pe(struct pnv_phb *phb,
+-					  struct pnv_ioda_pe *pe)
++#ifdef CONFIG_IOMMU_API
++static void pnv_ioda2_take_ownership(struct iommu_table_group *table_group)
+ {
++	struct pnv_ioda_pe *pe = container_of(table_group, struct pnv_ioda_pe,
++						table_group);
++
++	iommu_take_ownership(table_group->tables[0]);
++	pnv_pci_ioda2_set_bypass(pe, false);
++}
++
++static void pnv_ioda2_release_ownership(struct iommu_table_group *table_group)
 +{
-+	long ret = pnv_tce_xchg(tbl, index, tce, direction);
-+
-+	if (!ret && (tbl->it_type &
-+			(TCE_PCI_SWINV_CREATE | TCE_PCI_SWINV_FREE)))
-+		pnv_pci_ioda1_tce_invalidate(tbl, index, 1, false);
-+
-+	return ret;
++	struct pnv_ioda_pe *pe = container_of(table_group, struct pnv_ioda_pe,
++						table_group);
++
++	iommu_release_ownership(table_group->tables[0]);
++	pnv_pci_ioda2_set_bypass(pe, true);
 +}
 +
- static void pnv_ioda1_tce_free_vm(struct iommu_table *tbl, long index,
- 		long npages)
- {
-@@ -1139,6 +1151,7 @@ static void pnv_ioda1_tce_free_vm(struct iommu_table *tbl, long index,
- 
- struct iommu_table_ops pnv_ioda1_iommu_ops = {
- 	.set = pnv_ioda1_tce_build_vm,
-+	.exchange = pnv_ioda1_tce_xchg_vm,
- 	.clear = pnv_ioda1_tce_free_vm,
- 	.get = pnv_tce_get,
- };
-@@ -1190,6 +1203,18 @@ static int pnv_ioda2_tce_build_vm(struct iommu_table *tbl, long index,
- 	return ret;
- }
- 
-+static int pnv_ioda2_tce_xchg_vm(struct iommu_table *tbl, long index,
-+		unsigned long *tce, enum dma_data_direction *direction)
++static struct iommu_table_group_ops pnv_pci_ioda2_ops = {
++	.take_ownership = pnv_ioda2_take_ownership,
++	.release_ownership = pnv_ioda2_release_ownership,
++};
++#endif
++
++static void pnv_pci_ioda2_setup_dma_pe(struct pnv_phb *phb,
++				       struct pnv_ioda_pe *pe)
 +{
-+	long ret = pnv_tce_xchg(tbl, index, tce, direction);
-+
-+	if (!ret && (tbl->it_type &
-+			(TCE_PCI_SWINV_CREATE | TCE_PCI_SWINV_FREE)))
-+		pnv_pci_ioda2_tce_invalidate(tbl, index, 1, false);
-+
-+	return ret;
++	struct page *tce_mem = NULL;
++	void *addr;
++	const __be64 *swinvp;
++	struct iommu_table *tbl;
++	unsigned int tce_table_size, end;
++	int64_t rc;
++
++	/* We shouldn't already have a 32-bit DMA associated */
++	if (WARN_ON(pe->tce32_seg >= 0))
++		return;
++
+ 	/* TVE #1 is selected by PCI address bit 59 */
+ 	pe->tce_bypass_base = 1ull << 59;
+ 
+-	/* Install set_bypass callback for VFIO */
+-	pe->table_group.tables[0]->set_bypass = pnv_pci_ioda2_set_bypass;
+-
+-	/* Enable bypass by default */
+-	pnv_pci_ioda2_set_bypass(pe->table_group.tables[0], true);
+-}
+-
+-static void pnv_pci_ioda2_setup_dma_pe(struct pnv_phb *phb,
+-				       struct pnv_ioda_pe *pe)
+-{
+-	struct page *tce_mem = NULL;
+-	void *addr;
+-	const __be64 *swinvp;
+-	struct iommu_table *tbl;
+-	unsigned int tce_table_size, end;
+-	int64_t rc;
+-
+-	/* We shouldn't already have a 32-bit DMA associated */
+-	if (WARN_ON(pe->tce32_seg >= 0))
+-		return;
+-
+ 	tbl = pnv_pci_table_alloc(phb->hose->node);
+ 	iommu_register_group(&pe->table_group, phb->hose->global_number,
+ 			pe->pe_number);
+@@ -2032,6 +2042,9 @@ static void pnv_pci_ioda2_setup_dma_pe(struct pnv_phb *phb,
+ 	}
+ 	tbl->it_ops = &pnv_ioda2_iommu_ops;
+ 	iommu_init_table(tbl, phb->hose->node);
++#ifdef CONFIG_IOMMU_API
++	pe->table_group.ops = &pnv_pci_ioda2_ops;
++#endif
+ 
+ 	if (pe->flags & PNV_IODA_PE_DEV) {
+ 		/*
+@@ -2046,7 +2059,7 @@ static void pnv_pci_ioda2_setup_dma_pe(struct pnv_phb *phb,
+ 
+ 	/* Also create a bypass window */
+ 	if (!pnv_iommu_bypass_disabled)
+-		pnv_pci_ioda2_setup_bypass_pe(phb, pe);
++		pnv_pci_ioda2_set_bypass(pe, true);
+ 
+ 	return;
+ fail:
+diff --git a/drivers/vfio/vfio_iommu_spapr_tce.c b/drivers/vfio/vfio_iommu_spapr_tce.c
+index ed3310b..2ead291 100644
+--- a/drivers/vfio/vfio_iommu_spapr_tce.c
++++ b/drivers/vfio/vfio_iommu_spapr_tce.c
+@@ -486,6 +486,47 @@ static long tce_iommu_ioctl(void *iommu_data,
+ 	return -ENOTTY;
+ }
+ 
++static void tce_iommu_release_ownership(struct tce_container *container,
++		struct iommu_table_group *table_group)
++{
++	int i;
++
++	for (i = 0; i < IOMMU_TABLE_GROUP_MAX_TABLES; ++i) {
++		struct iommu_table *tbl = table_group->tables[i];
++
++		if (!tbl)
++			continue;
++
++		tce_iommu_clear(container, tbl, tbl->it_offset, tbl->it_size);
++		if (tbl->it_map)
++			iommu_release_ownership(tbl);
++	}
 +}
 +
- static void pnv_ioda2_tce_free_vm(struct iommu_table *tbl, long index,
- 		long npages)
- {
-@@ -1201,6 +1226,7 @@ static void pnv_ioda2_tce_free_vm(struct iommu_table *tbl, long index,
- 
- static struct iommu_table_ops pnv_ioda2_iommu_ops = {
- 	.set = pnv_ioda2_tce_build_vm,
-+	.exchange = pnv_ioda2_tce_xchg_vm,
- 	.clear = pnv_ioda2_tce_free_vm,
- 	.get = pnv_tce_get,
- };
-diff --git a/arch/powerpc/platforms/powernv/pci-p5ioc2.c b/arch/powerpc/platforms/powernv/pci-p5ioc2.c
-index 6906a9c..5888b2c 100644
---- a/arch/powerpc/platforms/powernv/pci-p5ioc2.c
-+++ b/arch/powerpc/platforms/powernv/pci-p5ioc2.c
-@@ -85,6 +85,7 @@ static void pnv_pci_init_p5ioc2_msis(struct pnv_phb *phb) { }
- 
- static struct iommu_table_ops pnv_p5ioc2_iommu_ops = {
- 	.set = pnv_tce_build,
-+	.exchange = pnv_tce_xchg,
- 	.clear = pnv_tce_free,
- 	.get = pnv_tce_get,
- };
-diff --git a/arch/powerpc/platforms/powernv/pci.c b/arch/powerpc/platforms/powernv/pci.c
-index a8c05de..c5e1f05 100644
---- a/arch/powerpc/platforms/powernv/pci.c
-+++ b/arch/powerpc/platforms/powernv/pci.c
-@@ -615,6 +615,21 @@ int pnv_tce_build(struct iommu_table *tbl, long index, long npages,
- 	return 0;
- }
- 
-+int pnv_tce_xchg(struct iommu_table *tbl, long index,
-+		unsigned long *tce, enum dma_data_direction *direction)
++static int tce_iommu_take_ownership(struct tce_container *container,
++		struct iommu_table_group *table_group)
 +{
-+	u64 proto_tce = iommu_direction_to_tce_perm(*direction);
-+	unsigned long newtce =  __pa(*tce) | proto_tce;
-+	unsigned long idx = index - tbl->it_offset;
-+
-+	*tce = xchg(pnv_tce(tbl, idx), cpu_to_be64(newtce));
-+	*tce = (unsigned long) __va(be64_to_cpu(*tce));
-+	*direction = iommu_tce_direction(*tce);
-+	*tce &= ~(TCE_PCI_READ | TCE_PCI_WRITE);
++	int i, j, rc = 0;
++
++	for (i = 0; i < IOMMU_TABLE_GROUP_MAX_TABLES; ++i) {
++		struct iommu_table *tbl = table_group->tables[i];
++
++		if (!tbl || !tbl->it_map)
++			continue;
++
++		rc = iommu_take_ownership(tbl);
++		if (rc) {
++			for (j = 0; j < i; ++j)
++				iommu_release_ownership(
++						table_group->tables[j]);
++
++			return rc;
++		}
++	}
 +
 +	return 0;
 +}
 +
- void pnv_tce_free(struct iommu_table *tbl, long index, long npages)
+ static int tce_iommu_attach_group(void *iommu_data,
+ 		struct iommu_group *iommu_group)
  {
- 	long i;
-diff --git a/arch/powerpc/platforms/powernv/pci.h b/arch/powerpc/platforms/powernv/pci.h
-index 0d4df32..4d1a78c 100644
---- a/arch/powerpc/platforms/powernv/pci.h
-+++ b/arch/powerpc/platforms/powernv/pci.h
-@@ -220,6 +220,8 @@ extern int pnv_tce_build(struct iommu_table *tbl, long index, long npages,
- 		unsigned long uaddr, enum dma_data_direction direction,
- 		struct dma_attrs *attrs);
- extern void pnv_tce_free(struct iommu_table *tbl, long index, long npages);
-+extern int pnv_tce_xchg(struct iommu_table *tbl, long index,
-+		unsigned long *tce, enum dma_data_direction *direction);
- extern unsigned long pnv_tce_get(struct iommu_table *tbl, long index);
- extern struct iommu_table_ops pnv_ioda1_iommu_ops;
- 
-diff --git a/drivers/vfio/vfio_iommu_spapr_tce.c b/drivers/vfio/vfio_iommu_spapr_tce.c
-index 7f62e92..9d240b4 100644
---- a/drivers/vfio/vfio_iommu_spapr_tce.c
-+++ b/drivers/vfio/vfio_iommu_spapr_tce.c
-@@ -446,9 +446,6 @@ static void tce_iommu_unuse_page(struct tce_container *container,
+@@ -518,9 +559,23 @@ static int tce_iommu_attach_group(void *iommu_data,
+ 		goto unlock_exit;
+ 	}
+ 
+-	ret = iommu_take_ownership(table_group->tables[0]);
+-	if (!ret)
+-		container->grp = iommu_group;
++	if (!table_group->ops || !table_group->ops->take_ownership ||
++			!table_group->ops->release_ownership) {
++		ret = tce_iommu_take_ownership(container, table_group);
++	} else {
++		/*
++		 * Disable iommu bypass, otherwise the user can DMA to all of
++		 * our physical memory via the bypass window instead of just
++		 * the pages that has been explicitly mapped into the iommu
++		 */
++		table_group->ops->take_ownership(table_group);
++		ret = 0;
++	}
++
++	if (ret)
++		goto unlock_exit;
++
++	container->grp = iommu_group;
+ 
+ unlock_exit:
+ 	mutex_unlock(&container->lock);
+@@ -533,7 +588,6 @@ static void tce_iommu_detach_group(void *iommu_data,
  {
- 	struct page *page;
- 
--	if (!(oldtce & (TCE_PCI_READ | TCE_PCI_WRITE)))
--		return;
--
- 	/*
- 	 * VFIO cannot map/unmap when a container is not enabled so
- 	 * we would not need this check but KVM could map/unmap and if
-@@ -458,14 +455,10 @@ static void tce_iommu_unuse_page(struct tce_container *container,
- 	if (!container->enabled)
- 		return;
- 
--	page = pfn_to_page(__pa(oldtce) >> PAGE_SHIFT);
--
--	if (oldtce & TCE_PCI_WRITE)
--		SetPageDirty(page);
--
- 	if (tce_preregistered(container))
- 		return;
- 
-+	page = pfn_to_page(__pa(oldtce) >> PAGE_SHIFT);
- 	put_page(page);
- }
- 
-@@ -473,14 +466,19 @@ static int tce_iommu_clear(struct tce_container *container,
- 		struct iommu_table *tbl,
- 		unsigned long entry, unsigned long pages)
- {
--	unsigned long oldtce;
-+	long ret;
-+	enum dma_data_direction direction;
-+	unsigned long tce;
- 
- 	for ( ; pages; --pages, ++entry) {
--		oldtce = iommu_clear_tce(tbl, entry);
--		if (!oldtce)
-+		direction = DMA_NONE;
-+		tce = (unsigned long) __va(0);
-+		ret = iommu_tce_xchg(tbl, entry, &tce, &direction);
-+		if (ret)
- 			continue;
- 
--		tce_iommu_unuse_page(container, (unsigned long) __va(oldtce));
-+		if (direction != DMA_NONE)
-+			tce_iommu_unuse_page(container, tce);
- 	}
- 
- 	return 0;
-@@ -521,12 +519,13 @@ static int tce_get_hva_cached(struct tce_container *container,
- 
- static long tce_iommu_build(struct tce_container *container,
- 		struct iommu_table *tbl,
--		unsigned long entry, unsigned long tce, unsigned long pages)
-+		unsigned long entry, unsigned long tce, unsigned long pages,
-+		enum dma_data_direction direction)
- {
- 	long i, ret = 0;
- 	struct page *page;
- 	unsigned long hva;
--	enum dma_data_direction direction = iommu_tce_direction(tce);
-+	enum dma_data_direction dirtmp;
- 
- 	for (i = 0; i < pages; ++i) {
- 		if (tce_preregistered(container))
-@@ -546,15 +545,21 @@ static long tce_iommu_build(struct tce_container *container,
- 
- 		/* Preserve offset within IOMMU page */
- 		hva |= tce & IOMMU_PAGE_MASK(tbl) & ~PAGE_MASK;
-+		dirtmp = direction;
- 
--		ret = iommu_tce_build(tbl, entry + i, hva, direction);
-+		ret = iommu_tce_xchg(tbl, entry + i, &hva, &dirtmp);
- 		if (ret) {
-+			/* dirtmp cannot be DMA_NONE here */
- 			tce_iommu_unuse_page(container, hva);
- 			pr_err("iommu_tce: %s failed ioba=%lx, tce=%lx, ret=%ld\n",
- 					__func__, entry << tbl->it_page_shift,
- 					tce, ret);
- 			break;
- 		}
-+
-+		if (dirtmp != DMA_NONE)
-+			tce_iommu_unuse_page(container, hva);
-+
- 		tce += IOMMU_PAGE_SIZE(tbl);
- 	}
- 
-@@ -619,7 +624,7 @@ static long tce_iommu_ioctl(void *iommu_data,
- 	case VFIO_IOMMU_MAP_DMA: {
- 		struct vfio_iommu_type1_dma_map param;
- 		struct iommu_table *tbl;
--		unsigned long tce;
-+		enum dma_data_direction direction;
- 
- 		if (!container->enabled)
- 			return -EPERM;
-@@ -640,24 +645,33 @@ static long tce_iommu_ioctl(void *iommu_data,
- 		if (!tbl)
- 			return -ENXIO;
- 
--		if ((param.size & ~IOMMU_PAGE_MASK(tbl)) ||
--				(param.vaddr & ~IOMMU_PAGE_MASK(tbl)))
-+		if (param.size & ~IOMMU_PAGE_MASK(tbl))
-+			return -EINVAL;
-+
-+		if (param.vaddr & (TCE_PCI_READ | TCE_PCI_WRITE))
- 			return -EINVAL;
- 
- 		/* iova is checked by the IOMMU API */
--		tce = param.vaddr;
- 		if (param.flags & VFIO_DMA_MAP_FLAG_READ)
--			tce |= TCE_PCI_READ;
--		if (param.flags & VFIO_DMA_MAP_FLAG_WRITE)
--			tce |= TCE_PCI_WRITE;
-+			if (param.flags & VFIO_DMA_MAP_FLAG_WRITE)
-+				direction = DMA_BIDIRECTIONAL;
-+			else
-+				direction = DMA_TO_DEVICE;
-+		else
-+			if (param.flags & VFIO_DMA_MAP_FLAG_WRITE)
-+				direction = DMA_FROM_DEVICE;
-+			else
-+				return -EINVAL;
- 
--		ret = iommu_tce_put_param_check(tbl, param.iova, tce);
-+		ret = iommu_tce_put_param_check(tbl, param.iova, param.vaddr);
- 		if (ret)
- 			return ret;
- 
- 		ret = tce_iommu_build(container, tbl,
- 				param.iova >> tbl->it_page_shift,
--				tce, param.size >> tbl->it_page_shift);
-+				param.vaddr,
-+				param.size >> tbl->it_page_shift,
-+				direction);
- 
- 		iommu_flush_tce(tbl);
- 
+ 	struct tce_container *container = iommu_data;
+ 	struct iommu_table_group *table_group;
+-	struct iommu_table *tbl;
+ 
+ 	mutex_lock(&container->lock);
+ 	if (iommu_group != container->grp) {
+@@ -556,9 +610,11 @@ static void tce_iommu_detach_group(void *iommu_data,
+ 	table_group = iommu_group_get_iommudata(iommu_group);
+ 	BUG_ON(!table_group);
+ 
+-	tbl = table_group->tables[0];
+-	tce_iommu_clear(container, tbl, tbl->it_offset, tbl->it_size);
+-	iommu_release_ownership(tbl);
++	/* Kernel owns the device now, we can restore bypass */
++	if (!table_group->ops || !table_group->ops->release_ownership)
++		tce_iommu_release_ownership(container, table_group);
++	else
++		table_group->ops->release_ownership(table_group);
+ 
+ unlock_exit:
+ 	mutex_unlock(&container->lock);
 -- 
-2.0.0
+2.4.0.rc3.8.gfb3e7d5
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