Re: [PATCH kernel v9 23/32] powerpc/powernv/ioda: Define and implement DMA table/window management callbacks

On Wed, Apr 29, 2015 at 07:44:20PM +1000, Alexey Kardashevskiy wrote:

On 04/29/2015 03:30 PM, David Gibson wrote:

quoted

On Sat, Apr 25, 2015 at 10:14:47PM +1000, Alexey Kardashevskiy wrote:

quoted

This extends iommu_table_group_ops by a set of callbacks to support
dynamic DMA windows management.

create_table() creates a TCE table with specific parameters.
it receives iommu_table_group to know nodeid in order to allocate
TCE table memory closer to the PHB. The exact format of allocated
multi-level table might be also specific to the PHB model (not
the case now though).
This callback calculated the DMA window offset on a PCI bus from @num
and stores it in a just created table.

set_window() sets the window at specified TVT index + @num on PHB.

unset_window() unsets the window from specified TVT.

This adds a free() callback to iommu_table_ops to free the memory
(potentially a tree of tables) allocated for the TCE table.

Doesn't the free callback belong with the previous patch introducing
multi-level tables?

If I did that, you would say "why is it here if nothing calls it" on
"multilevel" patch and "I see the allocation but I do not see memory
release" ;)

Yeah, fair enough ;)

I need some rule of thumb here. I think it is a bit cleaner if the same
patch adds a callback for memory allocation and its counterpart, no?

On further consideration, yes, I think you're right.

quoted

quoted

create_table() and free() are supposed to be called once per
VFIO container and set_window()/unset_window() are supposed to be
called for every group in a container.

This adds IOMMU capabilities to iommu_table_group such as default
32bit window parameters and others.

Signed-off-by: Alexey Kardashevskiy <redacted>
---
 arch/powerpc/include/asm/iommu.h            | 19 ++++++++
 arch/powerpc/platforms/powernv/pci-ioda.c   | 75 ++++++++++++++++++++++++++---
 arch/powerpc/platforms/powernv/pci-p5ioc2.c | 12 +++--
 3 files changed, 96 insertions(+), 10 deletions(-)

diff --git a/arch/powerpc/include/asm/iommu.h b/arch/powerpc/include/asm/iommu.h
index 0f50ee2..7694546 100644
--- a/arch/powerpc/include/asm/iommu.h
+++ b/arch/powerpc/include/asm/iommu.h

@@ -70,6 +70,7 @@ struct iommu_table_ops {
 	/* get() returns a physical address */
 	unsigned long (*get)(struct iommu_table *tbl, long index);
 	void (*flush)(struct iommu_table *tbl);
+	void (*free)(struct iommu_table *tbl);
 };

 /* These are used by VIO */

@@ -148,6 +149,17 @@ extern struct iommu_table *iommu_init_table(struct iommu_table * tbl,
 struct iommu_table_group;

 struct iommu_table_group_ops {
+	long (*create_table)(struct iommu_table_group *table_group,
+			int num,
+			__u32 page_shift,
+			__u64 window_size,
+			__u32 levels,
+			struct iommu_table *tbl);
+	long (*set_window)(struct iommu_table_group *table_group,
+			int num,
+			struct iommu_table *tblnew);
+	long (*unset_window)(struct iommu_table_group *table_group,
+			int num);
 	/*
 	 * Switches ownership from the kernel itself to an external
 	 * user. While onwership is taken, the kernel cannot use IOMMU itself.

@@ -160,6 +172,13 @@ struct iommu_table_group {
 #ifdef CONFIG_IOMMU_API
 	struct iommu_group *group;
 #endif
+	/* Some key properties of IOMMU */
+	__u32 tce32_start;
+	__u32 tce32_size;
+	__u64 pgsizes; /* Bitmap of supported page sizes */
+	__u32 max_dynamic_windows_supported;
+	__u32 max_levels;

With this information, table_group seems even more like a bad name.
"iommu_state" maybe?

Please, no. We will never come to agreement then :( And "iommu_state" is too
general anyway, it won't pass.

quoted

quoted

 	struct iommu_table tables[IOMMU_TABLE_GROUP_MAX_TABLES];
 	struct iommu_table_group_ops *ops;
 };

diff --git a/arch/powerpc/platforms/powernv/pci-ioda.c b/arch/powerpc/platforms/powernv/pci-ioda.c
index cc1d09c..4828837 100644
--- a/arch/powerpc/platforms/powernv/pci-ioda.c
+++ b/arch/powerpc/platforms/powernv/pci-ioda.c

@@ -24,6 +24,7 @@
 #include <linux/msi.h>
 #include <linux/memblock.h>
 #include <linux/iommu.h>
+#include <linux/sizes.h>

 #include <asm/sections.h>
 #include <asm/io.h>

@@ -1846,6 +1847,7 @@ static struct iommu_table_ops pnv_ioda2_iommu_ops = {
 #endif
 	.clear = pnv_ioda2_tce_free,
 	.get = pnv_tce_get,
+	.free = pnv_pci_free_table,
 };

 static void pnv_pci_ioda_setup_opal_tce_kill(struct pnv_phb *phb,

@@ -1936,6 +1938,8 @@ static void pnv_pci_ioda_setup_dma_pe(struct pnv_phb *phb,
 				 TCE_PCI_SWINV_PAIR);

 	tbl->it_ops = &pnv_ioda1_iommu_ops;
+	pe->table_group.tce32_start = tbl->it_offset << tbl->it_page_shift;
+	pe->table_group.tce32_size = tbl->it_size << tbl->it_page_shift;
 	iommu_init_table(tbl, phb->hose->node);

 	if (pe->flags & PNV_IODA_PE_DEV) {

@@ -1961,7 +1965,7 @@ static void pnv_pci_ioda_setup_dma_pe(struct pnv_phb *phb,
 }

 static long pnv_pci_ioda2_set_window(struct iommu_table_group *table_group,
-		struct iommu_table *tbl)
+		int num, struct iommu_table *tbl)
 {
 	struct pnv_ioda_pe *pe = container_of(table_group, struct pnv_ioda_pe,
 			table_group);

@@ -1972,9 +1976,10 @@ static long pnv_pci_ioda2_set_window(struct iommu_table_group *table_group,
 	const __u64 start_addr = tbl->it_offset << tbl->it_page_shift;
 	const __u64 win_size = tbl->it_size << tbl->it_page_shift;

-	pe_info(pe, "Setting up window at %llx..%llx "
+	pe_info(pe, "Setting up window#%d at %llx..%llx "
 			"pgsize=0x%x tablesize=0x%lx "
 			"levels=%d levelsize=%x\n",
+			num,
 			start_addr, start_addr + win_size - 1,
 			1UL << tbl->it_page_shift, tbl->it_size << 3,
 			tbl->it_indirect_levels + 1, tbl->it_level_size << 3);

@@ -1987,7 +1992,7 @@ static long pnv_pci_ioda2_set_window(struct iommu_table_group *table_group,
 	 */
 	rc = opal_pci_map_pe_dma_window(phb->opal_id,
 			pe->pe_number,
-			pe->pe_number << 1,
+			(pe->pe_number << 1) + num,

Heh, yes, well, that makes it rather clear that only 2 tables are possible.

quoted

 			tbl->it_indirect_levels + 1,
 			__pa(tbl->it_base),
 			size << 3,

@@ -2000,7 +2005,7 @@ static long pnv_pci_ioda2_set_window(struct iommu_table_group *table_group,
 	pnv_pci_ioda2_tvt_invalidate(pe);

 	/* Store fully initialized *tbl (may be external) in PE */
-	pe->table_group.tables[0] = *tbl;
+	pe->table_group.tables[num] = *tbl;

I'm a bit confused by this whole set_window thing.  Is the idea that
with multiple groups in a container you have multiple table_group s
each with different copies of the iommu_table structures, but pointing
to the same actual TCE entries (it_base)?

Yes.

quoted

It seems to me not terribly
obvious when you "create" a table and when you "set" a window.

A table is not attached anywhere until its address is programmed (in
set_window()) to the hardware, it is just a table in memory. For
POWER8/IODA2, I create a table before I attach any group to a container,
then I program this table to every attached container, right now it is done
in container's attach_group(). So later we can hotplug any host PCI device
to a container - it will program same TCE table to every new group in the
container.

So you "create" once, then "set" it to one or more table_groups?  It
seems odd that "create" is a table_group callback in that case.

quoted

It's also kind of hard to assess whether the relative lifetimes are
correct of the table_group, struct iommu_table and the actual TCE tables.

That is true. Do not know how to improve this though.

So I think the scheme I suggested in reply to an earlier patch helps
this.  With that the lifetime of the struct iommu_table represents the
lifetime of the TCE table in the hardware sense as well, which I think
makes things clearer.

quoted

Would it make more sense for table_group to become the
non-vfio-specific counterpart to the vfio container?
i.e. representing one set of DMA mappings, which one or more PEs could
be bound to.

table_group is embedded into PE and table/table_group callbacks access PE
when invalidating TCE table. So I will need something to access PE. Or just
have an array of 2 iommu_table.

quoted

quoted

 	return 0;
 fail:

@@ -2061,6 +2066,53 @@ static void pnv_pci_ioda2_setup_bypass_pe(struct pnv_phb *phb,
 }

 #ifdef CONFIG_IOMMU_API
+static long pnv_pci_ioda2_create_table(struct iommu_table_group *table_group,
+		int num, __u32 page_shift, __u64 window_size, __u32 levels,
+		struct iommu_table *tbl)
+{
+	struct pnv_ioda_pe *pe = container_of(table_group, struct pnv_ioda_pe,
+			table_group);
+	int nid = pe->phb->hose->node;
+	__u64 bus_offset = num ? pe->tce_bypass_base : 0;
+	long ret;
+
+	ret = pnv_pci_create_table(table_group, nid, bus_offset, page_shift,
+			window_size, levels, tbl);
+	if (ret)
+		return ret;
+
+	tbl->it_ops = &pnv_ioda2_iommu_ops;
+	if (pe->tce_inval_reg)
+		tbl->it_type |= (TCE_PCI_SWINV_CREATE | TCE_PCI_SWINV_FREE);
+
+	return 0;
+}
+
+static long pnv_pci_ioda2_unset_window(struct iommu_table_group *table_group,
+		int num)
+{
+	struct pnv_ioda_pe *pe = container_of(table_group, struct pnv_ioda_pe,
+			table_group);
+	struct pnv_phb *phb = pe->phb;
+	struct iommu_table *tbl = &pe->table_group.tables[num];
+	long ret;
+
+	pe_info(pe, "Removing DMA window #%d\n", num);
+
+	ret = opal_pci_map_pe_dma_window(phb->opal_id, pe->pe_number,
+			(pe->pe_number << 1) + num,
+			0/* levels */, 0/* table address */,
+			0/* table size */, 0/* page size */);
+	if (ret)
+		pe_warn(pe, "Unmapping failed, ret = %ld\n", ret);
+	else
+		pnv_pci_ioda2_tvt_invalidate(pe);
+
+	memset(tbl, 0, sizeof(*tbl));
+
+	return ret;
+}
+
 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,

@@ -2080,6 +2132,9 @@ static void pnv_ioda2_release_ownership(struct iommu_table_group *table_group)
 }

 static struct iommu_table_group_ops pnv_pci_ioda2_ops = {
+	.create_table = pnv_pci_ioda2_create_table,
+	.set_window = pnv_pci_ioda2_set_window,
+	.unset_window = pnv_pci_ioda2_unset_window,
 	.take_ownership = pnv_ioda2_take_ownership,
 	.release_ownership = pnv_ioda2_release_ownership,
 };

@@ -2102,8 +2157,16 @@ static void pnv_pci_ioda2_setup_dma_pe(struct pnv_phb *phb,
 	pe_info(pe, "Setting up 32-bit TCE table at 0..%08x\n",
 		phb->ioda.m32_pci_base);

+	pe->table_group.tce32_start = 0;
+	pe->table_group.tce32_size = phb->ioda.m32_pci_base;
+	pe->table_group.max_dynamic_windows_supported =
+			IOMMU_TABLE_GROUP_MAX_TABLES;
+	pe->table_group.max_levels = POWERNV_IOMMU_MAX_LEVELS;
+	pe->table_group.pgsizes = SZ_4K | SZ_64K | SZ_16M;
+
 	rc = pnv_pci_create_table(&pe->table_group, pe->phb->hose->node,
-			0, IOMMU_PAGE_SHIFT_4K, phb->ioda.m32_pci_base,
+			pe->table_group.tce32_start, IOMMU_PAGE_SHIFT_4K,
+			pe->table_group.tce32_size,
 			POWERNV_IOMMU_DEFAULT_LEVELS, tbl);
 	if (rc) {
 		pe_err(pe, "Failed to create 32-bit TCE table, err %ld", rc);

@@ -2119,7 +2182,7 @@ static void pnv_pci_ioda2_setup_dma_pe(struct pnv_phb *phb,
 	pe->table_group.ops = &pnv_pci_ioda2_ops;
 #endif

-	rc = pnv_pci_ioda2_set_window(&pe->table_group, tbl);
+	rc = pnv_pci_ioda2_set_window(&pe->table_group, 0, tbl);
 	if (rc) {
 		pe_err(pe, "Failed to configure 32-bit TCE table,"
 		       " err %ld\n", rc);

diff --git a/arch/powerpc/platforms/powernv/pci-p5ioc2.c b/arch/powerpc/platforms/powernv/pci-p5ioc2.c
index 7a6fd92..d9de4c7 100644
--- a/arch/powerpc/platforms/powernv/pci-p5ioc2.c
+++ b/arch/powerpc/platforms/powernv/pci-p5ioc2.c

@@ -116,6 +116,8 @@ static void __init pnv_pci_init_p5ioc2_phb(struct device_node *np, u64 hub_id,
 	u64 phb_id;
 	int64_t rc;
 	static int primary = 1;
+	struct iommu_table_group *table_group;
+	struct iommu_table *tbl;

 	pr_info(" Initializing p5ioc2 PHB %s\n", np->full_name);

@@ -181,14 +183,16 @@ static void __init pnv_pci_init_p5ioc2_phb(struct device_node *np, u64 hub_id,
 	pnv_pci_init_p5ioc2_msis(phb);

 	/* Setup iommu */
-	phb->p5ioc2.table_group.tables[0].it_table_group =
-			&phb->p5ioc2.table_group;
+	table_group = &phb->p5ioc2.table_group;
+	tbl = &phb->p5ioc2.table_group.tables[0];
+	tbl->it_table_group = table_group;

 	/* Setup TCEs */
 	phb->dma_dev_setup = pnv_pci_p5ioc2_dma_dev_setup;
-	pnv_pci_setup_iommu_table(&phb->p5ioc2.table_group.tables[0],
-				  tce_mem, tce_size, 0,
+	pnv_pci_setup_iommu_table(tbl, tce_mem, tce_size, 0,
 				  IOMMU_PAGE_SHIFT_4K);
+	table_group->tce32_start = tbl->it_offset << tbl->it_page_shift;
+	table_group->tce32_size = tbl->it_size << tbl->it_page_shift;

Doesn't pgsizes need to be set here (although it will only include 4K,
I'm assuming).

No, pgsizes are not returned to the userspace for p5ioc2/ioda1 as they do
not support DDW. No pgsize => no DDW.

Ah, ok.

-- 
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