Re: [PATCH kernel v10 16/34] powerpc/spapr: vfio: Replace iommu_table with iommu_table_group

From: Alexey Kardashevskiy
Date: Wed May 13 2015 - 23:31:53 EST

On 05/14/2015 11:21 AM, Gavin Shan wrote:
On Tue, May 12, 2015 at 01:39:05AM +1000, Alexey Kardashevskiy wrote:
Modern IBM POWERPC systems support multiple (currently two) TCE tables
per IOMMU group (a.k.a. PE). This adds a iommu_table_group container
for TCE tables. Right now just one table is supported.

This defines iommu_table_group struct which stores pointers to
iommu_group and iommu_table(s). This replaces iommu_table with
iommu_table_group where iommu_table was used to identify a group:
- iommu_register_group();
- iommudata of generic iommu_group;

This removes @data from iommu_table as it_table_group provides
same access to pnv_ioda_pe.

For IODA, instead of embedding iommu_table, the new iommu_table_group
keeps pointers to those. The iommu_table structs are allocated
dynamically.

For P5IOC2, both iommu_table_group and iommu_table are embedded into
PE struct. As there is no EEH and SRIOV support for P5IOC2,
iommu_free_table() should not be called on iommu_table struct pointers
so we can keep it embedded in pnv_phb::p5ioc2.

For pSeries, this replaces multiple calls of kzalloc_node() with a new
iommu_pseries_alloc_group() helper and stores the table group struct
pointer into the pci_dn struct. For release, a iommu_table_free_group()
helper is added.

This moves iommu_table struct allocation from SR-IOV code to
the generic DMA initialization code in pnv_pci_ioda_setup_dma_pe and
pnv_pci_ioda2_setup_dma_pe as this is where DMA is actually initialized.
This change is here because those lines had to be changed anyway.

This should cause no behavioural change.

Signed-off-by: Alexey Kardashevskiy <aik@xxxxxxxxx>

Reviewed-by: Gavin Shan <gwshan@xxxxxxxxxxxxxxxxxx>

---
Changes:
v10:
* new to the series, separated from
"powerpc/spapr: vfio: Switch from iommu_table to new iommu_table_group"
* iommu_table is not embedded into iommu_table_group but allocated
dynamically in most cases
* iommu_table allocation is moved to a single place for IODA2's
pnv_pci_ioda_setup_dma_pe where it belongs to
* added list of groups into iommu_table; most of the code just looks at
the first item to keep the patch simpler
---
arch/powerpc/include/asm/iommu.h | 17 +++--
arch/powerpc/include/asm/pci-bridge.h | 2 +-
arch/powerpc/kernel/iommu.c | 17 ++---
arch/powerpc/platforms/powernv/pci-ioda.c | 55 +++++++-------
arch/powerpc/platforms/powernv/pci-p5ioc2.c | 18 +++--
arch/powerpc/platforms/powernv/pci.h | 3 +-
arch/powerpc/platforms/pseries/iommu.c | 107 +++++++++++++++++++---------
drivers/vfio/vfio_iommu_spapr_tce.c | 23 +++---
8 files changed, 152 insertions(+), 90 deletions(-)

diff --git a/arch/powerpc/include/asm/iommu.h b/arch/powerpc/include/asm/iommu.h
index e2a45c3..61bde1a 100644
--- a/arch/powerpc/include/asm/iommu.h
+++ b/arch/powerpc/include/asm/iommu.h
@@ -92,13 +92,10 @@ struct iommu_table {
unsigned long *it_map; /* A simple allocation bitmap for now */
unsigned long it_page_shift;/* table iommu page size */
#ifdef CONFIG_IOMMU_API
- struct iommu_group *it_group;
+ struct iommu_table_group *it_table_group;
#endif
struct iommu_table_ops *it_ops;
void (*set_bypass)(struct iommu_table *tbl, bool enable);
-#ifdef CONFIG_PPC_POWERNV
- void *data;
-#endif
};

/* Pure 2^n version of get_order */
@@ -130,13 +127,21 @@ extern void iommu_free_table(struct iommu_table *tbl, const char *node_name);
extern struct iommu_table *iommu_init_table(struct iommu_table * tbl,
int nid);
#ifdef CONFIG_IOMMU_API
-extern void iommu_register_group(struct iommu_table *tbl,
+
+#define IOMMU_TABLE_GROUP_MAX_TABLES 1
+
+struct iommu_table_group {
+ struct iommu_group *group;
+ struct iommu_table *tables[IOMMU_TABLE_GROUP_MAX_TABLES];
+};
+
+extern void iommu_register_group(struct iommu_table_group *table_group,
int pci_domain_number, unsigned long pe_num);
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);
#else
-static inline void iommu_register_group(struct iommu_table *tbl,
+static inline void iommu_register_group(struct iommu_table_group *table_group,
int pci_domain_number,
unsigned long pe_num)
{
diff --git a/arch/powerpc/include/asm/pci-bridge.h b/arch/powerpc/include/asm/pci-bridge.h
index 1811c44..e2d7479 100644
--- a/arch/powerpc/include/asm/pci-bridge.h
+++ b/arch/powerpc/include/asm/pci-bridge.h
@@ -185,7 +185,7 @@ struct pci_dn {

struct pci_dn *parent;
struct pci_controller *phb; /* for pci devices */
- struct iommu_table *iommu_table; /* for phb's or bridges */
+ struct iommu_table_group *table_group; /* for phb's or bridges */
struct device_node *node; /* back-pointer to the device_node */

int pci_ext_config_space; /* for pci devices */
diff --git a/arch/powerpc/kernel/iommu.c b/arch/powerpc/kernel/iommu.c
index 16be6aa..79e8b43 100644
--- a/arch/powerpc/kernel/iommu.c
+++ b/arch/powerpc/kernel/iommu.c
@@ -886,11 +886,12 @@ EXPORT_SYMBOL_GPL(iommu_direction_to_tce_perm);
*/
static void group_release(void *iommu_data)
{
- struct iommu_table *tbl = iommu_data;
- tbl->it_group = NULL;
+ struct iommu_table_group *table_group = iommu_data;
+
+ table_group->group = NULL;
}

-void iommu_register_group(struct iommu_table *tbl,
+void iommu_register_group(struct iommu_table_group *table_group,
int pci_domain_number, unsigned long pe_num)
{
struct iommu_group *grp;
@@ -902,8 +903,8 @@ void iommu_register_group(struct iommu_table *tbl,
PTR_ERR(grp));
return;
}
- tbl->it_group = grp;
- iommu_group_set_iommudata(grp, tbl, group_release);
+ table_group->group = grp;
+ iommu_group_set_iommudata(grp, table_group, group_release);
name = kasprintf(GFP_KERNEL, "domain%d-pe%lx",
pci_domain_number, pe_num);
if (!name)
@@ -1091,7 +1092,7 @@ int iommu_add_device(struct device *dev)
}

tbl = get_iommu_table_base(dev);
- if (!tbl || !tbl->it_group) {
+ if (!tbl || !tbl->it_table_group || !tbl->it_table_group->group) {
pr_debug("%s: Skipping device %s with no tbl\n",
__func__, dev_name(dev));
return 0;
@@ -1099,7 +1100,7 @@ int iommu_add_device(struct device *dev)

pr_debug("%s: Adding %s to iommu group %d\n",
__func__, dev_name(dev),
- iommu_group_id(tbl->it_group));
+ iommu_group_id(tbl->it_table_group->group));

if (PAGE_SIZE < IOMMU_PAGE_SIZE(tbl)) {
pr_err("%s: Invalid IOMMU page size %lx (%lx) on %s\n",
@@ -1108,7 +1109,7 @@ int iommu_add_device(struct device *dev)
return -EINVAL;
}

- return iommu_group_add_device(tbl->it_group, dev);
+ return iommu_group_add_device(tbl->it_table_group->group, dev);
}
EXPORT_SYMBOL_GPL(iommu_add_device);

diff --git a/arch/powerpc/platforms/powernv/pci-ioda.c b/arch/powerpc/platforms/powernv/pci-ioda.c
index 1b43e25..02ed448 100644
--- a/arch/powerpc/platforms/powernv/pci-ioda.c
+++ b/arch/powerpc/platforms/powernv/pci-ioda.c
@@ -1087,10 +1087,6 @@ static void pnv_ioda_setup_bus_PE(struct pci_bus *bus, int all)
return;
}

- pe->tce32_table = kzalloc_node(sizeof(struct iommu_table),
- GFP_KERNEL, hose->node);
- pe->tce32_table->data = pe;
-
/* Associate it with all child devices */
pnv_ioda_setup_same_PE(bus, pe);

@@ -1292,11 +1288,12 @@ static void pnv_pci_ioda2_release_dma_pe(struct pci_dev *dev, struct pnv_ioda_pe
struct iommu_table *tbl;
unsigned long addr;
int64_t rc;
+ struct iommu_table_group *table_group;

bus = dev->bus;
hose = pci_bus_to_host(bus);
phb = hose->private_data;
- tbl = pe->tce32_table;
+ tbl = pe->table_group.tables[0];
addr = tbl->it_base;

opal_pci_map_pe_dma_window(phb->opal_id, pe->pe_number,
@@ -1311,13 +1308,14 @@ static void pnv_pci_ioda2_release_dma_pe(struct pci_dev *dev, struct pnv_ioda_pe
if (rc)
pe_warn(pe, "OPAL error %ld release DMA window\n", rc);

- if (tbl->it_group) {
- iommu_group_put(tbl->it_group);
- BUG_ON(tbl->it_group);
+ table_group = tbl->it_table_group;
+ if (table_group->group) {
+ iommu_group_put(table_group->group);
+ BUG_ON(table_group->group);
}
iommu_free_table(tbl, of_node_full_name(dev->dev.of_node));
free_pages(addr, get_order(TCE32_TABLE_SIZE));
- pe->tce32_table = NULL;
+ pe->table_group.tables[0] = NULL;
}

static void pnv_ioda_release_vf_PE(struct pci_dev *pdev, u16 num_vfs)
@@ -1465,10 +1463,6 @@ static void pnv_ioda_setup_vf_PE(struct pci_dev *pdev, u16 num_vfs)
continue;
}

- pe->tce32_table = kzalloc_node(sizeof(struct iommu_table),
- GFP_KERNEL, hose->node);
- pe->tce32_table->data = pe;
-
/* Put PE to the list */
mutex_lock(&phb->ioda.pe_list_mutex);
list_add_tail(&pe->list, &phb->ioda.pe_list);
@@ -1603,7 +1597,7 @@ static void pnv_pci_ioda_dma_dev_setup(struct pnv_phb *phb, struct pci_dev *pdev

pe = &phb->ioda.pe_array[pdn->pe_number];
WARN_ON(get_dma_ops(&pdev->dev) != &dma_iommu_ops);
- set_iommu_table_base(&pdev->dev, pe->tce32_table);
+ set_iommu_table_base(&pdev->dev, pe->table_group.tables[0]);
/*
* Note: iommu_add_device() will fail here as
* for physical PE: the device is already added by now;
@@ -1636,7 +1630,7 @@ static int pnv_pci_ioda_dma_set_mask(struct pnv_phb *phb,
} else {
dev_info(&pdev->dev, "Using 32-bit DMA via iommu\n");
set_dma_ops(&pdev->dev, &dma_iommu_ops);
- set_iommu_table_base(&pdev->dev, pe->tce32_table);
+ set_iommu_table_base(&pdev->dev, pe->table_group.tables[0]);
}
*pdev->dev.dma_mask = dma_mask;
return 0;
@@ -1670,7 +1664,7 @@ static void pnv_ioda_setup_bus_dma(struct pnv_ioda_pe *pe,
struct pci_dev *dev;

list_for_each_entry(dev, &bus->devices, bus_list) {
- set_iommu_table_base(&dev->dev, pe->tce32_table);
+ set_iommu_table_base(&dev->dev, pe->table_group.tables[0]);
iommu_add_device(&dev->dev);

if (dev->subordinate)
@@ -1681,7 +1675,8 @@ static void pnv_ioda_setup_bus_dma(struct pnv_ioda_pe *pe,
static void pnv_pci_ioda1_tce_invalidate(struct iommu_table *tbl,
unsigned long index, unsigned long npages, bool rm)
{
- struct pnv_ioda_pe *pe = tbl->data;
+ struct pnv_ioda_pe *pe = container_of(tbl->it_table_group,
+ struct pnv_ioda_pe, table_group);
__be64 __iomem *invalidate = rm ?
(__be64 __iomem *)pe->tce_inval_reg_phys :
(__be64 __iomem *)tbl->it_index;
@@ -1758,7 +1753,8 @@ static struct iommu_table_ops pnv_ioda1_iommu_ops = {
static void pnv_pci_ioda2_tce_invalidate(struct iommu_table *tbl,
unsigned long index, unsigned long npages, bool rm)
{
- struct pnv_ioda_pe *pe = tbl->data;
+ struct pnv_ioda_pe *pe = container_of(tbl->it_table_group,
+ struct pnv_ioda_pe, table_group);
unsigned long start, end, inc;
__be64 __iomem *invalidate = rm ?
(__be64 __iomem *)pe->tce_inval_reg_phys :
@@ -1834,8 +1830,12 @@ static void pnv_pci_ioda_setup_dma_pe(struct pnv_phb *phb,
if (WARN_ON(pe->tce32_seg >= 0))
return;

- tbl = pe->tce32_table;
- iommu_register_group(tbl, phb->hose->global_number, pe->pe_number);
+ tbl = kzalloc_node(sizeof(struct iommu_table), GFP_KERNEL,
+ phb->hose->node);
+ tbl->it_table_group = &pe->table_group;
+ pe->table_group.tables[0] = tbl;
+ iommu_register_group(&pe->table_group, phb->hose->global_number,
+ pe->pe_number);

/* Grab a 32-bit TCE table */
pe->tce32_seg = base;
@@ -1914,7 +1914,8 @@ 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)
{
- struct pnv_ioda_pe *pe = tbl->data;
+ struct pnv_ioda_pe *pe = container_of(tbl->it_table_group,
+ struct pnv_ioda_pe, table_group);
uint16_t window_id = (pe->pe_number << 1 ) + 1;
int64_t rc;

@@ -1948,10 +1949,10 @@ static void pnv_pci_ioda2_setup_bypass_pe(struct pnv_phb *phb,
pe->tce_bypass_base = 1ull << 59;

/* Install set_bypass callback for VFIO */
- pe->tce32_table->set_bypass = pnv_pci_ioda2_set_bypass;
+ pe->table_group.tables[0]->set_bypass = pnv_pci_ioda2_set_bypass;

It could be simplied as:

tbl->set_bypass = pnv_pci_ioda2_set_bypass;

No, this is worse in this case. The whole idea of the patch to be mechanical as much as we can. That means:
s/tce32_table/table_group.tables[0]/
If I do what you suggest, the reviewers will have to look further if "tbl" has been initialized properly, etc.

And later in this patchset I am getting rid of pnv_pci_ioda2_setup_bypass_pe so there is no point to try making it look nice :)


/* Enable bypass by default */
- pnv_pci_ioda2_set_bypass(pe->tce32_table, true);
+ pnv_pci_ioda2_set_bypass(pe->table_group.tables[0], true);

Similar to above:

tbl->set_bypass(tbl, true);

}

static void pnv_pci_ioda2_setup_dma_pe(struct pnv_phb *phb,
@@ -1968,8 +1969,12 @@ static void pnv_pci_ioda2_setup_dma_pe(struct pnv_phb *phb,
if (WARN_ON(pe->tce32_seg >= 0))
return;

- tbl = pe->tce32_table;
- iommu_register_group(tbl, phb->hose->global_number, pe->pe_number);
+ tbl = kzalloc_node(sizeof(struct iommu_table), GFP_KERNEL,
+ phb->hose->node);
+ tbl->it_table_group = &pe->table_group;
+ pe->table_group.tables[0] = tbl;
+ iommu_register_group(&pe->table_group, phb->hose->global_number,
+ pe->pe_number);

/* The PE will reserve all possible 32-bits space */
pe->tce32_seg = 0;
diff --git a/arch/powerpc/platforms/powernv/pci-p5ioc2.c b/arch/powerpc/platforms/powernv/pci-p5ioc2.c
index 2722c1a..4ea9def 100644
--- a/arch/powerpc/platforms/powernv/pci-p5ioc2.c
+++ b/arch/powerpc/platforms/powernv/pci-p5ioc2.c
@@ -92,14 +92,16 @@ static struct iommu_table_ops pnv_p5ioc2_iommu_ops = {
static void pnv_pci_p5ioc2_dma_dev_setup(struct pnv_phb *phb,
struct pci_dev *pdev)
{
- if (phb->p5ioc2.iommu_table.it_map == NULL) {
- phb->p5ioc2.iommu_table.it_ops = &pnv_p5ioc2_iommu_ops;
- iommu_init_table(&phb->p5ioc2.iommu_table, phb->hose->node);
- iommu_register_group(&phb->p5ioc2.iommu_table,
+ struct iommu_table *tbl = phb->p5ioc2.table_group.tables[0];
+
+ if (!tbl->it_map) {
+ tbl->it_ops = &pnv_p5ioc2_iommu_ops;
+ iommu_init_table(tbl, phb->hose->node);
+ iommu_register_group(&phb->p5ioc2.table_group,
pci_domain_nr(phb->hose->bus), phb->opal_id);
}

- set_iommu_table_base(&pdev->dev, &phb->p5ioc2.iommu_table);
+ set_iommu_table_base(&pdev->dev, tbl);
iommu_add_device(&pdev->dev);
}

@@ -180,6 +182,12 @@ static void __init pnv_pci_init_p5ioc2_phb(struct device_node *np, u64 hub_id,
pnv_pci_setup_iommu_table(&phb->p5ioc2.iommu_table,
tce_mem, tce_size, 0,
IOMMU_PAGE_SHIFT_4K);
+ /*
+ * We do not allocate iommu_table as we do not support
+ * hotplug or SRIOV on P5IOC2 and therefore iommu_free_table()
+ * should not be called for phb->p5ioc2.table_group.tables[0] ever.
+ */
+ phb->p5ioc2.table_group.tables[0] = &phb->p5ioc2.iommu_table;
}

void __init pnv_pci_init_p5ioc2_hub(struct device_node *np)
diff --git a/arch/powerpc/platforms/powernv/pci.h b/arch/powerpc/platforms/powernv/pci.h
index ec26afd..720cc99 100644
--- a/arch/powerpc/platforms/powernv/pci.h
+++ b/arch/powerpc/platforms/powernv/pci.h
@@ -57,7 +57,7 @@ struct pnv_ioda_pe {
/* "Base" iommu table, ie, 4K TCEs, 32-bit DMA */
int tce32_seg;
int tce32_segcount;
- struct iommu_table *tce32_table;
+ struct iommu_table_group table_group;
phys_addr_t tce_inval_reg_phys;

/* 64-bit TCE bypass region */
@@ -123,6 +123,7 @@ struct pnv_phb {
union {
struct {
struct iommu_table iommu_table;
+ struct iommu_table_group table_group;
} p5ioc2;

struct {
diff --git a/arch/powerpc/platforms/pseries/iommu.c b/arch/powerpc/platforms/pseries/iommu.c
index 4f2ab90..ad5ac6d 100644
--- a/arch/powerpc/platforms/pseries/iommu.c
+++ b/arch/powerpc/platforms/pseries/iommu.c
@@ -52,14 +52,49 @@

#include "pseries.h"

-static void iommu_pseries_free_table(struct iommu_table *tbl,
+static struct iommu_table_group *iommu_pseries_alloc_group(int node)

Since it's a static function, the name could be simplied to
iommu_group_alloc(), or alloc_iommu_group(). But it might
not the style you like :-)

Giving it the name like this I am telling people not to try reusing it for anything else + easier to grep.



+{
+ struct iommu_table_group *table_group = NULL;
+ struct iommu_table *tbl = NULL;
+
+ table_group = kzalloc_node(sizeof(struct iommu_table_group), GFP_KERNEL,
+ node);
+ if (!table_group)
+ goto fail_exit;
+
+ tbl = kzalloc_node(sizeof(struct iommu_table), GFP_KERNEL, node);
+ if (!tbl)
+ goto fail_exit;
+
+ tbl->it_table_group = table_group;
+ table_group->tables[0] = tbl;
+
+ return table_group;
+
+fail_exit:
+ kfree(table_group);
+ kfree(tbl);
+
+ return NULL;
+}
+
+static void iommu_pseries_free_group(struct iommu_table_group *table_group,
const char *node_name)

Same suggestion as above.

{
- if (tbl->it_group) {
- iommu_group_put(tbl->it_group);
- BUG_ON(tbl->it_group);
+ struct iommu_table *tbl;
+
+ if (!table_group)
+ return;
+
+ if (table_group->group) {
+ iommu_group_put(table_group->group);
+ BUG_ON(table_group->group);
}
+
+ tbl = table_group->tables[0];
iommu_free_table(tbl, node_name);

It might worthy to have one check:

if (table_group->tables[0])
iommu_free_table(table_group->tables[0], node_name);


BUG_ON() - may be. (table_group->tables[0] == NULL) cannot happen normally (no memory corruption, etc) as iommu_pseries_alloc_group() allocated both table_group and table or nothing.



+
+ kfree(table_group);
}

static void tce_invalidate_pSeries_sw(struct iommu_table *tbl,
@@ -629,13 +664,13 @@ static void pci_dma_bus_setup_pSeries(struct pci_bus *bus)
pci->phb->dma_window_size = 0x8000000ul;
pci->phb->dma_window_base_cur = 0x8000000ul;

- tbl = kzalloc_node(sizeof(struct iommu_table), GFP_KERNEL,
- pci->phb->node);
+ pci->table_group = iommu_pseries_alloc_group(pci->phb->node);
+ tbl = pci->table_group->tables[0];

The orginal code isn't checking "!pci->table_group". If this function is
called only at bootup time, it would be nice to see kernel crash. Otherwise,
I guess it's still worthy to have the check :-)


kzalloc_node() is supposed to print something when fails.



--
Alexey
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