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

David Gibson
2015-04-29T05:50:09Z

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

> 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 <aik@ozlabs.ru>
> ---
> 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?

> 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.

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

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.

> 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).

> }
>
> void __init pnv_pci_init_p5ioc2_hub(struct device_node *np)

--
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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