ioda2: Add get_table_size() to calculate the size of future table

Alexey Kardashevskiy Thu, 30 Apr 2015 21:11:34 -0700

On 04/29/2015 04:40 PM, David Gibson wrote:

On Sat, Apr 25, 2015 at 10:14:51PM +1000, Alexey Kardashevskiy wrote:

This adds a way for the IOMMU user to know how much a new table will
use so it can be accounted in the locked_vm limit before allocation
happens.


This stores the allocated table size in pnv_pci_create_table()
so the locked_vm counter can be updated correctly when a table is
being disposed.

This defines an iommu_table_group_ops callback to let VFIO know
how much memory will be locked if a table is created.

Signed-off-by: Alexey Kardashevskiy <a...@ozlabs.ru>
---
Changes:
v9:
* reimplemented the whole patch
---
  arch/powerpc/include/asm/iommu.h          |  5 +++++
  arch/powerpc/platforms/powernv/pci-ioda.c | 14 ++++++++++++
  arch/powerpc/platforms/powernv/pci.c      | 36 +++++++++++++++++++++++++++++++
  arch/powerpc/platforms/powernv/pci.h      |  2 ++
  4 files changed, 57 insertions(+)

diff --git a/arch/powerpc/include/asm/iommu.h b/arch/powerpc/include/asm/iommu.h
index 1472de3..9844c106 100644
--- a/arch/powerpc/include/asm/iommu.h
+++ b/arch/powerpc/include/asm/iommu.h
@@ -99,6 +99,7 @@ struct iommu_table {
        unsigned long  it_size;      /* Size of iommu table in entries */
        unsigned long  it_indirect_levels;
        unsigned long  it_level_size;
+       unsigned long  it_allocated_size;
        unsigned long  it_offset;    /* Offset into global table */
        unsigned long  it_base;      /* mapped address of tce table */
        unsigned long  it_index;     /* which iommu table this is */
@@ -155,6 +156,10 @@ extern struct iommu_table *iommu_init_table(struct 
iommu_table * tbl,
  struct iommu_table_group;

  struct iommu_table_group_ops {
+       unsigned long (*get_table_size)(
+                       __u32 page_shift,
+                       __u64 window_size,
+                       __u32 levels);
        long (*create_table)(struct iommu_table_group *table_group,
                        int num,
                        __u32 page_shift,
diff --git a/arch/powerpc/platforms/powernv/pci-ioda.c 
b/arch/powerpc/platforms/powernv/pci-ioda.c
index e0be556..7f548b4 100644
--- a/arch/powerpc/platforms/powernv/pci-ioda.c
+++ b/arch/powerpc/platforms/powernv/pci-ioda.c
@@ -2062,6 +2062,18 @@ static void pnv_pci_ioda2_setup_bypass_pe(struct pnv_phb 
*phb,
  }

  #ifdef CONFIG_IOMMU_API
+static unsigned long pnv_pci_ioda2_get_table_size(__u32 page_shift,
+               __u64 window_size, __u32 levels)
+{
+       unsigned long ret = pnv_get_table_size(page_shift, window_size, levels);
+
+       if (!ret)
+               return ret;
+
+       /* Add size of it_userspace */
+       return ret + (window_size >> page_shift) * sizeof(unsigned long);


This doesn't make much sense.  The userspace view can't possibly be a
property of the specific low-level IOMMU model.



This it_userspace thing is all about memory preregistration.

I need some way to track how many actual mappings themm_iommu_table_group_mem_t has in order to decide whether to allowunregistering or not.

When I clear TCE, I can read the old value which is host physical addresswhich I cannot use to find the preregistered region and adjust the mappingscounter; I can only use userspace addresses for this (not even guestphysical addresses as it is VFIO and probably no KVM).

So I have to keep userspace addresses somewhere, one per IOMMU page, andthe iommu_table seems a natural place for this.

+}
+
  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)
@@ -2086,6 +2098,7 @@ static long pnv_pci_ioda2_create_table(struct 
iommu_table_group *table_group,

        BUG_ON(tbl->it_userspace);
        tbl->it_userspace = uas;
+       tbl->it_allocated_size += uas_cb;
        tbl->it_ops = &pnv_ioda2_iommu_ops;
        if (pe->tce_inval_reg)
                tbl->it_type |= (TCE_PCI_SWINV_CREATE | TCE_PCI_SWINV_FREE);
@@ -2160,6 +2173,7 @@ static void pnv_ioda2_release_ownership(struct 
iommu_table_group *table_group)
  }

  static struct iommu_table_group_ops pnv_pci_ioda2_ops = {
+       .get_table_size = pnv_pci_ioda2_get_table_size,
        .create_table = pnv_pci_ioda2_create_table,
        .set_window = pnv_pci_ioda2_set_window,
        .unset_window = pnv_pci_ioda2_unset_window,
diff --git a/arch/powerpc/platforms/powernv/pci.c 
b/arch/powerpc/platforms/powernv/pci.c
index fc129c4..1b5b48a 100644
--- a/arch/powerpc/platforms/powernv/pci.c
+++ b/arch/powerpc/platforms/powernv/pci.c
@@ -662,6 +662,38 @@ void pnv_pci_setup_iommu_table(struct iommu_table *tbl,
        tbl->it_type = TCE_PCI;
  }

+unsigned long pnv_get_table_size(__u32 page_shift,
+               __u64 window_size, __u32 levels)
+{
+       unsigned long bytes = 0;
+       const unsigned window_shift = ilog2(window_size);
+       unsigned entries_shift = window_shift - page_shift;
+       unsigned table_shift = entries_shift + 3;
+       unsigned long tce_table_size = max(0x1000UL, 1UL << table_shift);
+       unsigned long direct_table_size;
+
+       if (!levels || (levels > POWERNV_IOMMU_MAX_LEVELS) ||
+                       (window_size > memory_hotplug_max()) ||
+                       !is_power_of_2(window_size))
+               return 0;
+
+       /* Calculate a direct table size from window_size and levels */
+       entries_shift = ROUND_UP(entries_shift, levels) / levels;
+       table_shift = entries_shift + 3;
+       table_shift = max_t(unsigned, table_shift, PAGE_SHIFT);
+       direct_table_size =  1UL << table_shift;
+
+       for ( ; levels; --levels) {
+               bytes += ROUND_UP(tce_table_size, direct_table_size);
+
+               tce_table_size /= direct_table_size;
+               tce_table_size <<= 3;
+               tce_table_size = ROUND_UP(tce_table_size, direct_table_size);
+       }
+
+       return bytes;
+}
+
  static __be64 *pnv_alloc_tce_table_pages(int nid, unsigned shift,
                unsigned levels, unsigned long limit,
                unsigned long *tce_table_allocated)
@@ -741,6 +773,10 @@ long pnv_pci_create_table(struct iommu_table_group 
*table_group, int nid,
                return -ENOMEM;
        }

+       tbl->it_allocated_size = pnv_get_table_size(page_shift, window_size,
+                       levels);
+       WARN_ON(!tbl->it_allocated_size);
+
        /* Setup linux iommu table */
        pnv_pci_setup_iommu_table(tbl, addr, tce_table_size, bus_offset,
                        page_shift);
diff --git a/arch/powerpc/platforms/powernv/pci.h 
b/arch/powerpc/platforms/powernv/pci.h
index 3d1ff584..ce4bc3c 100644
--- a/arch/powerpc/platforms/powernv/pci.h
+++ b/arch/powerpc/platforms/powernv/pci.h
@@ -224,6 +224,8 @@ extern long pnv_pci_create_table(struct iommu_table_group 
*table_group, int nid,
                __u64 bus_offset, __u32 page_shift, __u64 window_size,
                __u32 levels, struct iommu_table *tbl);
  extern void pnv_pci_free_table(struct iommu_table *tbl);
+extern unsigned long pnv_get_table_size(__u32 page_shift,
+               __u64 window_size, __u32 levels);
  extern void pnv_pci_init_p5ioc2_hub(struct device_node *np);
  extern void pnv_pci_init_ioda_hub(struct device_node *np);
  extern void pnv_pci_init_ioda2_phb(struct device_node *np);



--
Alexey
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Re: [PATCH kernel v9 27/32] powerpc/iommu/ioda2: Add get_table_size() to calculate the size of future table

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