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    SubjectRe: [PATCH v5 06/11] powerpc/pseries/iommu: Add ddw_property_create() and refactor enable_ddw()
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    On 16/07/2021 10:27, Leonardo Bras wrote:
    > Code used to create a ddw property that was previously scattered in
    > enable_ddw() is now gathered in ddw_property_create(), which deals with
    > allocation and filling the property, letting it ready for
    > of_property_add(), which now occurs in sequence.
    >
    > This created an opportunity to reorganize the second part of enable_ddw():
    >
    > Without this patch enable_ddw() does, in order:
    > kzalloc() property & members, create_ddw(), fill ddwprop inside property,
    > ddw_list_new_entry(), do tce_setrange_multi_pSeriesLP_walk in all memory,
    > of_add_property(), and list_add().
    >
    > With this patch enable_ddw() does, in order:
    > create_ddw(), ddw_property_create(), of_add_property(),
    > ddw_list_new_entry(), do tce_setrange_multi_pSeriesLP_walk in all memory,
    > and list_add().
    >
    > This change requires of_remove_property() in case anything fails after
    > of_add_property(), but we get to do tce_setrange_multi_pSeriesLP_walk
    > in all memory, which looks the most expensive operation, only if
    > everything else succeeds.
    >
    > Signed-off-by: Leonardo Bras <leobras.c@gmail.com>
    > Reviewed-by: Alexey Kardashevskiy <aik@ozlabs.ru>
    > ---
    > arch/powerpc/platforms/pseries/iommu.c | 93 ++++++++++++++++----------
    > 1 file changed, 57 insertions(+), 36 deletions(-)
    >
    > diff --git a/arch/powerpc/platforms/pseries/iommu.c b/arch/powerpc/platforms/pseries/iommu.c
    > index b34b473bbdc1..7ca79a04fa52 100644
    > --- a/arch/powerpc/platforms/pseries/iommu.c
    > +++ b/arch/powerpc/platforms/pseries/iommu.c
    > @@ -1153,6 +1153,35 @@ static int iommu_get_page_shift(u32 query_page_size)
    > return 0;
    > }
    >
    > +static struct property *ddw_property_create(const char *propname, u32 liobn, u64 dma_addr,
    > + u32 page_shift, u32 window_shift)
    > +{
    > + struct dynamic_dma_window_prop *ddwprop;
    > + struct property *win64;
    > +
    > + win64 = kzalloc(sizeof(*win64), GFP_KERNEL);
    > + if (!win64)
    > + return NULL;
    > +
    > + win64->name = kstrdup(propname, GFP_KERNEL);
    > + ddwprop = kzalloc(sizeof(*ddwprop), GFP_KERNEL);
    > + win64->value = ddwprop;
    > + win64->length = sizeof(*ddwprop);
    > + if (!win64->name || !win64->value) {
    > + kfree(win64->name);
    > + kfree(win64->value);
    > + kfree(win64);
    > + return NULL;
    > + }
    > +
    > + ddwprop->liobn = cpu_to_be32(liobn);
    > + ddwprop->dma_base = cpu_to_be64(dma_addr);
    > + ddwprop->tce_shift = cpu_to_be32(page_shift);
    > + ddwprop->window_shift = cpu_to_be32(window_shift);
    > +
    > + return win64;
    > +}
    > +
    > /*
    > * If the PE supports dynamic dma windows, and there is space for a table
    > * that can map all pages in a linear offset, then setup such a table,
    > @@ -1171,12 +1200,12 @@ static bool enable_ddw(struct pci_dev *dev, struct device_node *pdn)
    > struct ddw_query_response query;
    > struct ddw_create_response create;
    > int page_shift;
    > + u64 win_addr;
    > struct device_node *dn;
    > u32 ddw_avail[DDW_APPLICABLE_SIZE];
    > struct direct_window *window;
    > struct property *win64;
    > bool ddw_enabled = false;
    > - struct dynamic_dma_window_prop *ddwprop;
    > struct failed_ddw_pdn *fpdn;
    > bool default_win_removed = false;
    > bool pmem_present;
    > @@ -1293,72 +1322,64 @@ static bool enable_ddw(struct pci_dev *dev, struct device_node *pdn)
    > 1ULL << page_shift);
    > goto out_failed;
    > }
    > - win64 = kzalloc(sizeof(struct property), GFP_KERNEL);
    > - if (!win64) {
    > - dev_info(&dev->dev,
    > - "couldn't allocate property for 64bit dma window\n");
    > - goto out_failed;
    > - }
    > - win64->name = kstrdup(DIRECT64_PROPNAME, GFP_KERNEL);
    > - win64->value = ddwprop = kmalloc(sizeof(*ddwprop), GFP_KERNEL);
    > - win64->length = sizeof(*ddwprop);
    > - if (!win64->name || !win64->value) {
    > - dev_info(&dev->dev,
    > - "couldn't allocate property name and value\n");
    > - goto out_free_prop;
    > - }
    >
    > ret = create_ddw(dev, ddw_avail, &create, page_shift, len);
    > if (ret != 0)
    > - goto out_free_prop;
    > -
    > - ddwprop->liobn = cpu_to_be32(create.liobn);
    > - ddwprop->dma_base = cpu_to_be64(((u64)create.addr_hi << 32) |
    > - create.addr_lo);
    > - ddwprop->tce_shift = cpu_to_be32(page_shift);
    > - ddwprop->window_shift = cpu_to_be32(len);
    > + goto out_failed;
    >
    > dev_dbg(&dev->dev, "created tce table LIOBN 0x%x for %pOF\n",
    > create.liobn, dn);
    >
    > - window = ddw_list_new_entry(pdn, ddwprop);
    > + win_addr = ((u64)create.addr_hi << 32) | create.addr_lo;
    > + win64 = ddw_property_create(DIRECT64_PROPNAME, create.liobn, win_addr,
    > + page_shift, len);
    > + if (!win64) {
    > + dev_info(&dev->dev,
    > + "couldn't allocate property, property name, or value\n");
    > + goto out_remove_win;
    > + }
    > +
    > + ret = of_add_property(pdn, win64);
    > + if (ret) {
    > + dev_err(&dev->dev, "unable to add dma window property for %pOF: %d",
    > + pdn, ret);
    > + goto out_free_prop;
    > + }
    > +
    > + window = ddw_list_new_entry(pdn, win64->value);
    > if (!window)
    > - goto out_clear_window;
    > + goto out_del_prop;
    >
    > ret = walk_system_ram_range(0, memblock_end_of_DRAM() >> PAGE_SHIFT,
    > win64->value, tce_setrange_multi_pSeriesLP_walk);
    > if (ret) {
    > dev_info(&dev->dev, "failed to map direct window for %pOF: %d\n",
    > dn, ret);
    > - goto out_free_window;
    > - }
    > -
    > - ret = of_add_property(pdn, win64);
    > - if (ret) {
    > - dev_err(&dev->dev, "unable to add dma window property for %pOF: %d",
    > - pdn, ret);
    > - goto out_free_window;
    > + goto out_del_list;
    > }
    >
    > spin_lock(&direct_window_list_lock);
    > list_add(&window->list, &direct_window_list);
    > spin_unlock(&direct_window_list_lock);
    >
    > - dev->dev.archdata.dma_offset = be64_to_cpu(ddwprop->dma_base);
    > + dev->dev.archdata.dma_offset = win_addr;
    > ddw_enabled = true;
    > goto out_unlock;
    >
    > -out_free_window:
    > +out_del_list:
    > kfree(window);
    >
    > -out_clear_window:
    > - remove_ddw(pdn, true);
    > +out_del_prop:
    > + of_remove_property(pdn, win64);
    >
    > out_free_prop:
    > kfree(win64->name);
    > kfree(win64->value);
    > kfree(win64);
    >
    > +out_remove_win:
    > + remove_ddw(pdn, true);


    I believe there's a small problem here. We jump directly to
    out_remove_win if allocating the property failed. Yet, the first thing
    remove_ddw() does is look for the property. So it will never find it and
    the window is never removed by the hypervisor.

    Fred


    > +
    > out_failed:
    > if (default_win_removed)
    > reset_dma_window(dev, pdn);
    >

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