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SubjectRe: [PATCH v2] powerpc/iommu/ddw: Fix endianness

Hi Alexey,

> ddw_avail is a pointer to the "ibm,ddw-applicable" property which
> contains 3 cells which are big-endian as it is a device tree.
> rtas_call() accepts a RTAS token in CPU-endian. This converts RTAS
> tokens from big-endian to CPU-endian. Since every token is used once
> till guest is rebooted, there is no much sense in caching RTAS tokens
> in CPU-endian.

I see a few sparse endian warnings with this. This patch (that applies
on top of yours) uses of_property_read_u32_array to byte swap and avoid
the need for a number of be32_to_cpu calls.

Can you verify this works and then fold it into yours? Also mark it for
inclusion in stable v3.13+.

You can add:

Reviewed-by: Anton Blanchard <anton@samba.org>

Thanks!
Anton

Index: b/arch/powerpc/platforms/pseries/iommu.c
===================================================================
--- a/arch/powerpc/platforms/pseries/iommu.c
+++ b/arch/powerpc/platforms/pseries/iommu.c
@@ -725,16 +725,18 @@ static void remove_ddw(struct device_nod
{
struct dynamic_dma_window_prop *dwp;
struct property *win64;
- const u32 *ddw_avail;
+ u32 ddw_avail[3];
u64 liobn;
- int len, ret = 0;
+ int ret = 0;
+
+ ret = of_property_read_u32_array(np, "ibm,ddw-applicable",
+ &ddw_avail[0], 3);

- ddw_avail = of_get_property(np, "ibm,ddw-applicable", &len);
win64 = of_find_property(np, DIRECT64_PROPNAME, NULL);
if (!win64)
return;

- if (!ddw_avail || len < 3 * sizeof(u32) || win64->length < sizeof(*dwp))
+ if (ret || win64->length < sizeof(*dwp))
goto delprop;

dwp = win64->value;
@@ -750,7 +752,7 @@ static void remove_ddw(struct device_nod
pr_debug("%s successfully cleared tces in window.\n",
np->full_name);

- ret = rtas_call(be32_to_cpu(ddw_avail[2]), 1, 1, NULL, liobn);
+ ret = rtas_call(ddw_avail[2], 1, 1, NULL, liobn);
if (ret)
pr_warning("%s: failed to remove direct window: rtas returned "
"%d to ibm,remove-pe-dma-window(%x) %llx\n",
@@ -841,7 +843,7 @@ static int query_ddw(struct pci_dev *dev
cfg_addr = edev->pe_config_addr;
buid = edev->phb->buid;

- ret = rtas_call(be32_to_cpu(ddw_avail[0]), 3, 5, (u32 *)query,
+ ret = rtas_call(ddw_avail[0], 3, 5, (u32 *)query,
cfg_addr, BUID_HI(buid), BUID_LO(buid));
dev_info(&dev->dev, "ibm,query-pe-dma-windows(%x) %x %x %x"
" returned %d\n", ddw_avail[0], cfg_addr, BUID_HI(buid),
@@ -872,7 +874,7 @@ static int create_ddw(struct pci_dev *de

do {
/* extra outputs are LIOBN and dma-addr (hi, lo) */
- ret = rtas_call(be32_to_cpu(ddw_avail[1]), 5, 4, (u32 *)create,
+ ret = rtas_call(ddw_avail[1], 5, 4, (u32 *)create,
cfg_addr, BUID_HI(buid), BUID_LO(buid),
page_shift, window_shift);
} while (rtas_busy_delay(ret));
@@ -911,7 +913,7 @@ static u64 enable_ddw(struct pci_dev *de
int page_shift;
u64 dma_addr, max_addr;
struct device_node *dn;
- const u32 *uninitialized_var(ddw_avail);
+ u32 ddw_avail[3];
struct direct_window *window;
struct property *win64;
struct dynamic_dma_window_prop *ddwprop;
@@ -943,8 +945,9 @@ static u64 enable_ddw(struct pci_dev *de
* for the given node in that order.
* the property is actually in the parent, not the PE
*/
- ddw_avail = of_get_property(pdn, "ibm,ddw-applicable", &len);
- if (!ddw_avail || len < 3 * sizeof(u32))
+ ret = of_property_read_u32_array(pdn, "ibm,ddw-applicable",
+ &ddw_avail[0], 3);
+ if (ret)
goto out_failed;

/*

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