On LoPAR "DMA Window Manipulation Calls", it's recommended to remove the
default DMA window for the device, before attempting to configure a DDW,
in order to make the maximum resources available for the next DDW to be
created.
This is a requirement for some devices to use DDW, given they only
allow one DMA window.
If setting up a new DDW fails anywhere after the removal of this
default DMA window, it's needed to restore the default DMA window.
For this, an implementation of ibm,reset-pe-dma-windows rtas call is
needed:
Platforms supporting the DDW option starting with LoPAR level 2.7 implement
ibm,ddw-extensions. The first extension available (index 2) carries the
token for ibm,reset-pe-dma-windows rtas call, which is used to restore
the default DMA window for a device, if it has been deleted.
It does so by resetting the TCE table allocation for the PE to it's
boot time value, available in "ibm,dma-window" device tree node.
Signed-off-by: Leonardo Bras <leobra...@gmail.com>
---
arch/powerpc/platforms/pseries/iommu.c | 70 ++++++++++++++++++++++----
1 file changed, 61 insertions(+), 9 deletions(-)
diff --git a/arch/powerpc/platforms/pseries/iommu.c
b/arch/powerpc/platforms/pseries/iommu.c
index a8840d9e1c35..4fcf00016fb1 100644
--- a/arch/powerpc/platforms/pseries/iommu.c
+++ b/arch/powerpc/platforms/pseries/iommu.c
@@ -1029,6 +1029,39 @@ static phys_addr_t ddw_memory_hotplug_max(void)
return max_addr;
}
+/*
+ * Platforms supporting the DDW option starting with LoPAR level 2.7 implement
+ * ibm,ddw-extensions, which carries the rtas token for
+ * ibm,reset-pe-dma-windows.
+ * That rtas-call can be used to restore the default DMA window for the device.
+ */
+static void reset_dma_window(struct pci_dev *dev, struct device_node *par_dn)
+{
+ int ret;
+ u32 cfg_addr, ddw_ext[DDW_EXT_RESET_DMA_WIN + 1];
+ u64 buid;
+ struct device_node *dn;
+ struct pci_dn *pdn;
+
+ ret = of_property_read_u32_array(par_dn, "ibm,ddw-extensions",
+ &ddw_ext[0], DDW_EXT_RESET_DMA_WIN +
1);
+ if (ret)
+ return;
+
+ dn = pci_device_to_OF_node(dev);
+ pdn = PCI_DN(dn);
+ buid = pdn->phb->buid;
+ cfg_addr = ((pdn->busno << 16) | (pdn->devfn << 8));
+
+ ret = rtas_call(ddw_ext[DDW_EXT_RESET_DMA_WIN], 3, 1, NULL, cfg_addr,
+ BUID_HI(buid), BUID_LO(buid));
+ if (ret)
+ dev_info(&dev->dev,
+ "ibm,reset-pe-dma-windows(%x) %x %x %x returned %d ",
+ ddw_ext[1], cfg_addr, BUID_HI(buid), BUID_LO(buid),
+ ret);
+}
+
/*
* 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,
@@ -1049,8 +1082,9 @@ static u64 enable_ddw(struct pci_dev *dev, struct
device_node *pdn)
u64 dma_addr, max_addr;
struct device_node *dn;
u32 ddw_avail[DDW_APPLICABLE_SIZE];
+
struct direct_window *window;
- struct property *win64;
+ struct property *win64, *default_win = NULL, *ddw_ext = NULL;
struct dynamic_dma_window_prop *ddwprop;
struct failed_ddw_pdn *fpdn;
@@ -1085,7 +1119,7 @@ static u64 enable_ddw(struct pci_dev *dev, struct
device_node *pdn)
if (ret)
goto out_failed;
- /*
+ /*
* Query if there is a second window of size to map the
* whole partition. Query returns number of windows, largest
* block assigned to PE (partition endpoint), and two bitmasks
@@ -1096,15 +1130,31 @@ static u64 enable_ddw(struct pci_dev *dev, struct
device_node *pdn)
if (ret != 0)
goto out_failed;
+ /*
+ * If there is no window available, remove the default DMA window,
+ * if it's present. This will make all the resources available to the
+ * new DDW window.
+ * If anything fails after this, we need to restore it, so also check
+ * for extensions presence.
+ */
if (query.windows_available == 0) {
- /*
- * no additional windows are available for this device.
- * We might be able to reallocate the existing window,
- * trading in for a larger page size.
- */
- dev_dbg(&dev->dev, "no free dynamic windows");
- goto out_failed;
+ default_win = of_find_property(pdn, "ibm,dma-window", NULL);
+ ddw_ext = of_find_property(pdn, "ibm,ddw-extensions", NULL);
+ if (default_win && ddw_ext)
+ remove_dma_window(pdn, ddw_avail, default_win);
+
+ /* Query again, to check if the window is available */
+ ret = query_ddw(dev, ddw_avail, &query, pdn);
+ if (ret != 0)
+ goto out_failed;
+
+ if (query.windows_available == 0) {
+ /* no windows are available for this device. */
+ dev_dbg(&dev->dev, "no free dynamic windows");
+ goto out_failed;
+ }
}
+
if (query.page_size & 4) {
page_shift = 24; /* 16MB */
} else if (query.page_size & 2) {
@@ -1194,6 +1244,8 @@ static u64 enable_ddw(struct pci_dev *dev, struct
device_node *pdn)
kfree(win64);
out_failed:
+ if (default_win && ddw_ext)
+ reset_dma_window(dev, pdn);
fpdn = kzalloc(sizeof(*fpdn), GFP_KERNEL);
if (!fpdn)
--
2.25.4
