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powerpc/pseries/iommu: Allow bigger 64bit window by removing default DMA window 

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 using DDW on devices in which hypervisor
allows only 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 <leobras.c@gmail.com>
Tested-by: David Dai <zdai@linux.vnet.ibm.com>
Reviewed-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200805030455.123024-5-leobras.c@gmail.com
This commit is contained in:
Leonardo Bras 2020-08-05 00:04:55 -03:00 committed by Michael Ellerman
parent 74d0b3994e
commit 8c0d51592f
1 changed files with 66 additions and 7 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

73
arch/powerpc/platforms/pseries/iommu.c
View File

@ -1066,6 +1066,38 @@ 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, reset_dma_win;
u64 buid;
struct device_node *dn;
struct pci_dn *pdn;
ret = ddw_read_ext(par_dn, DDW_EXT_RESET_DMA_WIN, &reset_dma_win);
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(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 ",
reset_dma_win, 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,
@ -1090,6 +1122,7 @@ static u64 enable_ddw(struct pci_dev *dev, struct device_node *pdn)
struct property *win64;
struct dynamic_dma_window_prop *ddwprop;
struct failed_ddw_pdn *fpdn;
bool default_win_removed = false;
mutex_lock(&direct_window_init_mutex);
@ -1133,14 +1166,38 @@ 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;
struct property *default_win;
int reset_win_ext;
default_win = of_find_property(pdn, "ibm,dma-window", NULL);
if (!default_win)
goto out_failed;
reset_win_ext = ddw_read_ext(pdn, DDW_EXT_RESET_DMA_WIN, NULL);
if (reset_win_ext)
goto out_failed;
remove_dma_window(pdn, ddw_avail, default_win);
default_win_removed = true;
/* 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 */
@ -1231,6 +1288,8 @@ out_free_prop:
kfree(win64);
out_failed:
if (default_win_removed)
reset_dma_window(dev, pdn);
fpdn = kzalloc(sizeof(*fpdn), GFP_KERNEL);
if (!fpdn)