Commit 8c0d5159 authored by Leonardo Bras's avatar Leonardo Bras Committed by Michael Ellerman
Browse files

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: default avatarLeonardo Bras <leobras.c@gmail.com>
Tested-by: default avatarDavid Dai <zdai@linux.vnet.ibm.com>
Reviewed-by: default avatarAlexey Kardashevskiy <aik@ozlabs.ru>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200805030455.123024-5-leobras.c@gmail.com
parent 74d0b399

arch/powerpc/platforms/pseries/iommu.c

+66 −7
Original line number Diff line number Diff line
@@ -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);
@@ -1133,15 +1166,39 @@ static u64 enable_ddw(struct pci_dev *dev, struct device_node *pdn) 
	if (ret != 0)

		goto out_failed;



	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.

	 * 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) {

		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 */

	} else if (query.page_size & 2) {
@@ -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)

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