From 8c0d51592f6f0123953633d1ecf21e843fce0bfd Mon Sep 17 00:00:00 2001 From: Leonardo Bras Date: Wed, 5 Aug 2020 00:04:55 -0300 Subject: [PATCH] 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 Tested-by: David Dai Reviewed-by: Alexey Kardashevskiy Signed-off-by: Michael Ellerman Link: https://lore.kernel.org/r/20200805030455.123024-5-leobras.c@gmail.com --- arch/powerpc/platforms/pseries/iommu.c | 73 +++++++++++++++++++++++--- 1 file changed, 66 insertions(+), 7 deletions(-) diff --git a/arch/powerpc/platforms/pseries/iommu.c b/arch/powerpc/platforms/pseries/iommu.c index 4e33147825cc..e4198700ed1a 100644 --- a/arch/powerpc/platforms/pseries/iommu.c +++ b/arch/powerpc/platforms/pseries/iommu.c @@ -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 @@ static u64 enable_ddw(struct pci_dev *dev, struct device_node *pdn) kfree(win64); out_failed: + if (default_win_removed) + reset_dma_window(dev, pdn); fpdn = kzalloc(sizeof(*fpdn), GFP_KERNEL); if (!fpdn)