6.14-stable review patch. If anyone has any objections, please let me know.
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From: Gaurav Batra gbatra@linux.ibm.com
[ Upstream commit 67dfc11982f7e3c37f0977e74671da2391b29181 ]
Starting with PAPR level 2.13, platform supports placing PHB in limited address mode. Devices that support DMA masks less that 64-bit but greater than 32-bits are placed in limited address mode. In this mode, the starting DMA address returned by the DDW is 4GB.
When the device driver calls dma_supported, with mask less then 64-bit, the PowerPC IOMMU driver places PHB in the Limited Addressing Mode before creating DDW.
Signed-off-by: Gaurav Batra gbatra@linux.ibm.com Signed-off-by: Madhavan Srinivasan maddy@linux.ibm.com Link: https://patch.msgid.link/20250108164814.73250-1-gbatra@linux.ibm.com Signed-off-by: Sasha Levin sashal@kernel.org --- arch/powerpc/platforms/pseries/iommu.c | 110 +++++++++++++++++++++---- 1 file changed, 94 insertions(+), 16 deletions(-)
diff --git a/arch/powerpc/platforms/pseries/iommu.c b/arch/powerpc/platforms/pseries/iommu.c index 8f32340960e21..d6ebc19fb99c5 100644 --- a/arch/powerpc/platforms/pseries/iommu.c +++ b/arch/powerpc/platforms/pseries/iommu.c @@ -52,7 +52,8 @@ enum { enum { DDW_EXT_SIZE = 0, DDW_EXT_RESET_DMA_WIN = 1, - DDW_EXT_QUERY_OUT_SIZE = 2 + DDW_EXT_QUERY_OUT_SIZE = 2, + DDW_EXT_LIMITED_ADDR_MODE = 3 };
static struct iommu_table *iommu_pseries_alloc_table(int node) @@ -1327,6 +1328,54 @@ static void reset_dma_window(struct pci_dev *dev, struct device_node *par_dn) ret); }
+/* + * Platforms support placing PHB in limited address mode starting with LoPAR + * level 2.13 implement. In this mode, the DMA address returned by DDW is over + * 4GB but, less than 64-bits. This benefits IO adapters that don't support + * 64-bits for DMA addresses. + */ +static int limited_dma_window(struct pci_dev *dev, struct device_node *par_dn) +{ + int ret; + u32 cfg_addr, reset_dma_win, las_supported; + 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) + goto out; + + ret = ddw_read_ext(par_dn, DDW_EXT_LIMITED_ADDR_MODE, &las_supported); + + /* Limited Address Space extension available on the platform but DDW in + * limited addressing mode not supported + */ + if (!ret && !las_supported) + ret = -EPROTO; + + if (ret) { + dev_info(&dev->dev, "Limited Address Space for DDW not Supported, err: %d", ret); + goto out; + } + + 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, 4, 1, NULL, cfg_addr, BUID_HI(buid), + BUID_LO(buid), 1); + if (ret) + dev_info(&dev->dev, + "ibm,reset-pe-dma-windows(%x) for Limited Addr Support: %x %x %x returned %d ", + reset_dma_win, cfg_addr, BUID_HI(buid), BUID_LO(buid), + ret); + +out: + return ret; +} + /* Return largest page shift based on "IO Page Sizes" output of ibm,query-pe-dma-window. */ static int iommu_get_page_shift(u32 query_page_size) { @@ -1394,7 +1443,7 @@ static struct property *ddw_property_create(const char *propname, u32 liobn, u64 * * returns true if can map all pages (direct mapping), false otherwise.. */ -static bool enable_ddw(struct pci_dev *dev, struct device_node *pdn) +static bool enable_ddw(struct pci_dev *dev, struct device_node *pdn, u64 dma_mask) { int len = 0, ret; int max_ram_len = order_base_2(ddw_memory_hotplug_max()); @@ -1413,6 +1462,9 @@ static bool enable_ddw(struct pci_dev *dev, struct device_node *pdn) bool pmem_present; struct pci_dn *pci = PCI_DN(pdn); struct property *default_win = NULL; + bool limited_addr_req = false, limited_addr_enabled = false; + int dev_max_ddw; + int ddw_sz;
dn = of_find_node_by_type(NULL, "ibm,pmemory"); pmem_present = dn != NULL; @@ -1439,7 +1491,6 @@ static bool enable_ddw(struct pci_dev *dev, struct device_node *pdn) * the ibm,ddw-applicable property holds the tokens for: * ibm,query-pe-dma-window * ibm,create-pe-dma-window - * ibm,remove-pe-dma-window * for the given node in that order. * the property is actually in the parent, not the PE */ @@ -1459,6 +1510,20 @@ static bool enable_ddw(struct pci_dev *dev, struct device_node *pdn) if (ret != 0) goto out_failed;
+ /* DMA Limited Addressing required? This is when the driver has + * requested to create DDW but supports mask which is less than 64-bits + */ + limited_addr_req = (dma_mask != DMA_BIT_MASK(64)); + + /* place the PHB in Limited Addressing mode */ + if (limited_addr_req) { + if (limited_dma_window(dev, pdn)) + goto out_failed; + + /* PHB is in Limited address mode */ + limited_addr_enabled = true; + } + /* * If there is no window available, remove the default DMA window, * if it's present. This will make all the resources available to the @@ -1505,6 +1570,15 @@ static bool enable_ddw(struct pci_dev *dev, struct device_node *pdn) goto out_failed; }
+ /* Maximum DMA window size that the device can address (in log2) */ + dev_max_ddw = fls64(dma_mask); + + /* If the device DMA mask is less than 64-bits, make sure the DMA window + * size is not bigger than what the device can access + */ + ddw_sz = min(order_base_2(query.largest_available_block << page_shift), + dev_max_ddw); + /* * The "ibm,pmemory" can appear anywhere in the address space. * Assuming it is still backed by page structs, try MAX_PHYSMEM_BITS @@ -1513,23 +1587,21 @@ static bool enable_ddw(struct pci_dev *dev, struct device_node *pdn) */ len = max_ram_len; if (pmem_present) { - if (query.largest_available_block >= - (1ULL << (MAX_PHYSMEM_BITS - page_shift))) + if (ddw_sz >= MAX_PHYSMEM_BITS) len = MAX_PHYSMEM_BITS; else dev_info(&dev->dev, "Skipping ibm,pmemory"); }
/* check if the available block * number of ptes will map everything */ - if (query.largest_available_block < (1ULL << (len - page_shift))) { + if (ddw_sz < len) { dev_dbg(&dev->dev, "can't map partition max 0x%llx with %llu %llu-sized pages\n", 1ULL << len, query.largest_available_block, 1ULL << page_shift);
- len = order_base_2(query.largest_available_block << page_shift); - + len = ddw_sz; dynamic_mapping = true; } else { direct_mapping = !default_win_removed || @@ -1543,8 +1615,9 @@ static bool enable_ddw(struct pci_dev *dev, struct device_node *pdn) */ if (default_win_removed && pmem_present && !direct_mapping) { /* DDW is big enough to be split */ - if ((query.largest_available_block << page_shift) >= - MIN_DDW_VPMEM_DMA_WINDOW + (1ULL << max_ram_len)) { + if ((1ULL << ddw_sz) >= + MIN_DDW_VPMEM_DMA_WINDOW + (1ULL << max_ram_len)) { + direct_mapping = true;
/* offset of the Dynamic part of DDW */ @@ -1555,8 +1628,7 @@ static bool enable_ddw(struct pci_dev *dev, struct device_node *pdn) dynamic_mapping = true;
/* create max size DDW possible */ - len = order_base_2(query.largest_available_block - << page_shift); + len = ddw_sz; } }
@@ -1685,7 +1757,7 @@ static bool enable_ddw(struct pci_dev *dev, struct device_node *pdn) __remove_dma_window(pdn, ddw_avail, create.liobn);
out_failed: - if (default_win_removed) + if (default_win_removed || limited_addr_enabled) reset_dma_window(dev, pdn);
fpdn = kzalloc(sizeof(*fpdn), GFP_KERNEL); @@ -1704,6 +1776,9 @@ static bool enable_ddw(struct pci_dev *dev, struct device_node *pdn) dev->dev.bus_dma_limit = dev->dev.archdata.dma_offset + (1ULL << max_ram_len);
+ dev_info(&dev->dev, "lsa_required: %x, lsa_enabled: %x, direct mapping: %x\n", + limited_addr_req, limited_addr_enabled, direct_mapping); + return direct_mapping; }
@@ -1829,8 +1904,11 @@ static bool iommu_bypass_supported_pSeriesLP(struct pci_dev *pdev, u64 dma_mask) { struct device_node *dn = pci_device_to_OF_node(pdev), *pdn;
- /* only attempt to use a new window if 64-bit DMA is requested */ - if (dma_mask < DMA_BIT_MASK(64)) + /* For DDW, DMA mask should be more than 32-bits. For mask more then + * 32-bits but less then 64-bits, DMA addressing is supported in + * Limited Addressing mode. + */ + if (dma_mask <= DMA_BIT_MASK(32)) return false;
dev_dbg(&pdev->dev, "node is %pOF\n", dn); @@ -1843,7 +1921,7 @@ static bool iommu_bypass_supported_pSeriesLP(struct pci_dev *pdev, u64 dma_mask) */ pdn = pci_dma_find(dn, NULL); if (pdn && PCI_DN(pdn)) - return enable_ddw(pdev, pdn); + return enable_ddw(pdev, pdn, dma_mask);
return false; }