According to LoPAR, ibm,query-pe-dma-window output named "IO Page Sizes" will let the OS know all possible pagesizes that can be used for creating a new DDW.
Currently Linux will only try using 3 of the 8 available options: 4K, 64K and 16M. According to LoPAR, Hypervisor may also offer 32M, 64M, 128M, 256M and 16G. Enabling bigger pages would be interesting for direct mapping systems with a lot of RAM, while using less TCE entries. Signed-off-by: Leonardo Bras <leobra...@gmail.com> --- arch/powerpc/platforms/pseries/iommu.c | 49 ++++++++++++++++++++++---- 1 file changed, 42 insertions(+), 7 deletions(-) diff --git a/arch/powerpc/platforms/pseries/iommu.c b/arch/powerpc/platforms/pseries/iommu.c index 9fc5217f0c8e..6cda1c92597d 100644 --- a/arch/powerpc/platforms/pseries/iommu.c +++ b/arch/powerpc/platforms/pseries/iommu.c @@ -53,6 +53,20 @@ enum { DDW_EXT_QUERY_OUT_SIZE = 2 }; +#define QUERY_DDW_PGSIZE_4K 0x01 +#define QUERY_DDW_PGSIZE_64K 0x02 +#define QUERY_DDW_PGSIZE_16M 0x04 +#define QUERY_DDW_PGSIZE_32M 0x08 +#define QUERY_DDW_PGSIZE_64M 0x10 +#define QUERY_DDW_PGSIZE_128M 0x20 +#define QUERY_DDW_PGSIZE_256M 0x40 +#define QUERY_DDW_PGSIZE_16G 0x80 + +struct iommu_ddw_pagesize { + u32 mask; + int shift; +}; + static struct iommu_table_group *iommu_pseries_alloc_group(int node) { struct iommu_table_group *table_group; @@ -1099,6 +1113,31 @@ static void reset_dma_window(struct pci_dev *dev, struct device_node *par_dn) ret); } +/* Returns page shift based on "IO Page Sizes" output at ibm,query-pe-dma-window. See LoPAR */ +static int iommu_get_page_shift(u32 query_page_size) +{ + const struct iommu_ddw_pagesize ddw_pagesize[] = { + { QUERY_DDW_PGSIZE_16G, __builtin_ctz(SZ_16G) }, + { QUERY_DDW_PGSIZE_256M, __builtin_ctz(SZ_256M) }, + { QUERY_DDW_PGSIZE_128M, __builtin_ctz(SZ_128M) }, + { QUERY_DDW_PGSIZE_64M, __builtin_ctz(SZ_64M) }, + { QUERY_DDW_PGSIZE_32M, __builtin_ctz(SZ_32M) }, + { QUERY_DDW_PGSIZE_16M, __builtin_ctz(SZ_16M) }, + { QUERY_DDW_PGSIZE_64K, __builtin_ctz(SZ_64K) }, + { QUERY_DDW_PGSIZE_4K, __builtin_ctz(SZ_4K) } + }; + + int i; + + for (i = 0; i < ARRAY_SIZE(ddw_pagesize); i++) { + if (query_page_size & ddw_pagesize[i].mask) + return ddw_pagesize[i].shift; + } + + /* No valid page size found. */ + return 0; +} + /* * 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, @@ -1206,13 +1245,9 @@ static u64 enable_ddw(struct pci_dev *dev, struct device_node *pdn) goto out_failed; } } - if (query.page_size & 4) { - page_shift = 24; /* 16MB */ - } else if (query.page_size & 2) { - page_shift = 16; /* 64kB */ - } else if (query.page_size & 1) { - page_shift = 12; /* 4kB */ - } else { + + page_shift = iommu_get_page_shift(query.page_size); + if (!page_shift) { dev_dbg(&dev->dev, "no supported direct page size in mask %x", query.page_size); goto out_failed; -- 2.30.2