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powerpc/iommu: Enable remaining IOMMU Pagesizes present in LoPAR

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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 <leobras.c@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210408201915.174217-1-leobras.c@gmail.com
This commit is contained in:
Leonardo Bras 2021-04-08 17:19:16 -03:00 committed by Michael Ellerman
parent 672bff581e
commit 472724111f
1 changed files with 30 additions and 7 deletions
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37
arch/powerpc/platforms/pseries/iommu.c
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@ -1099,6 +1099,33 @@ static void reset_dma_window(struct pci_dev *dev, struct device_node *par_dn)
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)
{
/* Supported IO page-sizes according to LoPAR */
const int shift[] = {
__builtin_ctzll(SZ_4K), __builtin_ctzll(SZ_64K), __builtin_ctzll(SZ_16M),
__builtin_ctzll(SZ_32M), __builtin_ctzll(SZ_64M), __builtin_ctzll(SZ_128M),
__builtin_ctzll(SZ_256M), __builtin_ctzll(SZ_16G)
};
int i = ARRAY_SIZE(shift) - 1;
/*
* On LoPAR, ibm,query-pe-dma-window outputs "IO Page Sizes" using a bit field:
* - bit 31 means 4k pages are supported,
* - bit 30 means 64k pages are supported, and so on.
* Larger pagesizes map more memory with the same amount of TCEs, so start probing them.
*/
for (; i >= 0 ; i--) {
if (query_page_size & (1 << i))
return shift[i];
}
/* 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 +1233,9 @@ 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;