Messages in this thread | | | Date | Tue, 23 Mar 2021 18:41:09 +1100 | Subject | Re: [PATCH 1/1] powerpc/iommu: Enable remaining IOMMU Pagesizes present in LoPAR | From | Alexey Kardashevskiy <> |
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On 23/03/2021 06:09, Leonardo Bras wrote: > 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> > --- > arch/powerpc/include/asm/iommu.h | 8 ++++++++ > arch/powerpc/platforms/pseries/iommu.c | 28 +++++++++++++++++++------- > 2 files changed, 29 insertions(+), 7 deletions(-) > > diff --git a/arch/powerpc/include/asm/iommu.h b/arch/powerpc/include/asm/iommu.h > index deef7c94d7b6..c170048b7a1b 100644 > --- a/arch/powerpc/include/asm/iommu.h > +++ b/arch/powerpc/include/asm/iommu.h > @@ -19,6 +19,14 @@ > #include <asm/pci-bridge.h> > #include <asm/asm-const.h> > > +#define IOMMU_PAGE_SHIFT_16G 34 > +#define IOMMU_PAGE_SHIFT_256M 28 > +#define IOMMU_PAGE_SHIFT_128M 27 > +#define IOMMU_PAGE_SHIFT_64M 26 > +#define IOMMU_PAGE_SHIFT_32M 25 > +#define IOMMU_PAGE_SHIFT_16M 24 > +#define IOMMU_PAGE_SHIFT_64K 16
These are not very descriptive, these are just normal shifts, could be as simple as __builtin_ctz(SZ_4K) (gcc will optimize this) and so on.
OTOH the PAPR page sizes need macros as they are the ones which are weird and screaming for macros.
I'd steal/rework spapr_page_mask_to_query_mask() from QEMU. Thanks,
> + > #define IOMMU_PAGE_SHIFT_4K 12 > #define IOMMU_PAGE_SIZE_4K (ASM_CONST(1) << IOMMU_PAGE_SHIFT_4K) > #define IOMMU_PAGE_MASK_4K (~((1 << IOMMU_PAGE_SHIFT_4K) - 1)) > diff --git a/arch/powerpc/platforms/pseries/iommu.c b/arch/powerpc/platforms/pseries/iommu.c > index 9fc5217f0c8e..02958e80aa91 100644 > --- a/arch/powerpc/platforms/pseries/iommu.c > +++ b/arch/powerpc/platforms/pseries/iommu.c > @@ -1099,6 +1099,24 @@ 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. SeeL LoPAR */ > +static int iommu_get_page_shift(u32 query_page_size) > +{ > + const int shift[] = {IOMMU_PAGE_SHIFT_4K, IOMMU_PAGE_SHIFT_64K, IOMMU_PAGE_SHIFT_16M, > + IOMMU_PAGE_SHIFT_32M, IOMMU_PAGE_SHIFT_64M, IOMMU_PAGE_SHIFT_128M, > + IOMMU_PAGE_SHIFT_256M, IOMMU_PAGE_SHIFT_16G}; > + int i = ARRAY_SIZE(shift) - 1; > + > + /* Looks for the largest page size supported */ > + 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 +1224,9 @@ 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; >
-- Alexey
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