[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [PATCH RFCv2 02/15] xen/arm: lpae: Use the generic helpers to defined the Xen PT helpers
On Sun, 25 Apr 2021, Julien Grall wrote: > From: Julien Grall <jgrall@xxxxxxxxxx> > > Currently, Xen PT helpers are only working with 4KB page granularity > and open-code the generic helpers. To allow more flexibility, we can > re-use the generic helpers and pass Xen's page granularity > (PAGE_SHIFT). > > As Xen PT helpers are used in both C and assembly, we need to move > the generic helpers definition outside of the !__ASSEMBLY__ section. > > Note the aliases for each level are still kept for the time being so we > can avoid a massive patch to change all the callers. > > Signed-off-by: Julien Grall <jgrall@xxxxxxxxxx> The patch is OK as is. I have a couple of suggestions for improvement below. If you feel like making them, good, otherwise I am also OK if you don't want to change anything. > --- > Changes in v2: > - New patch > --- > xen/include/asm-arm/lpae.h | 71 +++++++++++++++++++++----------------- > 1 file changed, 40 insertions(+), 31 deletions(-) > > diff --git a/xen/include/asm-arm/lpae.h b/xen/include/asm-arm/lpae.h > index 4fb9a40a4ca9..310f5225e056 100644 > --- a/xen/include/asm-arm/lpae.h > +++ b/xen/include/asm-arm/lpae.h > @@ -159,6 +159,17 @@ static inline bool lpae_is_superpage(lpae_t pte, > unsigned int level) > #define lpae_get_mfn(pte) (_mfn((pte).walk.base)) > #define lpae_set_mfn(pte, mfn) ((pte).walk.base = mfn_x(mfn)) > > +/* Generate an array @var containing the offset for each level from @addr */ > +#define DECLARE_OFFSETS(var, addr) \ > + const unsigned int var[4] = { \ > + zeroeth_table_offset(addr), \ > + first_table_offset(addr), \ > + second_table_offset(addr), \ > + third_table_offset(addr) \ > + } > + > +#endif /* __ASSEMBLY__ */ > + > /* > * AArch64 supports pages with different sizes (4K, 16K, and 64K). > * Provide a set of generic helpers that will compute various > @@ -190,17 +201,6 @@ static inline bool lpae_is_superpage(lpae_t pte, > unsigned int level) > #define LPAE_TABLE_INDEX_GS(gs, lvl, addr) \ > (((addr) >> LEVEL_SHIFT_GS(gs, lvl)) & LPAE_ENTRY_MASK_GS(gs)) > > -/* Generate an array @var containing the offset for each level from @addr */ > -#define DECLARE_OFFSETS(var, addr) \ > - const unsigned int var[4] = { \ > - zeroeth_table_offset(addr), \ > - first_table_offset(addr), \ > - second_table_offset(addr), \ > - third_table_offset(addr) \ > - } > - > -#endif /* __ASSEMBLY__ */ > - > /* > * These numbers add up to a 48-bit input address space. > * > @@ -211,26 +211,35 @@ static inline bool lpae_is_superpage(lpae_t pte, > unsigned int level) > * therefore 39-bits are sufficient. > */ > > -#define LPAE_SHIFT 9 > -#define LPAE_ENTRIES (_AC(1,U) << LPAE_SHIFT) > -#define LPAE_ENTRY_MASK (LPAE_ENTRIES - 1) > - > -#define THIRD_SHIFT (PAGE_SHIFT) > -#define THIRD_ORDER (THIRD_SHIFT - PAGE_SHIFT) > -#define THIRD_SIZE (_AT(paddr_t, 1) << THIRD_SHIFT) > -#define THIRD_MASK (~(THIRD_SIZE - 1)) > -#define SECOND_SHIFT (THIRD_SHIFT + LPAE_SHIFT) > -#define SECOND_ORDER (SECOND_SHIFT - PAGE_SHIFT) > -#define SECOND_SIZE (_AT(paddr_t, 1) << SECOND_SHIFT) > -#define SECOND_MASK (~(SECOND_SIZE - 1)) > -#define FIRST_SHIFT (SECOND_SHIFT + LPAE_SHIFT) > -#define FIRST_ORDER (FIRST_SHIFT - PAGE_SHIFT) > -#define FIRST_SIZE (_AT(paddr_t, 1) << FIRST_SHIFT) > -#define FIRST_MASK (~(FIRST_SIZE - 1)) > -#define ZEROETH_SHIFT (FIRST_SHIFT + LPAE_SHIFT) > -#define ZEROETH_ORDER (ZEROETH_SHIFT - PAGE_SHIFT) > -#define ZEROETH_SIZE (_AT(paddr_t, 1) << ZEROETH_SHIFT) > -#define ZEROETH_MASK (~(ZEROETH_SIZE - 1)) Should we add a one-line in-code comment saying that the definitions below are for 4KB pages? It is not immediately obvious any longer. > +#define LPAE_SHIFT LPAE_SHIFT_GS(PAGE_SHIFT) > +#define LPAE_ENTRIES LPAE_ENTRIES_GS(PAGE_SHIFT) > +#define LPAE_ENTRY_MASK LPAE_ENTRY_MASK_GS(PAGE_SHIFT) > > +#define LEVEL_SHIFT(lvl) LEVEL_SHIFT_GS(PAGE_SHIFT, lvl) > +#define LEVEL_ORDER(lvl) LEVEL_ORDER_GS(PAGE_SHIFT, lvl) > +#define LEVEL_SIZE(lvl) LEVEL_SIZE_GS(PAGE_SHIFT, lvl) > +#define LEVEL_MASK(lvl) (~(LEVEL_SIZE(lvl) - 1)) I would avoid adding these 4 macros. It would be OK if they were just used within this file but lpae.h is a header: they could end up be used anywhere in the xen/ code and they have a very generic name. My suggestion would be to skip them and just do: #define THIRD_SHIFT LEVEL_SHIFT_GS(PAGE_SHIFT, 3) etc. > +/* Convenience aliases */ > +#define THIRD_SHIFT LEVEL_SHIFT(3) > +#define THIRD_ORDER LEVEL_ORDER(3) > +#define THIRD_SIZE LEVEL_SIZE(3) > +#define THIRD_MASK LEVEL_MASK(3) > + > +#define SECOND_SHIFT LEVEL_SHIFT(2) > +#define SECOND_ORDER LEVEL_ORDER(2) > +#define SECOND_SIZE LEVEL_SIZE(2) > +#define SECOND_MASK LEVEL_MASK(2) > + > +#define FIRST_SHIFT LEVEL_SHIFT(1) > +#define FIRST_ORDER LEVEL_ORDER(1) > +#define FIRST_SIZE LEVEL_SIZE(1) > +#define FIRST_MASK LEVEL_MASK(1) > + > +#define ZEROETH_SHIFT LEVEL_SHIFT(0) > +#define ZEROETH_ORDER LEVEL_ORDER(0) > +#define ZEROETH_SIZE LEVEL_SIZE(0) > +#define ZEROETH_MASK LEVEL_MASK(0) > > /* Calculate the offsets into the pagetables for a given VA */ > #define zeroeth_linear_offset(va) ((va) >> ZEROETH_SHIFT) > -- > 2.17.1 >
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