Re: [Xen-devel] [PATCH v5 02/12] arm/mem_access: Move PAGE_SHIFT_* macros to lib.h

[Sergej Proskurin <proskurin@xxxxxxxxxxxxx>]

Hi Jan,


On 06/27/2017 02:04 PM, Jan Beulich wrote:
>>>> Sergej Proskurin <proskurin@xxxxxxxxxxxxx> 06/27/17 1:52 PM >>>
>> The following commits introduce a software guest page table walk
>> software implementation that supports varying guest page size
>> granularities. This commit moves already existing PAGE_SHIFT_(4K|64K)
>> and the new PAGE_SHIFT_16K defines to a common place in xen/lib.h as
>> to allow the following commits to use the consolidated defines.
> I don't think the PAGE_SHIFT_* should live far away from the other PAGE_*_*
> macros derived from them. I'm also not convinced lib.h is a good place.

I agree. I can move related PAGE_*_* from xen/iommu.h together with
PAGE_SIZE_* macros into a common place. As we already define PAGE_*
macros in asm/config.h, I believe it would make sense to extend these by
the upper PAGE_*_* macros. What do you think?

If you believe asm/config.h is a good place for the upper macros, I
would move them and simultaneously (as a separate patch) remove the
IOMMU_PAGE_* defines from xen/iommu.h. AFAICT they act only as helpers
and are not used elsewhere. Instead, I could add similar helpers in
asm/config.h. S.th. like the following:

---

#define PAGE_SIZE_GRAN(sz)          (1UL << PAGE_SHIFT_##sz)
#define PAGE_MASK_GRAN(sz)          (~(PAGE_SIZE_##sz - 1))
#define PAGE_ALIGN_GRAN(sz, addr)   (((addr) + ~PAGE_MASK_##sz) &
PAGE_MASK_##sz)

#define PAGE_SHIFT_4K               (12)
#define PAGE_SIZE_4K                PAGE_SIZE_GRAN(4K)
#define PAGE_MASK_4K                PAGE_MASK_GRAN(4K)
#define PAGE_ALIGN_4K(addr)         PAGE_ALIGN_GRAN(4K, addr)

#define PAGE_SHIFT_16K              (14)
#define PAGE_SIZE_16K               PAGE_SIZE_GRAN(16K)
#define PAGE_MASK_16K               PAGE_MASK_GRAN(16K)
#define PAGE_ALIGN_16K(addr)        PAGE_ALIGN_GRAN(16K, addr)

#define PAGE_SHIFT_64K              (16)
#define PAGE_SIZE_64K               PAGE_SIZE_GRAN(64K)
#define PAGE_MASK_64K               PAGE_MASK_GRAN(64K)
#define PAGE_ALIGN_64K(addr)        PAGE_ALIGN_GRAN(64K, addr)

---

Thanks,
~Sergej


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