On Thu, Apr 06, 2017 at 01:37:41PM -0500, Brijesh Singh wrote:
> I did thought about prot idea but ran into another corner case which may require
> us changing the signature of phys_pud_init and phys_pmd_init. The paddr_start
> and paddr_end args into kernel_physical_mapping_init() should be aligned on PMD
> level down (see comment [1]). So, if we encounter a case where our address range
> is part of large page but we need to clear only one entry (i.e asked to clear just
> one page into 2M region). In that case, now we need to pass additional arguments
> into kernel_physical_mapping, phys_pud_init and phys_pmd_init to hint the splitting
> code that it should use our prot for specific entries and all other entries will use
> the old_prot.
Ok, but your !4K case:
+ /*
+ * virtual address is part of large page, create the page
+ * table mapping to use smaller pages (4K). The virtual and
+ * physical address must be aligned to PMD level.
+ */
+ kernel_physical_mapping_init(__pa(vaddr & PMD_MASK),
+ __pa((vaddr_end & PMD_MASK) + PMD_SIZE),
+ 0);
would map a 2M page as encrypted by default. What if we want to map a 2M page
frame as ~_PAGE_ENC?
IOW, if you're adding a new interface, it should be generic enough, like
with prot argument.
--
Regards/Gruss,
Boris.
SUSE Linux GmbH, GF: Felix Imendörffer, Jane Smithard, Graham Norton, HRB 21284 (AG Nürnberg)
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