Re: [PATCH] i386: For debugging, make the initial page table setup less forgiving.

Eric W. Biederman wrote:

I suspect what we want to do is come up with a function to call
to test to see if a page should be read-only and map such pages
_PAGE_KERNEL_RO, or _PAGE_KERNEL_RO_EXEC if it's code.

Speaking of things what are paravirt_alloc_pd and parafirt_alloc_pd supposed to do?

For hypervisors which shadow kernel page tables, none of these concerns with keeping page tables read-only arise. However, another set of concerns does arise with maintaining shadow synchronization. One of those problems is keeping the hypervisor aware of when pages are being used as page tables.

However, it turns out both direct page table and shadow page table implementations can be made to use one page table allocation function; in the direct page table case (as for Xen), this is the point where page tables can be recognized and made read-only. So this is the dual purpose of the paravirt_alloc_p[dt] functions.

Zach
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• References:
  • [PATCH] i386: For debugging, make the initial page table setup less forgiving.
    • From: "H. Peter Anvin" <[email protected]>
  • Re: [PATCH] i386: For debugging, make the initial page table setup less forgiving.
    • From: Andrew Morton <[email protected]>
  • Re: [PATCH] i386: For debugging, make the initial page table setup less forgiving.
    • From: "H. Peter Anvin" <[email protected]>
  • Re: [PATCH] i386: For debugging, make the initial page table setup less forgiving.
    • From: [email protected] (Eric W. Biederman)
  • Re: [PATCH] i386: For debugging, make the initial page table setup less forgiving.
    • From: Jeremy Fitzhardinge <[email protected]>
  • Re: [PATCH] i386: For debugging, make the initial page table setup less forgiving.
    • From: [email protected] (Eric W. Biederman)
  • Re: [PATCH] i386: For debugging, make the initial page table setup less forgiving.
    • From: Jeremy Fitzhardinge <[email protected]>
  • Re: [PATCH] i386: For debugging, make the initial page table setup less forgiving.
    • From: [email protected] (Eric W. Biederman)
  • Re: [PATCH] i386: For debugging, make the initial page table setup less forgiving.
    • From: Jeremy Fitzhardinge <[email protected]>
  • Re: [PATCH] i386: For debugging, make the initial page table setup less forgiving.
    • From: [email protected] (Eric W. Biederman)

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