Messages in this thread | | | Date | Fri, 2 Jun 2023 16:48:11 +0200 | Subject | Re: [RESUBMIT][PATCH] x86/mm: Fix PAT bit missing from page protection modify mask | From | Juergen Gross <> |
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On 02.06.23 16:43, Borislav Petkov wrote: > On Thu, Jun 01, 2023 at 10:47:39AM +0200, Juergen Gross wrote: >> As described in the commit message, this only works on bare metal due to the >> PAT bit not being needed for WC mappings. >> >> Making this patch Xen specific would try to cure the symptoms without fixing >> the underlying problem: _PAGE_PAT should be regarded the same way as the bits >> for caching mode (_PAGE_CHG_MASK). > > So why isn't _PAGE_PAT part of _PAGE_CHG_MASK?
This would result in problems for large pages: _PAGE_PSE is at the same position as _PAGE_PAT (large pages are using _PAGE_PAT_LARGE instead).
Yes, x86 ABI is a mess.
Juergen
[unhandled content-type:application/pgp-keys][unhandled content-type:application/pgp-signature] | |