Messages in this thread | | | Date | Wed, 24 Feb 2016 19:33:15 +0000 | From | Matt Fleming <> | Subject | Re: [tip:efi/core] x86/mm/pat: Use _PAGE_GLOBAL bit for EFI page table mappings |
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On Wed, 24 Feb, at 08:36:33AM, Andy Lutomirski wrote: > On Wed, Feb 24, 2016 at 8:20 AM, Borislav Petkov <bp@alien8.de> wrote: > > On Wed, Feb 24, 2016 at 02:10:46PM +0000, Matt Fleming wrote: > >> > Normally, the only pages with are _PAGE_GLOBAL are those that are in > >> > the normal kernel mappings (swapper_pg_dir and normal mm_struct pgds). > >> > By allowing _PAGE_GLOBAL to be set in EFI mappings, you're breaking > >> > that convention, which forces you to use extra-expensive > >> > __flush_tlb_all calls in efi_call_virt. > > > > Hold on, do you mean the __flush_tlb_all() in the CONFIG_EFI_MIXED code? > > > > That's mixed mode. I think you mean the FLUSH_TLB_ALL in efi_call. > > That's EFI on 64-bit but that is mandated by the spec, AFAIR. > > I mean the one in efi_call_virt. Why would the spec mandate a TLB > flush at all? EFI runtime services have no business touching the > paging structures directly. Heck, the 32-bit ones don't even know the > *format* of the paging structures.
Right, and it would necessitate copying out arguments because the firmware won't understand where/how the kernel has mapped things.
No firmware is going to be doing that.
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