On Fri, Oct 16, 2015 at 04:20:27PM -0700, Sai Praneeth Prakhya wrote: > From: Sai Praneeth <sai.praneeth.prakhya@xxxxxxxxx> > > When CONFIG_DEBUG_VIRTUAL is enabled, all accesses to __pa(address) are > monitored to see whether address falls in direct mapping or kernel text > mapping (see Documentation/x86/x86_64/mm.txt for details), if it does > not kernel panics. At least a comma and a "the" here: "..., if it does not, the kernel panics." > During 1:1 mapping of EFI runtime services we access > virtual addresses which are == physical addresses, thus the 1:1 mapping > and these addresses donot fall in either of the above two regions and do not > hence when passed as arguments to __pa() kernel panics as reported by > Dave Hansen here https://lkml.kernel.org/r/5462999A.7090706@xxxxxxxxx. > So, before calling __pa() virtual addresses should be validated which > results in skipping call to split_page_count() and that should be fine > because it is used to keep track of everything *but* 1:1 mappings. > > Signed-off-by: Sai Praneeth Prakhya <sai.praneeth.prakhya@xxxxxxxxx> > Reported-by: Dave Hansen <dave.hansen@xxxxxxxxx> > Cc: Matt Fleming <matt.fleming@xxxxxxxxx> > Cc: Ricardo Neri <ricardo.neri@xxxxxxxxx> > Cc: Glenn P Williamson <glenn.p.williamson@xxxxxxxxx> > Cc: Ravi Shankar <ravi.v.shankar@xxxxxxxxx> > > Changes since v1: > Made commit message more clear by adding reference to > Documentation/x86/x86_64/mm.txt, instead of addresses "below 4G" > changed it to "virtual addresses == physical addresses" quoted > mail with k.org redirector and changed last line "to keep track of > evrything *but* 1:1 mappings." Also made code more readable by adding a > variable. > --- > arch/x86/mm/pageattr.c | 9 ++++++--- > 1 file changed, 6 insertions(+), 3 deletions(-) > > diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c > index 727158cb3b3c..9abe0c9b1098 100644 > --- a/arch/x86/mm/pageattr.c > +++ b/arch/x86/mm/pageattr.c > @@ -648,9 +648,12 @@ __split_large_page(struct cpa_data *cpa, pte_t *kpte, unsigned long address, > for (i = 0; i < PTRS_PER_PTE; i++, pfn += pfninc) > set_pte(&pbase[i], pfn_pte(pfn, canon_pgprot(ref_prot))); > > - if (pfn_range_is_mapped(PFN_DOWN(__pa(address)), > - PFN_DOWN(__pa(address)) + 1)) > - split_page_count(level); > + if (virt_addr_valid(address)) { > + unsigned long pfn = PFN_DOWN(__pa(address)); > + > + if (pfn_range_is_mapped(pfn, pfn + 1)) > + split_page_count(level); > + } > > /* > * Install the new, split up pagetable. > -- Looks ok to me, these minor nitpicks can be adjusted when applying, no need to send another version. Which brings me to the next question: Matt, are you picking this up or should I? If you, then Reviewed-by: Borislav Petkov <bp@xxxxxxx> Thanks! -- Regards/Gruss, Boris. ECO tip #101: Trim your mails when you reply. -- To unsubscribe from this list: send the line "unsubscribe linux-efi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
