On Sat, Aug 25, 2018 at 06:50:15AM -0700, Andi Kleen wrote: > From: Andi Kleen <ak@xxxxxxxxxxxxxxx> > > Patch for stable only to fix boot resets caused by the L1TF patches. > > Stable trees reverted the following patch > > Revert "x86/mm/pat: Ensure cpa->pfn only contains page frame numbers" > > This reverts commit 87e2bd898d3a79a8c609f183180adac47879a2a4 which is > commit edc3b9129cecd0f0857112136f5b8b1bc1d45918 upstream. > > but the L1TF patch backported here > > x86/mm/pat: Make set_memory_np() L1TF safe > > commit 958f79b9ee55dfaf00c8106ed1c22a2919e0028b upstream > > set_memory_np() is used to mark kernel mappings not present, but it has > it's own open coded mechanism which does not have the L1TF protection of > inverting the address bits. > > assumed that cpa->pfn contains a PFN. With the above patch reverted > it does not, which causes the PMD to be set to an incorrect address > shifted by 12 bits, which can cause early boot reset on some > systems, like an Apollo Lake embedded system. > > Convert the address to a PFN before passing it to pmd_pfn() > > Thanks to Bernhard for bisecting and testing. > Thanks a lot to you for tracking it down, and sorry for messing it up. > Cc: stable@xxxxxxxxxxxxxxx # 4.4 and 4.9 LGTM for v4.4.y but ... are you sure that this patch applies to v4.9.y ? Commit edc3b9129cec is 'native' in v4.9.y and has not been reverted there. $ git log --oneline v4.4..linux-4.9.y | grep "x86/mm/pat: Ensure cpa->pfn only contains page frame numbers" edc3b9129cec x86/mm/pat: Ensure cpa->pfn only contains page frame numbers Guenter > Reported-by: Bernhard Kaindl <bernhard.kaindl@xxxxxxxxxxxxxxx> > Tested-by: Bernhard Kaindl <bernhard.kaindl@xxxxxxxxxxxxxxx> > Signed-off-by: Andi Kleen <ak@xxxxxxxxxxxxxxx> > --- > arch/x86/mm/pageattr.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c > index 27610c2d1821..1007fa80f5a6 100644 > --- a/arch/x86/mm/pageattr.c > +++ b/arch/x86/mm/pageattr.c > @@ -1006,7 +1006,7 @@ static int populate_pmd(struct cpa_data *cpa, > > pmd = pmd_offset(pud, start); > > - set_pmd(pmd, pmd_mkhuge(pfn_pmd(cpa->pfn, > + set_pmd(pmd, pmd_mkhuge(pfn_pmd(cpa->pfn >> PAGE_SHIFT, > canon_pgprot(pmd_pgprot)))); > > start += PMD_SIZE;
