From adaba23ccd7d1625942f2c27612d2b416c87e011 Mon Sep 17 00:00:00 2001 From: Andi Kleen Date: Sat, 25 Aug 2018 06:50:15 -0700 Subject: [PATCH] x86/mm/pat: Fix L1TF stable backport for CPA 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. Cc: stable@vger.kernel.org # 4.4 and 4.9 Reported-by: Bernhard Kaindl Tested-by: Bernhard Kaindl Signed-off-by: Andi Kleen Signed-off-by: Greg Kroah-Hartman --- 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 27610c2..1007fa8 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; -- 2.7.4