From 8cfa86623c75457aa2eec12e15ff7fd0b9fbf035 Mon Sep 17 00:00:00 2001 From: Konrad Rzeszutek Wilk Date: Fri, 4 Nov 2011 13:18:15 -0400 Subject: [PATCH] x86/paravirt: Use pte_val instead of pte_flags on CPA pageattr_test For details refer to patch "x86/paravirt: Use pte_attrs instead of pte_flags on CPA/set_p.._wb/wc operations." which explains that some pages have the _PAGE_PWT bit set in the _PAGE_PSE field when running under Xen. When pageattr_test is running it uses pte_flags to check whether it succedded in setting _PAGE_UNUSED1 bit, but also whether the page had _PAGE_PSE. This can happen when one of the randomly selected pages to be tested is a page that has been set to be _PAGE_WC as under Xen, that field is under _PAGE_PSE. Since the 'pte_huge' call is using the pte_flags(x) macro, which extracts the "raw" contents of the PTE, the translation of _PAGE_PSE -> _PAGE_PWT does not happen and we incorrectly identify the PTE as bad. Using the 'pte_val' instead of 'pte_flags' fixes the problem and this patch does that. Signed-off-by: Konrad Rzeszutek Wilk CC: stable@kernel.org --- arch/x86/mm/pageattr-test.c | 6 +++++- 1 file changed, 5 insertions(+), 1 deletion(-) diff --git a/arch/x86/mm/pageattr-test.c b/arch/x86/mm/pageattr-test.c index e1d1069092186..ac66feb0c5bb8 100644 --- a/arch/x86/mm/pageattr-test.c +++ b/arch/x86/mm/pageattr-test.c @@ -38,6 +38,10 @@ static int pte_testbit(pte_t pte) { return pte_flags(pte) & _PAGE_UNUSED1; } +static int pte_testhuge(pte_t pte) +{ + return pte_val(pte) & _PAGE_PSE; +} struct split_state { long lpg, gpg, spg, exec; @@ -181,7 +185,7 @@ static int pageattr_test(void) } pte = lookup_address(addr[i], &level); - if (!pte || !pte_testbit(*pte) || pte_huge(*pte)) { + if (!pte || !pte_testbit(*pte) || pte_testhuge(*pte)) { printk(KERN_ERR "CPA %lx: bad pte %Lx\n", addr[i], pte ? (u64)pte_val(*pte) : 0ULL); failed++; -- 2.50.1