Messages in this thread Patch in this message | | | From | Konrad Rzeszutek Wilk <> | Subject | [PATCH 3/3] x86/paravirt: Use pte_val instead of pte_flags on CPA pageattr_test | Date | Tue, 8 Nov 2011 16:15:14 -0500 |
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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 <konrad.wilk@oracle.com> CC: stable@kernel.org --- arch/x86/mm/pageattr-test.c | 6 +++++- 1 files changed, 5 insertions(+), 1 deletions(-)
diff --git a/arch/x86/mm/pageattr-test.c b/arch/x86/mm/pageattr-test.c index b008656..da853e3 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; @@ -180,7 +184,7 @@ 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++; -- 1.7.7.1
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