3.14-stable review patch. If anyone has any objections, please let me know. ------------------ From: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx> commit 8762e5092828c4dc0f49da5a47a644c670df77f3 upstream. init_espfix_ap() is currently off by one level when informing hypervisor that allocated pages will be used for ministacks' page tables. The most immediate effect of this on a PV guest is that if 'stack_page = __get_free_page()' returns a non-zeroed-out page the hypervisor will refuse to use it for a page table (which it shouldn't be anyway). This will result in warnings by both Xen and Linux. More importantly, a subsequent write to that page (again, by a PV guest) is likely to result in fatal page fault. Signed-off-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx> Link: http://lkml.kernel.org/r/1404926298-5565-1-git-send-email-boris.ostrovsky@xxxxxxxxxx Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx> Signed-off-by: H. Peter Anvin <hpa@xxxxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- arch/x86/kernel/espfix_64.c | 5 ++--- 1 file changed, 2 insertions(+), 3 deletions(-) --- a/arch/x86/kernel/espfix_64.c +++ b/arch/x86/kernel/espfix_64.c @@ -175,7 +175,7 @@ void init_espfix_ap(void) if (!pud_present(pud)) { pmd_p = (pmd_t *)__get_free_page(PGALLOC_GFP); pud = __pud(__pa(pmd_p) | (PGTABLE_PROT & ptemask)); - paravirt_alloc_pud(&init_mm, __pa(pmd_p) >> PAGE_SHIFT); + paravirt_alloc_pmd(&init_mm, __pa(pmd_p) >> PAGE_SHIFT); for (n = 0; n < ESPFIX_PUD_CLONES; n++) set_pud(&pud_p[n], pud); } @@ -185,7 +185,7 @@ void init_espfix_ap(void) if (!pmd_present(pmd)) { pte_p = (pte_t *)__get_free_page(PGALLOC_GFP); pmd = __pmd(__pa(pte_p) | (PGTABLE_PROT & ptemask)); - paravirt_alloc_pmd(&init_mm, __pa(pte_p) >> PAGE_SHIFT); + paravirt_alloc_pte(&init_mm, __pa(pte_p) >> PAGE_SHIFT); for (n = 0; n < ESPFIX_PMD_CLONES; n++) set_pmd(&pmd_p[n], pmd); } @@ -193,7 +193,6 @@ void init_espfix_ap(void) pte_p = pte_offset_kernel(&pmd, addr); stack_page = (void *)__get_free_page(GFP_KERNEL); pte = __pte(__pa(stack_page) | (__PAGE_KERNEL_RO & ptemask)); - paravirt_alloc_pte(&init_mm, __pa(stack_page) >> PAGE_SHIFT); for (n = 0; n < ESPFIX_PTE_CLONES; n++) set_pte(&pte_p[n*PTE_STRIDE], pte); -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html