x86/espfix/xen: Fix allocation of pages for paravirt page tables
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@oracle.com> Link: http://lkml.kernel.org/r/1404926298-5565-1-git-send-email-boris.ostrovsky@oracle.com Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Signed-off-by: H. Peter Anvin <hpa@linux.intel.com> Cc: <stable@vger.kernel.org>
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@ -175,7 +175,7 @@ void init_espfix_ap(void)
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if (!pud_present(pud)) {
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if (!pud_present(pud)) {
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pmd_p = (pmd_t *)__get_free_page(PGALLOC_GFP);
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pmd_p = (pmd_t *)__get_free_page(PGALLOC_GFP);
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pud = __pud(__pa(pmd_p) | (PGTABLE_PROT & ptemask));
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pud = __pud(__pa(pmd_p) | (PGTABLE_PROT & ptemask));
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paravirt_alloc_pud(&init_mm, __pa(pmd_p) >> PAGE_SHIFT);
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paravirt_alloc_pmd(&init_mm, __pa(pmd_p) >> PAGE_SHIFT);
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for (n = 0; n < ESPFIX_PUD_CLONES; n++)
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for (n = 0; n < ESPFIX_PUD_CLONES; n++)
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set_pud(&pud_p[n], pud);
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set_pud(&pud_p[n], pud);
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}
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}
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@ -185,7 +185,7 @@ void init_espfix_ap(void)
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if (!pmd_present(pmd)) {
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if (!pmd_present(pmd)) {
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pte_p = (pte_t *)__get_free_page(PGALLOC_GFP);
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pte_p = (pte_t *)__get_free_page(PGALLOC_GFP);
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pmd = __pmd(__pa(pte_p) | (PGTABLE_PROT & ptemask));
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pmd = __pmd(__pa(pte_p) | (PGTABLE_PROT & ptemask));
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paravirt_alloc_pmd(&init_mm, __pa(pte_p) >> PAGE_SHIFT);
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paravirt_alloc_pte(&init_mm, __pa(pte_p) >> PAGE_SHIFT);
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for (n = 0; n < ESPFIX_PMD_CLONES; n++)
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for (n = 0; n < ESPFIX_PMD_CLONES; n++)
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set_pmd(&pmd_p[n], pmd);
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set_pmd(&pmd_p[n], pmd);
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}
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}
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@ -193,7 +193,6 @@ void init_espfix_ap(void)
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pte_p = pte_offset_kernel(&pmd, addr);
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pte_p = pte_offset_kernel(&pmd, addr);
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stack_page = (void *)__get_free_page(GFP_KERNEL);
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stack_page = (void *)__get_free_page(GFP_KERNEL);
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pte = __pte(__pa(stack_page) | (__PAGE_KERNEL_RO & ptemask));
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pte = __pte(__pa(stack_page) | (__PAGE_KERNEL_RO & ptemask));
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paravirt_alloc_pte(&init_mm, __pa(stack_page) >> PAGE_SHIFT);
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for (n = 0; n < ESPFIX_PTE_CLONES; n++)
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for (n = 0; n < ESPFIX_PTE_CLONES; n++)
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set_pte(&pte_p[n*PTE_STRIDE], pte);
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set_pte(&pte_p[n*PTE_STRIDE], pte);
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