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| author | Boris Ostrovsky <boris.ostrovsky@oracle.com> | 2014-07-09 13:18:18 -0400 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2014-08-07 16:53:54 -0700 |
| commit | 8f0d9e956f8000880cb0fce47c25e7bc16d79d41 (patch) | |
| tree | 0a62b92c4416083ec215de60ba2802a7700889a3 | |
| parent | 849c177302db129212c3c5432191fc3c88f75620 (diff) | |
| download | lwn-8f0d9e956f8000880cb0fce47c25e7bc16d79d41.tar.gz lwn-8f0d9e956f8000880cb0fce47c25e7bc16d79d41.zip | |
x86/espfix/xen: Fix allocation of pages for paravirt page tables
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@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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
| -rw-r--r-- | arch/x86/kernel/espfix_64.c | 5 |
1 files changed, 2 insertions, 3 deletions
diff --git a/arch/x86/kernel/espfix_64.c b/arch/x86/kernel/espfix_64.c index 6afbb16e9b79..94d857fb1033 100644 --- 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); |