[Xen-devel] [PATCH v2 4/6] x86-64/xen: Enable the vvar mapping

[Andy Lutomirski <luto@xxxxxxx>]

Xen needs to handle VVAR_PAGE, introduced in git commit:
9fd67b4ed0714ab718f1f9bd14c344af336a6df7
x86-64: Give vvars their own page

Otherwise we die during bootup with a message like:

(XEN) mm.c:940:d10 Error getting mfn 1888 (pfn 1e3e48) from L1 entry
      8000000001888465 for l1e_owner=10, pg_owner=10
(XEN) mm.c:5049:d10 ptwr_emulate: could not get_page_from_l1e()
[    0.000000] BUG: unable to handle kernel NULL pointer dereference at (null)
[    0.000000] IP: [<ffffffff8103a930>] xen_set_pte+0x20/0xe0

Signed-off-by: Andy Lutomirski <luto@xxxxxxx>
Reported-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
---
 arch/x86/xen/mmu.c |    4 +++-
 1 files changed, 3 insertions(+), 1 deletions(-)

diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
index f987bde..8cce339 100644
--- a/arch/x86/xen/mmu.c
+++ b/arch/x86/xen/mmu.c
@@ -1916,6 +1916,7 @@ static void xen_set_fixmap(unsigned idx, phys_addr_t 
phys, pgprot_t prot)
 # endif
 #else
        case VSYSCALL_LAST_PAGE ... VSYSCALL_FIRST_PAGE:
+       case VVAR_PAGE:
 #endif
        case FIX_TEXT_POKE0:
        case FIX_TEXT_POKE1:
@@ -1956,7 +1957,8 @@ static void xen_set_fixmap(unsigned idx, phys_addr_t 
phys, pgprot_t prot)
 #ifdef CONFIG_X86_64
        /* Replicate changes to map the vsyscall page into the user
           pagetable vsyscall mapping. */
-       if (idx >= VSYSCALL_LAST_PAGE && idx <= VSYSCALL_FIRST_PAGE) {
+       if ((idx >= VSYSCALL_LAST_PAGE && idx <= VSYSCALL_FIRST_PAGE) ||
+           idx == VVAR_PAGE) {
                unsigned long vaddr = __fix_to_virt(idx);
                set_pte_vaddr_pud(level3_user_vsyscall, vaddr, pte);
        }
-- 
1.7.6


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