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[Xen-devel] [PATCH 02 of 31] xen: fix UP setup of shared_info



We need to set up the shared_info pointer once we've mapped the real
shared_info into its fixmap slot.  That needs to happen once the general
pagetable setup has been done.  Previously, the UP shared_info was set
up one in xen_start_kernel, but that was left pointing to the dummy
shared info.  Unfortunately there's no really good place to do a later
setup of the shared_info in UP, so just do it once the pagetable setup
has been done.

[ Stable: needed in 2.6.24.x ]

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@xxxxxxxxxx>
Cc: Stable Kernel <stable@xxxxxxxxxx>
---
 arch/x86/xen/enlighten.c |   51 +++++++++++++++++++++++++---------------------
 1 file changed, 28 insertions(+), 23 deletions(-)

diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -104,6 +104,7 @@
        int err;
        struct vcpu_info *vcpup;
 
+       BUG_ON(HYPERVISOR_shared_info == &dummy_shared_info);
        per_cpu(xen_vcpu, cpu) = &HYPERVISOR_shared_info->vcpu_info[cpu];
 
        if (!have_vcpu_info_placement)
@@ -806,6 +807,31 @@
                          PFN_DOWN(__pa(xen_start_info->pt_base)));
 }
 
+static __init void setup_shared_info(void)
+{
+       if (!xen_feature(XENFEAT_auto_translated_physmap)) {
+               unsigned long addr = fix_to_virt(FIX_PARAVIRT_BOOTMAP);
+
+               /*
+                * Create a mapping for the shared info page.
+                * Should be set_fixmap(), but shared_info is a machine
+                * address with no corresponding pseudo-phys address.
+                */
+               set_pte_mfn(addr,
+                           PFN_DOWN(xen_start_info->shared_info),
+                           PAGE_KERNEL);
+
+               HYPERVISOR_shared_info = (struct shared_info *)addr;
+       } else
+               HYPERVISOR_shared_info =
+                       (struct shared_info *)__va(xen_start_info->shared_info);
+
+#ifndef CONFIG_SMP
+       /* In UP this is as good a place as any to set up shared info */
+       xen_setup_vcpu_info_placement();
+#endif
+}
+
 static __init void xen_pagetable_setup_done(pgd_t *base)
 {
        /* This will work as long as patching hasn't happened yet
@@ -816,22 +842,7 @@
        pv_mmu_ops.release_pd = xen_release_pt;
        pv_mmu_ops.set_pte = xen_set_pte;
 
-       if (!xen_feature(XENFEAT_auto_translated_physmap)) {
-               /*
-                * Create a mapping for the shared info page.
-                * Should be set_fixmap(), but shared_info is a machine
-                * address with no corresponding pseudo-phys address.
-                */
-               set_pte_mfn(fix_to_virt(FIX_PARAVIRT_BOOTMAP),
-                           PFN_DOWN(xen_start_info->shared_info),
-                           PAGE_KERNEL);
-
-               HYPERVISOR_shared_info =
-                       (struct shared_info *)fix_to_virt(FIX_PARAVIRT_BOOTMAP);
-
-       } else
-               HYPERVISOR_shared_info =
-                       (struct shared_info *)__va(xen_start_info->shared_info);
+       setup_shared_info();
 
        /* Actually pin the pagetable down, but we can't set PG_pinned
           yet because the page structures don't exist yet. */
@@ -1182,15 +1193,9 @@
        x86_write_percpu(xen_cr3, __pa(pgd));
        x86_write_percpu(xen_current_cr3, __pa(pgd));
 
-#ifdef CONFIG_SMP
        /* Don't do the full vcpu_info placement stuff until we have a
-          possible map. */
+          possible map and a non-dummy shared_info. */
        per_cpu(xen_vcpu, 0) = &HYPERVISOR_shared_info->vcpu_info[0];
-#else
-       /* May as well do it now, since there's no good time to call
-          it later on UP. */
-       xen_setup_vcpu_info_placement();
-#endif
 
        pv_info.kernel_rpl = 1;
        if (xen_feature(XENFEAT_supervisor_mode_kernel))



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