xen: make xen_load_gdt simpler

Remove use of multicall machinery which is unused (gdt loading
is never performance critical).  This removes the implicit use
of percpu variables, which simplifies understanding how
the percpu code's use of load_gdt interacts with this code.

Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>

diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index 8e024554a3e1e0940e0b691356beb9ed154d1145..334d2ffc4e2a0b1d46c6d466724b3cd71d270111 100644 (file)
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -284,12 +284,11 @@ static void xen_set_ldt(const void *addr, unsigned entries)
 
 static void xen_load_gdt(const struct desc_ptr *dtr)
 {
-       unsigned long *frames;
        unsigned long va = dtr->address;
        unsigned int size = dtr->size + 1;
        unsigned pages = (size + PAGE_SIZE - 1) / PAGE_SIZE;
+       unsigned long frames[pages];
        int f;
-       struct multicall_space mcs;
 
        /* A GDT can be up to 64k in size, which corresponds to 8192
           8-byte entries, or 16 4k pages.. */
@@ -297,9 +296,6 @@ static void xen_load_gdt(const struct desc_ptr *dtr)
        BUG_ON(size > 65536);
        BUG_ON(va & ~PAGE_MASK);
 
-       mcs = xen_mc_entry(sizeof(*frames) * pages);
-       frames = mcs.args;
-
        for (f = 0; va < dtr->address + size; va += PAGE_SIZE, f++) {
                int level;
                pte_t *ptep = lookup_address(va, &level);
@@ -314,13 +310,15 @@ static void xen_load_gdt(const struct desc_ptr *dtr)
 
                frames[f] = mfn;
 
+               printk("xen_load_gdt: %d va=%p mfn=%lx pfn=%lx va'=%p\n",
+                      f, (void *)va, mfn, pfn, virt);
+
                make_lowmem_page_readonly((void *)va);
                make_lowmem_page_readonly(virt);
        }
 
-       MULTI_set_gdt(mcs.mc, frames, size / sizeof(struct desc_struct));
-
-       xen_mc_issue(PARAVIRT_LAZY_CPU);
+       if (HYPERVISOR_set_gdt(frames, size / sizeof(struct desc_struct)))
+               BUG();
 }
 
 static void load_TLS_descriptor(struct thread_struct *t,