x86_64: add workaround for no %gs-based percpu
As a stopgap until Mike Travis's x86-64 gs-based percpu patches are
ready, provide workaround functions for x86_read/write_percpu for
Xen's use.
Specifically, this means that we can't really make use of vcpu
placement, because we can't use a single gs-based memory access to get
to vcpu fields. So disable all that for now.
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Cc: Stephen Tweedie <sct@redhat.com>
Cc: Eduardo Habkost <ehabkost@redhat.com>
Cc: Mark McLoughlin <markmc@redhat.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c
index a85f447..f3f11ac 100644
--- a/arch/x86/xen/enlighten.c
+++ b/arch/x86/xen/enlighten.c
@@ -971,6 +971,7 @@
/* xen_vcpu_setup managed to place the vcpu_info within the
percpu area for all cpus, so make use of it */
+#ifdef CONFIG_X86_32
if (have_vcpu_info_placement) {
printk(KERN_INFO "Xen: using vcpu_info placement\n");
@@ -980,6 +981,7 @@
pv_irq_ops.irq_enable = xen_irq_enable_direct;
pv_mmu_ops.read_cr2 = xen_read_cr2_direct;
}
+#endif
}
static unsigned xen_patch(u8 type, u16 clobbers, void *insnbuf,
@@ -1000,10 +1002,12 @@
goto patch_site
switch (type) {
+#ifdef CONFIG_X86_32
SITE(pv_irq_ops, irq_enable);
SITE(pv_irq_ops, irq_disable);
SITE(pv_irq_ops, save_fl);
SITE(pv_irq_ops, restore_fl);
+#endif /* CONFIG_X86_32 */
#undef SITE
patch_site:
@@ -1323,6 +1327,7 @@
#ifdef CONFIG_X86_64
/* Disable until direct per-cpu data access. */
have_vcpu_info_placement = 0;
+ x86_64_init_pda();
#endif
xen_smp_init();