x86: fix probe_nr_irqs for xen
otherwise Xen is _completely_ unusable with 5 or more VCPUs.
(when !CONFIG_HAVE_SPARSE_IRQ).
based on Alex Nixon's patch.
also add +1 offset after redir_entries
Signed-off-by: Yinghai Lu <yhlu.kernel@gmail.com>
Acked-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Acked-by: Alex Nixon <alex.nixon@citrix.com>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/arch/x86/kernel/io_apic.c b/arch/x86/kernel/io_apic.c
index 4e44fd1..d28128e 100644
--- a/arch/x86/kernel/io_apic.c
+++ b/arch/x86/kernel/io_apic.c
@@ -3625,16 +3625,21 @@
{
int idx;
int nr = 0;
+#ifndef CONFIG_XEN
+ int nr_min = 32;
+#else
+ int nr_min = NR_IRQS;
+#endif
for (idx = 0; idx < nr_ioapics; idx++)
- nr += io_apic_get_redir_entries(idx);
+ nr += io_apic_get_redir_entries(idx) + 1;
/* double it for hotplug and msi and nmi */
nr <<= 1;
/* something wrong ? */
- if (nr < 32)
- nr = 32;
+ if (nr < nr_min)
+ nr = nr_min;
return nr;
}