x86: MSI start irq numbering from nr_irqs_gsi
Impact: sanitize MSI irq number ordering from top-down to bottom-up
Increase new MSI IRQs starting from nr_irqs_gsi (which is somewhere below
256), instead of decreasing from NR_IRQS. (The latter method can result
in confusingly high IRQ numbers - if NR_CPUS is set to a high value and
NR_IRQS scales up to a high value.)
Signed-off-by: Yinghai Lu <yinghai@kernel.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
diff --git a/arch/x86/include/asm/io_apic.h b/arch/x86/include/asm/io_apic.h
index 6afd993..b35e94c 100644
--- a/arch/x86/include/asm/io_apic.h
+++ b/arch/x86/include/asm/io_apic.h
@@ -188,7 +188,7 @@
extern void reinit_intr_remapped_IO_APIC(int);
#endif
-extern int probe_nr_irqs(void);
+extern void probe_nr_irqs_gsi(void);
#else /* !CONFIG_X86_IO_APIC */
#define io_apic_assign_pci_irqs 0
diff --git a/arch/x86/kernel/io_apic.c b/arch/x86/kernel/io_apic.c
index 9870461..0dcde74 100644
--- a/arch/x86/kernel/io_apic.c
+++ b/arch/x86/kernel/io_apic.c
@@ -2973,7 +2973,7 @@
irq = 0;
spin_lock_irqsave(&vector_lock, flags);
- for (new = irq_want; new > 0; new--) {
+ for (new = irq_want; new < NR_IRQS; new++) {
if (platform_legacy_irq(new))
continue;
@@ -3001,11 +3001,14 @@
return irq;
}
+static int nr_irqs_gsi = NR_IRQS_LEGACY;
int create_irq(void)
{
+ unsigned int irq_want;
int irq;
- irq = create_irq_nr(nr_irqs - 1);
+ irq_want = nr_irqs_gsi;
+ irq = create_irq_nr(irq_want);
if (irq == 0)
irq = -1;
@@ -3281,7 +3284,7 @@
int ret;
unsigned int irq_want;
- irq_want = nr_irqs - 1;
+ irq_want = nr_irqs_gsi;
irq = create_irq_nr(irq_want);
if (irq == 0)
return -1;
@@ -3321,11 +3324,11 @@
int index = 0;
#endif
- irq_want = nr_irqs - 1;
+ irq_want = nr_irqs_gsi;
sub_handle = 0;
list_for_each_entry(msidesc, &dev->msi_list, list) {
irq = create_irq_nr(irq_want);
- irq_want--;
+ irq_want++;
if (irq == 0)
return -1;
#ifdef CONFIG_INTR_REMAP
@@ -3674,9 +3677,16 @@
return reg_01.bits.entries;
}
-int __init probe_nr_irqs(void)
+void __init probe_nr_irqs_gsi(void)
{
- return NR_IRQS;
+ int idx;
+ int nr = 0;
+
+ for (idx = 0; idx < nr_ioapics; idx++)
+ nr += io_apic_get_redir_entries(idx) + 1;
+
+ if (nr > nr_irqs_gsi)
+ nr_irqs_gsi = nr;
}
/* --------------------------------------------------------------------------
diff --git a/arch/x86/kernel/setup.c b/arch/x86/kernel/setup.c
index 9d5674f..a3834f1 100644
--- a/arch/x86/kernel/setup.c
+++ b/arch/x86/kernel/setup.c
@@ -1082,7 +1082,7 @@
ioapic_init_mappings();
/* need to wait for io_apic is mapped */
- nr_irqs = probe_nr_irqs();
+ probe_nr_irqs_gsi();
kvm_guest_init();