[PATCH v2 11/12] x86/jailhouse: Wire up IOAPIC for legacy UART ports

Jan Kiszka
2017-11-27T08:12:31Z

From: Jan Kiszka <jan.kiszka@siemens.com>

The typical I/O interrupts in non-root cells are MSI-based. However, the
platform UARTs do not support MSI. In order to run a non-root cell that
shall be use one of them, we need to register the standard IOAPIC and
set 1:1 routing for IRQ 3 and 4.

If an IOAPIC is not available, the boot loader clears standard_ioapic in
the setup data, and we skip the registration. If we should not be
allowed to use one of those pins, Jailhouse will simply ignore our
accesses.

Signed-off-by: Jan Kiszka <jan.kiszka@siemens.com>
---
arch/x86/kernel/jailhouse.c | 21 +++++++++++++++++++++
1 file changed, 21 insertions(+)

diff --git a/arch/x86/kernel/jailhouse.c b/arch/x86/kernel/jailhouse.c
index c8ee638b6bce..8ff21e1534de 100644
--- a/arch/x86/kernel/jailhouse.c
+++ b/arch/x86/kernel/jailhouse.c
@@ -17,6 +17,7 @@
#include <asm/cpu.h>
#include <asm/hypervisor.h>
#include <asm/i8259.h>
+#include <asm/irqdomain.h>
#include <asm/reboot.h>
#include <asm/setup.h>

@@ -54,6 +55,15 @@ static unsigned long jailhouse_get_tsc(void)

static void __init jailhouse_get_smp_config(unsigned int early)
{
+ struct ioapic_domain_cfg ioapic_cfg = {
+ .type = IOAPIC_DOMAIN_STRICT,
+ .ops = &mp_ioapic_irqdomain_ops,
+ };
+ struct mpc_intsrc mp_irq = {
+ .type = MP_INTSRC,
+ .irqtype = mp_INT,
+ .irqflag = MP_IRQPOL_ACTIVE_HIGH | MP_IRQTRIG_EDGE,
+ };
unsigned int cpu;

if (x2apic_enabled()) {
@@ -79,6 +89,17 @@ static void __init jailhouse_get_smp_config(unsigned int early)
}

smp_found_config = 1;
+
+ if (setup_data.standard_ioapic) {
+ mp_register_ioapic(0, 0xfec00000, gsi_top, &ioapic_cfg);
+
+ /* Register 1:1 mapping for legacy UART IRQs 3 and 4 */
+ mp_irq.srcbusirq = mp_irq.dstirq = 3;
+ mp_save_irq(&mp_irq);
+
+ mp_irq.srcbusirq = mp_irq.dstirq = 4;
+ mp_save_irq(&mp_irq);
+ }
}

static void jailhouse_no_restart(void)
--
2.12.3