linux-kernel - [PATCH 09/10] x86: jailhouse: Wire up IOAPIC for legacy UART ports

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Message-Id: <fa788dcd139d567b23467db848b97494721ec3cf.1510817211.git.jan.kiszka@siemens.com>
Date:   Thu, 16 Nov 2017 08:26:51 +0100
From:   Jan Kiszka <jan.kiszka@...mens.com>
To:     Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>,
        "H . Peter Anvin" <hpa@...or.com>
Cc:     x86@...nel.org,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        jailhouse-dev@...glegroups.com
Subject: [PATCH 09/10] x86: jailhouse: Wire up IOAPIC for legacy UART ports

From: Jan Kiszka <jan.kiszka@...mens.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@...mens.com>
---
 arch/x86/kernel/jailhouse.c | 20 ++++++++++++++++++++
 1 file changed, 20 insertions(+)

diff --git a/arch/x86/kernel/jailhouse.c b/arch/x86/kernel/jailhouse.c
index 0bcca175c35e..05459ea0ecc7 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>
 
@@ -148,6 +149,14 @@ static unsigned int x2apic_get_apic_id(unsigned long id)
 
 static void __init jailhouse_init_platform(void)
 {
+	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,
+	};
 	u64 pa_data = boot_params.hdr.setup_data;
 	struct jailhouse_setup_data *data;
 	unsigned int cpu;
@@ -189,6 +198,17 @@ static void __init jailhouse_init_platform(void)
 				       boot_cpu_apic_version);
 	smp_found_config = 1;
 
+	if (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);
+	}
+
 	early_memunmap(data, sizeof(*data));
 
 	/*
-- 
2.12.3