linux-kernel - [PATCH v2 08/12] x86/jailhouse: Avoid access of unsupported platform resources

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Date:   Mon, 27 Nov 2017 09:11:50 +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 v2 08/12] x86/jailhouse: Avoid access of unsupported platform resources

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

Non-root cells do not have CMOS access, thus the warm reset cannot be
enabled. There is no RTC, thus also no wall clock. Furthermore, there
are no ISA IRQs and no PIC.

Also disable probing of i8042 devices that are typically blocked for
non-root cells. In theory, access could also be granted to a non-root
cell, provided the root cell is not using the devices. But there is no
concrete scenario in sight, and disabling probing over Jailhouse allows
to build generic kernels that keep CONFIG_SERIO enabled for use in
normal systems.

Signed-off-by: Jan Kiszka <jan.kiszka@...mens.com>
---
 arch/x86/kernel/jailhouse.c | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/arch/x86/kernel/jailhouse.c b/arch/x86/kernel/jailhouse.c
index effec7d2b480..f5f459bb7aac 100644
--- a/arch/x86/kernel/jailhouse.c
+++ b/arch/x86/kernel/jailhouse.c
@@ -15,6 +15,7 @@
 #include <asm/apic.h>
 #include <asm/cpu.h>
 #include <asm/hypervisor.h>
+#include <asm/i8259.h>
 #include <asm/setup.h>
 
 static __initdata struct jailhouse_setup_data setup_data;
@@ -34,6 +35,11 @@ static uint32_t __init jailhouse_detect(void)
 	return jailhouse_cpuid_base();
 }
 
+static void jailhouse_get_wallclock(struct timespec *now)
+{
+	memset(now, 0, sizeof(*now));
+}
+
 static void __init jailhouse_timer_init(void)
 {
 	lapic_timer_frequency = setup_data.apic_khz * (1000 / HZ);
@@ -79,11 +85,18 @@ static void __init jailhouse_init_platform(void)
 	struct setup_data header;
 	void *mapping;
 
+	x86_init.irqs.pre_vector_init	= x86_init_noop;
 	x86_init.timers.timer_init	= jailhouse_timer_init;
 	x86_init.mpparse.get_smp_config	= jailhouse_get_smp_config;
 
 	x86_platform.calibrate_cpu	= jailhouse_get_tsc;
 	x86_platform.calibrate_tsc	= jailhouse_get_tsc;
+	x86_platform.get_wallclock	= jailhouse_get_wallclock;
+	x86_platform.legacy.rtc		= 0;
+	x86_platform.legacy.warm_reset	= 0;
+	x86_platform.legacy.i8042	= X86_LEGACY_I8042_PLATFORM_ABSENT;
+
+	legacy_pic			= &null_legacy_pic;
 
 	while (pa_data) {
 		mapping = early_memremap(pa_data, sizeof(header));
-- 
2.12.3