@@ -19,6 +19,12 @@ static inline int paravirt_enabled(void)
return pv_info.paravirt_enabled;
}
+static inline int paravirt_has_feature(unsigned int feature)
+{
+ WARN_ON_ONCE(!pv_info.paravirt_enabled);
+ return (pv_info.features & feature);
+}
+
static inline void load_sp0(struct tss_struct *tss,
struct thread_struct *thread)
{
@@ -70,9 +70,14 @@ struct pv_info {
#endif
int paravirt_enabled;
+ unsigned int features; /* valid only if paravirt_enabled is set */
const char *name;
};
+#define paravirt_has(x) paravirt_has_feature(PV_SUPPORTED_##x)
+/* Supported features */
+#define PV_SUPPORTED_RTC (1<<0)
+
struct pv_init_ops {
/*
* Patch may replace one of the defined code sequences with
@@ -478,6 +478,7 @@ static inline unsigned long current_top_of_stack(void)
#else
#define __cpuid native_cpuid
#define paravirt_enabled() 0
+#define paravirt_has(x) 0
static inline void load_sp0(struct tss_struct *tss,
struct thread_struct *thread)
@@ -200,6 +200,9 @@ static __init int add_rtc_cmos(void)
}
#endif
+ if (paravirt_enabled() && !paravirt_has(RTC))
+ return -ENODEV;
+
platform_device_register(&rtc_device);
dev_info(&rtc_device.dev,
"registered platform RTC device (no PNP device found)\n");
@@ -1419,6 +1419,7 @@ __init void lguest_init(void)
pv_info.kernel_rpl = 1;
/* Everyone except Xen runs with this set. */
pv_info.shared_kernel_pmd = 1;
+ pv_info.features = 0;
/*
* We set up all the lguest overrides for sensitive operations. These
@@ -1186,7 +1186,7 @@ static const struct pv_info xen_info __initconst = {
#ifdef CONFIG_X86_64
.extra_user_64bit_cs = FLAT_USER_CS64,
#endif
-
+ .features = 0,
.name = "Xen",
};
@@ -1528,6 +1528,8 @@ asmlinkage __visible void __init xen_start_kernel(void)
/* Install Xen paravirt ops */
pv_info = xen_info;
+ if (xen_initial_domain())
+ pv_info.features |= PV_SUPPORTED_RTC;
pv_init_ops = xen_init_ops;
pv_apic_ops = xen_apic_ops;
if (!xen_pvh_domain()) {
This is a note to let you know that I have just added a patch titled x86/paravirt: Prevent rtc_cmos platform device init on PV guests to the linux-4.2.y-queue branch of the 4.2.y-ckt extended stable tree which can be found at: http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-4.2.y-queue This patch is scheduled to be released in version 4.2.8-ckt2. If you, or anyone else, feels it should not be added to this tree, please reply to this email. For more information about the 4.2.y-ckt tree, see https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable Thanks. -Kamal ---8<------------------------------------------------------------ From 0dd88836fb7f14a4d4a3d5e179e70f4aff8d9e6c Mon Sep 17 00:00:00 2001 From: David Vrabel <david.vrabel@citrix.com> Date: Fri, 11 Dec 2015 09:07:53 -0500 Subject: x86/paravirt: Prevent rtc_cmos platform device init on PV guests commit d8c98a1d1488747625ad6044d423406e17e99b7a upstream. Adding the rtc platform device in non-privileged Xen PV guests causes an IRQ conflict because these guests do not have legacy PIC and may allocate irqs in the legacy range. In a single VCPU Xen PV guest we should have: /proc/interrupts: CPU0 0: 4934 xen-percpu-virq timer0 1: 0 xen-percpu-ipi spinlock0 2: 0 xen-percpu-ipi resched0 3: 0 xen-percpu-ipi callfunc0 4: 0 xen-percpu-virq debug0 5: 0 xen-percpu-ipi callfuncsingle0 6: 0 xen-percpu-ipi irqwork0 7: 321 xen-dyn-event xenbus 8: 90 xen-dyn-event hvc_console ... But hvc_console cannot get its interrupt because it is already in use by rtc0 and the console does not work. genirq: Flags mismatch irq 8. 00000000 (hvc_console) vs. 00000000 (rtc0) We can avoid this problem by realizing that unprivileged PV guests (both Xen and lguests) are not supposed to have rtc_cmos device and so adding it is not necessary. Privileged guests (i.e. Xen's dom0) do use it but they should not have irq conflicts since they allocate irqs above legacy range (above gsi_top, in fact). Instead of explicitly testing whether the guest is privileged we can extend pv_info structure to include information about guest's RTC support. Reported-and-tested-by: Sander Eikelenboom <linux@eikelenboom.it> Signed-off-by: David Vrabel <david.vrabel@citrix.com> Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com> Cc: vkuznets@redhat.com Cc: xen-devel@lists.xenproject.org Cc: konrad.wilk@oracle.com Link: http://lkml.kernel.org/r/1449842873-2613-1-git-send-email-boris.ostrovsky@oracle.com Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Kamal Mostafa <kamal@canonical.com> --- arch/x86/include/asm/paravirt.h | 6 ++++++ arch/x86/include/asm/paravirt_types.h | 5 +++++ arch/x86/include/asm/processor.h | 1 + arch/x86/kernel/rtc.c | 3 +++ arch/x86/lguest/boot.c | 1 + arch/x86/xen/enlighten.c | 4 +++- 6 files changed, 19 insertions(+), 1 deletion(-) -- 1.9.1