x86/paravirt: Prevent rtc_cmos platform device init on PV guests (d8c98a1d) · Commits · 戴 / test

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 Cc: stable@vger.kernel.org # 4.2+ Link: http://lkml.kernel.org/r/1449842873-2613-1-git-send-email-boris.ostrovsky@oracle.com Signed-off-by:

Thomas Gleixner <tglx@linutronix.de>

arch/x86/include/asm/paravirt.h

+6 −0

Original line number	Diff line number	Diff line
		@@ -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)
		{

arch/x86/include/asm/paravirt_types.h

+5 −0

Original line number	Diff line number	Diff line
		@@ -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

arch/x86/include/asm/processor.h

+1 −0

Original line number	Diff line number	Diff line
		@@ -472,6 +472,7 @@ 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)

arch/x86/kernel/rtc.c

+3 −0

Original line number	Diff line number	Diff line
		@@ -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");

arch/x86/lguest/boot.c

+1 −0

Original line number	Diff line number	Diff line
		@@ -1414,6 +1414,7 @@ __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

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