x86/xen/time: setup vcpu 0 time info page (2229f70b) · Commits · 戴 / test

arch/x86/xen/suspend.c

+4 −0

Original line number	Diff line number	Diff line
		@@ -16,6 +16,8 @@

		void xen_arch_pre_suspend(void)
		{
		xen_save_time_memory_area();

		if (xen_pv_domain())
		xen_pv_pre_suspend();
		}
		@@ -26,6 +28,8 @@ void xen_arch_post_suspend(int cancelled)
		xen_pv_post_suspend(cancelled);
		else
		xen_hvm_post_suspend(cancelled);

		xen_restore_time_memory_area();
		}

		static void xen_vcpu_notify_restore(void *data)

arch/x86/xen/time.c

+89 −1

Original line number	Diff line number	Diff line
		@@ -370,6 +370,92 @@ static const struct pv_time_ops xen_time_ops __initconst = {
		.steal_clock = xen_steal_clock,
		};

		static struct pvclock_vsyscall_time_info *xen_clock __read_mostly;

		void xen_save_time_memory_area(void)
		{
		struct vcpu_register_time_memory_area t;
		int ret;

		if (!xen_clock)
		return;

		t.addr.v = NULL;

		ret = HYPERVISOR_vcpu_op(VCPUOP_register_vcpu_time_memory_area, 0, &t);
		if (ret != 0)
		pr_notice("Cannot save secondary vcpu_time_info (err %d)",
		ret);
		else
		clear_page(xen_clock);
		}

		void xen_restore_time_memory_area(void)
		{
		struct vcpu_register_time_memory_area t;
		int ret;

		if (!xen_clock)
		return;

		t.addr.v = &xen_clock->pvti;

		ret = HYPERVISOR_vcpu_op(VCPUOP_register_vcpu_time_memory_area, 0, &t);

		/*
		* We don't disable VCLOCK_PVCLOCK entirely if it fails to register the
		* secondary time info with Xen or if we migrated to a host without the
		* necessary flags. On both of these cases what happens is either
		* process seeing a zeroed out pvti or seeing no PVCLOCK_TSC_STABLE_BIT
		* bit set. Userspace checks the latter and if 0, it discards the data
		* in pvti and fallbacks to a system call for a reliable timestamp.
		*/
		if (ret != 0)
		pr_notice("Cannot restore secondary vcpu_time_info (err %d)",
		ret);
		}

		static void xen_setup_vsyscall_time_info(void)
		{
		struct vcpu_register_time_memory_area t;
		struct pvclock_vsyscall_time_info *ti;
		int ret;

		ti = (struct pvclock_vsyscall_time_info *)get_zeroed_page(GFP_KERNEL);
		if (!ti)
		return;

		t.addr.v = &ti->pvti;

		ret = HYPERVISOR_vcpu_op(VCPUOP_register_vcpu_time_memory_area, 0, &t);
		if (ret) {
		pr_notice("xen: VCLOCK_PVCLOCK not supported (err %d)\n", ret);
		free_page((unsigned long)ti);
		return;
		}

		/*
		* If primary time info had this bit set, secondary should too since
		* it's the same data on both just different memory regions. But we
		* still check it in case hypervisor is buggy.
		*/
		if (!(ti->pvti.flags & PVCLOCK_TSC_STABLE_BIT)) {
		t.addr.v = NULL;
		ret = HYPERVISOR_vcpu_op(VCPUOP_register_vcpu_time_memory_area,
		0, &t);
		if (!ret)
		free_page((unsigned long)ti);

		pr_notice("xen: VCLOCK_PVCLOCK not supported (tsc unstable)\n");
		return;
		}

		xen_clock = ti;
		pvclock_set_pvti_cpu0_va(xen_clock);

		xen_clocksource.archdata.vclock_mode = VCLOCK_PVCLOCK;
		}

		static void __init xen_time_init(void)
		{
		struct pvclock_vcpu_time_info *pvti;
		@@ -401,8 +487,10 @@ static void __init xen_time_init(void)
		* bit is supported hence speeding up Xen clocksource.
		*/
		pvti = &__this_cpu_read(xen_vcpu)->time;
		if (pvti->flags & PVCLOCK_TSC_STABLE_BIT)
		if (pvti->flags & PVCLOCK_TSC_STABLE_BIT) {
		pvclock_set_flags(PVCLOCK_TSC_STABLE_BIT);
		xen_setup_vsyscall_time_info();
		}

		xen_setup_runstate_info(cpu);
		xen_setup_timer(cpu);

arch/x86/xen/xen-ops.h

+2 −0

Original line number	Diff line number	Diff line
		@@ -69,6 +69,8 @@ void xen_setup_runstate_info(int cpu);
		void xen_teardown_timer(int cpu);
		u64 xen_clocksource_read(void);
		void xen_setup_cpu_clockevents(void);
		void xen_save_time_memory_area(void);
		void xen_restore_time_memory_area(void);
		void __init xen_init_time_ops(void);
		void __init xen_hvm_init_time_ops(void);

include/xen/interface/vcpu.h

+42 −0

Original line number	Diff line number	Diff line
		@@ -178,4 +178,46 @@ DEFINE_GUEST_HANDLE_STRUCT(vcpu_register_vcpu_info);

		/* Send an NMI to the specified VCPU. @extra_arg == NULL. */
		#define VCPUOP_send_nmi 11

		/*
		* Get the physical ID information for a pinned vcpu's underlying physical
		* processor. The physical ID informmation is architecture-specific.
		* On x86: id[31:0]=apic_id, id[63:32]=acpi_id.
		* This command returns -EINVAL if it is not a valid operation for this VCPU.
		*/
		#define VCPUOP_get_physid 12 /* arg == vcpu_get_physid_t */
		struct vcpu_get_physid {
		uint64_t phys_id;
		};
		DEFINE_GUEST_HANDLE_STRUCT(vcpu_get_physid);
		#define xen_vcpu_physid_to_x86_apicid(physid) ((uint32_t)(physid))
		#define xen_vcpu_physid_to_x86_acpiid(physid) ((uint32_t)((physid) >> 32))

		/*
		* Register a memory location to get a secondary copy of the vcpu time
		* parameters. The master copy still exists as part of the vcpu shared
		* memory area, and this secondary copy is updated whenever the master copy
		* is updated (and using the same versioning scheme for synchronisation).
		*
		* The intent is that this copy may be mapped (RO) into userspace so
		* that usermode can compute system time using the time info and the
		* tsc. Usermode will see an array of vcpu_time_info structures, one
		* for each vcpu, and choose the right one by an existing mechanism
		* which allows it to get the current vcpu number (such as via a
		* segment limit). It can then apply the normal algorithm to compute
		* system time from the tsc.
		*
		* @extra_arg == pointer to vcpu_register_time_info_memory_area structure.
		*/
		#define VCPUOP_register_vcpu_time_memory_area 13
		DEFINE_GUEST_HANDLE_STRUCT(vcpu_time_info);
		struct vcpu_register_time_memory_area {
		union {
		GUEST_HANDLE(vcpu_time_info) h;
		struct pvclock_vcpu_time_info *v;
		uint64_t p;
		} addr;
		};
		DEFINE_GUEST_HANDLE_STRUCT(vcpu_register_time_memory_area);

		#endif /* __XEN_PUBLIC_VCPU_H__ */

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