xen: Place vcpu_info structure into per-cpu memory (60223a32) · Commits · 戴 / test

arch/i386/xen/enlighten.c

+148 −4

Original line number	Diff line number	Diff line
		@@ -61,9 +61,63 @@ DEFINE_PER_CPU(unsigned long, xen_cr3);
		struct start_info *xen_start_info;
		EXPORT_SYMBOL_GPL(xen_start_info);

		void xen_vcpu_setup(int cpu)
		static /* __initdata */ struct shared_info dummy_shared_info;

		/*
		* Point at some empty memory to start with. We map the real shared_info
		* page as soon as fixmap is up and running.
		*/
		struct shared_info HYPERVISOR_shared_info = (void )&dummy_shared_info;

		/*
		* Flag to determine whether vcpu info placement is available on all
		* VCPUs. We assume it is to start with, and then set it to zero on
		* the first failure. This is because it can succeed on some VCPUs
		* and not others, since it can involve hypervisor memory allocation,
		* or because the guest failed to guarantee all the appropriate
		* constraints on all VCPUs (ie buffer can't cross a page boundary).
		*
		* Note that any particular CPU may be using a placed vcpu structure,
		* but we can only optimise if the all are.
		*
		* 0: not available, 1: available
		*/
		static int have_vcpu_info_placement = 1;

		static void __init xen_vcpu_setup(int cpu)
		{
		struct vcpu_register_vcpu_info info;
		int err;
		struct vcpu_info *vcpup;

		per_cpu(xen_vcpu, cpu) = &HYPERVISOR_shared_info->vcpu_info[cpu];

		if (!have_vcpu_info_placement)
		return; /* already tested, not available */

		vcpup = &per_cpu(xen_vcpu_info, cpu);

		info.mfn = virt_to_mfn(vcpup);
		info.offset = offset_in_page(vcpup);

		printk(KERN_DEBUG "trying to map vcpu_info %d at %p, mfn %x, offset %d\n",
		cpu, vcpup, info.mfn, info.offset);

		/* Check to see if the hypervisor will put the vcpu_info
		structure where we want it, which allows direct access via
		a percpu-variable. */
		err = HYPERVISOR_vcpu_op(VCPUOP_register_vcpu_info, cpu, &info);

		if (err) {
		printk(KERN_DEBUG "register_vcpu_info failed: err=%d\n", err);
		have_vcpu_info_placement = 0;
		} else {
		/* This cpu is using the registered vcpu info, even if
		later ones fail to. */
		per_cpu(xen_vcpu, cpu) = vcpup;
		printk(KERN_DEBUG "cpu %d using vcpu_info at %p\n",
		cpu, vcpup);
		}
		}

		static void __init xen_banner(void)
		@@ -123,6 +177,20 @@ static unsigned long xen_save_fl(void)
		return (-flags) & X86_EFLAGS_IF;
		}

		static unsigned long xen_save_fl_direct(void)
		{
		unsigned long flags;

		/* flag has opposite sense of mask */
		flags = !x86_read_percpu(xen_vcpu_info.evtchn_upcall_mask);

		/* convert to IF type flag
		-0 -> 0x00000000
		-1 -> 0xffffffff
		*/
		return (-flags) & X86_EFLAGS_IF;
		}

		static void xen_restore_fl(unsigned long flags)
		{
		struct vcpu_info *vcpu;
		@@ -149,6 +217,25 @@ static void xen_restore_fl(unsigned long flags)
		}
		}

		static void xen_restore_fl_direct(unsigned long flags)
		{
		/* convert from IF type flag */
		flags = !(flags & X86_EFLAGS_IF);

		/* This is an atomic update, so no need to worry about
		preemption. */
		x86_write_percpu(xen_vcpu_info.evtchn_upcall_mask, flags);

		/* If we get preempted here, then any pending event will be
		handled anyway. */

		if (flags == 0) {
		barrier(); /* unmask then check (avoid races) */
		if (unlikely(x86_read_percpu(xen_vcpu_info.evtchn_upcall_pending)))
		force_evtchn_callback();
		}
		}

		static void xen_irq_disable(void)
		{
		/* There's a one instruction preempt window here. We need to
		@@ -159,6 +246,12 @@ static void xen_irq_disable(void)
		preempt_enable_no_resched();
		}

		static void xen_irq_disable_direct(void)
		{
		/* Atomic update, so preemption not a concern. */
		x86_write_percpu(xen_vcpu_info.evtchn_upcall_mask, 1);
		}

		static void xen_irq_enable(void)
		{
		struct vcpu_info *vcpu;
		@@ -179,6 +272,19 @@ static void xen_irq_enable(void)
		force_evtchn_callback();
		}

		static void xen_irq_enable_direct(void)
		{
		/* Atomic update, so preemption not a concern. */
		x86_write_percpu(xen_vcpu_info.evtchn_upcall_mask, 0);

		/* Doesn't matter if we get preempted here, because any
		pending event will get dealt with anyway. */

		barrier(); /* unmask then check (avoid races) */
		if (unlikely(x86_read_percpu(xen_vcpu_info.evtchn_upcall_pending)))
		force_evtchn_callback();
		}

		static void xen_safe_halt(void)
		{
		/* Blocking includes an implicit local_irq_enable(). */
		@@ -551,11 +657,21 @@ static void xen_flush_tlb_others(const cpumask_t cpus, struct mm_struct mm,
		xen_mc_issue(PARAVIRT_LAZY_MMU);
		}

		static void xen_write_cr2(unsigned long cr2)
		{
		x86_read_percpu(xen_vcpu)->arch.cr2 = cr2;
		}

		static unsigned long xen_read_cr2(void)
		{
		return x86_read_percpu(xen_vcpu)->arch.cr2;
		}

		static unsigned long xen_read_cr2_direct(void)
		{
		return x86_read_percpu(xen_vcpu_info.arch.cr2);
		}

		static void xen_write_cr4(unsigned long cr4)
		{
		/* never allow TSC to be disabled */
		@@ -753,8 +869,27 @@ static __init void xen_pagetable_setup_done(pgd_t *base)
		if (HYPERVISOR_mmuext_op(&op, 1, NULL, DOMID_SELF))
		BUG();
		}
		}

		xen_vcpu_setup(smp_processor_id());
		/* This is called once we have the cpu_possible_map */
		void __init xen_setup_vcpu_info_placement(void)
		{
		int cpu;

		for_each_possible_cpu(cpu)
		xen_vcpu_setup(cpu);

		/* xen_vcpu_setup managed to place the vcpu_info within the
		percpu area for all cpus, so make use of it */
		if (have_vcpu_info_placement) {
		printk(KERN_INFO "Xen: using vcpu_info placement\n");

		paravirt_ops.save_fl = xen_save_fl_direct;
		paravirt_ops.restore_fl = xen_restore_fl_direct;
		paravirt_ops.irq_disable = xen_irq_disable_direct;
		paravirt_ops.irq_enable = xen_irq_enable_direct;
		paravirt_ops.read_cr2 = xen_read_cr2_direct;
		}
		}

		static const struct paravirt_ops xen_paravirt_ops __initdata = {
		@@ -788,7 +923,7 @@ static const struct paravirt_ops xen_paravirt_ops __initdata = {
		.write_cr0 = native_write_cr0,

		.read_cr2 = xen_read_cr2,
		.write_cr2 = native_write_cr2,
		.write_cr2 = xen_write_cr2,

		.read_cr3 = xen_read_cr3,
		.write_cr3 = xen_write_cr3,
		@@ -974,7 +1109,16 @@ asmlinkage void __init xen_start_kernel(void)
		/* keep using Xen gdt for now; no urgent need to change it */

		x86_write_percpu(xen_cr3, __pa(pgd));
		xen_vcpu_setup(0);

		#ifdef CONFIG_SMP
		/* Don't do the full vcpu_info placement stuff until we have a
		possible map. */
		per_cpu(xen_vcpu, 0) = &HYPERVISOR_shared_info->vcpu_info[0];
		#else
		/* May as well do it now, since there's no good time to call
		it later on UP. */
		xen_setup_vcpu_info_placement();
		#endif

		paravirt_ops.kernel_rpl = 1;
		if (xen_feature(XENFEAT_supervisor_mode_kernel))

arch/i386/xen/setup.c

+0 −8

Original line number	Diff line number	Diff line
		@@ -24,14 +24,6 @@
		extern const char xen_hypervisor_callback[];
		extern const char xen_failsafe_callback[];

		static __initdata struct shared_info init_shared;

		/*
		* Point at some empty memory to start with. We map the real shared_info
		* page as soon as fixmap is up and running.
		*/
		struct shared_info *HYPERVISOR_shared_info = &init_shared;

		unsigned long *phys_to_machine_mapping;
		EXPORT_SYMBOL(phys_to_machine_mapping);

arch/i386/xen/smp.c

+2 −3

Original line number	Diff line number	Diff line
		@@ -142,8 +142,6 @@ void __init xen_smp_prepare_boot_cpu(void)
		BUG_ON(smp_processor_id() != 0);
		native_smp_prepare_boot_cpu();

		xen_vcpu_setup(0);

		/* We've switched to the "real" per-cpu gdt, so make sure the
		old memory can be recycled */
		make_lowmem_page_readwrite(&per_cpu__gdt_page);
		@@ -152,6 +150,8 @@ void __init xen_smp_prepare_boot_cpu(void)
		cpus_clear(cpu_sibling_map[cpu]);
		cpus_clear(cpu_core_map[cpu]);
		}

		xen_setup_vcpu_info_placement();
		}

		void __init xen_smp_prepare_cpus(unsigned int max_cpus)
		@@ -262,7 +262,6 @@ int __cpuinit xen_cpu_up(unsigned int cpu)

		init_gdt(cpu);
		per_cpu(current_task, cpu) = idle;
		xen_vcpu_setup(cpu);
		irq_ctx_init(cpu);
		xen_setup_timer(cpu);

arch/i386/xen/xen-ops.h

+1 −1

Original line number	Diff line number	Diff line
		@@ -38,7 +38,7 @@ static inline unsigned xen_get_lazy_mode(void)

		void __init xen_fill_possible_map(void);

		void xen_vcpu_setup(int cpu);
		void __init xen_setup_vcpu_info_placement(void);
		void xen_smp_prepare_boot_cpu(void);
		void xen_smp_prepare_cpus(unsigned int max_cpus);
		int xen_cpu_up(unsigned int cpu);

include/xen/interface/vcpu.h

+13 −0

Original line number	Diff line number	Diff line
		@@ -151,4 +151,17 @@ struct vcpu_set_singleshot_timer {
		#define _VCPU_SSHOTTMR_future (0)
		#define VCPU_SSHOTTMR_future (1U << _VCPU_SSHOTTMR_future)

		/*
		* Register a memory location in the guest address space for the
		* vcpu_info structure. This allows the guest to place the vcpu_info
		* structure in a convenient place, such as in a per-cpu data area.
		* The pointer need not be page aligned, but the structure must not
		* cross a page boundary.
		*/
		#define VCPUOP_register_vcpu_info 10 /* arg == struct vcpu_info */
		struct vcpu_register_vcpu_info {
		uint32_t mfn; /* mfn of page to place vcpu_info */
		uint32_t offset; /* offset within page */
		};

		#endif /* __XEN_PUBLIC_VCPU_H__ */

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