arch/x86/xen/enlighten.c - arm/linux - Git at Google

 #include <linux/cpu.h>
 #include <linux/kexec.h>

 #include <xen/features.h>
 #include <xen/page.h>

 #include <asm/xen/hypercall.h>
 #include <asm/xen/hypervisor.h>
 #include <asm/cpu.h>
 #include <asm/e820/api.h>

 #include "xen-ops.h"
 #include "smp.h"
 #include "pmu.h"

 EXPORT_SYMBOL_GPL(hypercall_page);

 /*
  * Pointer to the xen_vcpu_info structure or
  * &HYPERVISOR_shared_info->vcpu_info[cpu]. See xen_hvm_init_shared_info
  * and xen_vcpu_setup for details. By default it points to share_info->vcpu_info
  * but if the hypervisor supports VCPUOP_register_vcpu_info then it can point
  * to xen_vcpu_info. The pointer is used in __xen_evtchn_do_upcall to
  * acknowledge pending events.
  * Also more subtly it is used by the patched version of irq enable/disable
  * e.g. xen_irq_enable_direct and xen_iret in PV mode.
  *
  * The desire to be able to do those mask/unmask operations as a single
  * instruction by using the per-cpu offset held in %gs is the real reason
  * vcpu info is in a per-cpu pointer and the original reason for this
  * hypercall.
  *
  */
 DEFINE_PER_CPU(struct vcpu_info *, xen_vcpu);

 /*
  * Per CPU pages used if hypervisor supports VCPUOP_register_vcpu_info
  * hypercall. This can be used both in PV and PVHVM mode. The structure
  * overrides the default per_cpu(xen_vcpu, cpu) value.
  */
 DEFINE_PER_CPU(struct vcpu_info, xen_vcpu_info);

 /* Linux <-> Xen vCPU id mapping */
 DEFINE_PER_CPU(uint32_t, xen_vcpu_id);
 EXPORT_PER_CPU_SYMBOL(xen_vcpu_id);

 enum xen_domain_type xen_domain_type = XEN_NATIVE;
 EXPORT_SYMBOL_GPL(xen_domain_type);

 unsigned long *machine_to_phys_mapping = (void *)MACH2PHYS_VIRT_START;
 EXPORT_SYMBOL(machine_to_phys_mapping);
 unsigned long  machine_to_phys_nr;
 EXPORT_SYMBOL(machine_to_phys_nr);

 struct start_info *xen_start_info;
 EXPORT_SYMBOL_GPL(xen_start_info);

 struct shared_info xen_dummy_shared_info;

 __read_mostly int xen_have_vector_callback;
 EXPORT_SYMBOL_GPL(xen_have_vector_callback);

 /*
  * 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 = &xen_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
  */
 int xen_have_vcpu_info_placement = 1;

 static int xen_cpu_up_online(unsigned int cpu)
 {
 	xen_init_lock_cpu(cpu);
 	return 0;
 }

 int xen_cpuhp_setup(int (*cpu_up_prepare_cb)(unsigned int),
 		    int (*cpu_dead_cb)(unsigned int))
 {
 	int rc;

 	rc = cpuhp_setup_state_nocalls(CPUHP_XEN_PREPARE,
 				       "x86/xen/guest:prepare",
 				       cpu_up_prepare_cb, cpu_dead_cb);
 	if (rc >= 0) {
 		rc = cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN,
 					       "x86/xen/guest:online",
 					       xen_cpu_up_online, NULL);
 		if (rc < 0)
 			cpuhp_remove_state_nocalls(CPUHP_XEN_PREPARE);
 	}

 	return rc >= 0 ? 0 : rc;
 }

 static int xen_vcpu_setup_restore(int cpu)
 {
 	int rc = 0;

 	/* Any per_cpu(xen_vcpu) is stale, so reset it */
 	xen_vcpu_info_reset(cpu);

 	/*
 	 * For PVH and PVHVM, setup online VCPUs only. The rest will
 	 * be handled by hotplug.
 	 */
 	if (xen_pv_domain() ||
 	    (xen_hvm_domain() && cpu_online(cpu))) {
 		rc = xen_vcpu_setup(cpu);
 	}

 	return rc;
 }

 /*
  * On restore, set the vcpu placement up again.
  * If it fails, then we're in a bad state, since
  * we can't back out from using it...
  */
 void xen_vcpu_restore(void)
 {
 	int cpu, rc;

 	for_each_possible_cpu(cpu) {
 		bool other_cpu = (cpu != smp_processor_id());
 		bool is_up;

 		if (xen_vcpu_nr(cpu) == XEN_VCPU_ID_INVALID)
 			continue;

 		/* Only Xen 4.5 and higher support this. */
 		is_up = HYPERVISOR_vcpu_op(VCPUOP_is_up,
 					   xen_vcpu_nr(cpu), NULL) > 0;

 		if (other_cpu && is_up &&
 		    HYPERVISOR_vcpu_op(VCPUOP_down, xen_vcpu_nr(cpu), NULL))
 			BUG();

 		if (xen_pv_domain() || xen_feature(XENFEAT_hvm_safe_pvclock))
 			xen_setup_runstate_info(cpu);

 		rc = xen_vcpu_setup_restore(cpu);
 		if (rc)
 			pr_emerg_once("vcpu restore failed for cpu=%d err=%d. "
 					"System will hang.\n", cpu, rc);
 		/*
 		 * In case xen_vcpu_setup_restore() fails, do not bring up the
 		 * VCPU. This helps us avoid the resulting OOPS when the VCPU
 		 * accesses pvclock_vcpu_time via xen_vcpu (which is NULL.)
 		 * Note that this does not improve the situation much -- now the
 		 * VM hangs instead of OOPSing -- with the VCPUs that did not
 		 * fail, spinning in stop_machine(), waiting for the failed
 		 * VCPUs to come up.
 		 */
 		if (other_cpu && is_up && (rc == 0) &&
 		    HYPERVISOR_vcpu_op(VCPUOP_up, xen_vcpu_nr(cpu), NULL))
 			BUG();
 	}
 }

 void xen_vcpu_info_reset(int cpu)
 {
 	if (xen_vcpu_nr(cpu) < MAX_VIRT_CPUS) {
 		per_cpu(xen_vcpu, cpu) =
 			&HYPERVISOR_shared_info->vcpu_info[xen_vcpu_nr(cpu)];
 	} else {
 		/* Set to NULL so that if somebody accesses it we get an OOPS */
 		per_cpu(xen_vcpu, cpu) = NULL;
 	}
 }

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

 	BUG_ON(HYPERVISOR_shared_info == &xen_dummy_shared_info);

 	/*
 	 * This path is called on PVHVM at bootup (xen_hvm_smp_prepare_boot_cpu)
 	 * and at restore (xen_vcpu_restore). Also called for hotplugged
 	 * VCPUs (cpu_init -> xen_hvm_cpu_prepare_hvm).
 	 * However, the hypercall can only be done once (see below) so if a VCPU
 	 * is offlined and comes back online then let's not redo the hypercall.
 	 *
 	 * For PV it is called during restore (xen_vcpu_restore) and bootup
 	 * (xen_setup_vcpu_info_placement). The hotplug mechanism does not
 	 * use this function.
 	 */
 	if (xen_hvm_domain()) {
 		if (per_cpu(xen_vcpu, cpu) == &per_cpu(xen_vcpu_info, cpu))
 			return 0;
 	}

 	if (xen_have_vcpu_info_placement) {
 		vcpup = &per_cpu(xen_vcpu_info, cpu);
 		info.mfn = arbitrary_virt_to_mfn(vcpup);
 		info.offset = offset_in_page(vcpup);

 		/*
 		 * Check to see if the hypervisor will put the vcpu_info
 		 * structure where we want it, which allows direct access via
 		 * a percpu-variable.
 		 * N.B. This hypercall can _only_ be called once per CPU.
 		 * Subsequent calls will error out with -EINVAL. This is due to
 		 * the fact that hypervisor has no unregister variant and this
 		 * hypercall does not allow to over-write info.mfn and
 		 * info.offset.
 		 */
 		err = HYPERVISOR_vcpu_op(VCPUOP_register_vcpu_info,
 					 xen_vcpu_nr(cpu), &info);

 		if (err) {
 			pr_warn_once("register_vcpu_info failed: cpu=%d err=%d\n",
 				     cpu, err);
 			xen_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;
 		}
 	}

 	if (!xen_have_vcpu_info_placement)
 		xen_vcpu_info_reset(cpu);

 	return ((per_cpu(xen_vcpu, cpu) == NULL) ? -ENODEV : 0);
 }

 void xen_reboot(int reason)
 {
 	struct sched_shutdown r = { .reason = reason };
 	int cpu;

 	for_each_online_cpu(cpu)
 		xen_pmu_finish(cpu);

 	if (HYPERVISOR_sched_op(SCHEDOP_shutdown, &r))
 		BUG();
 }

 void xen_emergency_restart(void)
 {
 	xen_reboot(SHUTDOWN_reboot);
 }

 static int
 xen_panic_event(struct notifier_block *this, unsigned long event, void *ptr)
 {
 	if (!kexec_crash_loaded())
 		xen_reboot(SHUTDOWN_crash);
 	return NOTIFY_DONE;
 }

 static struct notifier_block xen_panic_block = {
 	.notifier_call = xen_panic_event,
 	.priority = INT_MIN
 };

 int xen_panic_handler_init(void)
 {
 	atomic_notifier_chain_register(&panic_notifier_list, &xen_panic_block);
 	return 0;
 }

 void xen_pin_vcpu(int cpu)
 {
 	static bool disable_pinning;
 	struct sched_pin_override pin_override;
 	int ret;

 	if (disable_pinning)
 		return;

 	pin_override.pcpu = cpu;
 	ret = HYPERVISOR_sched_op(SCHEDOP_pin_override, &pin_override);

 	/* Ignore errors when removing override. */
 	if (cpu < 0)
 		return;

 	switch (ret) {
 	case -ENOSYS:
 		pr_warn("Unable to pin on physical cpu %d. In case of problems consider vcpu pinning.\n",
 			cpu);
 		disable_pinning = true;
 		break;
 	case -EPERM:
 		WARN(1, "Trying to pin vcpu without having privilege to do so\n");
 		disable_pinning = true;
 		break;
 	case -EINVAL:
 	case -EBUSY:
 		pr_warn("Physical cpu %d not available for pinning. Check Xen cpu configuration.\n",
 			cpu);
 		break;
 	case 0:
 		break;
 	default:
 		WARN(1, "rc %d while trying to pin vcpu\n", ret);
 		disable_pinning = true;
 	}
 }

 #ifdef CONFIG_HOTPLUG_CPU
 void xen_arch_register_cpu(int num)
 {
 	arch_register_cpu(num);
 }
 EXPORT_SYMBOL(xen_arch_register_cpu);

 void xen_arch_unregister_cpu(int num)
 {
 	arch_unregister_cpu(num);
 }
 EXPORT_SYMBOL(xen_arch_unregister_cpu);
 #endif
	#include <linux/cpu.h>
	#include <linux/kexec.h>

	#include <xen/features.h>
	#include <xen/page.h>

	#include <asm/xen/hypercall.h>
	#include <asm/xen/hypervisor.h>
	#include <asm/cpu.h>
	#include <asm/e820/api.h>

	#include "xen-ops.h"
	#include "smp.h"
	#include "pmu.h"

	EXPORT_SYMBOL_GPL(hypercall_page);

	/*
	* Pointer to the xen_vcpu_info structure or
	* &HYPERVISOR_shared_info->vcpu_info[cpu]. See xen_hvm_init_shared_info
	* and xen_vcpu_setup for details. By default it points to share_info->vcpu_info
	* but if the hypervisor supports VCPUOP_register_vcpu_info then it can point
	* to xen_vcpu_info. The pointer is used in __xen_evtchn_do_upcall to
	* acknowledge pending events.
	* Also more subtly it is used by the patched version of irq enable/disable
	* e.g. xen_irq_enable_direct and xen_iret in PV mode.
	*
	* The desire to be able to do those mask/unmask operations as a single
	* instruction by using the per-cpu offset held in %gs is the real reason
	* vcpu info is in a per-cpu pointer and the original reason for this
	* hypercall.
	*
	*/
	DEFINE_PER_CPU(struct vcpu_info *, xen_vcpu);

	/*
	* Per CPU pages used if hypervisor supports VCPUOP_register_vcpu_info
	* hypercall. This can be used both in PV and PVHVM mode. The structure
	* overrides the default per_cpu(xen_vcpu, cpu) value.
	*/
	DEFINE_PER_CPU(struct vcpu_info, xen_vcpu_info);

	/* Linux <-> Xen vCPU id mapping */
	DEFINE_PER_CPU(uint32_t, xen_vcpu_id);
	EXPORT_PER_CPU_SYMBOL(xen_vcpu_id);

	enum xen_domain_type xen_domain_type = XEN_NATIVE;
	EXPORT_SYMBOL_GPL(xen_domain_type);

	unsigned long machine_to_phys_mapping = (void )MACH2PHYS_VIRT_START;
	EXPORT_SYMBOL(machine_to_phys_mapping);
	unsigned long machine_to_phys_nr;
	EXPORT_SYMBOL(machine_to_phys_nr);

	struct start_info *xen_start_info;
	EXPORT_SYMBOL_GPL(xen_start_info);

	struct shared_info xen_dummy_shared_info;

	__read_mostly int xen_have_vector_callback;
	EXPORT_SYMBOL_GPL(xen_have_vector_callback);

	/*
	* 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 = &xen_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
	*/
	int xen_have_vcpu_info_placement = 1;

	static int xen_cpu_up_online(unsigned int cpu)
	{
	xen_init_lock_cpu(cpu);
	return 0;
	}

	int xen_cpuhp_setup(int (*cpu_up_prepare_cb)(unsigned int),
	int (*cpu_dead_cb)(unsigned int))
	{
	int rc;

	rc = cpuhp_setup_state_nocalls(CPUHP_XEN_PREPARE,
	"x86/xen/guest:prepare",
	cpu_up_prepare_cb, cpu_dead_cb);
	if (rc >= 0) {
	rc = cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN,
	"x86/xen/guest:online",
	xen_cpu_up_online, NULL);
	if (rc < 0)
	cpuhp_remove_state_nocalls(CPUHP_XEN_PREPARE);
	}

	return rc >= 0 ? 0 : rc;
	}

	static int xen_vcpu_setup_restore(int cpu)
	{
	int rc = 0;

	/* Any per_cpu(xen_vcpu) is stale, so reset it */
	xen_vcpu_info_reset(cpu);

	/*
	* For PVH and PVHVM, setup online VCPUs only. The rest will
	* be handled by hotplug.
	*/
	if (xen_pv_domain() \|\|
	(xen_hvm_domain() && cpu_online(cpu))) {
	rc = xen_vcpu_setup(cpu);
	}

	return rc;
	}

	/*
	* On restore, set the vcpu placement up again.
	* If it fails, then we're in a bad state, since
	* we can't back out from using it...
	*/
	void xen_vcpu_restore(void)
	{
	int cpu, rc;

	for_each_possible_cpu(cpu) {
	bool other_cpu = (cpu != smp_processor_id());
	bool is_up;

	if (xen_vcpu_nr(cpu) == XEN_VCPU_ID_INVALID)
	continue;

	/* Only Xen 4.5 and higher support this. */
	is_up = HYPERVISOR_vcpu_op(VCPUOP_is_up,
	xen_vcpu_nr(cpu), NULL) > 0;

	if (other_cpu && is_up &&
	HYPERVISOR_vcpu_op(VCPUOP_down, xen_vcpu_nr(cpu), NULL))
	BUG();

	if (xen_pv_domain() \|\| xen_feature(XENFEAT_hvm_safe_pvclock))
	xen_setup_runstate_info(cpu);

	rc = xen_vcpu_setup_restore(cpu);
	if (rc)
	pr_emerg_once("vcpu restore failed for cpu=%d err=%d. "
	"System will hang.\n", cpu, rc);
	/*
	* In case xen_vcpu_setup_restore() fails, do not bring up the
	* VCPU. This helps us avoid the resulting OOPS when the VCPU
	* accesses pvclock_vcpu_time via xen_vcpu (which is NULL.)
	* Note that this does not improve the situation much -- now the
	* VM hangs instead of OOPSing -- with the VCPUs that did not
	* fail, spinning in stop_machine(), waiting for the failed
	* VCPUs to come up.
	*/
	if (other_cpu && is_up && (rc == 0) &&
	HYPERVISOR_vcpu_op(VCPUOP_up, xen_vcpu_nr(cpu), NULL))
	BUG();
	}
	}

	void xen_vcpu_info_reset(int cpu)
	{
	if (xen_vcpu_nr(cpu) < MAX_VIRT_CPUS) {
	per_cpu(xen_vcpu, cpu) =
	&HYPERVISOR_shared_info->vcpu_info[xen_vcpu_nr(cpu)];
	} else {
	/* Set to NULL so that if somebody accesses it we get an OOPS */
	per_cpu(xen_vcpu, cpu) = NULL;
	}
	}

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

	BUG_ON(HYPERVISOR_shared_info == &xen_dummy_shared_info);

	/*
	* This path is called on PVHVM at bootup (xen_hvm_smp_prepare_boot_cpu)
	* and at restore (xen_vcpu_restore). Also called for hotplugged
	* VCPUs (cpu_init -> xen_hvm_cpu_prepare_hvm).
	* However, the hypercall can only be done once (see below) so if a VCPU
	* is offlined and comes back online then let's not redo the hypercall.
	*
	* For PV it is called during restore (xen_vcpu_restore) and bootup
	* (xen_setup_vcpu_info_placement). The hotplug mechanism does not
	* use this function.
	*/
	if (xen_hvm_domain()) {
	if (per_cpu(xen_vcpu, cpu) == &per_cpu(xen_vcpu_info, cpu))
	return 0;
	}

	if (xen_have_vcpu_info_placement) {
	vcpup = &per_cpu(xen_vcpu_info, cpu);
	info.mfn = arbitrary_virt_to_mfn(vcpup);
	info.offset = offset_in_page(vcpup);

	/*
	* Check to see if the hypervisor will put the vcpu_info
	* structure where we want it, which allows direct access via
	* a percpu-variable.
	* N.B. This hypercall can _only_ be called once per CPU.
	* Subsequent calls will error out with -EINVAL. This is due to
	* the fact that hypervisor has no unregister variant and this
	* hypercall does not allow to over-write info.mfn and
	* info.offset.
	*/
	err = HYPERVISOR_vcpu_op(VCPUOP_register_vcpu_info,
	xen_vcpu_nr(cpu), &info);

	if (err) {
	pr_warn_once("register_vcpu_info failed: cpu=%d err=%d\n",
	cpu, err);
	xen_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;
	}
	}

	if (!xen_have_vcpu_info_placement)
	xen_vcpu_info_reset(cpu);

	return ((per_cpu(xen_vcpu, cpu) == NULL) ? -ENODEV : 0);
	}

	void xen_reboot(int reason)
	{
	struct sched_shutdown r = { .reason = reason };
	int cpu;

	for_each_online_cpu(cpu)
	xen_pmu_finish(cpu);

	if (HYPERVISOR_sched_op(SCHEDOP_shutdown, &r))
	BUG();
	}

	void xen_emergency_restart(void)
	{
	xen_reboot(SHUTDOWN_reboot);
	}

	static int
	xen_panic_event(struct notifier_block this, unsigned long event, void ptr)
	{
	if (!kexec_crash_loaded())
	xen_reboot(SHUTDOWN_crash);
	return NOTIFY_DONE;
	}

	static struct notifier_block xen_panic_block = {
	.notifier_call = xen_panic_event,
	.priority = INT_MIN
	};

	int xen_panic_handler_init(void)
	{
	atomic_notifier_chain_register(&panic_notifier_list, &xen_panic_block);
	return 0;
	}

	void xen_pin_vcpu(int cpu)
	{
	static bool disable_pinning;
	struct sched_pin_override pin_override;
	int ret;

	if (disable_pinning)
	return;

	pin_override.pcpu = cpu;
	ret = HYPERVISOR_sched_op(SCHEDOP_pin_override, &pin_override);

	/* Ignore errors when removing override. */
	if (cpu < 0)
	return;

	switch (ret) {
	case -ENOSYS:
	pr_warn("Unable to pin on physical cpu %d. In case of problems consider vcpu pinning.\n",
	cpu);
	disable_pinning = true;
	break;
	case -EPERM:
	WARN(1, "Trying to pin vcpu without having privilege to do so\n");
	disable_pinning = true;
	break;
	case -EINVAL:
	case -EBUSY:
	pr_warn("Physical cpu %d not available for pinning. Check Xen cpu configuration.\n",
	cpu);
	break;
	case 0:
	break;
	default:
	WARN(1, "rc %d while trying to pin vcpu\n", ret);
	disable_pinning = true;
	}
	}

	#ifdef CONFIG_HOTPLUG_CPU
	void xen_arch_register_cpu(int num)
	{
	arch_register_cpu(num);
	}
	EXPORT_SYMBOL(xen_arch_register_cpu);

	void xen_arch_unregister_cpu(int num)
	{
	arch_unregister_cpu(num);
	}
	EXPORT_SYMBOL(xen_arch_unregister_cpu);
	#endif