blob: 0e7ef69e853151207c985d5306927c09d335acdc [file] [log] [blame]
#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"
* 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);
enum xen_domain_type xen_domain_type = XEN_NATIVE;
unsigned long *machine_to_phys_mapping = (void *)MACH2PHYS_VIRT_START;
unsigned long machine_to_phys_nr;
struct start_info *xen_start_info;
struct shared_info xen_dummy_shared_info;
__read_mostly int 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)
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,
cpu_up_prepare_cb, cpu_dead_cb);
if (rc >= 0) {
rc = cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN,
xen_cpu_up_online, NULL);
if (rc < 0)
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 */
* 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)
/* 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))
if (xen_pv_domain() || xen_feature(XENFEAT_hvm_safe_pvclock))
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))
void xen_vcpu_info_reset(int cpu)
if (xen_vcpu_nr(cpu) < MAX_VIRT_CPUS) {
per_cpu(xen_vcpu, 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)
return ((per_cpu(xen_vcpu, cpu) == NULL) ? -ENODEV : 0);
void xen_reboot(int reason)
struct sched_shutdown r = { .reason = reason };
int cpu;
if (HYPERVISOR_sched_op(SCHEDOP_shutdown, &r))
void xen_emergency_restart(void)
static int
xen_panic_event(struct notifier_block *this, unsigned long event, void *ptr)
if (!kexec_crash_loaded())
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)
pin_override.pcpu = cpu;
ret = HYPERVISOR_sched_op(SCHEDOP_pin_override, &pin_override);
/* Ignore errors when removing override. */
if (cpu < 0)
switch (ret) {
case -ENOSYS:
pr_warn("Unable to pin on physical cpu %d. In case of problems consider vcpu pinning.\n",
disable_pinning = true;
case -EPERM:
WARN(1, "Trying to pin vcpu without having privilege to do so\n");
disable_pinning = true;
case -EINVAL:
case -EBUSY:
pr_warn("Physical cpu %d not available for pinning. Check Xen cpu configuration.\n",
case 0:
WARN(1, "rc %d while trying to pin vcpu\n", ret);
disable_pinning = true;
void xen_arch_register_cpu(int num)
void xen_arch_unregister_cpu(int num)