diff options
Diffstat (limited to 'arch/x86/xen/enlighten.c')
| -rw-r--r-- | arch/x86/xen/enlighten.c | 154 |
1 files changed, 112 insertions, 42 deletions
diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c index a5ffcbb20cc0..0e7ef69e8531 100644 --- a/arch/x86/xen/enlighten.c +++ b/arch/x86/xen/enlighten.c @@ -106,15 +106,83 @@ int xen_cpuhp_setup(int (*cpu_up_prepare_cb)(unsigned int), return rc >= 0 ? 0 : rc; } -static void clamp_max_cpus(void) +static int xen_vcpu_setup_restore(int cpu) { -#ifdef CONFIG_SMP - if (setup_max_cpus > MAX_VIRT_CPUS) - setup_max_cpus = MAX_VIRT_CPUS; -#endif + 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_setup(int cpu) +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; @@ -123,11 +191,11 @@ void xen_vcpu_setup(int cpu) BUG_ON(HYPERVISOR_shared_info == &xen_dummy_shared_info); /* - * This path is called twice on PVHVM - first during bootup via - * smp_init -> xen_hvm_cpu_notify, and then if the VCPU is being - * hotplugged: cpu_up -> xen_hvm_cpu_notify. - * As we can only do the VCPUOP_register_vcpu_info once lets - * not over-write its result. + * 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 @@ -135,42 +203,44 @@ void xen_vcpu_setup(int cpu) */ if (xen_hvm_domain()) { if (per_cpu(xen_vcpu, cpu) == &per_cpu(xen_vcpu_info, cpu)) - return; + return 0; } - if (xen_vcpu_nr(cpu) < MAX_VIRT_CPUS) - per_cpu(xen_vcpu, cpu) = - &HYPERVISOR_shared_info->vcpu_info[xen_vcpu_nr(cpu)]; - if (!xen_have_vcpu_info_placement) { - if (cpu >= MAX_VIRT_CPUS) - clamp_max_cpus(); - return; + 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; + } } - 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 (!xen_have_vcpu_info_placement) + xen_vcpu_info_reset(cpu); - if (err) { - printk(KERN_DEBUG "register_vcpu_info failed: err=%d\n", err); - xen_have_vcpu_info_placement = 0; - clamp_max_cpus(); - } else { - /* This cpu is using the registered vcpu info, even if - later ones fail to. */ - per_cpu(xen_vcpu, cpu) = vcpup; - } + return ((per_cpu(xen_vcpu, cpu) == NULL) ? -ENODEV : 0); } void xen_reboot(int reason) |