diff options
Diffstat (limited to 'arch/x86/xen/enlighten.c')
| -rw-r--r-- | arch/x86/xen/enlighten.c | 50 |
1 files changed, 49 insertions, 1 deletions
diff --git a/arch/x86/xen/enlighten.c b/arch/x86/xen/enlighten.c index 53d4f680c9b..a492be2635a 100644 --- a/arch/x86/xen/enlighten.c +++ b/arch/x86/xen/enlighten.c @@ -85,7 +85,29 @@ 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); enum xen_domain_type xen_domain_type = XEN_NATIVE; @@ -157,6 +179,21 @@ static 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. + * + * 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; + } if (cpu < MAX_VIRT_CPUS) per_cpu(xen_vcpu,cpu) = &HYPERVISOR_shared_info->vcpu_info[cpu]; @@ -172,7 +209,12 @@ static void xen_vcpu_setup(int cpu) /* Check to see if the hypervisor will put the vcpu_info structure where we want it, which allows direct access via - a percpu-variable. */ + 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, cpu, &info); if (err) { @@ -387,6 +429,9 @@ static void __init xen_init_cpuid_mask(void) cpuid_leaf1_edx_mask &= ~((1 << X86_FEATURE_APIC) | /* disable local APIC */ (1 << X86_FEATURE_ACPI)); /* disable ACPI */ + + cpuid_leaf1_ecx_mask &= ~(1 << (X86_FEATURE_X2APIC % 32)); + ax = 1; cx = 0; xen_cpuid(&ax, &bx, &cx, &dx); @@ -1603,6 +1648,9 @@ void __ref xen_hvm_init_shared_info(void) * online but xen_hvm_init_shared_info is run at resume time too and * in that case multiple vcpus might be online. */ for_each_online_cpu(cpu) { + /* Leave it to be NULL. */ + if (cpu >= MAX_VIRT_CPUS) + continue; per_cpu(xen_vcpu, cpu) = &HYPERVISOR_shared_info->vcpu_info[cpu]; } } |