348 lines
9.1 KiB
C
348 lines
9.1 KiB
C
// SPDX-License-Identifier: GPL-2.0
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#ifdef CONFIG_XEN_BALLOON_MEMORY_HOTPLUG
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#include <linux/memblock.h>
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#endif
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#include <linux/cpu.h>
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#include <linux/kexec.h>
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#include <linux/slab.h>
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#include <xen/xen.h>
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#include <xen/features.h>
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#include <xen/page.h>
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#include <asm/xen/hypercall.h>
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#include <asm/xen/hypervisor.h>
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#include <asm/cpu.h>
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#include <asm/e820/api.h>
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#include "xen-ops.h"
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#include "smp.h"
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#include "pmu.h"
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EXPORT_SYMBOL_GPL(hypercall_page);
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/*
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* Pointer to the xen_vcpu_info structure or
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* &HYPERVISOR_shared_info->vcpu_info[cpu]. See xen_hvm_init_shared_info
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* and xen_vcpu_setup for details. By default it points to share_info->vcpu_info
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* but if the hypervisor supports VCPUOP_register_vcpu_info then it can point
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* to xen_vcpu_info. The pointer is used in __xen_evtchn_do_upcall to
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* acknowledge pending events.
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* Also more subtly it is used by the patched version of irq enable/disable
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* e.g. xen_irq_enable_direct and xen_iret in PV mode.
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*
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* The desire to be able to do those mask/unmask operations as a single
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* instruction by using the per-cpu offset held in %gs is the real reason
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* vcpu info is in a per-cpu pointer and the original reason for this
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* hypercall.
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*
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*/
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DEFINE_PER_CPU(struct vcpu_info *, xen_vcpu);
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/*
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* Per CPU pages used if hypervisor supports VCPUOP_register_vcpu_info
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* hypercall. This can be used both in PV and PVHVM mode. The structure
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* overrides the default per_cpu(xen_vcpu, cpu) value.
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*/
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DEFINE_PER_CPU(struct vcpu_info, xen_vcpu_info);
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/* Linux <-> Xen vCPU id mapping */
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DEFINE_PER_CPU(uint32_t, xen_vcpu_id);
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EXPORT_PER_CPU_SYMBOL(xen_vcpu_id);
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enum xen_domain_type xen_domain_type = XEN_NATIVE;
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EXPORT_SYMBOL_GPL(xen_domain_type);
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unsigned long *machine_to_phys_mapping = (void *)MACH2PHYS_VIRT_START;
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EXPORT_SYMBOL(machine_to_phys_mapping);
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unsigned long machine_to_phys_nr;
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EXPORT_SYMBOL(machine_to_phys_nr);
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struct start_info *xen_start_info;
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EXPORT_SYMBOL_GPL(xen_start_info);
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struct shared_info xen_dummy_shared_info;
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__read_mostly int xen_have_vector_callback;
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EXPORT_SYMBOL_GPL(xen_have_vector_callback);
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/*
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* NB: needs to live in .data because it's used by xen_prepare_pvh which runs
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* before clearing the bss.
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*/
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uint32_t xen_start_flags __attribute__((section(".data"))) = 0;
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EXPORT_SYMBOL(xen_start_flags);
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/*
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* Point at some empty memory to start with. We map the real shared_info
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* page as soon as fixmap is up and running.
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*/
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struct shared_info *HYPERVISOR_shared_info = &xen_dummy_shared_info;
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/*
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* Flag to determine whether vcpu info placement is available on all
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* VCPUs. We assume it is to start with, and then set it to zero on
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* the first failure. This is because it can succeed on some VCPUs
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* and not others, since it can involve hypervisor memory allocation,
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* or because the guest failed to guarantee all the appropriate
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* constraints on all VCPUs (ie buffer can't cross a page boundary).
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*
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* Note that any particular CPU may be using a placed vcpu structure,
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* but we can only optimise if the all are.
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*
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* 0: not available, 1: available
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*/
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int xen_have_vcpu_info_placement = 1;
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static int xen_cpu_up_online(unsigned int cpu)
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{
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xen_init_lock_cpu(cpu);
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return 0;
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}
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int xen_cpuhp_setup(int (*cpu_up_prepare_cb)(unsigned int),
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int (*cpu_dead_cb)(unsigned int))
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{
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int rc;
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rc = cpuhp_setup_state_nocalls(CPUHP_XEN_PREPARE,
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"x86/xen/guest:prepare",
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cpu_up_prepare_cb, cpu_dead_cb);
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if (rc >= 0) {
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rc = cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN,
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"x86/xen/guest:online",
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xen_cpu_up_online, NULL);
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if (rc < 0)
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cpuhp_remove_state_nocalls(CPUHP_XEN_PREPARE);
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}
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return rc >= 0 ? 0 : rc;
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}
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static int xen_vcpu_setup_restore(int cpu)
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{
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int rc = 0;
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/* Any per_cpu(xen_vcpu) is stale, so reset it */
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xen_vcpu_info_reset(cpu);
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/*
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* For PVH and PVHVM, setup online VCPUs only. The rest will
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* be handled by hotplug.
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*/
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if (xen_pv_domain() ||
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(xen_hvm_domain() && cpu_online(cpu))) {
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rc = xen_vcpu_setup(cpu);
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}
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return rc;
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}
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/*
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* On restore, set the vcpu placement up again.
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* If it fails, then we're in a bad state, since
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* we can't back out from using it...
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*/
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void xen_vcpu_restore(void)
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{
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int cpu, rc;
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for_each_possible_cpu(cpu) {
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bool other_cpu = (cpu != smp_processor_id());
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bool is_up;
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if (xen_vcpu_nr(cpu) == XEN_VCPU_ID_INVALID)
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continue;
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/* Only Xen 4.5 and higher support this. */
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is_up = HYPERVISOR_vcpu_op(VCPUOP_is_up,
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xen_vcpu_nr(cpu), NULL) > 0;
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if (other_cpu && is_up &&
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HYPERVISOR_vcpu_op(VCPUOP_down, xen_vcpu_nr(cpu), NULL))
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BUG();
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if (xen_pv_domain() || xen_feature(XENFEAT_hvm_safe_pvclock))
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xen_setup_runstate_info(cpu);
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rc = xen_vcpu_setup_restore(cpu);
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if (rc)
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pr_emerg_once("vcpu restore failed for cpu=%d err=%d. "
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"System will hang.\n", cpu, rc);
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/*
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* In case xen_vcpu_setup_restore() fails, do not bring up the
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* VCPU. This helps us avoid the resulting OOPS when the VCPU
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* accesses pvclock_vcpu_time via xen_vcpu (which is NULL.)
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* Note that this does not improve the situation much -- now the
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* VM hangs instead of OOPSing -- with the VCPUs that did not
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* fail, spinning in stop_machine(), waiting for the failed
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* VCPUs to come up.
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*/
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if (other_cpu && is_up && (rc == 0) &&
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HYPERVISOR_vcpu_op(VCPUOP_up, xen_vcpu_nr(cpu), NULL))
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BUG();
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}
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}
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void xen_vcpu_info_reset(int cpu)
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{
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if (xen_vcpu_nr(cpu) < MAX_VIRT_CPUS) {
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per_cpu(xen_vcpu, cpu) =
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&HYPERVISOR_shared_info->vcpu_info[xen_vcpu_nr(cpu)];
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} else {
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/* Set to NULL so that if somebody accesses it we get an OOPS */
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per_cpu(xen_vcpu, cpu) = NULL;
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}
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}
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int xen_vcpu_setup(int cpu)
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{
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struct vcpu_register_vcpu_info info;
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int err;
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struct vcpu_info *vcpup;
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BUG_ON(HYPERVISOR_shared_info == &xen_dummy_shared_info);
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/*
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* This path is called on PVHVM at bootup (xen_hvm_smp_prepare_boot_cpu)
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* and at restore (xen_vcpu_restore). Also called for hotplugged
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* VCPUs (cpu_init -> xen_hvm_cpu_prepare_hvm).
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* However, the hypercall can only be done once (see below) so if a VCPU
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* is offlined and comes back online then let's not redo the hypercall.
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*
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* For PV it is called during restore (xen_vcpu_restore) and bootup
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* (xen_setup_vcpu_info_placement). The hotplug mechanism does not
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* use this function.
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*/
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if (xen_hvm_domain()) {
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if (per_cpu(xen_vcpu, cpu) == &per_cpu(xen_vcpu_info, cpu))
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return 0;
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}
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if (xen_have_vcpu_info_placement) {
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vcpup = &per_cpu(xen_vcpu_info, cpu);
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info.mfn = arbitrary_virt_to_mfn(vcpup);
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info.offset = offset_in_page(vcpup);
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/*
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* Check to see if the hypervisor will put the vcpu_info
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* structure where we want it, which allows direct access via
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* a percpu-variable.
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* N.B. This hypercall can _only_ be called once per CPU.
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* Subsequent calls will error out with -EINVAL. This is due to
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* the fact that hypervisor has no unregister variant and this
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* hypercall does not allow to over-write info.mfn and
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* info.offset.
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*/
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err = HYPERVISOR_vcpu_op(VCPUOP_register_vcpu_info,
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xen_vcpu_nr(cpu), &info);
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if (err) {
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pr_warn_once("register_vcpu_info failed: cpu=%d err=%d\n",
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cpu, err);
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xen_have_vcpu_info_placement = 0;
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} else {
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/*
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* This cpu is using the registered vcpu info, even if
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* later ones fail to.
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*/
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per_cpu(xen_vcpu, cpu) = vcpup;
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}
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}
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if (!xen_have_vcpu_info_placement)
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xen_vcpu_info_reset(cpu);
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return ((per_cpu(xen_vcpu, cpu) == NULL) ? -ENODEV : 0);
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}
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void xen_reboot(int reason)
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{
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struct sched_shutdown r = { .reason = reason };
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int cpu;
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for_each_online_cpu(cpu)
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xen_pmu_finish(cpu);
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if (HYPERVISOR_sched_op(SCHEDOP_shutdown, &r))
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BUG();
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}
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void xen_emergency_restart(void)
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{
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xen_reboot(SHUTDOWN_reboot);
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}
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static int
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xen_panic_event(struct notifier_block *this, unsigned long event, void *ptr)
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{
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if (!kexec_crash_loaded())
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xen_reboot(SHUTDOWN_crash);
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return NOTIFY_DONE;
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}
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static struct notifier_block xen_panic_block = {
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.notifier_call = xen_panic_event,
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.priority = INT_MIN
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};
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int xen_panic_handler_init(void)
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{
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atomic_notifier_chain_register(&panic_notifier_list, &xen_panic_block);
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return 0;
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}
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void xen_pin_vcpu(int cpu)
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{
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static bool disable_pinning;
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struct sched_pin_override pin_override;
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int ret;
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if (disable_pinning)
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return;
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pin_override.pcpu = cpu;
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ret = HYPERVISOR_sched_op(SCHEDOP_pin_override, &pin_override);
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/* Ignore errors when removing override. */
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if (cpu < 0)
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return;
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switch (ret) {
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case -ENOSYS:
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pr_warn("Unable to pin on physical cpu %d. In case of problems consider vcpu pinning.\n",
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cpu);
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disable_pinning = true;
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break;
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case -EPERM:
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WARN(1, "Trying to pin vcpu without having privilege to do so\n");
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disable_pinning = true;
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break;
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case -EINVAL:
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case -EBUSY:
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pr_warn("Physical cpu %d not available for pinning. Check Xen cpu configuration.\n",
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cpu);
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break;
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case 0:
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break;
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default:
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WARN(1, "rc %d while trying to pin vcpu\n", ret);
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disable_pinning = true;
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}
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}
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#ifdef CONFIG_HOTPLUG_CPU
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void xen_arch_register_cpu(int num)
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{
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arch_register_cpu(num);
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}
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EXPORT_SYMBOL(xen_arch_register_cpu);
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void xen_arch_unregister_cpu(int num)
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{
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arch_unregister_cpu(num);
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}
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EXPORT_SYMBOL(xen_arch_unregister_cpu);
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#endif
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