linux-stable/arch/x86/xen/smp_pv.c
Juergen Gross de2ae403b4 xen: fix is_xen_pmu()
is_xen_pmu() is taking the cpu number as parameter, but it is not using
it. Instead it just tests whether the Xen PMU initialization on the
current cpu did succeed. As this test is done by checking a percpu
pointer, preemption needs to be disabled in order to avoid switching
the cpu while doing the test. While resuming from suspend() this seems
not to be the case:

[   88.082751] ACPI: PM: Low-level resume complete
[   88.087933] ACPI: EC: EC started
[   88.091464] ACPI: PM: Restoring platform NVS memory
[   88.097166] xen_acpi_processor: Uploading Xen processor PM info
[   88.103850] Enabling non-boot CPUs ...
[   88.108128] installing Xen timer for CPU 1
[   88.112763] BUG: using smp_processor_id() in preemptible [00000000] code: systemd-sleep/7138
[   88.122256] caller is is_xen_pmu+0x12/0x30
[   88.126937] CPU: 0 PID: 7138 Comm: systemd-sleep Tainted: G        W         5.16.13-2.fc32.qubes.x86_64 #1
[   88.137939] Hardware name: Star Labs StarBook/StarBook, BIOS 7.97 03/21/2022
[   88.145930] Call Trace:
[   88.148757]  <TASK>
[   88.151193]  dump_stack_lvl+0x48/0x5e
[   88.155381]  check_preemption_disabled+0xde/0xe0
[   88.160641]  is_xen_pmu+0x12/0x30
[   88.164441]  xen_smp_intr_init_pv+0x75/0x100

Fix that by replacing is_xen_pmu() by a simple boolean variable which
reflects the Xen PMU initialization state on cpu 0.

Modify xen_pmu_init() to return early in case it is being called for a
cpu other than cpu 0 and the boolean variable not being set.

Fixes: bf6dfb154d ("xen/PMU: PMU emulation code")
Reported-by: Marek Marczykowski-Górecki <marmarek@invisiblethingslab.com>
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Link: https://lore.kernel.org/r/20220325142002.31789-1-jgross@suse.com
Signed-off-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
2022-03-25 14:22:53 -05:00

466 lines
11 KiB
C

// SPDX-License-Identifier: GPL-2.0
/*
* Xen SMP support
*
* This file implements the Xen versions of smp_ops. SMP under Xen is
* very straightforward. Bringing a CPU up is simply a matter of
* loading its initial context and setting it running.
*
* IPIs are handled through the Xen event mechanism.
*
* Because virtual CPUs can be scheduled onto any real CPU, there's no
* useful topology information for the kernel to make use of. As a
* result, all CPUs are treated as if they're single-core and
* single-threaded.
*/
#include <linux/sched.h>
#include <linux/sched/task_stack.h>
#include <linux/err.h>
#include <linux/slab.h>
#include <linux/smp.h>
#include <linux/irq_work.h>
#include <linux/tick.h>
#include <linux/nmi.h>
#include <linux/cpuhotplug.h>
#include <linux/stackprotector.h>
#include <linux/pgtable.h>
#include <asm/paravirt.h>
#include <asm/idtentry.h>
#include <asm/desc.h>
#include <asm/cpu.h>
#include <asm/io_apic.h>
#include <xen/interface/xen.h>
#include <xen/interface/vcpu.h>
#include <xen/interface/xenpmu.h>
#include <asm/spec-ctrl.h>
#include <asm/xen/interface.h>
#include <asm/xen/hypercall.h>
#include <xen/xen.h>
#include <xen/page.h>
#include <xen/events.h>
#include <xen/hvc-console.h>
#include "xen-ops.h"
#include "mmu.h"
#include "smp.h"
#include "pmu.h"
cpumask_var_t xen_cpu_initialized_map;
static DEFINE_PER_CPU(struct xen_common_irq, xen_irq_work) = { .irq = -1 };
static DEFINE_PER_CPU(struct xen_common_irq, xen_pmu_irq) = { .irq = -1 };
static irqreturn_t xen_irq_work_interrupt(int irq, void *dev_id);
void asm_cpu_bringup_and_idle(void);
static void cpu_bringup(void)
{
int cpu;
cr4_init();
cpu_init();
touch_softlockup_watchdog();
/* PVH runs in ring 0 and allows us to do native syscalls. Yay! */
if (!xen_feature(XENFEAT_supervisor_mode_kernel)) {
xen_enable_sysenter();
xen_enable_syscall();
}
cpu = smp_processor_id();
smp_store_cpu_info(cpu);
cpu_data(cpu).x86_max_cores = 1;
set_cpu_sibling_map(cpu);
speculative_store_bypass_ht_init();
xen_setup_cpu_clockevents();
notify_cpu_starting(cpu);
set_cpu_online(cpu, true);
cpu_set_state_online(cpu); /* Implies full memory barrier. */
/* We can take interrupts now: we're officially "up". */
local_irq_enable();
}
asmlinkage __visible void cpu_bringup_and_idle(void)
{
cpu_bringup();
cpu_startup_entry(CPUHP_AP_ONLINE_IDLE);
}
void xen_smp_intr_free_pv(unsigned int cpu)
{
if (per_cpu(xen_irq_work, cpu).irq >= 0) {
unbind_from_irqhandler(per_cpu(xen_irq_work, cpu).irq, NULL);
per_cpu(xen_irq_work, cpu).irq = -1;
kfree(per_cpu(xen_irq_work, cpu).name);
per_cpu(xen_irq_work, cpu).name = NULL;
}
if (per_cpu(xen_pmu_irq, cpu).irq >= 0) {
unbind_from_irqhandler(per_cpu(xen_pmu_irq, cpu).irq, NULL);
per_cpu(xen_pmu_irq, cpu).irq = -1;
kfree(per_cpu(xen_pmu_irq, cpu).name);
per_cpu(xen_pmu_irq, cpu).name = NULL;
}
}
int xen_smp_intr_init_pv(unsigned int cpu)
{
int rc;
char *callfunc_name, *pmu_name;
callfunc_name = kasprintf(GFP_KERNEL, "irqwork%d", cpu);
rc = bind_ipi_to_irqhandler(XEN_IRQ_WORK_VECTOR,
cpu,
xen_irq_work_interrupt,
IRQF_PERCPU|IRQF_NOBALANCING,
callfunc_name,
NULL);
if (rc < 0)
goto fail;
per_cpu(xen_irq_work, cpu).irq = rc;
per_cpu(xen_irq_work, cpu).name = callfunc_name;
if (is_xen_pmu) {
pmu_name = kasprintf(GFP_KERNEL, "pmu%d", cpu);
rc = bind_virq_to_irqhandler(VIRQ_XENPMU, cpu,
xen_pmu_irq_handler,
IRQF_PERCPU|IRQF_NOBALANCING,
pmu_name, NULL);
if (rc < 0)
goto fail;
per_cpu(xen_pmu_irq, cpu).irq = rc;
per_cpu(xen_pmu_irq, cpu).name = pmu_name;
}
return 0;
fail:
xen_smp_intr_free_pv(cpu);
return rc;
}
static void __init _get_smp_config(unsigned int early)
{
int i, rc;
unsigned int subtract = 0;
if (early)
return;
num_processors = 0;
disabled_cpus = 0;
for (i = 0; i < nr_cpu_ids; i++) {
rc = HYPERVISOR_vcpu_op(VCPUOP_is_up, i, NULL);
if (rc >= 0) {
num_processors++;
set_cpu_possible(i, true);
} else {
set_cpu_possible(i, false);
set_cpu_present(i, false);
subtract++;
}
}
#ifdef CONFIG_HOTPLUG_CPU
/* This is akin to using 'nr_cpus' on the Linux command line.
* Which is OK as when we use 'dom0_max_vcpus=X' we can only
* have up to X, while nr_cpu_ids is greater than X. This
* normally is not a problem, except when CPU hotplugging
* is involved and then there might be more than X CPUs
* in the guest - which will not work as there is no
* hypercall to expand the max number of VCPUs an already
* running guest has. So cap it up to X. */
if (subtract)
nr_cpu_ids = nr_cpu_ids - subtract;
#endif
}
static void __init xen_pv_smp_prepare_boot_cpu(void)
{
BUG_ON(smp_processor_id() != 0);
native_smp_prepare_boot_cpu();
if (!xen_feature(XENFEAT_writable_page_tables))
/* We've switched to the "real" per-cpu gdt, so make
* sure the old memory can be recycled. */
make_lowmem_page_readwrite(xen_initial_gdt);
xen_setup_vcpu_info_placement();
/*
* The alternative logic (which patches the unlock/lock) runs before
* the smp bootup up code is activated. Hence we need to set this up
* the core kernel is being patched. Otherwise we will have only
* modules patched but not core code.
*/
xen_init_spinlocks();
}
static void __init xen_pv_smp_prepare_cpus(unsigned int max_cpus)
{
unsigned cpu;
if (skip_ioapic_setup) {
char *m = (max_cpus == 0) ?
"The nosmp parameter is incompatible with Xen; " \
"use Xen dom0_max_vcpus=1 parameter" :
"The noapic parameter is incompatible with Xen";
xen_raw_printk(m);
panic(m);
}
xen_init_lock_cpu(0);
smp_prepare_cpus_common();
cpu_data(0).x86_max_cores = 1;
speculative_store_bypass_ht_init();
xen_pmu_init(0);
if (xen_smp_intr_init(0) || xen_smp_intr_init_pv(0))
BUG();
if (!alloc_cpumask_var(&xen_cpu_initialized_map, GFP_KERNEL))
panic("could not allocate xen_cpu_initialized_map\n");
cpumask_copy(xen_cpu_initialized_map, cpumask_of(0));
/* Restrict the possible_map according to max_cpus. */
while ((num_possible_cpus() > 1) && (num_possible_cpus() > max_cpus)) {
for (cpu = nr_cpu_ids - 1; !cpu_possible(cpu); cpu--)
continue;
set_cpu_possible(cpu, false);
}
for_each_possible_cpu(cpu)
set_cpu_present(cpu, true);
}
static int
cpu_initialize_context(unsigned int cpu, struct task_struct *idle)
{
struct vcpu_guest_context *ctxt;
struct desc_struct *gdt;
unsigned long gdt_mfn;
/* used to tell cpu_init() that it can proceed with initialization */
cpumask_set_cpu(cpu, cpu_callout_mask);
if (cpumask_test_and_set_cpu(cpu, xen_cpu_initialized_map))
return 0;
ctxt = kzalloc(sizeof(*ctxt), GFP_KERNEL);
if (ctxt == NULL)
return -ENOMEM;
gdt = get_cpu_gdt_rw(cpu);
/*
* Bring up the CPU in cpu_bringup_and_idle() with the stack
* pointing just below where pt_regs would be if it were a normal
* kernel entry.
*/
ctxt->user_regs.eip = (unsigned long)asm_cpu_bringup_and_idle;
ctxt->flags = VGCF_IN_KERNEL;
ctxt->user_regs.eflags = 0x1000; /* IOPL_RING1 */
ctxt->user_regs.ds = __USER_DS;
ctxt->user_regs.es = __USER_DS;
ctxt->user_regs.ss = __KERNEL_DS;
ctxt->user_regs.cs = __KERNEL_CS;
ctxt->user_regs.esp = (unsigned long)task_pt_regs(idle);
xen_copy_trap_info(ctxt->trap_ctxt);
BUG_ON((unsigned long)gdt & ~PAGE_MASK);
gdt_mfn = arbitrary_virt_to_mfn(gdt);
make_lowmem_page_readonly(gdt);
make_lowmem_page_readonly(mfn_to_virt(gdt_mfn));
ctxt->gdt_frames[0] = gdt_mfn;
ctxt->gdt_ents = GDT_ENTRIES;
/*
* Set SS:SP that Xen will use when entering guest kernel mode
* from guest user mode. Subsequent calls to load_sp0() can
* change this value.
*/
ctxt->kernel_ss = __KERNEL_DS;
ctxt->kernel_sp = task_top_of_stack(idle);
ctxt->gs_base_kernel = per_cpu_offset(cpu);
ctxt->event_callback_eip =
(unsigned long)xen_asm_exc_xen_hypervisor_callback;
ctxt->failsafe_callback_eip =
(unsigned long)xen_failsafe_callback;
per_cpu(xen_cr3, cpu) = __pa(swapper_pg_dir);
ctxt->ctrlreg[3] = xen_pfn_to_cr3(virt_to_gfn(swapper_pg_dir));
if (HYPERVISOR_vcpu_op(VCPUOP_initialise, xen_vcpu_nr(cpu), ctxt))
BUG();
kfree(ctxt);
return 0;
}
static int xen_pv_cpu_up(unsigned int cpu, struct task_struct *idle)
{
int rc;
rc = common_cpu_up(cpu, idle);
if (rc)
return rc;
xen_setup_runstate_info(cpu);
/*
* PV VCPUs are always successfully taken down (see 'while' loop
* in xen_cpu_die()), so -EBUSY is an error.
*/
rc = cpu_check_up_prepare(cpu);
if (rc)
return rc;
/* make sure interrupts start blocked */
per_cpu(xen_vcpu, cpu)->evtchn_upcall_mask = 1;
rc = cpu_initialize_context(cpu, idle);
if (rc)
return rc;
xen_pmu_init(cpu);
rc = HYPERVISOR_vcpu_op(VCPUOP_up, xen_vcpu_nr(cpu), NULL);
BUG_ON(rc);
while (cpu_report_state(cpu) != CPU_ONLINE)
HYPERVISOR_sched_op(SCHEDOP_yield, NULL);
return 0;
}
#ifdef CONFIG_HOTPLUG_CPU
static int xen_pv_cpu_disable(void)
{
unsigned int cpu = smp_processor_id();
if (cpu == 0)
return -EBUSY;
cpu_disable_common();
load_cr3(swapper_pg_dir);
return 0;
}
static void xen_pv_cpu_die(unsigned int cpu)
{
while (HYPERVISOR_vcpu_op(VCPUOP_is_up,
xen_vcpu_nr(cpu), NULL)) {
__set_current_state(TASK_UNINTERRUPTIBLE);
schedule_timeout(HZ/10);
}
if (common_cpu_die(cpu) == 0) {
xen_smp_intr_free(cpu);
xen_uninit_lock_cpu(cpu);
xen_teardown_timer(cpu);
xen_pmu_finish(cpu);
}
}
static void xen_pv_play_dead(void) /* used only with HOTPLUG_CPU */
{
play_dead_common();
HYPERVISOR_vcpu_op(VCPUOP_down, xen_vcpu_nr(smp_processor_id()), NULL);
cpu_bringup();
/*
* commit 4b0c0f294 (tick: Cleanup NOHZ per cpu data on cpu down)
* clears certain data that the cpu_idle loop (which called us
* and that we return from) expects. The only way to get that
* data back is to call:
*/
tick_nohz_idle_enter();
tick_nohz_idle_stop_tick_protected();
cpuhp_online_idle(CPUHP_AP_ONLINE_IDLE);
}
#else /* !CONFIG_HOTPLUG_CPU */
static int xen_pv_cpu_disable(void)
{
return -ENOSYS;
}
static void xen_pv_cpu_die(unsigned int cpu)
{
BUG();
}
static void xen_pv_play_dead(void)
{
BUG();
}
#endif
static void stop_self(void *v)
{
int cpu = smp_processor_id();
/* make sure we're not pinning something down */
load_cr3(swapper_pg_dir);
/* should set up a minimal gdt */
set_cpu_online(cpu, false);
HYPERVISOR_vcpu_op(VCPUOP_down, xen_vcpu_nr(cpu), NULL);
BUG();
}
static void xen_pv_stop_other_cpus(int wait)
{
smp_call_function(stop_self, NULL, wait);
}
static irqreturn_t xen_irq_work_interrupt(int irq, void *dev_id)
{
irq_work_run();
inc_irq_stat(apic_irq_work_irqs);
return IRQ_HANDLED;
}
static const struct smp_ops xen_smp_ops __initconst = {
.smp_prepare_boot_cpu = xen_pv_smp_prepare_boot_cpu,
.smp_prepare_cpus = xen_pv_smp_prepare_cpus,
.smp_cpus_done = xen_smp_cpus_done,
.cpu_up = xen_pv_cpu_up,
.cpu_die = xen_pv_cpu_die,
.cpu_disable = xen_pv_cpu_disable,
.play_dead = xen_pv_play_dead,
.stop_other_cpus = xen_pv_stop_other_cpus,
.smp_send_reschedule = xen_smp_send_reschedule,
.send_call_func_ipi = xen_smp_send_call_function_ipi,
.send_call_func_single_ipi = xen_smp_send_call_function_single_ipi,
};
void __init xen_smp_init(void)
{
smp_ops = xen_smp_ops;
/* Avoid searching for BIOS MP tables */
x86_init.mpparse.find_smp_config = x86_init_noop;
x86_init.mpparse.get_smp_config = _get_smp_config;
}