Contributors: 23
| Author |
Tokens |
Token Proportion |
Commits |
Commit Proportion |
| Xiaoyao Li |
396 |
39.80% |
1 |
1.64% |
| Sean Christopherson |
264 |
26.53% |
28 |
45.90% |
| Paolo Bonzini |
55 |
5.53% |
4 |
6.56% |
| Zhao Yan |
35 |
3.52% |
1 |
1.64% |
| Isaku Yamahata |
30 |
3.02% |
2 |
3.28% |
| Marcelo Tosatti |
28 |
2.81% |
3 |
4.92% |
| Vitaly Kuznetsov |
27 |
2.71% |
4 |
6.56% |
| Vishal Verma |
26 |
2.61% |
1 |
1.64% |
| Li RongQing |
26 |
2.61% |
1 |
1.64% |
| Avi Kivity |
24 |
2.41% |
1 |
1.64% |
| Chao Gao |
19 |
1.91% |
1 |
1.64% |
| Binbin Wu |
17 |
1.71% |
1 |
1.64% |
| Feng Wu |
13 |
1.31% |
2 |
3.28% |
| Jim Mattson |
8 |
0.80% |
1 |
1.64% |
| Jacob jun Pan |
7 |
0.70% |
1 |
1.64% |
| Xiantao Zhang |
6 |
0.60% |
1 |
1.64% |
| Uros Bizjak |
4 |
0.40% |
2 |
3.28% |
| Eric Auger |
3 |
0.30% |
1 |
1.64% |
| Kai Huang |
3 |
0.30% |
1 |
1.64% |
| Yao Yuan |
1 |
0.10% |
1 |
1.64% |
| Tiejun Chen |
1 |
0.10% |
1 |
1.64% |
| Dave Hansen |
1 |
0.10% |
1 |
1.64% |
| Thomas Gleixner |
1 |
0.10% |
1 |
1.64% |
| Total |
995 |
|
61 |
|
// SPDX-License-Identifier: GPL-2.0-only
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/kvm_host.h>
#include <linux/kvm_irqfd.h>
#include <asm/irq_remapping.h>
#include <asm/cpu.h>
#include "lapic.h"
#include "irq.h"
#include "posted_intr.h"
#include "trace.h"
#include "vmx.h"
#include "tdx.h"
/*
* Maintain a per-CPU list of vCPUs that need to be awakened by wakeup_handler()
* when a WAKEUP_VECTOR interrupted is posted. vCPUs are added to the list when
* the vCPU is scheduled out and is blocking (e.g. in HLT) with IRQs enabled.
* The vCPUs posted interrupt descriptor is updated at the same time to set its
* notification vector to WAKEUP_VECTOR, so that posted interrupt from devices
* wake the target vCPUs. vCPUs are removed from the list and the notification
* vector is reset when the vCPU is scheduled in.
*/
static DEFINE_PER_CPU(struct list_head, wakeup_vcpus_on_cpu);
/*
* Protect the per-CPU list with a per-CPU spinlock to handle task migration.
* When a blocking vCPU is awakened _and_ migrated to a different pCPU, the
* ->sched_in() path will need to take the vCPU off the list of the _previous_
* CPU. IRQs must be disabled when taking this lock, otherwise deadlock will
* occur if a wakeup IRQ arrives and attempts to acquire the lock.
*/
static DEFINE_PER_CPU(raw_spinlock_t, wakeup_vcpus_on_cpu_lock);
#define PI_LOCK_SCHED_OUT SINGLE_DEPTH_NESTING
static struct pi_desc *vcpu_to_pi_desc(struct kvm_vcpu *vcpu)
{
return &(to_vt(vcpu)->pi_desc);
}
static int pi_try_set_control(struct pi_desc *pi_desc, u64 *pold, u64 new)
{
/*
* PID.ON can be set at any time by a different vCPU or by hardware,
* e.g. a device. PID.control must be written atomically, and the
* update must be retried with a fresh snapshot an ON change causes
* the cmpxchg to fail.
*/
if (!try_cmpxchg64(&pi_desc->control, pold, new))
return -EBUSY;
return 0;
}
void vmx_vcpu_pi_load(struct kvm_vcpu *vcpu, int cpu)
{
struct pi_desc *pi_desc = vcpu_to_pi_desc(vcpu);
struct vcpu_vt *vt = to_vt(vcpu);
struct pi_desc old, new;
unsigned long flags;
unsigned int dest;
/*
* To simplify hot-plug and dynamic toggling of APICv, keep PI.NDST and
* PI.SN up-to-date even if there is no assigned device or if APICv is
* deactivated due to a dynamic inhibit bit, e.g. for Hyper-V's SyncIC.
*/
if (!enable_apicv || !lapic_in_kernel(vcpu))
return;
/*
* If the vCPU wasn't on the wakeup list and wasn't migrated, then the
* full update can be skipped as neither the vector nor the destination
* needs to be changed. Clear SN even if there is no assigned device,
* again for simplicity.
*/
if (pi_desc->nv != POSTED_INTR_WAKEUP_VECTOR && vcpu->cpu == cpu) {
if (pi_test_and_clear_sn(pi_desc))
goto after_clear_sn;
return;
}
local_irq_save(flags);
/*
* If the vCPU was waiting for wakeup, remove the vCPU from the wakeup
* list of the _previous_ pCPU, which will not be the same as the
* current pCPU if the task was migrated.
*/
if (pi_desc->nv == POSTED_INTR_WAKEUP_VECTOR) {
raw_spinlock_t *spinlock = &per_cpu(wakeup_vcpus_on_cpu_lock, vcpu->cpu);
/*
* In addition to taking the wakeup lock for the regular/IRQ
* context, tell lockdep it is being taken for the "sched out"
* context as well. vCPU loads happens in task context, and
* this is taking the lock of the *previous* CPU, i.e. can race
* with both the scheduler and the wakeup handler.
*/
raw_spin_lock(spinlock);
spin_acquire(&spinlock->dep_map, PI_LOCK_SCHED_OUT, 0, _RET_IP_);
list_del(&vt->pi_wakeup_list);
spin_release(&spinlock->dep_map, _RET_IP_);
raw_spin_unlock(spinlock);
}
dest = cpu_physical_id(cpu);
if (!x2apic_mode)
dest = (dest << 8) & 0xFF00;
old.control = READ_ONCE(pi_desc->control);
do {
new.control = old.control;
/*
* Clear SN (as above) and refresh the destination APIC ID to
* handle task migration (@cpu != vcpu->cpu).
*/
new.ndst = dest;
__pi_clear_sn(&new);
/*
* Restore the notification vector; in the blocking case, the
* descriptor was modified on "put" to use the wakeup vector.
*/
new.nv = POSTED_INTR_VECTOR;
} while (pi_try_set_control(pi_desc, &old.control, new.control));
local_irq_restore(flags);
after_clear_sn:
/*
* Clear SN before reading the bitmap. The VT-d firmware
* writes the bitmap and reads SN atomically (5.2.3 in the
* spec), so it doesn't really have a memory barrier that
* pairs with this, but we cannot do that and we need one.
*/
smp_mb__after_atomic();
if (!pi_is_pir_empty(pi_desc))
pi_set_on(pi_desc);
}
static bool vmx_can_use_vtd_pi(struct kvm *kvm)
{
/*
* Note, reading the number of possible bypass IRQs can race with a
* bypass IRQ being attached to the VM. vmx_pi_start_bypass() ensures
* blockng vCPUs will see an elevated count or get KVM_REQ_UNBLOCK.
*/
return irqchip_in_kernel(kvm) && kvm_arch_has_irq_bypass() &&
READ_ONCE(kvm->arch.nr_possible_bypass_irqs);
}
/*
* Put the vCPU on this pCPU's list of vCPUs that needs to be awakened and set
* WAKEUP as the notification vector in the PI descriptor.
*/
static void pi_enable_wakeup_handler(struct kvm_vcpu *vcpu)
{
struct pi_desc *pi_desc = vcpu_to_pi_desc(vcpu);
struct vcpu_vt *vt = to_vt(vcpu);
struct pi_desc old, new;
lockdep_assert_irqs_disabled();
/*
* Acquire the wakeup lock using the "sched out" context to workaround
* a lockdep false positive. When this is called, schedule() holds
* various per-CPU scheduler locks. When the wakeup handler runs, it
* holds this CPU's wakeup lock while calling try_to_wake_up(), which
* can eventually take the aforementioned scheduler locks, which causes
* lockdep to assume there is deadlock.
*
* Deadlock can't actually occur because IRQs are disabled for the
* entirety of the sched_out critical section, i.e. the wakeup handler
* can't run while the scheduler locks are held.
*/
raw_spin_lock_nested(&per_cpu(wakeup_vcpus_on_cpu_lock, vcpu->cpu),
PI_LOCK_SCHED_OUT);
list_add_tail(&vt->pi_wakeup_list,
&per_cpu(wakeup_vcpus_on_cpu, vcpu->cpu));
raw_spin_unlock(&per_cpu(wakeup_vcpus_on_cpu_lock, vcpu->cpu));
WARN(pi_test_sn(pi_desc), "PI descriptor SN field set before blocking");
old.control = READ_ONCE(pi_desc->control);
do {
/* set 'NV' to 'wakeup vector' */
new.control = old.control;
new.nv = POSTED_INTR_WAKEUP_VECTOR;
} while (pi_try_set_control(pi_desc, &old.control, new.control));
/*
* Send a wakeup IPI to this CPU if an interrupt may have been posted
* before the notification vector was updated, in which case the IRQ
* will arrive on the non-wakeup vector. An IPI is needed as calling
* try_to_wake_up() from ->sched_out() isn't allowed (IRQs are not
* enabled until it is safe to call try_to_wake_up() on the task being
* scheduled out).
*/
if (pi_test_on(&new))
__apic_send_IPI_self(POSTED_INTR_WAKEUP_VECTOR);
}
static bool vmx_needs_pi_wakeup(struct kvm_vcpu *vcpu)
{
/*
* The default posted interrupt vector does nothing when
* invoked outside guest mode. Return whether a blocked vCPU
* can be the target of posted interrupts, as is the case when
* using either IPI virtualization or VT-d PI, so that the
* notification vector is switched to the one that calls
* back to the pi_wakeup_handler() function.
*/
return (vmx_can_use_ipiv(vcpu) && !is_td_vcpu(vcpu)) ||
vmx_can_use_vtd_pi(vcpu->kvm);
}
void vmx_vcpu_pi_put(struct kvm_vcpu *vcpu)
{
struct pi_desc *pi_desc = vcpu_to_pi_desc(vcpu);
if (!vmx_needs_pi_wakeup(vcpu))
return;
/*
* If the vCPU is blocking with IRQs enabled and ISN'T being preempted,
* enable the wakeup handler so that notification IRQ wakes the vCPU as
* expected. There is no need to enable the wakeup handler if the vCPU
* is preempted between setting its wait state and manually scheduling
* out, as the task is still runnable, i.e. doesn't need a wake event
* from KVM to be scheduled in.
*
* If the wakeup handler isn't being enabled, Suppress Notifications as
* the cost of propagating PIR.IRR to PID.ON is negligible compared to
* the cost of a spurious IRQ, and vCPU put/load is a slow path.
*/
if (!vcpu->preempted && kvm_vcpu_is_blocking(vcpu) &&
((is_td_vcpu(vcpu) && tdx_interrupt_allowed(vcpu)) ||
(!is_td_vcpu(vcpu) && !vmx_interrupt_blocked(vcpu))))
pi_enable_wakeup_handler(vcpu);
else
pi_set_sn(pi_desc);
}
/*
* Handler for POSTED_INTERRUPT_WAKEUP_VECTOR.
*/
void pi_wakeup_handler(void)
{
int cpu = smp_processor_id();
struct list_head *wakeup_list = &per_cpu(wakeup_vcpus_on_cpu, cpu);
raw_spinlock_t *spinlock = &per_cpu(wakeup_vcpus_on_cpu_lock, cpu);
struct vcpu_vt *vt;
raw_spin_lock(spinlock);
list_for_each_entry(vt, wakeup_list, pi_wakeup_list) {
if (pi_test_on(&vt->pi_desc))
kvm_vcpu_wake_up(vt_to_vcpu(vt));
}
raw_spin_unlock(spinlock);
}
void __init pi_init_cpu(int cpu)
{
INIT_LIST_HEAD(&per_cpu(wakeup_vcpus_on_cpu, cpu));
raw_spin_lock_init(&per_cpu(wakeup_vcpus_on_cpu_lock, cpu));
}
void pi_apicv_pre_state_restore(struct kvm_vcpu *vcpu)
{
struct pi_desc *pi = vcpu_to_pi_desc(vcpu);
pi_clear_on(pi);
memset(pi->pir, 0, sizeof(pi->pir));
}
bool pi_has_pending_interrupt(struct kvm_vcpu *vcpu)
{
struct pi_desc *pi_desc = vcpu_to_pi_desc(vcpu);
return pi_test_on(pi_desc) ||
(pi_test_sn(pi_desc) && !pi_is_pir_empty(pi_desc));
}
/*
* Kick all vCPUs when the first possible bypass IRQ is attached to a VM, as
* blocking vCPUs may scheduled out without reconfiguring PID.NV to the wakeup
* vector, i.e. if the bypass IRQ came along after vmx_vcpu_pi_put().
*/
void vmx_pi_start_bypass(struct kvm *kvm)
{
if (WARN_ON_ONCE(!vmx_can_use_vtd_pi(kvm)))
return;
kvm_make_all_cpus_request(kvm, KVM_REQ_UNBLOCK);
}
int vmx_pi_update_irte(struct kvm_kernel_irqfd *irqfd, struct kvm *kvm,
unsigned int host_irq, uint32_t guest_irq,
struct kvm_vcpu *vcpu, u32 vector)
{
if (vcpu) {
struct intel_iommu_pi_data pi_data = {
.pi_desc_addr = __pa(vcpu_to_pi_desc(vcpu)),
.vector = vector,
};
return irq_set_vcpu_affinity(host_irq, &pi_data);
} else {
return irq_set_vcpu_affinity(host_irq, NULL);
}
}