linux/arch/x86/kvm/vmx/posted_intr.c

// SPDX-License-Identifier: GPL-2.0-only
#define pr_fmt(fmt) …

#include <linux/kvm_host.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"

/*
 * 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);

static inline struct pi_desc *vcpu_to_pi_desc(struct kvm_vcpu *vcpu)
{ … }

static int pi_try_set_control(struct pi_desc *pi_desc, u64 *pold, u64 new)
{ … }

void vmx_vcpu_pi_load(struct kvm_vcpu *vcpu, int cpu)
{ … }

static bool vmx_can_use_vtd_pi(struct kvm *kvm)
{ … }

/*
 * 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)
{ … }

static bool vmx_needs_pi_wakeup(struct kvm_vcpu *vcpu)
{ … }

void vmx_vcpu_pi_put(struct kvm_vcpu *vcpu)
{ … }

/*
 * Handler for POSTED_INTERRUPT_WAKEUP_VECTOR.
 */
void pi_wakeup_handler(void)
{ … }

void __init pi_init_cpu(int cpu)
{ … }

bool pi_has_pending_interrupt(struct kvm_vcpu *vcpu)
{ … }


/*
 * Bail out of the block loop if the VM has an assigned
 * device, but the blocking vCPU didn't reconfigure the
 * PI.NV to the wakeup vector, i.e. the assigned device
 * came along after the initial check in vmx_vcpu_pi_put().
 */
void vmx_pi_start_assignment(struct kvm *kvm)
{ … }

/*
 * vmx_pi_update_irte - set IRTE for Posted-Interrupts
 *
 * @kvm: kvm
 * @host_irq: host irq of the interrupt
 * @guest_irq: gsi of the interrupt
 * @set: set or unset PI
 * returns 0 on success, < 0 on failure
 */
int vmx_pi_update_irte(struct kvm *kvm, unsigned int host_irq,
		       uint32_t guest_irq, bool set)
{ … }