blob: 1c94783b5a54c5520466bb8b3753c89cfa1d5850 [file] [log] [blame]
// SPDX-License-Identifier: GPL-2.0-only
#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"
/*
* We maintain a per-CPU linked-list of vCPU, so in wakeup_handler() we
* can find which vCPU should be waken up.
*/
static DEFINE_PER_CPU(struct list_head, blocked_vcpu_on_cpu);
static DEFINE_PER_CPU(spinlock_t, blocked_vcpu_on_cpu_lock);
static inline struct pi_desc *vcpu_to_pi_desc(struct kvm_vcpu *vcpu)
{
return &(to_vmx(vcpu)->pi_desc);
}
void vmx_vcpu_pi_load(struct kvm_vcpu *vcpu, int cpu)
{
struct pi_desc *pi_desc = vcpu_to_pi_desc(vcpu);
struct pi_desc old, new;
unsigned int dest;
/*
* In case of hot-plug or hot-unplug, we may have to undo
* vmx_vcpu_pi_put even if there is no assigned device. And we
* always keep PI.NDST up to date for simplicity: it makes the
* code easier, and CPU migration is not a fast path.
*/
if (!pi_test_sn(pi_desc) && vcpu->cpu == cpu)
return;
/*
* If the 'nv' field is POSTED_INTR_WAKEUP_VECTOR, do not change
* PI.NDST: pi_post_block is the one expected to change PID.NDST and the
* wakeup handler expects the vCPU to be on the blocked_vcpu_list that
* matches PI.NDST. Otherwise, a vcpu may not be able to be woken up
* correctly.
*/
if (pi_desc->nv == POSTED_INTR_WAKEUP_VECTOR || vcpu->cpu == cpu) {
pi_clear_sn(pi_desc);
goto after_clear_sn;
}
/* The full case. */
do {
old.control = new.control = pi_desc->control;
dest = cpu_physical_id(cpu);
if (x2apic_mode)
new.ndst = dest;
else
new.ndst = (dest << 8) & 0xFF00;
new.sn = 0;
} while (cmpxchg64(&pi_desc->control, old.control,
new.control) != old.control);
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)
{
return irqchip_in_kernel(kvm) && enable_apicv &&
kvm_arch_has_assigned_device(kvm) &&
irq_remapping_cap(IRQ_POSTING_CAP);
}
void vmx_vcpu_pi_put(struct kvm_vcpu *vcpu)
{
struct pi_desc *pi_desc = vcpu_to_pi_desc(vcpu);
if (!vmx_can_use_vtd_pi(vcpu->kvm))
return;
/* Set SN when the vCPU is preempted */
if (vcpu->preempted)
pi_set_sn(pi_desc);
}
static void __pi_post_block(struct kvm_vcpu *vcpu)
{
struct pi_desc *pi_desc = vcpu_to_pi_desc(vcpu);
struct pi_desc old, new;
unsigned int dest;
do {
old.control = new.control = pi_desc->control;
WARN(old.nv != POSTED_INTR_WAKEUP_VECTOR,
"Wakeup handler not enabled while the VCPU is blocked\n");
dest = cpu_physical_id(vcpu->cpu);
if (x2apic_mode)
new.ndst = dest;
else
new.ndst = (dest << 8) & 0xFF00;
/* set 'NV' to 'notification vector' */
new.nv = POSTED_INTR_VECTOR;
} while (cmpxchg64(&pi_desc->control, old.control,
new.control) != old.control);
if (!WARN_ON_ONCE(vcpu->pre_pcpu == -1)) {
spin_lock(&per_cpu(blocked_vcpu_on_cpu_lock, vcpu->pre_pcpu));
list_del(&vcpu->blocked_vcpu_list);
spin_unlock(&per_cpu(blocked_vcpu_on_cpu_lock, vcpu->pre_pcpu));
vcpu->pre_pcpu = -1;
}
}
/*
* This routine does the following things for vCPU which is going
* to be blocked if VT-d PI is enabled.
* - Store the vCPU to the wakeup list, so when interrupts happen
* we can find the right vCPU to wake up.
* - Change the Posted-interrupt descriptor as below:
* 'NDST' <-- vcpu->pre_pcpu
* 'NV' <-- POSTED_INTR_WAKEUP_VECTOR
* - If 'ON' is set during this process, which means at least one
* interrupt is posted for this vCPU, we cannot block it, in
* this case, return 1, otherwise, return 0.
*
*/
int pi_pre_block(struct kvm_vcpu *vcpu)
{
unsigned int dest;
struct pi_desc old, new;
struct pi_desc *pi_desc = vcpu_to_pi_desc(vcpu);
if (!vmx_can_use_vtd_pi(vcpu->kvm))
return 0;
WARN_ON(irqs_disabled());
local_irq_disable();
if (!WARN_ON_ONCE(vcpu->pre_pcpu != -1)) {
vcpu->pre_pcpu = vcpu->cpu;
spin_lock(&per_cpu(blocked_vcpu_on_cpu_lock, vcpu->pre_pcpu));
list_add_tail(&vcpu->blocked_vcpu_list,
&per_cpu(blocked_vcpu_on_cpu,
vcpu->pre_pcpu));
spin_unlock(&per_cpu(blocked_vcpu_on_cpu_lock, vcpu->pre_pcpu));
}
do {
old.control = new.control = pi_desc->control;
WARN((pi_desc->sn == 1),
"Warning: SN field of posted-interrupts "
"is set before blocking\n");
/*
* Since vCPU can be preempted during this process,
* vcpu->cpu could be different with pre_pcpu, we
* need to set pre_pcpu as the destination of wakeup
* notification event, then we can find the right vCPU
* to wakeup in wakeup handler if interrupts happen
* when the vCPU is in blocked state.
*/
dest = cpu_physical_id(vcpu->pre_pcpu);
if (x2apic_mode)
new.ndst = dest;
else
new.ndst = (dest << 8) & 0xFF00;
/* set 'NV' to 'wakeup vector' */
new.nv = POSTED_INTR_WAKEUP_VECTOR;
} while (cmpxchg64(&pi_desc->control, old.control,
new.control) != old.control);
/* We should not block the vCPU if an interrupt is posted for it. */
if (pi_test_on(pi_desc) == 1)
__pi_post_block(vcpu);
local_irq_enable();
return (vcpu->pre_pcpu == -1);
}
void pi_post_block(struct kvm_vcpu *vcpu)
{
if (vcpu->pre_pcpu == -1)
return;
WARN_ON(irqs_disabled());
local_irq_disable();
__pi_post_block(vcpu);
local_irq_enable();
}
/*
* Handler for POSTED_INTERRUPT_WAKEUP_VECTOR.
*/
void pi_wakeup_handler(void)
{
struct kvm_vcpu *vcpu;
int cpu = smp_processor_id();
spin_lock(&per_cpu(blocked_vcpu_on_cpu_lock, cpu));
list_for_each_entry(vcpu, &per_cpu(blocked_vcpu_on_cpu, cpu),
blocked_vcpu_list) {
struct pi_desc *pi_desc = vcpu_to_pi_desc(vcpu);
if (pi_test_on(pi_desc) == 1)
kvm_vcpu_kick(vcpu);
}
spin_unlock(&per_cpu(blocked_vcpu_on_cpu_lock, cpu));
}
void __init pi_init_cpu(int cpu)
{
INIT_LIST_HEAD(&per_cpu(blocked_vcpu_on_cpu, cpu));
spin_lock_init(&per_cpu(blocked_vcpu_on_cpu_lock, cpu));
}
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));
}
/*
* 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 pi_pre_block().
*/
void vmx_pi_start_assignment(struct kvm *kvm)
{
if (!irq_remapping_cap(IRQ_POSTING_CAP))
return;
kvm_make_all_cpus_request(kvm, KVM_REQ_UNBLOCK);
}
/*
* 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 pi_update_irte(struct kvm *kvm, unsigned int host_irq, uint32_t guest_irq,
bool set)
{
struct kvm_kernel_irq_routing_entry *e;
struct kvm_irq_routing_table *irq_rt;
struct kvm_lapic_irq irq;
struct kvm_vcpu *vcpu;
struct vcpu_data vcpu_info;
int idx, ret = 0;
if (!vmx_can_use_vtd_pi(kvm))
return 0;
idx = srcu_read_lock(&kvm->irq_srcu);
irq_rt = srcu_dereference(kvm->irq_routing, &kvm->irq_srcu);
if (guest_irq >= irq_rt->nr_rt_entries ||
hlist_empty(&irq_rt->map[guest_irq])) {
pr_warn_once("no route for guest_irq %u/%u (broken user space?)\n",
guest_irq, irq_rt->nr_rt_entries);
goto out;
}
hlist_for_each_entry(e, &irq_rt->map[guest_irq], link) {
if (e->type != KVM_IRQ_ROUTING_MSI)
continue;
/*
* VT-d PI cannot support posting multicast/broadcast
* interrupts to a vCPU, we still use interrupt remapping
* for these kind of interrupts.
*
* For lowest-priority interrupts, we only support
* those with single CPU as the destination, e.g. user
* configures the interrupts via /proc/irq or uses
* irqbalance to make the interrupts single-CPU.
*
* We will support full lowest-priority interrupt later.
*
* In addition, we can only inject generic interrupts using
* the PI mechanism, refuse to route others through it.
*/
kvm_set_msi_irq(kvm, e, &irq);
if (!kvm_intr_is_single_vcpu(kvm, &irq, &vcpu) ||
!kvm_irq_is_postable(&irq)) {
/*
* Make sure the IRTE is in remapped mode if
* we don't handle it in posted mode.
*/
ret = irq_set_vcpu_affinity(host_irq, NULL);
if (ret < 0) {
printk(KERN_INFO
"failed to back to remapped mode, irq: %u\n",
host_irq);
goto out;
}
continue;
}
vcpu_info.pi_desc_addr = __pa(&to_vmx(vcpu)->pi_desc);
vcpu_info.vector = irq.vector;
trace_kvm_pi_irte_update(host_irq, vcpu->vcpu_id, e->gsi,
vcpu_info.vector, vcpu_info.pi_desc_addr, set);
if (set)
ret = irq_set_vcpu_affinity(host_irq, &vcpu_info);
else
ret = irq_set_vcpu_affinity(host_irq, NULL);
if (ret < 0) {
printk(KERN_INFO "%s: failed to update PI IRTE\n",
__func__);
goto out;
}
}
ret = 0;
out:
srcu_read_unlock(&kvm->irq_srcu, idx);
return ret;
}