Adding upstream version 6.6.15.upstream/6.6.15

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 353 insertions, 0 deletions

diff --git a/arch/x86/kvm/vmx/posted_intr.c b/arch/x86/kvm/vmx/posted_intr.c
new file mode 100644
index 000000000..af662312f
--- /dev/null
+++ b/arch/x86/kvm/vmx/posted_intr.c
@@ -0,0 +1,353 @@
+// SPDX-License-Identifier: GPL-2.0-only
+#define pr_fmt(fmt) KBUILD_MODNAME ": " 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)
+{
+	return &(to_vmx(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_vmx *vmx = to_vmx(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.
+	 */
+	if (pi_desc->nv != POSTED_INTR_WAKEUP_VECTOR && vcpu->cpu == cpu) {
+		/*
+		 * Clear SN if it was set due to being preempted.  Again, do
+		 * this even if there is no assigned device for simplicity.
+		 */
+		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_spin_lock(&per_cpu(wakeup_vcpus_on_cpu_lock, vcpu->cpu));
+		list_del(&vmx->pi_wakeup_list);
+		raw_spin_unlock(&per_cpu(wakeup_vcpus_on_cpu_lock, vcpu->cpu));
+	}
+
+	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;
+		new.sn = 0;
+
+		/*
+		 * 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)
+{
+	return irqchip_in_kernel(kvm) && enable_apicv &&
+		kvm_arch_has_assigned_device(kvm) &&
+		irq_remapping_cap(IRQ_POSTING_CAP);
+}
+
+/*
+ * 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_vmx *vmx = to_vmx(vcpu);
+	struct pi_desc old, new;
+	unsigned long flags;
+
+	local_irq_save(flags);
+
+	raw_spin_lock(&per_cpu(wakeup_vcpus_on_cpu_lock, vcpu->cpu));
+	list_add_tail(&vmx->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_desc->sn, "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);
+
+	local_irq_restore(flags);
+}
+
+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) || 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 (kvm_vcpu_is_blocking(vcpu) && !vmx_interrupt_blocked(vcpu))
+		pi_enable_wakeup_handler(vcpu);
+
+	/*
+	 * Set SN when the vCPU is preempted.  Note, the vCPU can both be seen
+	 * as blocking and preempted, e.g. if it's preempted between setting
+	 * its wait state and manually scheduling out.
+	 */
+	if (vcpu->preempted)
+		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_vmx *vmx;
+
+	raw_spin_lock(spinlock);
+	list_for_each_entry(vmx, wakeup_list, pi_wakeup_list) {
+
+		if (pi_test_on(&vmx->pi_desc))
+			kvm_vcpu_wake_up(&vmx->vcpu);
+	}
+	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));
+}
+
+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 vmx_vcpu_pi_put().
+ */
+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);
+}
+
+/*
+ * 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)
+{
+	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(vcpu_to_pi_desc(vcpu));
+		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;
+}