Re: [PATCH] KVM: arm64: vgic-v4: Move the GICv4 residency flow to be driven by vcpu_load/put

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



Hi Marc,

I've run this patch on my box and got the following messages:

---8<

[ 2258.490030] BUG: sleeping function called from invalid context at kernel/irq/manage.c:138 [ 2258.490034] in_atomic(): 1, irqs_disabled(): 0, pid: 59278, name: CPU 0/KVM [ 2258.490039] CPU: 32 PID: 59278 Comm: CPU 0/KVM Kdump: loaded Tainted: G W 5.3.0+ #26 [ 2258.490041] Hardware name: Huawei TaiShan 2280 /BC11SPCD, BIOS 1.58 10/29/2018
[ 2258.490043] Call trace:
[ 2258.490056]  dump_backtrace+0x0/0x188
[ 2258.490060]  show_stack+0x24/0x30
[ 2258.490066]  dump_stack+0xb0/0xf4
[ 2258.490072]  ___might_sleep+0x10c/0x130
[ 2258.490074]  __might_sleep+0x58/0x90
[ 2258.490078]  synchronize_irq+0x58/0xd8
[ 2258.490079]  disable_irq+0x2c/0x38
[ 2258.490083]  vgic_v4_load+0x9c/0xc0
[ 2258.490084]  vgic_v3_load+0x94/0x170
[ 2258.490088]  kvm_vgic_load+0x3c/0x60
[ 2258.490092]  kvm_arch_vcpu_load+0xd4/0x1d0
[ 2258.490095]  vcpu_load+0x50/0x70
[ 2258.490097]  kvm_arch_vcpu_ioctl_run+0x94/0x978
[ 2258.490098]  kvm_vcpu_ioctl+0x3d8/0xa28
[ 2258.490104]  do_vfs_ioctl+0xc4/0x8e8
[ 2258.490106]  ksys_ioctl+0x8c/0xa0
[ 2258.490108]  __arm64_sys_ioctl+0x28/0x58
[ 2258.490112]  el0_svc_common.constprop.0+0x7c/0x188
[ 2258.490114]  el0_svc_handler+0x34/0xb8
[ 2258.490117]  el0_svc+0x8/0xc
[ 2259.497070] BUG: sleeping function called from invalid context at kernel/irq/manage.c:138 [ 2259.497077] in_atomic(): 1, irqs_disabled(): 0, pid: 59278, name: CPU 0/KVM [ 2259.497082] CPU: 33 PID: 59278 Comm: CPU 0/KVM Kdump: loaded Tainted: G W 5.3.0+ #26 [ 2259.497083] Hardware name: Huawei TaiShan 2280 /BC11SPCD, BIOS 1.58 10/29/2018
[ 2259.497086] Call trace:
[ 2259.497098]  dump_backtrace+0x0/0x188
[ 2259.497101]  show_stack+0x24/0x30
[ 2259.497109]  dump_stack+0xb0/0xf4
[ 2259.497115]  ___might_sleep+0x10c/0x130
[ 2259.497117]  __might_sleep+0x58/0x90
[ 2259.497120]  synchronize_irq+0x58/0xd8
[ 2259.497122]  disable_irq+0x2c/0x38
[ 2259.497126]  vgic_v4_load+0x9c/0xc0
[ 2259.497127]  vgic_v3_load+0x94/0x170
[ 2259.497130]  kvm_vgic_load+0x3c/0x60
[ 2259.497134]  kvm_arch_vcpu_load+0xd4/0x1d0
[ 2259.497137]  kvm_sched_in+0x30/0x40
[ 2259.497139]  finish_task_switch+0x134/0x258
[ 2259.497142]  __schedule+0x33c/0x780
[ 2259.497144]  schedule+0x48/0xd8
[ 2259.497147]  kvm_vcpu_block+0xb8/0x390
[ 2259.497148]  kvm_handle_wfx+0xa0/0x230
[ 2259.497150]  handle_exit+0x14c/0x1c8
[ 2259.497152]  kvm_arch_vcpu_ioctl_run+0x354/0x978
[ 2259.497154]  kvm_vcpu_ioctl+0x3d8/0xa28
[ 2259.497161]  do_vfs_ioctl+0xc4/0x8e8
[ 2259.497163]  ksys_ioctl+0x8c/0xa0
[ 2259.497165]  __arm64_sys_ioctl+0x28/0x58
[ 2259.497168]  el0_svc_common.constprop.0+0x7c/0x188
[ 2259.497171]  el0_svc_handler+0x34/0xb8
[ 2259.497175]  el0_svc+0x8/0xc


The logic of disabling the doorbell interrupt in vgic_v4_load() might
need a fix?


Thanks,
zenghui

On 2019/9/3 23:57, Marc Zyngier wrote:
When the VHE code was reworked, a lot of the vgic stuff was moved around,
but the GICv4 residency code did stay untouched, meaning that we come
in and out of residency on each flush/sync, which is obviously suboptimal.

To address this, let's move things around a bit:

- Residency entry (flush) moves to vcpu_load
- Residency exit (sync) moves to vcpu_put
- On blocking (entry to WFI), we "put"
- On unblocking (exit from WFI, we "load"

Because these can nest (load/block/put/load/unblock/put, for example),
we now have per-VPE tracking of the residency state.

Additionally, vgic_v4_put gains a "need doorbell" parameter, which only
gets set to true when blocking because of a WFI. This allows a finer
control of the doorbell, which now also gets disabled as soon as
it gets signaled.

Signed-off-by: Marc Zyngier <maz@xxxxxxxxxx>
---
  drivers/irqchip/irq-gic-v4.c       |  7 +++-
  include/kvm/arm_vgic.h             |  4 +--
  include/linux/irqchip/arm-gic-v4.h |  2 ++
  virt/kvm/arm/arm.c                 | 12 ++++---
  virt/kvm/arm/vgic/vgic-v3.c        |  4 +++
  virt/kvm/arm/vgic/vgic-v4.c        | 55 ++++++++++++++----------------
  virt/kvm/arm/vgic/vgic.c           |  4 ---
  virt/kvm/arm/vgic/vgic.h           |  2 --
  8 files changed, 48 insertions(+), 42 deletions(-)

diff --git a/drivers/irqchip/irq-gic-v4.c b/drivers/irqchip/irq-gic-v4.c
index 563e87ed0766..45969927cc81 100644
--- a/drivers/irqchip/irq-gic-v4.c
+++ b/drivers/irqchip/irq-gic-v4.c
@@ -141,12 +141,17 @@ static int its_send_vpe_cmd(struct its_vpe *vpe, struct its_cmd_info *info)
  int its_schedule_vpe(struct its_vpe *vpe, bool on)
  {
  	struct its_cmd_info info;
+	int ret;
WARN_ON(preemptible()); info.cmd_type = on ? SCHEDULE_VPE : DESCHEDULE_VPE; - return its_send_vpe_cmd(vpe, &info);
+	ret = its_send_vpe_cmd(vpe, &info);
+	if (!ret)
+		vpe->resident = on;
+
+	return ret;
  }
int its_invall_vpe(struct its_vpe *vpe)
diff --git a/include/kvm/arm_vgic.h b/include/kvm/arm_vgic.h
index af4f09c02bf1..4dc58d7a0010 100644
--- a/include/kvm/arm_vgic.h
+++ b/include/kvm/arm_vgic.h
@@ -396,7 +396,7 @@ int kvm_vgic_v4_set_forwarding(struct kvm *kvm, int irq,
  int kvm_vgic_v4_unset_forwarding(struct kvm *kvm, int irq,
  				 struct kvm_kernel_irq_routing_entry *irq_entry);
-void kvm_vgic_v4_enable_doorbell(struct kvm_vcpu *vcpu);
-void kvm_vgic_v4_disable_doorbell(struct kvm_vcpu *vcpu);
+int vgic_v4_load(struct kvm_vcpu *vcpu);
+int vgic_v4_put(struct kvm_vcpu *vcpu, bool need_db);
#endif /* __KVM_ARM_VGIC_H */
diff --git a/include/linux/irqchip/arm-gic-v4.h b/include/linux/irqchip/arm-gic-v4.h
index e6b155713b47..ab1396afe08a 100644
--- a/include/linux/irqchip/arm-gic-v4.h
+++ b/include/linux/irqchip/arm-gic-v4.h
@@ -35,6 +35,8 @@ struct its_vpe {
  	/* Doorbell interrupt */
  	int			irq;
  	irq_hw_number_t		vpe_db_lpi;
+	/* VPE resident */
+	bool			resident;
  	/* VPE proxy mapping */
  	int			vpe_proxy_event;
  	/*
diff --git a/virt/kvm/arm/arm.c b/virt/kvm/arm/arm.c
index 35a069815baf..4e69268621b6 100644
--- a/virt/kvm/arm/arm.c
+++ b/virt/kvm/arm/arm.c
@@ -321,20 +321,24 @@ void kvm_arch_vcpu_blocking(struct kvm_vcpu *vcpu)
  	/*
  	 * If we're about to block (most likely because we've just hit a
  	 * WFI), we need to sync back the state of the GIC CPU interface
-	 * so that we have the lastest PMR and group enables. This ensures
+	 * so that we have the latest PMR and group enables. This ensures
  	 * that kvm_arch_vcpu_runnable has up-to-date data to decide
  	 * whether we have pending interrupts.
+	 *
+	 * For the same reason, we want to tell GICv4 that we need
+	 * doorbells to be signalled, should an interrupt become pending.
  	 */
  	preempt_disable();
  	kvm_vgic_vmcr_sync(vcpu);
+	vgic_v4_put(vcpu, true);
  	preempt_enable();
-
-	kvm_vgic_v4_enable_doorbell(vcpu);
  }
void kvm_arch_vcpu_unblocking(struct kvm_vcpu *vcpu)
  {
-	kvm_vgic_v4_disable_doorbell(vcpu);
+	preempt_disable();
+	vgic_v4_load(vcpu);
+	preempt_enable();
  }
int kvm_arch_vcpu_init(struct kvm_vcpu *vcpu)
diff --git a/virt/kvm/arm/vgic/vgic-v3.c b/virt/kvm/arm/vgic/vgic-v3.c
index 8d69f007dd0c..48307a9eb1d8 100644
--- a/virt/kvm/arm/vgic/vgic-v3.c
+++ b/virt/kvm/arm/vgic/vgic-v3.c
@@ -664,6 +664,8 @@ void vgic_v3_load(struct kvm_vcpu *vcpu)
if (has_vhe())
  		__vgic_v3_activate_traps(vcpu);
+
+	WARN_ON(vgic_v4_load(vcpu));
  }
void vgic_v3_vmcr_sync(struct kvm_vcpu *vcpu)
@@ -676,6 +678,8 @@ void vgic_v3_vmcr_sync(struct kvm_vcpu *vcpu)
void vgic_v3_put(struct kvm_vcpu *vcpu)
  {
+	WARN_ON(vgic_v4_put(vcpu, false));
+
  	vgic_v3_vmcr_sync(vcpu);
kvm_call_hyp(__vgic_v3_save_aprs, vcpu);
diff --git a/virt/kvm/arm/vgic/vgic-v4.c b/virt/kvm/arm/vgic/vgic-v4.c
index 477af6aebb97..3a8a28854b13 100644
--- a/virt/kvm/arm/vgic/vgic-v4.c
+++ b/virt/kvm/arm/vgic/vgic-v4.c
@@ -85,6 +85,10 @@ static irqreturn_t vgic_v4_doorbell_handler(int irq, void *info)
  {
  	struct kvm_vcpu *vcpu = info;
+ /* We got the message, no need to fire again */
+	if (!irqd_irq_disabled(&irq_to_desc(irq)->irq_data))
+		disable_irq_nosync(irq);
+
  	vcpu->arch.vgic_cpu.vgic_v3.its_vpe.pending_last = true;
  	kvm_make_request(KVM_REQ_IRQ_PENDING, vcpu);
  	kvm_vcpu_kick(vcpu);
@@ -192,20 +196,30 @@ void vgic_v4_teardown(struct kvm *kvm)
  	its_vm->vpes = NULL;
  }
-int vgic_v4_sync_hwstate(struct kvm_vcpu *vcpu)
+int vgic_v4_put(struct kvm_vcpu *vcpu, bool need_db)
  {
-	if (!vgic_supports_direct_msis(vcpu->kvm))
+	struct its_vpe *vpe = &vcpu->arch.vgic_cpu.vgic_v3.its_vpe;
+	struct irq_desc *desc = irq_to_desc(vpe->irq);
+
+	if (!vgic_supports_direct_msis(vcpu->kvm) || !vpe->resident)
  		return 0;
- return its_schedule_vpe(&vcpu->arch.vgic_cpu.vgic_v3.its_vpe, false);
+	/*
+	 * If blocking, a doorbell is required. Undo the nested
+	 * disable_irq() calls...
+	 */
+	while (need_db && irqd_irq_disabled(&desc->irq_data))
+		enable_irq(vpe->irq);
+
+	return its_schedule_vpe(vpe, false);
  }
-int vgic_v4_flush_hwstate(struct kvm_vcpu *vcpu)
+int vgic_v4_load(struct kvm_vcpu *vcpu)
  {
-	int irq = vcpu->arch.vgic_cpu.vgic_v3.its_vpe.irq;
+	struct its_vpe *vpe = &vcpu->arch.vgic_cpu.vgic_v3.its_vpe;
  	int err;
- if (!vgic_supports_direct_msis(vcpu->kvm))
+	if (!vgic_supports_direct_msis(vcpu->kvm) || vpe->resident)
  		return 0;
/*
@@ -214,11 +228,14 @@ int vgic_v4_flush_hwstate(struct kvm_vcpu *vcpu)
  	 * doc in drivers/irqchip/irq-gic-v4.c to understand how this
  	 * turns into a VMOVP command at the ITS level.
  	 */
-	err = irq_set_affinity(irq, cpumask_of(smp_processor_id()));
+	err = irq_set_affinity(vpe->irq, cpumask_of(smp_processor_id()));
  	if (err)
  		return err;
- err = its_schedule_vpe(&vcpu->arch.vgic_cpu.vgic_v3.its_vpe, true);
+	/* Disabled the doorbell, as we're about to enter the guest */
+	disable_irq(vpe->irq);
+
+	err = its_schedule_vpe(vpe, true);
  	if (err)
  		return err;
@@ -226,9 +243,7 @@ int vgic_v4_flush_hwstate(struct kvm_vcpu *vcpu)
  	 * Now that the VPE is resident, let's get rid of a potential
  	 * doorbell interrupt that would still be pending.
  	 */
-	err = irq_set_irqchip_state(irq, IRQCHIP_STATE_PENDING, false);
-
-	return err;
+	return irq_set_irqchip_state(vpe->irq, IRQCHIP_STATE_PENDING, false);
  }
static struct vgic_its *vgic_get_its(struct kvm *kvm,
@@ -335,21 +350,3 @@ int kvm_vgic_v4_unset_forwarding(struct kvm *kvm, int virq,
  	mutex_unlock(&its->its_lock);
  	return ret;
  }
-
-void kvm_vgic_v4_enable_doorbell(struct kvm_vcpu *vcpu)
-{
-	if (vgic_supports_direct_msis(vcpu->kvm)) {
-		int irq = vcpu->arch.vgic_cpu.vgic_v3.its_vpe.irq;
-		if (irq)
-			enable_irq(irq);
-	}
-}
-
-void kvm_vgic_v4_disable_doorbell(struct kvm_vcpu *vcpu)
-{
-	if (vgic_supports_direct_msis(vcpu->kvm)) {
-		int irq = vcpu->arch.vgic_cpu.vgic_v3.its_vpe.irq;
-		if (irq)
-			disable_irq(irq);
-	}
-}
diff --git a/virt/kvm/arm/vgic/vgic.c b/virt/kvm/arm/vgic/vgic.c
index 45a870cb63f5..99b02ca730a8 100644
--- a/virt/kvm/arm/vgic/vgic.c
+++ b/virt/kvm/arm/vgic/vgic.c
@@ -857,8 +857,6 @@ void kvm_vgic_sync_hwstate(struct kvm_vcpu *vcpu)
  {
  	struct vgic_cpu *vgic_cpu = &vcpu->arch.vgic_cpu;
- WARN_ON(vgic_v4_sync_hwstate(vcpu));
-
  	/* An empty ap_list_head implies used_lrs == 0 */
  	if (list_empty(&vcpu->arch.vgic_cpu.ap_list_head))
  		return;
@@ -882,8 +880,6 @@ static inline void vgic_restore_state(struct kvm_vcpu *vcpu)
  /* Flush our emulation state into the GIC hardware before entering the guest. */
  void kvm_vgic_flush_hwstate(struct kvm_vcpu *vcpu)
  {
-	WARN_ON(vgic_v4_flush_hwstate(vcpu));
-
  	/*
  	 * If there are no virtual interrupts active or pending for this
  	 * VCPU, then there is no work to do and we can bail out without
diff --git a/virt/kvm/arm/vgic/vgic.h b/virt/kvm/arm/vgic/vgic.h
index 83066a81b16a..c7fefd6b1c80 100644
--- a/virt/kvm/arm/vgic/vgic.h
+++ b/virt/kvm/arm/vgic/vgic.h
@@ -316,7 +316,5 @@ void vgic_its_invalidate_cache(struct kvm *kvm);
  bool vgic_supports_direct_msis(struct kvm *kvm);
  int vgic_v4_init(struct kvm *kvm);
  void vgic_v4_teardown(struct kvm *kvm);
-int vgic_v4_sync_hwstate(struct kvm_vcpu *vcpu);
-int vgic_v4_flush_hwstate(struct kvm_vcpu *vcpu);
#endif


_______________________________________________
kvmarm mailing list
kvmarm@xxxxxxxxxxxxxxxxxxxxx
https://lists.cs.columbia.edu/mailman/listinfo/kvmarm



[Index of Archives]     [Linux KVM]     [Spice Development]     [Libvirt]     [Libvirt Users]     [Linux USB Devel]     [Linux Audio Users]     [Yosemite News]     [Linux Kernel]     [Linux SCSI]

  Powered by Linux