Re: [PATCH] kvm: arm/arm64 : fix vm's hanging at startup time

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

 





On 15/11/18 10:22, peng.hao2@xxxxxxxxxx wrote:
Hi Peng,

On 15/11/18 15:14, Peng Hao wrote:
When virtual machine starts, hang up. The kernel version of guest
is 4.16. Host support vgic_v3.

I don't understand the issue here. the vgic_irq->group field does not
exist in 4.16 (neither in the first nor the last version). Nor does the
line you are modifying.
Guest's kernel version is 4.16 and Host's kernel version is mainline.
vgic_irq is a structure of Host's kvm.

Both exist in mainline, but what you are mentioning shouldn't be an
issue in mainline since vgic_irq->group gets initialized in
kvm_vgic_vcpu_init for SGIs and PPIs (i.e. intid < 32) which includes
your interrupt.
Initialization sequence of several components is like this;
1.       kvm_vgic_vcpu_init ---- here, dist is not initialized at this time.
                                              and the value of irq->group depends on
                                               dist->vgic_model. but now dist->vgic_model = 0
                                                and irq->group=0.
  2.      vgic_create         -----  assign to dist->vgic_model.
  3.     kvm_vgic_dist_init


I see, thanks for explaining.

This means the initialization in kvm_vgic_vcpu_init depends on whether userland creates the GIC device first or the vcpus first...

I don't think the issue lies in vgic_v3_populate_lr, but in kvm_vgic_vcpu_init which clearly expects dist->vgic_model to be initialized in two places. However, the comment at the top of vgic-init.c states:

* CPU Interface:


*


* - kvm_vgic_vcpu_init(): initialization of static data that


* doesn't depend on any sizing information or emulation type. No


 *   allocation is allowed there.

So I don't think we're supposed to check for dist->vgic_model here. Those two checks should probably be moved elsewhere (maybe in kvm_vgic_vcpu_enable?) once the gic type has been set.

Thanks,

thanks.

Cheers,

It was mainly due to the incorrect vgic_irq's(intid=27) group value
during injection interruption. when kvm_vgic_vcpu_init is called,
dist is not initialized at this time. Unable to get vgic V3 or V2
correctly, so group is not set.
group is setted to 1 when vgic_mmio_write_group is invoked at some
time.
when irq->group=0 (intid=27), No ICH_LR_GROUP flag was set and
interrupt injection failed.

Signed-off-by: Peng Hao <peng.hao2@xxxxxxxxxx>
---
   virt/kvm/arm/vgic/vgic-v3.c | 2 +-
   1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/virt/kvm/arm/vgic/vgic-v3.c b/virt/kvm/arm/vgic/vgic-v3.c
index 9c0dd23..d101000 100644
--- a/virt/kvm/arm/vgic/vgic-v3.c
+++ b/virt/kvm/arm/vgic/vgic-v3.c
@@ -198,7 +198,7 @@ void vgic_v3_populate_lr(struct kvm_vcpu *vcpu, struct vgic_irq *irq, int lr)
       if (vgic_irq_is_mapped_level(irq) && (val & ICH_LR_PENDING_BIT))
           irq->line_level = false;

-    if (irq->group)
+    if (model == KVM_DEV_TYPE_ARM_VGIC_V3)
           val |= ICH_LR_GROUP;

       val |= (u64)irq->priority << ICH_LR_PRIORITY_SHIFT;


--
Julien Thierry

--
Julien Thierry
_______________________________________________
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