Re: [PATCH v2 02/11] KVM: SVM: Don't BUG if userspace injects a soft interrupt with GIF=0

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

 



On 28.04.2022 17:04, Sean Christopherson wrote:
On Thu, Apr 28, 2022, Maxim Levitsky wrote:
On Thu, 2022-04-28 at 15:27 +0200, Maciej S. Szmigiero wrote:
On 28.04.2022 09:35, Maxim Levitsky wrote:
On Sat, 2022-04-23 at 02:14 +0000, Sean Christopherson wrote:
From: Maciej S. Szmigiero <maciej.szmigiero@xxxxxxxxxx>

Don't BUG/WARN on interrupt injection due to GIF being cleared if the
injected event is a soft interrupt, which are not actually IRQs and thus

Are any injected events subject to GIF set? I think that EVENTINJ just injects
unconditionaly whatever hypervisor puts in it.

That's right, EVENTINJ will pretty much always inject, even when the CPU
is in a 'wrong' state (like for example, injecting a hardware interrupt
or a NMI with GIF masked).

But KVM as a L0 is not supposed to inject a hardware interrupt into guest
with GIF unset since the guest is obviously not expecting it then.
Hence this WARN_ON().

If you mean L0->L1 injection, that sure, but if L1 injects interrupt to L2,
then it should always be allowed to do so.

Yes, L1 can inject whatever it wants, whenever it wants.

I kept the WARN_ON() under the assumption that KVM would refuse to inject IRQs
stuffed by userspace if GIF is disabled, but looking at the code again, I have
no idea why I thought that.  KVM_SET_VCPU_EVENTS blindly takes whatever userspace
provides, I don't see anything that would prevent userspace from shoving in a
hardware IRQ.

You both are right, while KVM itself would not inject IRQ with GIF masked and
a nested VMRUN would enable GIF unconditionally, userspace via KVM_SET_VCPU_EVENTS
does not have this restriction.

Will remove this WARN_ON() then.

Thanks,
Maciej



[Index of Archives]     [KVM ARM]     [KVM ia64]     [KVM ppc]     [Virtualization Tools]     [Spice Development]     [Libvirt]     [Libvirt Users]     [Linux USB Devel]     [Linux Audio Users]     [Yosemite Questions]     [Linux Kernel]     [Linux SCSI]     [XFree86]

  Powered by Linux