Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]

Groups > linux.kernel > #1314994

Re: [PATCH v3 2/4] KVM: x86: Use vector-hashing to deliver lowest-priority interrupts

Show all headers | View raw

2016-01-22 12:00+0800, Yang Zhang:
> On 2016/1/22 1:21, rkrcmar@redhat.com wrote:
>>(I think there isn't a practical difference between *r=-1 and *r=0.)
> 
> Currently, if *r == -1, the remote_irr may get set. But it seems wrong. I

Yeah ...

> need to have a double check to see whether it is a bug in current code.

Looking forward to the patch!

Thanks.

>>'ret = true' is the better one.  We know that the interrupt is not
>>deliverable [1], so there's no point in trying to deliver with the slow
>>path.  We behave similarly when the interrupt targets a single disabled
>>APIC.
>>
>>---
>>1: Well ... it's possible that slowpath would deliver it thanks to
>>    different handling of disabled APICs, but it's undefined behavior,
> 
> why it is undefined behavior? Besides, why we will keep two different
> handling logic for the fast path and slow path? It looks weird.

It does look very weird ... the slow path would require refactoring,
though, so we save effort without a considerable drawback.
(I would love if it behaved identically, but I don't want to force it on
 someone and likely won't do it myself ...)

I consider it undefined because SMD says that an OS musn't configure
this behavior and doesn't say what should happen if the OS does => we
could do anything.  (Killing the guest would be great for debugging OS
issues, but ours behavior is fairly conservative.)

Back to linux.kernel | Previous | Next — Previous in thread | Next in thread | Find similar | Unroll thread

Thread

[PATCH v3 0/4] VT-d posted-interrupts follow ups Feng Wu <feng.wu@intel.com> - 2016-01-20 03:10 +0100
  [PATCH v3 4/4] KVM/VMX: Add host irq information in trace event when updating IRTE for posted interrupts Feng Wu <feng.wu@intel.com> - 2016-01-20 03:10 +0100
    Re: [PATCH v3 4/4] KVM/VMX: Add host irq information in trace event  when updating IRTE for posted interrupts Radim Krčmář <rkrcmar@redhat.com> - 2016-01-21 21:20 +0100
  [PATCH v3 2/4] KVM: x86: Use vector-hashing to deliver lowest-priority interrupts Feng Wu <feng.wu@intel.com> - 2016-01-20 03:10 +0100
    Re: [PATCH v3 2/4] KVM: x86: Use vector-hashing to deliver  lowest-priority interrupts Yang Zhang <yang.zhang.wz@gmail.com> - 2016-01-21 06:30 +0100
      RE: [PATCH v3 2/4] KVM: x86: Use vector-hashing to deliver  lowest-priority interrupts "Wu, Feng" <feng.wu@intel.com> - 2016-01-21 06:40 +0100
        RE: [PATCH v3 2/4] KVM: x86: Use vector-hashing to deliver  lowest-priority interrupts "Wu, Feng" <feng.wu@intel.com> - 2016-01-21 06:50 +0100
          Re: [PATCH v3 2/4] KVM: x86: Use vector-hashing to deliver  lowest-priority interrupts Yang Zhang <yang.zhang.wz@gmail.com> - 2016-01-21 07:00 +0100
            Re: [PATCH v3 2/4] KVM: x86: Use vector-hashing to deliver  lowest-priority interrupts Yang Zhang <yang.zhang.wz@gmail.com> - 2016-01-21 07:10 +0100
            RE: [PATCH v3 2/4] KVM: x86: Use vector-hashing to deliver  lowest-priority interrupts "Wu, Feng" <feng.wu@intel.com> - 2016-01-21 07:10 +0100
        Re: [PATCH v3 2/4] KVM: x86: Use vector-hashing to deliver  lowest-priority interrupts Yang Zhang <yang.zhang.wz@gmail.com> - 2016-01-21 06:50 +0100
        Re: [PATCH v3 2/4] KVM: x86: Use vector-hashing to deliver  lowest-priority interrupts "rkrcmar@redhat.com" <rkrcmar@redhat.com> - 2016-01-21 18:30 +0100
          RE: [PATCH v3 2/4] KVM: x86: Use vector-hashing to deliver  lowest-priority interrupts "Wu, Feng" <feng.wu@intel.com> - 2016-01-22 03:10 +0100
          Re: [PATCH v3 2/4] KVM: x86: Use vector-hashing to deliver  lowest-priority interrupts Yang Zhang <yang.zhang.wz@gmail.com> - 2016-01-22 05:10 +0100
            Re: [PATCH v3 2/4] KVM: x86: Use vector-hashing to deliver  lowest-priority interrupts "rkrcmar@redhat.com" <rkrcmar@redhat.com> - 2016-01-22 14:50 +0100
    Re: [PATCH v3 2/4] KVM: x86: Use vector-hashing to deliver  lowest-priority interrupts Radim Krčmář <rkrcmar@redhat.com> - 2016-01-21 21:00 +0100
      RE: [PATCH v3 2/4] KVM: x86: Use vector-hashing to deliver  lowest-priority interrupts "Wu, Feng" <feng.wu@intel.com> - 2016-01-22 06:20 +0100
        Re: [PATCH v3 2/4] KVM: x86: Use vector-hashing to deliver  lowest-priority interrupts Radim Krcmár <rkrcmar@redhat.com> - 2016-01-22 15:10 +0100
          Re: [PATCH v3 2/4] KVM: x86: Use vector-hashing to deliver  lowest-priority interrupts Paolo Bonzini <pbonzini@redhat.com> - 2016-01-25 13:30 +0100
            Re: [PATCH v3 2/4] KVM: x86: Use vector-hashing to deliver  lowest-priority interrupts Radim Krcmár <rkrcmar@redhat.com> - 2016-01-25 16:30 +0100
              Re: [PATCH v3 2/4] KVM: x86: Use vector-hashing to deliver  lowest-priority interrupts Paolo Bonzini <pbonzini@redhat.com> - 2016-01-25 17:20 +0100
                RE: [PATCH v3 2/4] KVM: x86: Use vector-hashing to deliver  lowest-priority interrupts "Wu, Feng" <feng.wu@intel.com> - 2016-01-26 02:20 +0100

csiph-web