Re: [PATCH 2/5] KVM: New guest debug interface

[Jan Kiszka <jan.kiszka@siemens.com>]

Avi Kivity wrote:
> Jan Kiszka wrote:
>> This rips out the support for KVM_DEBUG_GUEST and introduces a new IOCTL
>> instead: KVM_SET_GUEST_DEBUG. The IOCTL payload consists of a generic
>> part, controlling the "main switch" and the single-step feature. The
>> arch specific part adds an x86 interface for intercepting both types of
>> debug exceptions separately and re-injecting them when the host was not
>> interested. Moveover, the foundation for guest debugging via debug
>> registers is layed.
>>   
> 
> Have you tested compile-time compatibility with older userspace?

Yes, works.

> 
>> Note that both SVM and VTX are supported, but only the latter was tested
>> yet. Based on the experience with all those VTX corner case, I would be
>> fairly surprised if SVM will work out of the box.
>>
>>   
> 
> I'd like svm to work before applying.

To validate the design?

I will see if I can organize an SVM box, but I can't promise when I'll
be able to do the testing. Anyone willing to contribute time on this
would be warmly welcome!

> 
>> @@ -439,7 +437,8 @@ struct kvm_trace_rec {
>>  #define KVM_SET_SREGS             _IOW(KVMIO,  0x84, struct kvm_sregs)
>>  #define KVM_TRANSLATE             _IOWR(KVMIO, 0x85, struct
>> kvm_translation)
>>  #define KVM_INTERRUPT             _IOW(KVMIO,  0x86, struct
>> kvm_interrupt)
>> -#define KVM_DEBUG_GUEST           _IOW(KVMIO,  0x87, struct
>> kvm_debug_guest)
>> +/* KVM_DEBUG_GUEST is no longer supported, use KVM_SET_GUEST_DEBUG
>> instead */
>> +#define KVM_DEBUG_GUEST           __KVM_DEPRECATED_DEBUG_GUEST
>>  #define KVM_GET_MSRS              _IOWR(KVMIO, 0x88, struct kvm_msrs)
>>  #define KVM_SET_MSRS              _IOW(KVMIO,  0x89, struct kvm_msrs)
>>  #define KVM_SET_CPUID             _IOW(KVMIO,  0x8a, struct kvm_cpuid)
>> @@ -468,6 +467,26 @@ struct kvm_trace_rec {
>>  #define KVM_SET_MP_STATE          _IOW(KVMIO,  0x99, struct
>> kvm_mp_state)
>>  /* Available with KVM_CAP_NMI */
>>  #define KVM_NMI                   _IO(KVMIO,  0x9a)
>> +/* Available with KVM_CAP_SET_GUEST_DEBUG */
>> +#define KVM_SET_GUEST_DEBUG       _IOW(KVMIO,  0x9a, struct
>> kvm_guest_debug)
>> +
>>   
> 
> 0x9b...

Oh, rebased a bit too often.

Jan

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