Re: [PATCH] KVM: move DR register access handling into generic code.

Avi Kivity
2010-04-12T16:54:28Z

On 04/12/2010 07:52 PM, Gleb Natapov wrote:
> On Mon, Apr 12, 2010 at 06:09:50PM +0200, Jan Kiszka wrote:
>
>> Avi Kivity wrote:
>>
>>> On 04/12/2010 03:27 PM, Gleb Natapov wrote:
>>>
>>>> Currently both SVM and VMX have their own DR handling code. Move it to
>>>> x86.c.
>>>>
>>>>
>>>>
>>> The standard process is to make them identical first and finally merge
>>> identical code, but I guess we can skip it in this case (Jan?)
>>>
>> Looks OK, I would just...
>>
>>
>>> +int kvm_set_dr(struct kvm_vcpu *vcpu, int dr, unsigned long val)
>>> +{
>>> + switch (dr) {
>>> + case 0 ... 3:
>>> + vcpu->arch.db[dr] = val;
>>> + if (!(vcpu->guest_debug& KVM_GUESTDBG_USE_HW_BP))
>>> + vcpu->arch.eff_db[dr] = val;
>>> + break;
>>> + case 4:
>>> + if (kvm_read_cr4_bits(vcpu, X86_CR4_DE)) {
>>> + kvm_queue_exception(vcpu, UD_VECTOR);
>>> + return 1;
>>> + }
>>> + /* fall through */
>>> + case 6:
>>> + if (val& 0xffffffff00000000ULL) {
>>> + kvm_inject_gp(vcpu, 0);
>>> + return -1;
>>>
>> ...either return 1 or -1 on failure.
>>
>>
> This is a preparation for the future :) Exception injection will be
> moved outside the function so different return values are needed to
> distinguish different error conditions. Moving exception injection
> out is needed so emulator can call the function without it injecting
> exception behind emulators back.
>
>

Ugh, use symbolic names please. And I think that can be deferred for
that future patch.

--
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.