Re: [PATCH 3/3] KVM: x86/pmu: Segregate Intel and AMD specific logic

Ravi Bangoria
2022-03-03T16:25:45Z

On 03-Mar-22 10:08 AM, Jim Mattson wrote:
> On Mon, Feb 21, 2022 at 2:02 AM Ravi Bangoria <ravi.bangoria@amd.com> wrote:
>>
>>
>>
>> On 21-Feb-22 1:27 PM, Like Xu wrote:
>>> On 21/2/2022 3:31 pm, Ravi Bangoria wrote:
>>>> void reprogram_counter(struct kvm_pmu *pmu, int pmc_idx)
>>>> {
>>>> struct kvm_pmc *pmc = kvm_x86_ops.pmu_ops->pmc_idx_to_pmc(pmu, pmc_idx);
>>>> + bool is_intel = !strncmp(kvm_x86_ops.name, "kvm_intel", 9);
>>>
>>> How about using guest_cpuid_is_intel(vcpu)
>>
>> Yeah, that's better then strncmp().
>>
>>> directly in the reprogram_gp_counter() ?
>>
>> We need this flag in reprogram_fixed_counter() as well.
>
> Explicit "is_intel" checks in any form seem clumsy,

Indeed. However introducing arch specific callback for such tiny
logic seemed overkill to me. So thought to just do it this way.

> since we have
> already put some effort into abstracting away the implementation
> differences in struct kvm_pmu. It seems like these differences could
> be handled by adding three masks to that structure: the "raw event
> mask" (i.e. event selector and unit mask), the hsw_in_tx mask, and the
> hsw_in_tx_checkpointed mask.

struct kvm_pmu is arch independent. You mean struct kvm_pmu_ops?

>
> These changes should also be coordinated with Like's series that
> eliminates all of the PERF_TYPE_HARDWARE nonsense.

I'll rebase this on Like's patch series.

Thanks,
Ravi