Re: [PATCH 04/23] KVM: x86: Add IBPB_BRTYPE support

[Josh Poimboeuf]

On Fri, Aug 25, 2023 at 11:15:49AM -0700, Sean Christopherson wrote:
> On Fri, Aug 25, 2023, Josh Poimboeuf wrote:
> > Add support for the IBPB_BRTYPE CPUID flag, which indicates that IBPB
> > includes branch type prediction flushing.
> 
> Please add:
> 
>   Note, like SRSO_NO, advertise support for IBPB_BRTYPE even if it's not
>   enumerated by in the raw CPUID, i.e. bypass the cpuid_count() in
>   __kvm_cpu_cap_mask().  Some CPUs that gained support via a uCode patch
>   don't report IBPB_BRTYPE via CPUID (the kernel forces the flag).
> 
>   Opportunistically use kvm_cpu_cap_check_and_set() for SRSS_NO instead

"SRSO_NO"

>   of manually querying host support (cpu_feature_enabled() and
>   boot_cpu_has() yield the same end result in this case).

Sounds good.

> Feel free to take this through tip if this is urgent enough to go into 6.6,
> otherwise I'll grab it for 6.7.

Ingo grabbed all the patches except for the two KVM ones, so I think
he's expecting you to take them.

> Acked-by: Sean Christopherson <seanjc@xxxxxxxxxx>

Thanks!

-- 
Josh