Re: [PATCH v2 08/15] KVM: x86: Add Arch LBR MSRs to msrs_to_save_all list

Yang, Weijiang
2023-01-30T12:28:08Z

On 1/28/2023 5:43 AM, Sean Christopherson wrote:
> On Thu, Nov 24, 2022, Yang Weijiang wrote:
>> Arch LBR MSR_ARCH_LBR_DEPTH and MSR_ARCH_LBR_CTL are queried by
>> userspace application before it wants to {save|restore} the Arch LBR
>> data. Other LBR related data MSRs are omitted here intentionally due
>> to lengthy list(32*3). Userspace can still use KVM_{GET|SET}_MSRS to
>> access them if necessary.
> Absolutely not. "there are a lot of them" isn't sufficient justification. If
> the MSRs need to be migrated, then KVM needs to report them. If the expectation
> is that XSAVES will handle them, then KVM needs to take a dependency on XSAVES
> when enabling arch LBRs.

OK, will add the full MSR list.