Re: [PATCH v19 111/130] KVM: TDX: Implement callbacks for MSR operations for TDX

Binbin Wu
2024-04-18T13:36:41Z

On 4/5/2024 7:42 AM, Isaku Yamahata wrote:
> On Wed, Apr 03, 2024 at 08:14:04AM -0700,
> Sean Christopherson <seanjc@google.com> wrote:
>
>> On Mon, Feb 26, 2024, isaku.yamahata@intel.com wrote:
>>> diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c
>>> index 389bb95d2af0..c8f991b69720 100644
>>> --- a/arch/x86/kvm/vmx/tdx.c
>>> +++ b/arch/x86/kvm/vmx/tdx.c
>>> @@ -1877,6 +1877,76 @@ void tdx_get_exit_info(struct kvm_vcpu *vcpu, u32 *reason,
>>> *error_code = 0;
>>> }
>>>
>>> +static bool tdx_is_emulated_kvm_msr(u32 index, bool write)
>>> +{
>>> + switch (index) {
>>> + case MSR_KVM_POLL_CONTROL:
>>> + return true;
>>> + default:
>>> + return false;
>>> + }
>>> +}
>>> +
>>> +bool tdx_has_emulated_msr(u32 index, bool write)
>>> +{
>>> + switch (index) {
>>> + case MSR_IA32_UCODE_REV:
>>> + case MSR_IA32_ARCH_CAPABILITIES:
>>> + case MSR_IA32_POWER_CTL:
>>> + case MSR_IA32_CR_PAT:
>>> + case MSR_IA32_TSC_DEADLINE:
>>> + case MSR_IA32_MISC_ENABLE:
>>> + case MSR_PLATFORM_INFO:
>>> + case MSR_MISC_FEATURES_ENABLES:
>>> + case MSR_IA32_MCG_CAP:
>>> + case MSR_IA32_MCG_STATUS:
>>> + case MSR_IA32_MCG_CTL:
>>> + case MSR_IA32_MCG_EXT_CTL:
>>> + case MSR_IA32_MC0_CTL ... MSR_IA32_MCx_CTL(KVM_MAX_MCE_BANKS) - 1:
>>> + case MSR_IA32_MC0_CTL2 ... MSR_IA32_MCx_CTL2(KVM_MAX_MCE_BANKS) - 1:
>>> + /* MSR_IA32_MCx_{CTL, STATUS, ADDR, MISC, CTL2} */
>>> + return true;
>>> + case APIC_BASE_MSR ... APIC_BASE_MSR + 0xff:
>>> + /*
>>> + * x2APIC registers that are virtualized by the CPU can't be
>>> + * emulated, KVM doesn't have access to the virtual APIC page.
>>> + */
>>> + switch (index) {
>>> + case X2APIC_MSR(APIC_TASKPRI):
>>> + case X2APIC_MSR(APIC_PROCPRI):
>>> + case X2APIC_MSR(APIC_EOI):
>>> + case X2APIC_MSR(APIC_ISR) ... X2APIC_MSR(APIC_ISR + APIC_ISR_NR):
>>> + case X2APIC_MSR(APIC_TMR) ... X2APIC_MSR(APIC_TMR + APIC_ISR_NR):
>>> + case X2APIC_MSR(APIC_IRR) ... X2APIC_MSR(APIC_IRR + APIC_ISR_NR):
>>> + return false;
>>> + default:
>>> + return true;
>>> + }
>>> + case MSR_IA32_APICBASE:
>>> + case MSR_EFER:
>>> + return !write;
>> Meh, for literally two MSRs, just open code them in tdx_set_msr() and drop the
>> @write param. Or alternatively add:
>>
>> static bool tdx_is_read_only_msr(u32 msr){
>> {
>> return msr == MSR_IA32_APICBASE || msr == MSR_EFER;
>> }
> Sure will add.
>
>>> + case 0x4b564d00 ... 0x4b564dff:
>> This is silly, just do
>>
>> case MSR_KVM_POLL_CONTROL:
>> return false;

Shoud return true here, right?
>>
>> and let everything else go through the default statement, no?
> Now tdx_is_emulated_kvm_msr() is trivial, will open code it.
>
>
>>> + /* KVM custom MSRs */
>>> + return tdx_is_emulated_kvm_msr(index, write);
>>> + default:
>>> + return false;
>>> + }
>>> +}
>>> +
>>>