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

Sean Christopherson
2024-04-03T15:07:26Z

On Wed, Apr 03, 2024, Chao Gao wrote:
> On Mon, Feb 26, 2024 at 12:26:53AM -0800, isaku.yamahata@intel.com wrote:
> >+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;
> >+ case 0x4b564d00 ... 0x4b564dff:
> >+ /* KVM custom MSRs */
> >+ return tdx_is_emulated_kvm_msr(index, write);
> >+ default:
> >+ return false;
> >+ }
>
> The only call site with a non-Null KVM parameter is:
>
> r = static_call(kvm_x86_has_emulated_msr)(kvm, MSR_IA32_SMBASE);
>
> Only MSR_IA32_SMBASE needs to be handled. So, this function is much more
> complicated than it should be.

No, because it's also used by tdx_{g,s}et_msr().