Re: [PATCH v10 098/108] KVM: TDX: Implement callbacks for MSR operations for TDX

Isaku Yamahata
2022-12-16T01:40:00Z

On Wed, Dec 14, 2022 at 11:22:02AM +0000,
"Huang, Kai" <kai.huang@intel.com> wrote:

> On Sat, 2022-10-29 at 23:23 -0700, isaku.yamahata@intel.com wrote:
> > +bool tdx_is_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_MTRRcap:
> > + case 0x200 ... 0x26f:
> > + /* IA32_MTRR_PHYS{BASE, MASK}, IA32_MTRR_FIX*_* */
> > + case MSR_IA32_CR_PAT:
> > + case MSR_MTRRdefType:
> > + case MSR_IA32_TSC_DEADLINE:
> > + case MSR_IA32_MISC_ENABLE:
> > + case MSR_KVM_STEAL_TIME:
> > + case MSR_KVM_POLL_CONTROL:
>
> To me putting KVM para-virt MSRs and hardware MSRs together isn't good idea.
> You can introduce separate helpers for them.

Makes sense. updated as follows.

diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c
index ee8d395af849..b4132167e2bb 100644
--- a/arch/x86/kvm/vmx/tdx.c
+++ b/arch/x86/kvm/vmx/tdx.c
@@ -1606,6 +1606,17 @@ 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_STEAL_TIME:
+ case MSR_KVM_POLL_CONTROL:
+ return true;
+ default:
+ return false;
+ }
+}
+
bool tdx_is_emulated_msr(u32 index, bool write)
{
switch (index) {
@@ -1619,8 +1630,6 @@ bool tdx_is_emulated_msr(u32 index, bool write)
case MSR_MTRRdefType:
case MSR_IA32_TSC_DEADLINE:
case MSR_IA32_MISC_ENABLE:
- case MSR_KVM_STEAL_TIME:
- case MSR_KVM_POLL_CONTROL:
case MSR_PLATFORM_INFO:
case MSR_MISC_FEATURES_ENABLES:
case MSR_IA32_MCG_CAP:
@@ -1650,6 +1659,9 @@ bool tdx_is_emulated_msr(u32 index, bool write)
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;
}
--
Isaku Yamahata <isaku.yamahata@gmail.com>