[PATCH v19 122/130] KVM: TDX: Add methods to ignore accesses to TSC

isaku.yamahata
2024-02-26T08:29:16Z

From: Isaku Yamahata <isaku.yamahata@intel.com>

TDX protects TDX guest TSC state from VMM. Implement access methods to
ignore guest TSC.

Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com>
---
arch/x86/kvm/vmx/main.c | 44 +++++++++++++++++++++++++++++++++++++----
1 file changed, 40 insertions(+), 4 deletions(-)

diff --git a/arch/x86/kvm/vmx/main.c b/arch/x86/kvm/vmx/main.c
index ec5c0fda92e9..9fcd71999bba 100644
--- a/arch/x86/kvm/vmx/main.c
+++ b/arch/x86/kvm/vmx/main.c
@@ -834,6 +834,42 @@ static u8 vt_get_mt_mask(struct kvm_vcpu *vcpu, gfn_t gfn, bool is_mmio)
return vmx_get_mt_mask(vcpu, gfn, is_mmio);
}

+static u64 vt_get_l2_tsc_offset(struct kvm_vcpu *vcpu)
+{
+ /* TDX doesn't support L2 guest at the moment. */
+ if (KVM_BUG_ON(is_td_vcpu(vcpu), vcpu->kvm))
+ return 0;
+
+ return vmx_get_l2_tsc_offset(vcpu);
+}
+
+static u64 vt_get_l2_tsc_multiplier(struct kvm_vcpu *vcpu)
+{
+ /* TDX doesn't support L2 guest at the moment. */
+ if (KVM_BUG_ON(is_td_vcpu(vcpu), vcpu->kvm))
+ return 0;
+
+ return vmx_get_l2_tsc_multiplier(vcpu);
+}
+
+static void vt_write_tsc_offset(struct kvm_vcpu *vcpu)
+{
+ /* In TDX, tsc offset can't be changed. */
+ if (is_td_vcpu(vcpu))
+ return;
+
+ vmx_write_tsc_offset(vcpu);
+}
+
+static void vt_write_tsc_multiplier(struct kvm_vcpu *vcpu)
+{
+ /* In TDX, tsc multiplier can't be changed. */
+ if (is_td_vcpu(vcpu))
+ return;
+
+ vmx_write_tsc_multiplier(vcpu);
+}
+
static void vt_update_cpu_dirty_logging(struct kvm_vcpu *vcpu)
{
if (KVM_BUG_ON(is_td_vcpu(vcpu), vcpu->kvm))
@@ -1022,10 +1058,10 @@ struct kvm_x86_ops vt_x86_ops __initdata = {

.has_wbinvd_exit = cpu_has_vmx_wbinvd_exit,

- .get_l2_tsc_offset = vmx_get_l2_tsc_offset,
- .get_l2_tsc_multiplier = vmx_get_l2_tsc_multiplier,
- .write_tsc_offset = vmx_write_tsc_offset,
- .write_tsc_multiplier = vmx_write_tsc_multiplier,
+ .get_l2_tsc_offset = vt_get_l2_tsc_offset,
+ .get_l2_tsc_multiplier = vt_get_l2_tsc_multiplier,
+ .write_tsc_offset = vt_write_tsc_offset,
+ .write_tsc_multiplier = vt_write_tsc_multiplier,

.load_mmu_pgd = vt_load_mmu_pgd,

--
2.25.1