[14/18] KVM: TDX: Add methods to ignore accesses to TSC

Commit Message

Binbin Wu Dec. 10, 2024, 12:49 a.m. UTC

From: Isaku Yamahata <[e-mail]>

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

Signed-off-by: Isaku Yamahata <[e-mail]>
Signed-off-by: Binbin Wu <[e-mail]>
---
TDX "the rest" breakout:
- Dropped KVM_BUG_ON() in vt_get_l2_tsc_offset(). (Rick)
---
 arch/x86/kvm/vmx/main.c | 44 +++++++++++++++++++++++++++++++++++++----
 1 file changed, 40 insertions(+), 4 deletions(-)

Patch

diff --git a/arch/x86/kvm/vmx/main.c b/arch/x86/kvm/vmx/main.c
index 4a9b176b8a36..81ca5acb9964 100644
--- a/arch/x86/kvm/vmx/main.c
+++ b/arch/x86/kvm/vmx/main.c
@@ -757,6 +757,42 @@  static int vt_set_identity_map_addr(struct kvm *kvm, u64 ident_addr)
 	return vmx_set_identity_map_addr(kvm, ident_addr);
 }
 
+static u64 vt_get_l2_tsc_offset(struct kvm_vcpu *vcpu)
+{
+	/* TDX doesn't support L2 guest at the moment. */
+	if (is_td_vcpu(vcpu))
+		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 (is_td_vcpu(vcpu))
+		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);
+}
+
 #ifdef CONFIG_X86_64
 static int vt_set_hv_timer(struct kvm_vcpu *vcpu, u64 guest_deadline_tsc,
 			      bool *expired)
@@ -914,10 +950,10 @@  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,