[PATCH v19 119/130] KVM: TDX: Add methods to ignore guest instruction emulation

isaku.yamahata
2024-02-26T08:29:14Z

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

Because TDX protects TDX guest state from VMM, instructions in guest memory
cannot be emulated. Implement methods to ignore guest instruction
emulator.

Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com>
---
arch/x86/kvm/vmx/main.c | 28 ++++++++++++++++++++++++++--
1 file changed, 26 insertions(+), 2 deletions(-)

diff --git a/arch/x86/kvm/vmx/main.c b/arch/x86/kvm/vmx/main.c
index 9fb3f28d8259..9aaa9bd7abf3 100644
--- a/arch/x86/kvm/vmx/main.c
+++ b/arch/x86/kvm/vmx/main.c
@@ -320,6 +320,30 @@ static void vt_enable_smi_window(struct kvm_vcpu *vcpu)
}
#endif

+static int vt_check_emulate_instruction(struct kvm_vcpu *vcpu, int emul_type,
+ void *insn, int insn_len)
+{
+ if (is_td_vcpu(vcpu))
+ return X86EMUL_RETRY_INSTR;
+
+ return vmx_check_emulate_instruction(vcpu, emul_type, insn, insn_len);
+}
+
+static int vt_check_intercept(struct kvm_vcpu *vcpu,
+ struct x86_instruction_info *info,
+ enum x86_intercept_stage stage,
+ struct x86_exception *exception)
+{
+ /*
+ * This call back is triggered by the x86 instruction emulator. TDX
+ * doesn't allow guest memory inspection.
+ */
+ if (KVM_BUG_ON(is_td_vcpu(vcpu), vcpu->kvm))
+ return X86EMUL_UNHANDLEABLE;
+
+ return vmx_check_intercept(vcpu, info, stage, exception);
+}
+
static bool vt_apic_init_signal_blocked(struct kvm_vcpu *vcpu)
{
if (is_td_vcpu(vcpu))
@@ -976,7 +1000,7 @@ struct kvm_x86_ops vt_x86_ops __initdata = {

.load_mmu_pgd = vt_load_mmu_pgd,

- .check_intercept = vmx_check_intercept,
+ .check_intercept = vt_check_intercept,
.handle_exit_irqoff = vt_handle_exit_irqoff,

.request_immediate_exit = vt_request_immediate_exit,
@@ -1005,7 +1029,7 @@ struct kvm_x86_ops vt_x86_ops __initdata = {
.enable_smi_window = vt_enable_smi_window,
#endif

- .check_emulate_instruction = vmx_check_emulate_instruction,
+ .check_emulate_instruction = vt_check_emulate_instruction,
.apic_init_signal_blocked = vt_apic_init_signal_blocked,
.migrate_timers = vmx_migrate_timers,

--
2.25.1