[PATCH v13 108/113] KVM: TDX: Add a method to ignore for TDX to ignore hypercall patch

[isaku . yamahata]

From: Isaku Yamahata <isaku.yamahata@xxxxxxxxx>

Because guest TD memory is protected, VMM patching guest binary for
hypercall instruction isn't possible.  Add a method to ignore hypercall
patching with a warning.  Note: guest TD kernel needs to be modified to use
TDG.VP.VMCALL for hypercall.

Signed-off-by: Isaku Yamahata <isaku.yamahata@xxxxxxxxx>
---
 arch/x86/kvm/vmx/main.c | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/arch/x86/kvm/vmx/main.c b/arch/x86/kvm/vmx/main.c
index dfa072253397..21aebf38697a 100644
--- a/arch/x86/kvm/vmx/main.c
+++ b/arch/x86/kvm/vmx/main.c
@@ -725,6 +725,19 @@ static u32 vt_get_interrupt_shadow(struct kvm_vcpu *vcpu)
 	return vmx_get_interrupt_shadow(vcpu);
 }
 
+static void vt_patch_hypercall(struct kvm_vcpu *vcpu,
+				  unsigned char *hypercall)
+{
+	/*
+	 * Because guest memory is protected, guest can't be patched. TD kernel
+	 * is modified to use TDG.VP.VMCAL for hypercall.
+	 */
+	if (KVM_BUG_ON(is_td_vcpu(vcpu), vcpu->kvm))
+		return;
+
+	vmx_patch_hypercall(vcpu, hypercall);
+}
+
 static void vt_inject_irq(struct kvm_vcpu *vcpu, bool reinjected)
 {
 	if (is_td_vcpu(vcpu))
@@ -994,7 +1007,7 @@ struct kvm_x86_ops vt_x86_ops __initdata = {
 	.update_emulated_instruction = vmx_update_emulated_instruction,
 	.set_interrupt_shadow = vt_set_interrupt_shadow,
 	.get_interrupt_shadow = vt_get_interrupt_shadow,
-	.patch_hypercall = vmx_patch_hypercall,
+	.patch_hypercall = vt_patch_hypercall,
 	.inject_irq = vt_inject_irq,
 	.inject_nmi = vt_inject_nmi,
 	.inject_exception = vt_inject_exception,
-- 
2.25.1