linux-kernel - [PATCH v2 2/2] KVM: TDX: WARN if a SEAMCALL VM-Exit makes its way out to KVM

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Message-ID: <20251016182148.69085-3-seanjc@google.com>
Date: Thu, 16 Oct 2025 11:21:48 -0700
From: Sean Christopherson <seanjc@...gle.com>
To: Sean Christopherson <seanjc@...gle.com>, Paolo Bonzini <pbonzini@...hat.com>
Cc: kvm@...r.kernel.org, linux-kernel@...r.kernel.org, 
	Kai Huang <kai.huang@...el.com>, Xiaoyao Li <xiaoyao.li@...el.com>, 
	Rick Edgecombe <rick.p.edgecombe@...el.com>, Dan Williams <dan.j.williams@...el.com>, 
	Binbin Wu <binbin.wu@...ux.intel.com>
Subject: [PATCH v2 2/2] KVM: TDX: WARN if a SEAMCALL VM-Exit makes its way out
 to KVM

WARN if KVM observes a SEAMCALL VM-Exit while running a TD guest, as the
TDX-Module is supposed to inject a #UD, per the "Unconditionally Blocked
Instructions" section of the TDX-Module base specification.

Reported-by: Xiaoyao Li <xiaoyao.li@...el.com>
Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 arch/x86/kvm/vmx/tdx.c | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c
index 097304bf1e1d..ffcfe95f224f 100644
--- a/arch/x86/kvm/vmx/tdx.c
+++ b/arch/x86/kvm/vmx/tdx.c
@@ -2148,6 +2148,9 @@ int tdx_handle_exit(struct kvm_vcpu *vcpu, fastpath_t fastpath)
 		 * - If it's not an MSMI, no need to do anything here.
 		 */
 		return 1;
+	case EXIT_REASON_SEAMCALL:
+		WARN_ON_ONCE(1);
+		break;
 	default:
 		break;
 	}
-- 
2.51.0.858.gf9c4a03a3a-goog