linux-kernel - [RFC PATCH v5 091/104] KVM: TDX: Handle TDX PV CPUID hypercall

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Message-Id: <e3621e9893796d2bd8ea8b1f16c1616ae9df3f37.1646422845.git.isaku.yamahata@intel.com>
Date:   Fri,  4 Mar 2022 11:49:47 -0800
From:   isaku.yamahata@...el.com
To:     kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Cc:     isaku.yamahata@...el.com, isaku.yamahata@...il.com,
        Paolo Bonzini <pbonzini@...hat.com>,
        Jim Mattson <jmattson@...gle.com>, erdemaktas@...gle.com,
        Connor Kuehl <ckuehl@...hat.com>,
        Sean Christopherson <seanjc@...gle.com>
Subject: [RFC PATCH v5 091/104] KVM: TDX: Handle TDX PV CPUID hypercall

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

Wire up TDX PV CPUID hypercall to the KVM backend function.

Signed-off-by: Isaku Yamahata <isaku.yamahata@...el.com>
---
 arch/x86/kvm/vmx/tdx.c | 27 +++++++++++++++++++++++++++
 1 file changed, 27 insertions(+)

diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c
index 53f59fb92dcf..f7c9170d596a 100644
--- a/arch/x86/kvm/vmx/tdx.c
+++ b/arch/x86/kvm/vmx/tdx.c
@@ -893,6 +893,30 @@ static int tdx_emulate_vmcall(struct kvm_vcpu *vcpu)
 	return 1;
 }
 
+static int tdx_emulate_cpuid(struct kvm_vcpu *vcpu)
+{
+	u32 eax, ebx, ecx, edx;
+
+	/* EAX and ECX for cpuid is stored in R12 and R13. */
+	eax = tdvmcall_p1_read(vcpu);
+	ecx = tdvmcall_p2_read(vcpu);
+
+	kvm_cpuid(vcpu, &eax, &ebx, &ecx, &edx, true);
+
+	/*
+	 * The returned value for CPUID (EAX, EBX, ECX, and EDX) is stored into
+	 * R12, R13, R14, and R15.
+	 */
+	tdvmcall_p1_write(vcpu, eax);
+	tdvmcall_p2_write(vcpu, ebx);
+	tdvmcall_p3_write(vcpu, ecx);
+	tdvmcall_p4_write(vcpu, edx);
+
+	tdvmcall_set_return_code(vcpu, TDG_VP_VMCALL_SUCCESS);
+
+	return 1;
+}
+
 static int handle_tdvmcall(struct kvm_vcpu *vcpu)
 {
 	struct vcpu_tdx *tdx = to_tdx(vcpu);
@@ -904,6 +928,9 @@ static int handle_tdvmcall(struct kvm_vcpu *vcpu)
 		return tdx_emulate_vmcall(vcpu);
 
 	switch (tdvmcall_exit_reason(vcpu)) {
+	case EXIT_REASON_CPUID:
+		return tdx_emulate_cpuid(vcpu);
+
 	default:
 		break;
 	}
-- 
2.25.1