From:   isaku.yamahata@intel.com
To:     kvm@vger.kernel.org, linux-kernel@vger.kernel.org
Cc:     isaku.yamahata@intel.com, isaku.yamahata@gmail.com,
        Paolo Bonzini <pbonzini@redhat.com>, erdemaktas@google.com,
        Sean Christopherson <seanjc@google.com>,
        Sagi Shahar <sagis@google.com>,
        David Matlack <dmatlack@google.com>,
        Kai Huang <kai.huang@intel.com>,
        Zhi Wang <zhi.wang.linux@gmail.com>,
        Sean Christopherson <sean.j.christopherson@intel.com>
Subject: [PATCH v12 075/106] KVM: x86: Split core of hypercall emulation to helper function
Date:   Mon, 27 Feb 2023 00:23:14 -0800
Message-Id: <de9d55ffe25c566032eb44304d435e16a426c370.1677484918.git.isaku.yamahata@intel.com>
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From: Sean Christopherson <sean.j.christopherson@intel.com>

By necessity, TDX will use a different register ABI for hypercalls.
Break out the core functionality so that it may be reused for TDX.

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com>
---
 arch/x86/include/asm/kvm_host.h |  4 +++
 arch/x86/kvm/x86.c              | 54 ++++++++++++++++++++-------------
 2 files changed, 37 insertions(+), 21 deletions(-)

diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index 2051ae6da619..301059b2e882 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -2085,6 +2085,10 @@ static inline void kvm_clear_apicv_inhibit(struct kvm *kvm,
 	kvm_set_or_clear_apicv_inhibit(kvm, reason, false);
 }
 
+unsigned long __kvm_emulate_hypercall(struct kvm_vcpu *vcpu, unsigned long nr,
+				      unsigned long a0, unsigned long a1,
+				      unsigned long a2, unsigned long a3,
+				      int op_64_bit);
 int kvm_emulate_hypercall(struct kvm_vcpu *vcpu);
 
 int kvm_mmu_page_fault(struct kvm_vcpu *vcpu, gpa_t cr2_or_gpa, u64 error_code,
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 1b10f54c8acf..94416992868b 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -9731,26 +9731,15 @@ static int complete_hypercall_exit(struct kvm_vcpu *vcpu)
 	return kvm_skip_emulated_instruction(vcpu);
 }
 
-int kvm_emulate_hypercall(struct kvm_vcpu *vcpu)
+unsigned long __kvm_emulate_hypercall(struct kvm_vcpu *vcpu, unsigned long nr,
+				      unsigned long a0, unsigned long a1,
+				      unsigned long a2, unsigned long a3,
+				      int op_64_bit)
 {
-	unsigned long nr, a0, a1, a2, a3, ret;
-	int op_64_bit;
-
-	if (kvm_xen_hypercall_enabled(vcpu->kvm))
-		return kvm_xen_hypercall(vcpu);
-
-	if (kvm_hv_hypercall_enabled(vcpu))
-		return kvm_hv_hypercall(vcpu);
-
-	nr = kvm_rax_read(vcpu);
-	a0 = kvm_rbx_read(vcpu);
-	a1 = kvm_rcx_read(vcpu);
-	a2 = kvm_rdx_read(vcpu);
-	a3 = kvm_rsi_read(vcpu);
+	unsigned long ret;
 
 	trace_kvm_hypercall(nr, a0, a1, a2, a3);
 
-	op_64_bit = is_64_bit_hypercall(vcpu);
 	if (!op_64_bit) {
 		nr &= 0xFFFFFFFF;
 		a0 &= 0xFFFFFFFF;
@@ -9759,11 +9748,6 @@ int kvm_emulate_hypercall(struct kvm_vcpu *vcpu)
 		a3 &= 0xFFFFFFFF;
 	}
 
-	if (static_call(kvm_x86_get_cpl)(vcpu) != 0) {
-		ret = -KVM_EPERM;
-		goto out;
-	}
-
 	ret = -KVM_ENOSYS;
 
 	switch (nr) {
@@ -9822,6 +9806,34 @@ int kvm_emulate_hypercall(struct kvm_vcpu *vcpu)
 		ret = -KVM_ENOSYS;
 		break;
 	}
+	return ret;
+}
+EXPORT_SYMBOL_GPL(__kvm_emulate_hypercall);
+
+int kvm_emulate_hypercall(struct kvm_vcpu *vcpu)
+{
+	unsigned long nr, a0, a1, a2, a3, ret;
+	int op_64_bit;
+
+	if (kvm_xen_hypercall_enabled(vcpu->kvm))
+		return kvm_xen_hypercall(vcpu);
+
+	if (kvm_hv_hypercall_enabled(vcpu))
+		return kvm_hv_hypercall(vcpu);
+
+	nr = kvm_rax_read(vcpu);
+	a0 = kvm_rbx_read(vcpu);
+	a1 = kvm_rcx_read(vcpu);
+	a2 = kvm_rdx_read(vcpu);
+	a3 = kvm_rsi_read(vcpu);
+	op_64_bit = is_64_bit_hypercall(vcpu);
+
+	if (static_call(kvm_x86_get_cpl)(vcpu) != 0) {
+		ret = -KVM_EPERM;
+		goto out;
+	}
+
+	ret = __kvm_emulate_hypercall(vcpu, nr, a0, a1, a2, a3, op_64_bit);
 out:
 	if (!op_64_bit)
 		ret = (u32)ret;
-- 
2.25.1