linux-kernel - [PATCH v15 082/115] KVM: x86: Split core of hypercall emulation to helper function

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Message-Id: <74e951ee3015699c76c66210d6152ebdbb0ad48c.1690322424.git.isaku.yamahata@intel.com>
Date:   Tue, 25 Jul 2023 15:14:33 -0700
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>, erdemaktas@...gle.com,
        Sean Christopherson <seanjc@...gle.com>,
        Sagi Shahar <sagis@...gle.com>,
        David Matlack <dmatlack@...gle.com>,
        Kai Huang <kai.huang@...el.com>,
        Zhi Wang <zhi.wang.linux@...il.com>, chen.bo@...el.com,
        hang.yuan@...el.com, tina.zhang@...el.com,
        Sean Christopherson <sean.j.christopherson@...el.com>
Subject: [PATCH v15 082/115] KVM: x86: Split core of hypercall emulation to helper function

From: Sean Christopherson <sean.j.christopherson@...el.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@...el.com>
Signed-off-by: Isaku Yamahata <isaku.yamahata@...el.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 8bd2d7df15f9..c58ceded3437 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -2118,6 +2118,10 @@ 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 c7d34b04ccdf..747cc86c60dc 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -9838,26 +9838,15 @@ 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;
@@ -9866,11 +9855,6 @@ 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) {
@@ -9933,6 +9917,34 @@ 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