linux-kernel - [PATCH 11/22] KVM: x86: Use static_call() for copy/move encryption context ioctls()

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Date:   Fri, 28 Jan 2022 00:51:57 +0000
From:   Sean Christopherson <seanjc@...gle.com>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     Sean Christopherson <seanjc@...gle.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        Wanpeng Li <wanpengli@...cent.com>,
        Jim Mattson <jmattson@...gle.com>,
        Joerg Roedel <joro@...tes.org>, kvm@...r.kernel.org,
        linux-kernel@...r.kernel.org, Like Xu <like.xu.linux@...il.com>
Subject: [PATCH 11/22] KVM: x86: Use static_call() for copy/move encryption
 context ioctls()

Define and use static_call()s for .vm_{copy,move}_enc_context_from(),
mostly so that the op is defined in kvm-x86-ops.h.  This will allow using
KVM_X86_OP in vendor code to wire up the implementation.  Any performance
gains eeked out by using static_call() is a happy bonus and not the
primary motiviation.

Opportunistically refactor the code to reduce indentation and keep line
lengths reasonable, and to be consistent when wrapping versus running
a bit over the 80 char soft limit.

Signed-off-by: Sean Christopherson <seanjc@...gle.com>
---
 arch/x86/include/asm/kvm-x86-ops.h |  2 ++
 arch/x86/kvm/x86.c                 | 17 ++++++++++-------
 2 files changed, 12 insertions(+), 7 deletions(-)

diff --git a/arch/x86/include/asm/kvm-x86-ops.h b/arch/x86/include/asm/kvm-x86-ops.h
index eb93aa439d61..4ee046e60c34 100644
--- a/arch/x86/include/asm/kvm-x86-ops.h
+++ b/arch/x86/include/asm/kvm-x86-ops.h
@@ -110,6 +110,8 @@ KVM_X86_OP(enable_smi_window)
 KVM_X86_OP(mem_enc_op)
 KVM_X86_OP(mem_enc_reg_region)
 KVM_X86_OP(mem_enc_unreg_region)
+KVM_X86_OP(vm_copy_enc_context_from)
+KVM_X86_OP(vm_move_enc_context_from)
 KVM_X86_OP(get_msr_feature)
 KVM_X86_OP(can_emulate_instruction)
 KVM_X86_OP(apic_init_signal_blocked)
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index a8ea1b212267..580a2adaec7c 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -5958,15 +5958,18 @@ int kvm_vm_ioctl_enable_cap(struct kvm *kvm,
 #endif
 	case KVM_CAP_VM_COPY_ENC_CONTEXT_FROM:
 		r = -EINVAL;
-		if (kvm_x86_ops.vm_copy_enc_context_from)
-			r = kvm_x86_ops.vm_copy_enc_context_from(kvm, cap->args[0]);
-		return r;
+		if (!kvm_x86_ops.vm_copy_enc_context_from)
+			break;
+
+		r = static_call(kvm_x86_vm_copy_enc_context_from)(kvm, cap->args[0]);
+		break;
 	case KVM_CAP_VM_MOVE_ENC_CONTEXT_FROM:
 		r = -EINVAL;
-		if (kvm_x86_ops.vm_move_enc_context_from)
-			r = kvm_x86_ops.vm_move_enc_context_from(
-				kvm, cap->args[0]);
-		return r;
+		if (!kvm_x86_ops.vm_move_enc_context_from)
+			break;
+
+		r = static_call(kvm_x86_vm_move_enc_context_from)(kvm, cap->args[0]);
+		break;
 	case KVM_CAP_EXIT_HYPERCALL:
 		if (cap->args[0] & ~KVM_EXIT_HYPERCALL_VALID_MASK) {
 			r = -EINVAL;
-- 
2.35.0.rc0.227.g00780c9af4-goog