[PATCH v6 08/16] KVM: x86/pmu: Add support for KVM_X86_PMU_OP_OPTIONAL_RET0

[Yosry Ahmed]

Add definitions for KVM_X86_PMU_OP_OPTIONAL_RET0() to resolve to
__static_call_return0, similar to KVM_X86_OP_OPTIONAL_RET0(). Move the
definition of kvm_pmu_call() to pmu.h, and add declarations for the
static PMU calls in the header to allow making callbacks from the header
in following changes.

Suggested-by: Sean Christopherson <seanjc@xxxxxxxxxx>
Signed-off-by: Yosry Ahmed <yosry@xxxxxxxxxx>
---
 arch/x86/include/asm/kvm-x86-pmu-ops.h | 4 +++-
 arch/x86/include/asm/kvm_host.h        | 1 -
 arch/x86/kvm/pmu.c                     | 4 ++++
 arch/x86/kvm/pmu.h                     | 8 ++++++++
 4 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/arch/x86/include/asm/kvm-x86-pmu-ops.h b/arch/x86/include/asm/kvm-x86-pmu-ops.h
index d5452b3433b7d..03ed2c917bb56 100644
--- a/arch/x86/include/asm/kvm-x86-pmu-ops.h
+++ b/arch/x86/include/asm/kvm-x86-pmu-ops.h
@@ -1,6 +1,7 @@
 /* SPDX-License-Identifier: GPL-2.0 */
 #if !defined(KVM_X86_PMU_OP) || \
-    !defined(KVM_X86_PMU_OP_OPTIONAL)
+	!defined(KVM_X86_PMU_OP_OPTIONAL) || \
+	!defined(KVM_X86_PMU_OP_OPTIONAL_RET0)
 #error Missing one or more KVM_X86_PMU_OP #defines
 #else
 
@@ -31,3 +32,4 @@ KVM_X86_PMU_OP(mediated_put)
 
 #undef KVM_X86_PMU_OP
 #undef KVM_X86_PMU_OP_OPTIONAL
+#undef KVM_X86_PMU_OP_OPTIONAL_RET0
diff --git a/arch/x86/include/asm/kvm_host.h b/arch/x86/include/asm/kvm_host.h
index b191967c9c1e4..943adf62839fc 100644
--- a/arch/x86/include/asm/kvm_host.h
+++ b/arch/x86/include/asm/kvm_host.h
@@ -2041,7 +2041,6 @@ extern bool __read_mostly enable_device_posted_irqs;
 extern struct kvm_x86_ops kvm_x86_ops;
 
 #define kvm_x86_call(func) static_call(kvm_x86_##func)
-#define kvm_pmu_call(func) static_call(kvm_x86_pmu_##func)
 
 #define KVM_X86_OP(func) \
 	DECLARE_STATIC_CALL(kvm_x86_##func, *(((struct kvm_x86_ops *)0)->func));
diff --git a/arch/x86/kvm/pmu.c b/arch/x86/kvm/pmu.c
index 67dbbd4c73036..9b7e39610be22 100644
--- a/arch/x86/kvm/pmu.c
+++ b/arch/x86/kvm/pmu.c
@@ -98,6 +98,7 @@ static struct kvm_pmu_ops kvm_pmu_ops __read_mostly;
 	DEFINE_STATIC_CALL_NULL(kvm_x86_pmu_##func,			     \
 				*(((struct kvm_pmu_ops *)0)->func));
 #define KVM_X86_PMU_OP_OPTIONAL KVM_X86_PMU_OP
+#define KVM_X86_PMU_OP_OPTIONAL_RET0 KVM_X86_PMU_OP
 #include <asm/kvm-x86-pmu-ops.h>
 
 void kvm_pmu_ops_update(const struct kvm_pmu_ops *pmu_ops)
@@ -109,6 +110,9 @@ void kvm_pmu_ops_update(const struct kvm_pmu_ops *pmu_ops)
 #define KVM_X86_PMU_OP(func) \
 	WARN_ON(!kvm_pmu_ops.func); __KVM_X86_PMU_OP(func)
 #define KVM_X86_PMU_OP_OPTIONAL __KVM_X86_PMU_OP
+#define KVM_X86_PMU_OP_OPTIONAL_RET0(func) \
+	static_call_update(kvm_x86_pmu_##func, (void *)kvm_pmu_ops.func ? : \
+					       (void *)__static_call_return0);
 #include <asm/kvm-x86-pmu-ops.h>
 #undef __KVM_X86_PMU_OP
 }
diff --git a/arch/x86/kvm/pmu.h b/arch/x86/kvm/pmu.h
index 0e99022168a85..a062f0bc3dbb1 100644
--- a/arch/x86/kvm/pmu.h
+++ b/arch/x86/kvm/pmu.h
@@ -53,6 +53,14 @@ struct kvm_pmu_ops {
 	const u32 MSR_STRIDE;
 };
 
+#define kvm_pmu_call(func) static_call(kvm_x86_pmu_##func)
+
+#define KVM_X86_PMU_OP(func) \
+	DECLARE_STATIC_CALL(kvm_x86_pmu_##func, *(((struct kvm_pmu_ops *)0)->func));
+#define KVM_X86_PMU_OP_OPTIONAL KVM_X86_PMU_OP
+#define KVM_X86_PMU_OP_OPTIONAL_RET0 KVM_X86_PMU_OP
+#include <asm/kvm-x86-pmu-ops.h>
+
 extern bool enable_pmu;
 extern bool enable_mediated_pmu;
 
-- 
2.54.0.545.g6539524ca2-goog