linux-kernel - [PATCH 2/3] KVM: x86: Introduce definitions to support static calls for kvm_pmu

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Date:   Wed,  3 Nov 2021 15:03:09 +0800
From:   Like Xu <like.xu.linux@...il.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>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        kvm@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH 2/3] KVM: x86: Introduce definitions to support static calls for kvm_pmu_ops

Use static calls to improve kvm_pmu_ops performance. Introduce the
definitions that will be used by a subsequent patch to actualize the
savings. Add a new kvm-x86-pmu-ops.h header that can be used for the
definition of static calls. This header is also intended to be
used to simplify the defition of amd_pmu_ops and intel_pmu_ops.

Like what we did for kvm_x86_ops, 'pmu_ops' can be covered by
static calls in a simlilar manner for insignificant but not
negligible performance impact, especially on older models.

Signed-off-by: Like Xu <likexu@...cent.com>
---
 arch/x86/include/asm/kvm-x86-pmu-ops.h | 32 ++++++++++++++++++++++++++
 arch/x86/kvm/pmu.c                     |  7 ++++++
 arch/x86/kvm/pmu.h                     | 15 ++++++++++++
 3 files changed, 54 insertions(+)
 create mode 100644 arch/x86/include/asm/kvm-x86-pmu-ops.h

diff --git a/arch/x86/include/asm/kvm-x86-pmu-ops.h b/arch/x86/include/asm/kvm-x86-pmu-ops.h
new file mode 100644
index 000000000000..b7713b16d21d
--- /dev/null
+++ b/arch/x86/include/asm/kvm-x86-pmu-ops.h
@@ -0,0 +1,32 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+#if !defined(KVM_X86_PMU_OP) || !defined(KVM_X86_PMU_OP_NULL)
+BUILD_BUG_ON(1)
+#endif
+
+/*
+ * KVM_X86_PMU_OP() and KVM_X86_PMU_OP_NULL() are used to
+ * help generate "static_call()"s. They are also intended for use when defining
+ * the amd/intel KVM_X86_PMU_OPs. KVM_X86_PMU_OP() can be used
+ * for those functions that follow the [amd|intel]_func_name convention.
+ * KVM_X86_PMU_OP_NULL() can leave a NULL definition for the
+ * case where there is no definition or a function name that
+ * doesn't match the typical naming convention is supplied.
+ */
+KVM_X86_PMU_OP(find_arch_event);
+KVM_X86_PMU_OP(find_fixed_event);
+KVM_X86_PMU_OP(pmc_is_enabled);
+KVM_X86_PMU_OP(pmc_idx_to_pmc);
+KVM_X86_PMU_OP(rdpmc_ecx_to_pmc);
+KVM_X86_PMU_OP(msr_idx_to_pmc);
+KVM_X86_PMU_OP(is_valid_rdpmc_ecx);
+KVM_X86_PMU_OP(is_valid_msr);
+KVM_X86_PMU_OP(get_msr);
+KVM_X86_PMU_OP(set_msr);
+KVM_X86_PMU_OP(refresh);
+KVM_X86_PMU_OP(init);
+KVM_X86_PMU_OP(reset);
+KVM_X86_PMU_OP_NULL(deliver_pmi);
+KVM_X86_PMU_OP_NULL(cleanup);
+
+#undef KVM_X86_PMU_OP
+#undef KVM_X86_PMU_OP_NULL
diff --git a/arch/x86/kvm/pmu.c b/arch/x86/kvm/pmu.c
index 0db1887137d9..b6f08c719125 100644
--- a/arch/x86/kvm/pmu.c
+++ b/arch/x86/kvm/pmu.c
@@ -50,6 +50,13 @@
 struct kvm_pmu_ops kvm_pmu_ops __read_mostly;
 EXPORT_SYMBOL_GPL(kvm_pmu_ops);
 
+#define	KVM_X86_PMU_OP(func)	\
+	DEFINE_STATIC_CALL_NULL(kvm_x86_pmu_##func,	\
+				*(((struct kvm_pmu_ops *)0)->func))
+#define	KVM_X86_PMU_OP_NULL	KVM_X86_PMU_OP
+#include <asm/kvm-x86-pmu-ops.h>
+EXPORT_STATIC_CALL_GPL(kvm_x86_pmu_is_valid_msr);
+
 static void kvm_pmi_trigger_fn(struct irq_work *irq_work)
 {
 	struct kvm_pmu *pmu = container_of(irq_work, struct kvm_pmu, irq_work);
diff --git a/arch/x86/kvm/pmu.h b/arch/x86/kvm/pmu.h
index b2fe135d395a..e5550d4acf14 100644
--- a/arch/x86/kvm/pmu.h
+++ b/arch/x86/kvm/pmu.h
@@ -3,6 +3,8 @@
 #define __KVM_X86_PMU_H
 
 #include <linux/nospec.h>
+#include <linux/static_call_types.h>
+#include <linux/static_call.h>
 
 #define vcpu_to_pmu(vcpu) (&(vcpu)->arch.pmu)
 #define pmu_to_vcpu(pmu)  (container_of((pmu), struct kvm_vcpu, arch.pmu))
@@ -45,6 +47,19 @@ struct kvm_pmu_ops {
 	void (*cleanup)(struct kvm_vcpu *vcpu);
 };
 
+#define	KVM_X86_PMU_OP(func)	\
+	DECLARE_STATIC_CALL(kvm_x86_pmu_##func, *(((struct kvm_pmu_ops *)0)->func))
+#define	KVM_X86_PMU_OP_NULL	KVM_X86_PMU_OP
+#include <asm/kvm-x86-pmu-ops.h>
+
+static inline void kvm_pmu_ops_static_call_update(void)
+{
+#define	KVM_X86_PMU_OP(func)	\
+	static_call_update(kvm_x86_pmu_##func, kvm_pmu_ops.func)
+#define	KVM_X86_PMU_OP_NULL	KVM_X86_PMU_OP
+#include <asm/kvm-x86-pmu-ops.h>
+}
+
 static inline u64 pmc_bitmask(struct kvm_pmc *pmc)
 {
 	struct kvm_pmu *pmu = pmc_to_pmu(pmc);
-- 
2.33.0