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    SubjectRe: [PATCH v3 15/16] KVM: arm64: Drop perf.c and fold its tiny bits of code into arm.c / pmu.c
    On Wed, 22 Sep 2021 01:05:32 +0100,
    Sean Christopherson <seanjc@google.com> wrote:
    >
    > Call KVM's (un)register perf callbacks helpers directly from arm.c, and
    > move the PMU bits into pmu.c and rename the related helper accordingly.
    >
    > Signed-off-by: Sean Christopherson <seanjc@google.com>
    > ---
    > arch/arm64/include/asm/kvm_host.h | 3 ---
    > arch/arm64/kvm/Makefile | 2 +-
    > arch/arm64/kvm/arm.c | 6 ++++--
    > arch/arm64/kvm/perf.c | 27 ---------------------------
    > arch/arm64/kvm/pmu.c | 8 ++++++++
    > include/kvm/arm_pmu.h | 1 +
    > 6 files changed, 14 insertions(+), 33 deletions(-)
    > delete mode 100644 arch/arm64/kvm/perf.c
    >
    > diff --git a/arch/arm64/include/asm/kvm_host.h b/arch/arm64/include/asm/kvm_host.h
    > index 828b6eaa2c56..f141ac65f4f1 100644
    > --- a/arch/arm64/include/asm/kvm_host.h
    > +++ b/arch/arm64/include/asm/kvm_host.h
    > @@ -670,9 +670,6 @@ unsigned long kvm_mmio_read_buf(const void *buf, unsigned int len);
    > int kvm_handle_mmio_return(struct kvm_vcpu *vcpu);
    > int io_mem_abort(struct kvm_vcpu *vcpu, phys_addr_t fault_ipa);
    >
    > -void kvm_perf_init(void);
    > -void kvm_perf_teardown(void);
    > -
    > #ifdef CONFIG_GUEST_PERF_EVENTS
    > static inline bool kvm_arch_pmi_in_guest(struct kvm_vcpu *vcpu)
    > {
    > diff --git a/arch/arm64/kvm/Makefile b/arch/arm64/kvm/Makefile
    > index 989bb5dad2c8..0bcc378b7961 100644
    > --- a/arch/arm64/kvm/Makefile
    > +++ b/arch/arm64/kvm/Makefile
    > @@ -12,7 +12,7 @@ obj-$(CONFIG_KVM) += hyp/
    >
    > kvm-y := $(KVM)/kvm_main.o $(KVM)/coalesced_mmio.o $(KVM)/eventfd.o \
    > $(KVM)/vfio.o $(KVM)/irqchip.o $(KVM)/binary_stats.o \
    > - arm.o mmu.o mmio.o psci.o perf.o hypercalls.o pvtime.o \
    > + arm.o mmu.o mmio.o psci.o hypercalls.o pvtime.o \
    > inject_fault.o va_layout.o handle_exit.o \
    > guest.o debug.o reset.o sys_regs.o \
    > vgic-sys-reg-v3.o fpsimd.o pmu.o \
    > diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
    > index 2b542fdc237e..48f89d80f464 100644
    > --- a/arch/arm64/kvm/arm.c
    > +++ b/arch/arm64/kvm/arm.c
    > @@ -1744,7 +1744,9 @@ static int init_subsystems(void)
    > if (err)
    > goto out;
    >
    > - kvm_perf_init();
    > + kvm_pmu_init();
    > + kvm_register_perf_callbacks(NULL);
    > +
    > kvm_sys_reg_table_init();
    >
    > out:
    > @@ -2160,7 +2162,7 @@ int kvm_arch_init(void *opaque)
    > /* NOP: Compiling as a module not supported */
    > void kvm_arch_exit(void)
    > {
    > - kvm_perf_teardown();
    > + kvm_unregister_perf_callbacks();
    > }
    >
    > static int __init early_kvm_mode_cfg(char *arg)
    > diff --git a/arch/arm64/kvm/perf.c b/arch/arm64/kvm/perf.c
    > deleted file mode 100644
    > index 0b902e0d5b5d..000000000000
    > --- a/arch/arm64/kvm/perf.c
    > +++ /dev/null
    > @@ -1,27 +0,0 @@
    > -// SPDX-License-Identifier: GPL-2.0-only
    > -/*
    > - * Based on the x86 implementation.
    > - *
    > - * Copyright (C) 2012 ARM Ltd.
    > - * Author: Marc Zyngier <marc.zyngier@arm.com>
    > - */
    > -
    > -#include <linux/perf_event.h>
    > -#include <linux/kvm_host.h>
    > -
    > -#include <asm/kvm_emulate.h>
    > -
    > -DEFINE_STATIC_KEY_FALSE(kvm_arm_pmu_available);
    > -
    > -void kvm_perf_init(void)
    > -{
    > - if (kvm_pmu_probe_pmuver() != 0xf && !is_protected_kvm_enabled())
    > - static_branch_enable(&kvm_arm_pmu_available);
    > -
    > - kvm_register_perf_callbacks(NULL);
    > -}
    > -
    > -void kvm_perf_teardown(void)
    > -{
    > - kvm_unregister_perf_callbacks();
    > -}
    > diff --git a/arch/arm64/kvm/pmu.c b/arch/arm64/kvm/pmu.c
    > index 03a6c1f4a09a..d98b57a17043 100644
    > --- a/arch/arm64/kvm/pmu.c
    > +++ b/arch/arm64/kvm/pmu.c
    > @@ -7,6 +7,14 @@
    > #include <linux/perf_event.h>
    > #include <asm/kvm_hyp.h>
    >
    > +DEFINE_STATIC_KEY_FALSE(kvm_arm_pmu_available);
    > +
    > +void kvm_pmu_init(void)
    > +{
    > + if (kvm_pmu_probe_pmuver() != 0xf && !is_protected_kvm_enabled())
    > + static_branch_enable(&kvm_arm_pmu_available);
    > +}
    > +
    > /*
    > * Given the perf event attributes and system type, determine
    > * if we are going to need to switch counters at guest entry/exit.
    > diff --git a/include/kvm/arm_pmu.h b/include/kvm/arm_pmu.h
    > index 864b9997efb2..42270676498d 100644
    > --- a/include/kvm/arm_pmu.h
    > +++ b/include/kvm/arm_pmu.h
    > @@ -14,6 +14,7 @@
    > #define ARMV8_PMU_MAX_COUNTER_PAIRS ((ARMV8_PMU_MAX_COUNTERS + 1) >> 1)
    >
    > DECLARE_STATIC_KEY_FALSE(kvm_arm_pmu_available);
    > +void kvm_pmu_init(void);
    >
    > static __always_inline bool kvm_arm_support_pmu_v3(void)
    > {

    Note that this patch is now conflicting with e840f42a4992 ("KVM:
    arm64: Fix PMU probe ordering"), which was merged in -rc4. Moving the
    static key definition to arch/arm64/kvm/pmu-emul.c and getting rid of
    kvm_pmu_init() altogether should be enough to resolve it.

    With that,

    Reviewed-by: Marc Zyngier <maz@kernel.org>

    M.

    --
    Without deviation from the norm, progress is not possible.

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