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    Subject[PATCH 44/44] KVM: Opt out of generic hardware enabling on s390 and PPC
    From
    Allow architectures to opt out of the generic hardware enabling logic,
    and opt out on both s390 and PPC, which don't need to manually enable
    virtualization as it's always on (when available).

    In addition to letting s390 and PPC drop a bit of dead code, this will
    hopefully also allow ARM to clean up its related code, e.g. ARM has its
    own per-CPU flag to track which CPUs have enable hardware due to the
    need to keep hardware enabled indefinitely when pKVM is enabled.

    Signed-off-by: Sean Christopherson <seanjc@google.com>
    ---
    arch/arm64/kvm/Kconfig | 1 +
    arch/mips/kvm/Kconfig | 1 +
    arch/powerpc/include/asm/kvm_host.h | 1 -
    arch/powerpc/kvm/powerpc.c | 5 -----
    arch/riscv/kvm/Kconfig | 1 +
    arch/s390/include/asm/kvm_host.h | 1 -
    arch/s390/kvm/kvm-s390.c | 6 ------
    arch/x86/kvm/Kconfig | 1 +
    include/linux/kvm_host.h | 4 ++++
    virt/kvm/Kconfig | 3 +++
    virt/kvm/kvm_main.c | 30 +++++++++++++++++++++++------
    11 files changed, 35 insertions(+), 19 deletions(-)

    diff --git a/arch/arm64/kvm/Kconfig b/arch/arm64/kvm/Kconfig
    index 815cc118c675..0a7d2116b27b 100644
    --- a/arch/arm64/kvm/Kconfig
    +++ b/arch/arm64/kvm/Kconfig
    @@ -21,6 +21,7 @@ if VIRTUALIZATION
    menuconfig KVM
    bool "Kernel-based Virtual Machine (KVM) support"
    depends on HAVE_KVM
    + select KVM_GENERIC_HARDWARE_ENABLING
    select MMU_NOTIFIER
    select PREEMPT_NOTIFIERS
    select HAVE_KVM_CPU_RELAX_INTERCEPT
    diff --git a/arch/mips/kvm/Kconfig b/arch/mips/kvm/Kconfig
    index 91d197bee9c0..29e51649203b 100644
    --- a/arch/mips/kvm/Kconfig
    +++ b/arch/mips/kvm/Kconfig
    @@ -28,6 +28,7 @@ config KVM
    select MMU_NOTIFIER
    select SRCU
    select INTERVAL_TREE
    + select KVM_GENERIC_HARDWARE_ENABLING
    help
    Support for hosting Guest kernels.

    diff --git a/arch/powerpc/include/asm/kvm_host.h b/arch/powerpc/include/asm/kvm_host.h
    index 0a80e80c7b9e..959f566a455c 100644
    --- a/arch/powerpc/include/asm/kvm_host.h
    +++ b/arch/powerpc/include/asm/kvm_host.h
    @@ -876,7 +876,6 @@ struct kvm_vcpu_arch {
    #define __KVM_HAVE_ARCH_WQP
    #define __KVM_HAVE_CREATE_DEVICE

    -static inline void kvm_arch_hardware_disable(void) {}
    static inline void kvm_arch_sync_events(struct kvm *kvm) {}
    static inline void kvm_arch_memslots_updated(struct kvm *kvm, u64 gen) {}
    static inline void kvm_arch_flush_shadow_all(struct kvm *kvm) {}
    diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c
    index 51268be60dac..ed426c9ee0e9 100644
    --- a/arch/powerpc/kvm/powerpc.c
    +++ b/arch/powerpc/kvm/powerpc.c
    @@ -436,11 +436,6 @@ int kvmppc_ld(struct kvm_vcpu *vcpu, ulong *eaddr, int size, void *ptr,
    }
    EXPORT_SYMBOL_GPL(kvmppc_ld);

    -int kvm_arch_hardware_enable(void)
    -{
    - return 0;
    -}
    -
    int kvm_arch_init_vm(struct kvm *kvm, unsigned long type)
    {
    struct kvmppc_ops *kvm_ops = NULL;
    diff --git a/arch/riscv/kvm/Kconfig b/arch/riscv/kvm/Kconfig
    index f36a737d5f96..d5a658a047a7 100644
    --- a/arch/riscv/kvm/Kconfig
    +++ b/arch/riscv/kvm/Kconfig
    @@ -20,6 +20,7 @@ if VIRTUALIZATION
    config KVM
    tristate "Kernel-based Virtual Machine (KVM) support (EXPERIMENTAL)"
    depends on RISCV_SBI && MMU
    + select KVM_GENERIC_HARDWARE_ENABLING
    select MMU_NOTIFIER
    select PREEMPT_NOTIFIERS
    select KVM_MMIO
    diff --git a/arch/s390/include/asm/kvm_host.h b/arch/s390/include/asm/kvm_host.h
    index b1e98a9ed152..d3e4b5d7013a 100644
    --- a/arch/s390/include/asm/kvm_host.h
    +++ b/arch/s390/include/asm/kvm_host.h
    @@ -1023,7 +1023,6 @@ extern char sie_exit;
    extern int kvm_s390_gisc_register(struct kvm *kvm, u32 gisc);
    extern int kvm_s390_gisc_unregister(struct kvm *kvm, u32 gisc);

    -static inline void kvm_arch_hardware_disable(void) {}
    static inline void kvm_arch_sync_events(struct kvm *kvm) {}
    static inline void kvm_arch_sched_in(struct kvm_vcpu *vcpu, int cpu) {}
    static inline void kvm_arch_free_memslot(struct kvm *kvm,
    diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
    index 949231f1393e..129c159ab5ee 100644
    --- a/arch/s390/kvm/kvm-s390.c
    +++ b/arch/s390/kvm/kvm-s390.c
    @@ -248,12 +248,6 @@ debug_info_t *kvm_s390_dbf;
    debug_info_t *kvm_s390_dbf_uv;

    /* Section: not file related */
    -int kvm_arch_hardware_enable(void)
    -{
    - /* every s390 is virtualization enabled ;-) */
    - return 0;
    -}
    -
    /* forward declarations */
    static void kvm_gmap_notifier(struct gmap *gmap, unsigned long start,
    unsigned long end);
    diff --git a/arch/x86/kvm/Kconfig b/arch/x86/kvm/Kconfig
    index fbeaa9ddef59..8e578311ca9d 100644
    --- a/arch/x86/kvm/Kconfig
    +++ b/arch/x86/kvm/Kconfig
    @@ -49,6 +49,7 @@ config KVM
    select SRCU
    select INTERVAL_TREE
    select HAVE_KVM_PM_NOTIFIER if PM
    + select KVM_GENERIC_HARDWARE_ENABLING
    help
    Support hosting fully virtualized guest machines using hardware
    virtualization extensions. You will need a fairly recent
    diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
    index 0b96d836a051..23c89c1e7788 100644
    --- a/include/linux/kvm_host.h
    +++ b/include/linux/kvm_host.h
    @@ -1441,8 +1441,10 @@ void kvm_arch_create_vcpu_debugfs(struct kvm_vcpu *vcpu, struct dentry *debugfs_
    static inline void kvm_create_vcpu_debugfs(struct kvm_vcpu *vcpu) {}
    #endif

    +#ifdef CONFIG_KVM_GENERIC_HARDWARE_ENABLING
    int kvm_arch_hardware_enable(void);
    void kvm_arch_hardware_disable(void);
    +#endif
    int kvm_arch_vcpu_runnable(struct kvm_vcpu *vcpu);
    bool kvm_arch_vcpu_in_kernel(struct kvm_vcpu *vcpu);
    int kvm_arch_vcpu_should_kick(struct kvm_vcpu *vcpu);
    @@ -2074,7 +2076,9 @@ static inline bool kvm_check_request(int req, struct kvm_vcpu *vcpu)
    }
    }

    +#ifdef CONFIG_KVM_GENERIC_HARDWARE_ENABLING
    extern bool kvm_rebooting;
    +#endif

    extern unsigned int halt_poll_ns;
    extern unsigned int halt_poll_ns_grow;
    diff --git a/virt/kvm/Kconfig b/virt/kvm/Kconfig
    index 800f9470e36b..d28df77345e1 100644
    --- a/virt/kvm/Kconfig
    +++ b/virt/kvm/Kconfig
    @@ -86,3 +86,6 @@ config KVM_XFER_TO_GUEST_WORK

    config HAVE_KVM_PM_NOTIFIER
    bool
    +
    +config KVM_GENERIC_HARDWARE_ENABLING
    + bool
    diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
    index 859bc27091cd..6736b36cf469 100644
    --- a/virt/kvm/kvm_main.c
    +++ b/virt/kvm/kvm_main.c
    @@ -102,9 +102,6 @@ EXPORT_SYMBOL_GPL(halt_poll_ns_shrink);
    DEFINE_MUTEX(kvm_lock);
    LIST_HEAD(vm_list);

    -static DEFINE_PER_CPU(bool, hardware_enabled);
    -static int kvm_usage_count;
    -
    static struct kmem_cache *kvm_vcpu_cache;

    static __read_mostly struct preempt_ops kvm_preempt_ops;
    @@ -146,9 +143,6 @@ static void hardware_disable_all(void);

    static void kvm_io_bus_destroy(struct kvm_io_bus *bus);

    -__visible bool kvm_rebooting;
    -EXPORT_SYMBOL_GPL(kvm_rebooting);
    -
    #define KVM_EVENT_CREATE_VM 0
    #define KVM_EVENT_DESTROY_VM 1
    static void kvm_uevent_notify_change(unsigned int type, struct kvm *kvm);
    @@ -5005,6 +4999,13 @@ static struct miscdevice kvm_dev = {
    &kvm_chardev_ops,
    };

    +#ifdef CONFIG_KVM_GENERIC_HARDWARE_ENABLING
    +__visible bool kvm_rebooting;
    +EXPORT_SYMBOL_GPL(kvm_rebooting);
    +
    +static DEFINE_PER_CPU(bool, hardware_enabled);
    +static int kvm_usage_count;
    +
    static int __hardware_enable_nolock(void)
    {
    if (__this_cpu_read(hardware_enabled))
    @@ -5171,6 +5172,17 @@ static struct syscore_ops kvm_syscore_ops = {
    .suspend = kvm_suspend,
    .resume = kvm_resume,
    };
    +#else /* CONFIG_KVM_GENERIC_HARDWARE_ENABLING */
    +static int hardware_enable_all(void)
    +{
    + return 0;
    +}
    +
    +static void hardware_disable_all(void)
    +{
    +
    +}
    +#endif /* CONFIG_KVM_GENERIC_HARDWARE_ENABLING */

    static void kvm_io_bus_destroy(struct kvm_io_bus *bus)
    {
    @@ -5859,6 +5871,7 @@ int kvm_init(unsigned vcpu_size, unsigned vcpu_align, struct module *module)
    int r;
    int cpu;

    +#ifdef CONFIG_KVM_GENERIC_HARDWARE_ENABLING
    r = cpuhp_setup_state_nocalls(CPUHP_AP_KVM_ONLINE, "kvm/cpu:online",
    kvm_online_cpu, kvm_offline_cpu);
    if (r)
    @@ -5866,6 +5879,7 @@ int kvm_init(unsigned vcpu_size, unsigned vcpu_align, struct module *module)

    register_reboot_notifier(&kvm_reboot_notifier);
    register_syscore_ops(&kvm_syscore_ops);
    +#endif

    /* A kmem cache lets us meet the alignment requirements of fx_save. */
    if (!vcpu_align)
    @@ -5933,9 +5947,11 @@ int kvm_init(unsigned vcpu_size, unsigned vcpu_align, struct module *module)
    free_cpumask_var(per_cpu(cpu_kick_mask, cpu));
    kmem_cache_destroy(kvm_vcpu_cache);
    out_free_3:
    +#ifdef CONFIG_KVM_GENERIC_HARDWARE_ENABLING
    unregister_syscore_ops(&kvm_syscore_ops);
    unregister_reboot_notifier(&kvm_reboot_notifier);
    cpuhp_remove_state_nocalls(CPUHP_AP_KVM_ONLINE);
    +#endif
    return r;
    }
    EXPORT_SYMBOL_GPL(kvm_init);
    @@ -5957,9 +5973,11 @@ void kvm_exit(void)
    kmem_cache_destroy(kvm_vcpu_cache);
    kvm_vfio_ops_exit();
    kvm_async_pf_deinit();
    +#ifdef CONFIG_KVM_GENERIC_HARDWARE_ENABLING
    unregister_syscore_ops(&kvm_syscore_ops);
    unregister_reboot_notifier(&kvm_reboot_notifier);
    cpuhp_remove_state_nocalls(CPUHP_AP_KVM_ONLINE);
    +#endif
    kvm_irqfd_exit();
    }
    EXPORT_SYMBOL_GPL(kvm_exit);
    --
    2.38.1.431.g37b22c650d-goog
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