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Message-ID: <e4604ad23788a6d2950c091d04b7b805684a1a01.camel@intel.com>
Subject: Re: [PATCH v7 002/102] Partially revert "KVM: Pass kvm_init()'s
 opaque param to additional arch funcs"
From:   Kai Huang <kai.huang@intel.com>
To:     isaku.yamahata@intel.com, kvm@vger.kernel.org,
        linux-kernel@vger.kernel.org
Cc:     isaku.yamahata@gmail.com, Paolo Bonzini <pbonzini@redhat.com>,
        Chao Gao <chao.gao@intel.com>,
        Sean Christopherson <seanjc@google.com>,
        Suzuki K Poulose <suzuki.poulose@arm.com>,
        Anup Patel <anup@brainfault.org>,
        Claudio Imbrenda <imbrenda@linux.ibm.com>
Date:   Wed, 13 Jul 2022 13:55:46 +1200
In-Reply-To: <4566737e3c57c5ab17c0bc29d6f4758744b6eed1.1656366337.git.isaku.yamahata@intel.com>
References: <cover.1656366337.git.isaku.yamahata@intel.com>
         <4566737e3c57c5ab17c0bc29d6f4758744b6eed1.1656366337.git.isaku.yamahata@intel.com>
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On Mon, 2022-06-27 at 14:52 -0700, isaku.yamahata@intel.com wrote:
> From: Chao Gao <chao.gao@intel.com>
>=20
> This partially reverts commit b99040853738 ("KVM: Pass kvm_init()'s opaqu=
e
> param to additional arch funcs") remove opaque from
> kvm_arch_check_processor_compat because no one uses this opaque now.
> Address conflicts for ARM (due to file movement) and manually handle RISC=
-V
> which comes after the commit.
>=20
> And changes about kvm_arch_hardware_setup() in original commit are still
> needed so they are not reverted.

I tried to dig the history to find out why we are doing this.

IMHO it's better to give a reason why you need to revert the opaque.  I gue=
ss no
one uses this opaque now doesn't mean we need to remove it?

Perhaps you should mention this is a preparation to
hardware_enable_all()/hardware_disable_all() during module loading time.=
=20
Instead of extending hardware_enable_all()/hardware_disable_all() to take t=
he
opaque and pass to kvm_arch_check_process_compat(), just remove the opaque.

Or perhaps just merge this patch to next one?

>=20
> Signed-off-by: Chao Gao <chao.gao@intel.com>
> Reviewed-by: Sean Christopherson <seanjc@google.com>
> Reviewed-by: Suzuki K Poulose <suzuki.poulose@arm.com>
> Acked-by: Anup Patel <anup@brainfault.org>
> Acked-by: Claudio Imbrenda <imbrenda@linux.ibm.com>
> Link: https://lore.kernel.org/r/20220216031528.92558-3-chao.gao@intel.com
> Signed-off-by: Isaku Yamahata <isaku.yamahata@intel.com>
> ---
>  arch/arm64/kvm/arm.c       |  2 +-
>  arch/mips/kvm/mips.c       |  2 +-
>  arch/powerpc/kvm/powerpc.c |  2 +-
>  arch/riscv/kvm/main.c      |  2 +-
>  arch/s390/kvm/kvm-s390.c   |  2 +-
>  arch/x86/kvm/x86.c         |  2 +-
>  include/linux/kvm_host.h   |  2 +-
>  virt/kvm/kvm_main.c        | 16 +++-------------
>  8 files changed, 10 insertions(+), 20 deletions(-)
>=20
> diff --git a/arch/arm64/kvm/arm.c b/arch/arm64/kvm/arm.c
> index a0188144a122..7588efbac6be 100644
> --- a/arch/arm64/kvm/arm.c
> +++ b/arch/arm64/kvm/arm.c
> @@ -68,7 +68,7 @@ int kvm_arch_hardware_setup(void *opaque)
>  	return 0;
>  }
> =20
> -int kvm_arch_check_processor_compat(void *opaque)
> +int kvm_arch_check_processor_compat(void)
>  {
>  	return 0;
>  }
> diff --git a/arch/mips/kvm/mips.c b/arch/mips/kvm/mips.c
> index a25e0b73ee70..092d09fb6a7e 100644
> --- a/arch/mips/kvm/mips.c
> +++ b/arch/mips/kvm/mips.c
> @@ -140,7 +140,7 @@ int kvm_arch_hardware_setup(void *opaque)
>  	return 0;
>  }
> =20
> -int kvm_arch_check_processor_compat(void *opaque)
> +int kvm_arch_check_processor_compat(void)
>  {
>  	return 0;
>  }
> diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c
> index 191992fcb2c2..ca8ef51092c6 100644
> --- a/arch/powerpc/kvm/powerpc.c
> +++ b/arch/powerpc/kvm/powerpc.c
> @@ -446,7 +446,7 @@ int kvm_arch_hardware_setup(void *opaque)
>  	return 0;
>  }
> =20
> -int kvm_arch_check_processor_compat(void *opaque)
> +int kvm_arch_check_processor_compat(void)
>  {
>  	return kvmppc_core_check_processor_compat();
>  }
> diff --git a/arch/riscv/kvm/main.c b/arch/riscv/kvm/main.c
> index 1549205fe5fe..f8d6372d208f 100644
> --- a/arch/riscv/kvm/main.c
> +++ b/arch/riscv/kvm/main.c
> @@ -20,7 +20,7 @@ long kvm_arch_dev_ioctl(struct file *filp,
>  	return -EINVAL;
>  }
> =20
> -int kvm_arch_check_processor_compat(void *opaque)
> +int kvm_arch_check_processor_compat(void)
>  {
>  	return 0;
>  }
> diff --git a/arch/s390/kvm/kvm-s390.c b/arch/s390/kvm/kvm-s390.c
> index 72bd5c9b9617..a05493f1cacf 100644
> --- a/arch/s390/kvm/kvm-s390.c
> +++ b/arch/s390/kvm/kvm-s390.c
> @@ -251,7 +251,7 @@ int kvm_arch_hardware_enable(void)
>  	return 0;
>  }
> =20
> -int kvm_arch_check_processor_compat(void *opaque)
> +int kvm_arch_check_processor_compat(void)
>  {
>  	return 0;
>  }
> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
> index 3d9dbaf9828f..30af2bd0b4d5 100644
> --- a/arch/x86/kvm/x86.c
> +++ b/arch/x86/kvm/x86.c
> @@ -11799,7 +11799,7 @@ void kvm_arch_hardware_unsetup(void)
>  	static_call(kvm_x86_hardware_unsetup)();
>  }
> =20
> -int kvm_arch_check_processor_compat(void *opaque)
> +int kvm_arch_check_processor_compat(void)
>  {
>  	struct cpuinfo_x86 *c =3D &cpu_data(smp_processor_id());
> =20
> diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
> index c20f2d55840c..d4f130a9f5c8 100644
> --- a/include/linux/kvm_host.h
> +++ b/include/linux/kvm_host.h
> @@ -1442,7 +1442,7 @@ int kvm_arch_hardware_enable(void);
>  void kvm_arch_hardware_disable(void);
>  int kvm_arch_hardware_setup(void *opaque);
>  void kvm_arch_hardware_unsetup(void);
> -int kvm_arch_check_processor_compat(void *opaque);
> +int kvm_arch_check_processor_compat(void);
>  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);
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index a67e996cbf7f..a5bada53f1fe 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -5697,22 +5697,14 @@ void kvm_unregister_perf_callbacks(void)
>  }
>  #endif
> =20
> -struct kvm_cpu_compat_check {
> -	void *opaque;
> -	int *ret;
> -};
> -
> -static void check_processor_compat(void *data)
> +static void check_processor_compat(void *rtn)
>  {
> -	struct kvm_cpu_compat_check *c =3D data;
> -
> -	*c->ret =3D kvm_arch_check_processor_compat(c->opaque);
> +	*(int *)rtn =3D kvm_arch_check_processor_compat();
>  }
> =20
>  int kvm_init(void *opaque, unsigned vcpu_size, unsigned vcpu_align,
>  		  struct module *module)
>  {
> -	struct kvm_cpu_compat_check c;
>  	int r;
>  	int cpu;
> =20
> @@ -5740,10 +5732,8 @@ int kvm_init(void *opaque, unsigned vcpu_size, uns=
igned vcpu_align,
>  	if (r < 0)
>  		goto out_free_1;
> =20
> -	c.ret =3D &r;
> -	c.opaque =3D opaque;
>  	for_each_online_cpu(cpu) {
> -		smp_call_function_single(cpu, check_processor_compat, &c, 1);
> +		smp_call_function_single(cpu, check_processor_compat, &r, 1);
>  		if (r < 0)
>  			goto out_free_2;
>  	}