linux-kernel - Re: [PATCH v18 007/121] KVM: VMX: Reorder vmx initialization with kvm vendor initialization

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Date: Thu, 1 Feb 2024 09:47:14 +0800
From: Xiaoyao Li <xiaoyao.li@...el.com>
To: isaku.yamahata@...el.com, kvm@...r.kernel.org,
 linux-kernel@...r.kernel.org
Cc: isaku.yamahata@...il.com, Paolo Bonzini <pbonzini@...hat.com>,
 erdemaktas@...gle.com, Sean Christopherson <seanjc@...gle.com>,
 Sagi Shahar <sagis@...gle.com>, Kai Huang <kai.huang@...el.com>,
 chen.bo@...el.com, hang.yuan@...el.com, tina.zhang@...el.com
Subject: Re: [PATCH v18 007/121] KVM: VMX: Reorder vmx initialization with kvm
 vendor initialization

On 1/23/2024 7:52 AM, isaku.yamahata@...el.com wrote:
> From: Isaku Yamahata <isaku.yamahata@...el.com>
> 
> To match vmx_exit cleanup.  Now vmx_init() is before kvm_x86_vendor_init(),
> vmx_init() can initialize loaded_vmcss_on_cpu.  Oppertunistically move it
> back into vmx_init().

It sort of does a revert of Patch 05. Though I still don't get the 
reason why we need Patch 05, why not move this patch before patch 06, 
then we can drop Patch 05 and of course the revert part of this patch?

> Signed-off-by: Isaku Yamahata <isaku.yamahata@...el.com>
> ---
> v18:
> - move the loaded_vmcss_on_cpu initialization to vmx_init().
> - fix error path of vt_init(). by Chao and Binbin
> ---
>   arch/x86/kvm/vmx/main.c    | 17 +++++++----------
>   arch/x86/kvm/vmx/vmx.c     |  6 ++++--
>   arch/x86/kvm/vmx/x86_ops.h |  2 --
>   3 files changed, 11 insertions(+), 14 deletions(-)
> 
> diff --git a/arch/x86/kvm/vmx/main.c b/arch/x86/kvm/vmx/main.c
> index 18cecf12c7c8..443db8ec5cd5 100644
> --- a/arch/x86/kvm/vmx/main.c
> +++ b/arch/x86/kvm/vmx/main.c
> @@ -171,7 +171,7 @@ struct kvm_x86_init_ops vt_init_ops __initdata = {
>   static int __init vt_init(void)
>   {
>   	unsigned int vcpu_size, vcpu_align;
> -	int cpu, r;
> +	int r;
>   
>   	if (!kvm_is_vmx_supported())
>   		return -EOPNOTSUPP;
> @@ -182,18 +182,14 @@ static int __init vt_init(void)
>   	 */
>   	hv_init_evmcs();
>   
> -	/* vmx_hardware_disable() accesses loaded_vmcss_on_cpu. */
> -	for_each_possible_cpu(cpu)
> -		INIT_LIST_HEAD(&per_cpu(loaded_vmcss_on_cpu, cpu));
> -
> -	r = kvm_x86_vendor_init(&vt_init_ops);
> -	if (r)
> -		return r;
> -
>   	r = vmx_init();
>   	if (r)
>   		goto err_vmx_init;
>   
> +	r = kvm_x86_vendor_init(&vt_init_ops);
> +	if (r)
> +		goto err_vendor_init;
> +
>   	/*
>   	 * Common KVM initialization _must_ come last, after this, /dev/kvm is
>   	 * exposed to userspace!
> @@ -207,9 +203,10 @@ static int __init vt_init(void)
>   	return 0;
>   
>   err_kvm_init:
> +	kvm_x86_vendor_exit();
> +err_vendor_init:
>   	vmx_exit();
>   err_vmx_init:
> -	kvm_x86_vendor_exit();
>   	return r;
>   }
>   module_init(vt_init);
> diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
> index 8efb956591d5..3f4dad3acb13 100644
> --- a/arch/x86/kvm/vmx/vmx.c
> +++ b/arch/x86/kvm/vmx/vmx.c
> @@ -477,7 +477,7 @@ DEFINE_PER_CPU(struct vmcs *, current_vmcs);
>    * We maintain a per-CPU linked-list of VMCS loaded on that CPU. This is needed
>    * when a CPU is brought down, and we need to VMCLEAR all VMCSs loaded on it.
>    */
> -DEFINE_PER_CPU(struct list_head, loaded_vmcss_on_cpu);
> +static DEFINE_PER_CPU(struct list_head, loaded_vmcss_on_cpu);
>   
>   static DECLARE_BITMAP(vmx_vpid_bitmap, VMX_NR_VPIDS);
>   static DEFINE_SPINLOCK(vmx_vpid_lock);
> @@ -8528,8 +8528,10 @@ int __init vmx_init(void)
>   	if (r)
>   		return r;
>   
> -	for_each_possible_cpu(cpu)
> +	for_each_possible_cpu(cpu) {
> +		INIT_LIST_HEAD(&per_cpu(loaded_vmcss_on_cpu, cpu));
>   		pi_init_cpu(cpu);
> +	}
>   
>   	cpu_emergency_register_virt_callback(vmx_emergency_disable);
>   
> diff --git a/arch/x86/kvm/vmx/x86_ops.h b/arch/x86/kvm/vmx/x86_ops.h
> index b936388853ab..bca2d27b3dfd 100644
> --- a/arch/x86/kvm/vmx/x86_ops.h
> +++ b/arch/x86/kvm/vmx/x86_ops.h
> @@ -14,8 +14,6 @@ static inline __init void hv_init_evmcs(void) {}
>   static inline void hv_reset_evmcs(void) {}
>   #endif /* IS_ENABLED(CONFIG_HYPERV) */
>   
> -DECLARE_PER_CPU(struct list_head, loaded_vmcss_on_cpu);
> -
>   bool kvm_is_vmx_supported(void);
>   int __init vmx_init(void);
>   void vmx_exit(void);