linux-kernel - Re: [PATCH 02/19] x86/fpu: Prepare KVM for dynamically enabled states

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Date:   Mon, 13 Dec 2021 10:12:22 +0100
From:   Paolo Bonzini <pbonzini@...hat.com>
To:     Yang Zhong <yang.zhong@...el.com>, x86@...nel.org,
        kvm@...r.kernel.org, linux-kernel@...r.kernel.org,
        tglx@...utronix.de, mingo@...hat.com, bp@...en8.de,
        dave.hansen@...ux.intel.com
Cc:     seanjc@...gle.com, jun.nakajima@...el.com, kevin.tian@...el.com,
        jing2.liu@...ux.intel.com, jing2.liu@...el.com
Subject: Re: [PATCH 02/19] x86/fpu: Prepare KVM for dynamically enabled states

On 12/8/21 01:03, Yang Zhong wrote:
>    - user_xfeatures
> 
>      Track which features are currently enabled for the vCPU

Please rename to alloc_xfeatures

>    - user_perm
> 
>      Copied from guest_perm of the group leader thread. The first
>      vCPU which does the copy locks the guest_perm

Please rename to perm_xfeatures.

>    - realloc_request
> 
>      KVM sets this field to request dynamically-enabled features
>      which require reallocation of @fpstate

This field should be in vcpu->arch, and there is no need for 
fpu_guest_realloc_fpstate.  Rename __xfd_enable_feature to 
fpu_enable_xfd_feature and add it to the public API, then just do

	if (unlikely(vcpu->arch.xfd_realloc_request)) {
		u64 request = vcpu->arch.xfd_realloc_request;
		ret = fpu_enable_xfd(request, enter_guest);
	}

to kvm_put_guest_fpu.

Paolo