linux-kernel - Re: [PATCH v2 2/7] KVM: x86: Extract VMXON and EFER.SVME enablement to kernel

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Message-ID: <04886fe0-a796-4265-abd9-56bfe3a0aa0c@intel.com>
Date: Fri, 19 Dec 2025 10:48:38 -0800
From: Dave Hansen <dave.hansen@...el.com>
To: Sean Christopherson <seanjc@...gle.com>
Cc: Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>,
 Borislav Petkov <bp@...en8.de>, Dave Hansen <dave.hansen@...ux.intel.com>,
 x86@...nel.org, Kiryl Shutsemau <kas@...nel.org>,
 Paolo Bonzini <pbonzini@...hat.com>, linux-kernel@...r.kernel.org,
 linux-coco@...ts.linux.dev, kvm@...r.kernel.org,
 Chao Gao <chao.gao@...el.com>, Dan Williams <dan.j.williams@...el.com>
Subject: Re: [PATCH v2 2/7] KVM: x86: Extract VMXON and EFER.SVME enablement
 to kernel

On 12/19/25 10:35, Sean Christopherson wrote:
> I haven't tested yet, but I've got this:
> 
>   struct x86_virt_ops {
> 	int feature;
> 	int (*enable_virtualization_cpu)(void);
> 	int (*disable_virtualization_cpu)(void);
> 	void (*emergency_disable_virtualization_cpu)(void);
>   };
>   static struct x86_virt_ops virt_ops __ro_after_init;
> 
> and then usage like:
> 
>   int x86_virt_get_ref(int feat)
>   {
> 	int r;
> 
> 	if (!virt_ops.feature || virt_ops.feature != feat)
> 		return -EOPNOTSUPP;
> 
> 	if (this_cpu_inc_return(virtualization_nr_users) > 1)
> 		return 0;
> 
> 	r = virt_ops.enable_virtualization_cpu();
> 	if (r)
> 		WARN_ON_ONCE(this_cpu_dec_return(virtualization_nr_users));
> 
> 	return r;
>   }
>   EXPORT_SYMBOL_GPL(x86_virt_get_ref);

Yeah, that's much easier to follow, and fixes the naming collision thanks!