linux-kernel - Re: [PATCH 10/25] KVM: TDX: Initialize KVM supported capabilities when module setup

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Message-ID: <b8ed694f-3ab1-453c-b14b-25113defbdb6@suse.com>
Date: Mon, 26 Aug 2024 14:04:27 +0300
From: Nikolay Borisov <nik.borisov@...e.com>
To: Rick Edgecombe <rick.p.edgecombe@...el.com>, seanjc@...gle.com,
 pbonzini@...hat.com, kvm@...r.kernel.org
Cc: kai.huang@...el.com, isaku.yamahata@...il.com,
 tony.lindgren@...ux.intel.com, xiaoyao.li@...el.com,
 linux-kernel@...r.kernel.org
Subject: Re: [PATCH 10/25] KVM: TDX: Initialize KVM supported capabilities
 when module setup



On 13.08.24 г. 1:48 ч., Rick Edgecombe wrote:
> From: Xiaoyao Li <xiaoyao.li@...el.com>
> 
> While TDX module reports a set of capabilities/features that it
> supports, what KVM currently supports might be a subset of them.
> E.g., DEBUG and PERFMON are supported by TDX module but currently not
> supported by KVM.
> 
> Introduce a new struct kvm_tdx_caps to store KVM's capabilities of TDX.
> supported_attrs and suppported_xfam are validated against fixed0/1
> values enumerated by TDX module. Configurable CPUID bits derive from TDX
> module plus applying KVM's capabilities (KVM_GET_SUPPORTED_CPUID),
> i.e., mask off the bits that are configurable in the view of TDX module
> but not supported by KVM yet.
> 
> KVM_TDX_CPUID_NO_SUBLEAF is the concept from TDX module, switch it to 0
> and use KVM_CPUID_FLAG_SIGNIFCANT_INDEX, which are the concept of KVM.
> 
> Signed-off-by: Xiaoyao Li <xiaoyao.li@...el.com>
> Signed-off-by: Rick Edgecombe <rick.p.edgecombe@...el.com>
> ---
> uAPI breakout v1:
>   - Change setup_kvm_tdx_caps() to use the exported 'struct tdx_sysinfo'
>     pointer.
>   - Change how to copy 'kvm_tdx_cpuid_config' since 'struct tdx_sysinfo'
>     doesn't have 'kvm_tdx_cpuid_config'.
>   - Updates for uAPI changes
> ---

<snip>


> +
>   static int tdx_online_cpu(unsigned int cpu)
>   {
>   	unsigned long flags;
> @@ -217,11 +292,16 @@ static int __init __tdx_bringup(void)
>   		goto get_sysinfo_err;
>   	}
>   
> +	r = setup_kvm_tdx_caps();

nit: Since there are other similarly named functions that come later how 
about rename this to init_kvm_tdx_caps, so that it's clear that the 
functions that are executed ones are prefixed with "init_" and those 
that will be executed on every TDV boot up can be named prefixed with 
"setup_"


> +	if (r)
> +		goto get_sysinfo_err;
> +
>   	/*
>   	 * Leave hardware virtualization enabled after TDX is enabled
>   	 * successfully.  TDX CPU hotplug depends on this.
>   	 */
>   	return 0;
> +
>   get_sysinfo_err:
>   	__do_tdx_cleanup();
>   tdx_bringup_err:
> @@ -232,6 +312,7 @@ static int __init __tdx_bringup(void)
>   void tdx_cleanup(void)
>   {
>   	if (enable_tdx) {
> +		free_kvm_tdx_cap();
>   		__do_tdx_cleanup();
>   		kvm_disable_virtualization();
>   	}