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

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Message-ID: <caa4407a-b838-4e1b-bb3d-87518f3de66b@suse.com>
Date: Wed, 4 Sep 2024 14:58:48 +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
> ---
>   arch/x86/include/uapi/asm/kvm.h |  2 -
>   arch/x86/kvm/vmx/tdx.c          | 81 +++++++++++++++++++++++++++++++++
>   2 files changed, 81 insertions(+), 2 deletions(-)
> 
> diff --git a/arch/x86/include/uapi/asm/kvm.h b/arch/x86/include/uapi/asm/kvm.h
> index 47caf508cca7..c9eb2e2f5559 100644
> --- a/arch/x86/include/uapi/asm/kvm.h
> +++ b/arch/x86/include/uapi/asm/kvm.h
> @@ -952,8 +952,6 @@ struct kvm_tdx_cmd {
>   	__u64 hw_error;
>   };
>   
> -#define KVM_TDX_CPUID_NO_SUBLEAF	((__u32)-1)
> -
>   struct kvm_tdx_cpuid_config {
>   	__u32 leaf;
>   	__u32 sub_leaf;
> diff --git a/arch/x86/kvm/vmx/tdx.c b/arch/x86/kvm/vmx/tdx.c
> index 90b44ebaf864..d89973e554f6 100644
> --- a/arch/x86/kvm/vmx/tdx.c
> +++ b/arch/x86/kvm/vmx/tdx.c
> @@ -31,6 +31,19 @@ static void __used tdx_guest_keyid_free(int keyid)
>   	ida_free(&tdx_guest_keyid_pool, keyid);
>   }
>   
> +#define KVM_TDX_CPUID_NO_SUBLEAF	((__u32)-1)
> +
> +struct kvm_tdx_caps {
> +	u64 supported_attrs;
> +	u64 supported_xfam;
> +
> +	u16 num_cpuid_config;
> +	/* This must the last member. */
> +	DECLARE_FLEX_ARRAY(struct kvm_tdx_cpuid_config, cpuid_configs);
> +};
> +
> +static struct kvm_tdx_caps *kvm_tdx_caps;
> +
>   static int tdx_get_capabilities(struct kvm_tdx_cmd *cmd)
>   {
>   	const struct tdx_sysinfo_td_conf *td_conf = &tdx_sysinfo->td_conf;
> @@ -131,6 +144,68 @@ int tdx_vm_ioctl(struct kvm *kvm, void __user *argp)
>   	return r;
>   }
>   
> +#define KVM_SUPPORTED_TD_ATTRS (TDX_TD_ATTR_SEPT_VE_DISABLE)

Why isn't TDX_TD_ATTR_DEBUG added as well?

<snip>