linux-kernel - Re: [PATCH v19 027/130] KVM: TDX: Define TDX architectural definitions

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Date: Fri, 22 Mar 2024 10:57:53 +1300
From: "Huang, Kai" <kai.huang@...el.com>
To: "Yamahata, Isaku" <isaku.yamahata@...el.com>, "kvm@...r.kernel.org"
	<kvm@...r.kernel.org>, "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>
CC: "isaku.yamahata@...il.com" <isaku.yamahata@...il.com>, Paolo Bonzini
	<pbonzini@...hat.com>, "Aktas, Erdem" <erdemaktas@...gle.com>, "Sean
 Christopherson" <seanjc@...gle.com>, Sagi Shahar <sagis@...gle.com>, "Chen,
 Bo2" <chen.bo@...el.com>, "Yuan, Hang" <hang.yuan@...el.com>, "Zhang, Tina"
	<tina.zhang@...el.com>, Sean Christopherson
	<sean.j.christopherson@...el.com>, "Li, Xiaoyao" <Xiaoyao.Li@...el.com>
Subject: Re: [PATCH v19 027/130] KVM: TDX: Define TDX architectural
 definitions


> +/*
> + * TDX SEAMCALL API function leaves
> + */
> +#define TDH_VP_ENTER			0
> +#define TDH_MNG_ADDCX			1
> +#define TDH_MEM_PAGE_ADD		2
> +#define TDH_MEM_SEPT_ADD		3
> +#define TDH_VP_ADDCX			4
> +#define TDH_MEM_PAGE_RELOCATE		5

I don't think the "RELOCATE" is needed in this patchset?

> +#define TDH_MEM_PAGE_AUG		6
> +#define TDH_MEM_RANGE_BLOCK		7
> +#define TDH_MNG_KEY_CONFIG		8
> +#define TDH_MNG_CREATE			9
> +#define TDH_VP_CREATE			10
> +#define TDH_MNG_RD			11
> +#define TDH_MR_EXTEND			16
> +#define TDH_MR_FINALIZE			17
> +#define TDH_VP_FLUSH			18
> +#define TDH_MNG_VPFLUSHDONE		19
> +#define TDH_MNG_KEY_FREEID		20
> +#define TDH_MNG_INIT			21
> +#define TDH_VP_INIT			22
> +#define TDH_MEM_SEPT_RD			25
> +#define TDH_VP_RD			26
> +#define TDH_MNG_KEY_RECLAIMID		27
> +#define TDH_PHYMEM_PAGE_RECLAIM		28
> +#define TDH_MEM_PAGE_REMOVE		29
> +#define TDH_MEM_SEPT_REMOVE		30
> +#define TDH_SYS_RD			34
> +#define TDH_MEM_TRACK			38
> +#define TDH_MEM_RANGE_UNBLOCK		39
> +#define TDH_PHYMEM_CACHE_WB		40
> +#define TDH_PHYMEM_PAGE_WBINVD		41
> +#define TDH_VP_WR			43
> +#define TDH_SYS_LP_SHUTDOWN		44

And LP_SHUTDOWN is certainly not needed.

Could you check whether there are others that are not needed?

Perhaps we should just include macros that got used, but anyway.

[...]

> +
> +/*
> + * TD_PARAMS is provided as an input to TDH_MNG_INIT, the size of which is 1024B.
> + */

Why is this comment applied to TDX_MAX_VCPUS?

> +#define TDX_MAX_VCPUS	(~(u16)0)

And is (~(16)0) an architectural value defined by TDX spec, or just SW 
value that you just put here for convenience?

I mean, is it possible that different version of TDX module have 
different implementation of MAX_CPU, e.g., module 1.0 only supports X 
but module 1.5 increases to Y where Y > X?

Anyway, looks you can safely move this to the patch to enable CAP_MAX_CPU?

> +
> +struct td_params {
> +	u64 attributes;
> +	u64 xfam;
> +	u16 max_vcpus;
> +	u8 reserved0[6];
> +
> +	u64 eptp_controls;
> +	u64 exec_controls;
> +	u16 tsc_frequency;
> +	u8  reserved1[38];
> +
> +	u64 mrconfigid[6];
> +	u64 mrowner[6];
> +	u64 mrownerconfig[6];
> +	u64 reserved2[4];
> +
> +	union {
> +		DECLARE_FLEX_ARRAY(struct tdx_cpuid_value, cpuid_values);
> +		u8 reserved3[768];

I am not sure you need the 'reseved3[768]', unless you need to make 
sieof(struct td_params) return 1024?

> +	};
> +} __packed __aligned(1024); > +

[...]

> +
> +#define TDX_MD_ELEMENT_SIZE_8BITS      0
> +#define TDX_MD_ELEMENT_SIZE_16BITS     1
> +#define TDX_MD_ELEMENT_SIZE_32BITS     2
> +#define TDX_MD_ELEMENT_SIZE_64BITS     3
> +
> +union tdx_md_field_id {
> +	struct {
> +		u64 field                       : 24;
> +		u64 reserved0                   : 8;
> +		u64 element_size_code           : 2;
> +		u64 last_element_in_field       : 4;
> +		u64 reserved1                   : 3;
> +		u64 inc_size                    : 1;
> +		u64 write_mask_valid            : 1;
> +		u64 context                     : 3;
> +		u64 reserved2                   : 1;
> +		u64 class                       : 6;
> +		u64 reserved3                   : 1;
> +		u64 non_arch                    : 1;
> +	};
> +	u64 raw;
> +};

Could you clarify why we need such detailed definition?  For metadata 
element size you can use simple '&' and '<<' to get the result.

> +
> +#define TDX_MD_ELEMENT_SIZE_CODE(_field_id)			\
> +	({ union tdx_md_field_id _fid = { .raw = (_field_id)};  \
> +		_fid.element_size_code; })
> +
> +#endif /* __KVM_X86_TDX_ARCH_H */