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

[Isaku Yamahata]

On Fri, Mar 22, 2024 at 10:57:53AM +1300,
"Huang, Kai" <kai.huang@xxxxxxxxx> wrote:

> 
> > +/*
> > + * 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.

Ok, let's break this patch into other patches that uses the constants first.


> > +/*
> > + * 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?

This is architectural because it the field width is 16 bits.  Each version
of TDX module may have their own limitation with metadata, MAX_VCPUS_PER_TD.


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

Yes.


> > +
> > +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?

I'm trying to make it 1024 because the spec defines the struct size is 1024.
Maybe I can add BUILD_BUG_ON(sizeof(struct td_params) != 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.

Now your TDX host patch has the definition in arch/x86/include/asm/tdx.h,
I'll eliminate this one here and use your definition.
-- 
Isaku Yamahata <isaku.yamahata@xxxxxxxxx>