Re: [PATCHv7 14/14] x86/tdx: Add unaccepted memory support

Kirill A. Shutemov
2022-06-27T10:42:19Z

On Fri, Jun 24, 2022 at 09:22:03AM -0700, Dave Hansen wrote:
> On 6/14/22 05:02, Kirill A. Shutemov wrote:
> > static inline void __accept_memory(phys_addr_t start, phys_addr_t end)
> > {
> > /* Platform-specific memory-acceptance call goes here */
> > - error("Cannot accept memory");
> > + if (is_tdx_guest())
> > + tdx_accept_memory(start, end);
> > + else
> > + error("Cannot accept memory: unknown platform\n");
> > }
>
> There are quite a few of these
>
> if (tdx())
> ...
>
> conditions in common code here. Shouldn't this be something like a
> CC_ATTR_MEM_ACCEPT?
>
> if (cc_platform_has(CC_ATTR_MEM_ACCEPT))
> cc_accept_memory(...);
> else
> error("Cannot accept memory: unknown platform\n");
>
> I understand that TDX is the first one to the party. Is this the time
> to add the cc_ infrastructure?

We need if tdx() check *somewhere* as how exactly memory gets accepted is
specific to a particular platform.

There are two callsites where memory acceptance happens. One of them is in
boot stub where we don't have cc_ infrastructure. So it will boil down to
a single cc_accept_memory() that will have 'if tdx()' inside.

I don't see much sense in the exercise. We can as well keep the 'if' in
accept_memory().

--
Kirill A. Shutemov