Re: [PATCH 19/26] x86/tdx: Make pages shared in ioremap()

[Kirill A. Shutemov]

On Tue, Jan 04, 2022 at 04:43:09PM -0800, Dave Hansen wrote:
> On 1/4/22 4:31 PM, Kirill A. Shutemov wrote:
> > On Tue, Jan 04, 2022 at 12:36:06PM -0800, Dave Hansen wrote:
> >> @@ -57,7 +58,6 @@ typedef struct { unsigned long iopte; }
> >>  typedef struct { unsigned long pmd; } pmd_t;
> >>  typedef struct { unsigned long pgd; } pgd_t;
> >>  typedef struct { unsigned long ctxd; } ctxd_t;
> >> -typedef struct { unsigned long pgprot; } pgprot_t;
> >>  typedef struct { unsigned long iopgprot; } iopgprot_t;
> >>  
> >>  #define pte_val(x)	((x).pte)
> >> @@ -85,7 +85,6 @@ typedef unsigned long iopte_t;
> >>  typedef unsigned long pmd_t;
> >>  typedef unsigned long pgd_t;
> >>  typedef unsigned long ctxd_t;
> >> -typedef unsigned long pgprot_t;
> >>  typedef unsigned long iopgprot_t;
> >>  
> >>  #define pte_val(x)	(x)
> > 
> > Any arch that use STRICT_MM_TYPECHECKS hacks will get broken if compiled
> > without the define (as sparc by default).
> 
> My read of STRICT_MM_TYPECHECKS was that "typedef unsigned long
> pgprot_t" produces better code, but "typedef struct { unsigned long
> pgprot; } pgprot_t;" produces better type checking.

Apart from pgprot_t, __pgprot() and pgrot_val() helpers are defined
differently depending on STRICT_MM_TYPECHECKS.

> I just compiled these patches on sparc with no issues.

Hm. I can't see how

#define pgprot_val(x)	(x)

can work to access value for the pgprot_t defined as a struct.

-- 
 Kirill A. Shutemov