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

[Kirill A. Shutemov]

On Wed, Jan 05, 2022 at 03:57:20AM +0300, Kirill A. Shutemov wrote:
> 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.

Ah. I guess you compiled 64-bit sparc, right? STRICT_MM_TYPECHECKS is
default there, unline 32-bit.

-- 
 Kirill A. Shutemov