Date:   Wed, 5 Jan 2022 03:57:20 +0300
From:   "Kirill A. Shutemov" <kirill@shutemov.name>
To:     Dave Hansen <dave.hansen@intel.com>
Cc:     Borislav Petkov <bp@alien8.de>,
        "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
        Tom Lendacky <thomas.lendacky@amd.com>, tglx@linutronix.de,
        mingo@redhat.com, luto@kernel.org, peterz@infradead.org,
        sathyanarayanan.kuppuswamy@linux.intel.com, aarcange@redhat.com,
        ak@linux.intel.com, dan.j.williams@intel.com, david@redhat.com,
        hpa@zytor.com, jgross@suse.com, jmattson@google.com,
        joro@8bytes.org, jpoimboe@redhat.com, knsathya@kernel.org,
        pbonzini@redhat.com, sdeep@vmware.com, seanjc@google.com,
        tony.luck@intel.com, vkuznets@redhat.com, wanpengli@tencent.com,
        x86@kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 19/26] x86/tdx: Make pages shared in ioremap()
Message-ID: <20220105005720.zdtgwenqwqmuyxvi@box.shutemov.name>
References: <33914dc1-37e8-f0bb-6468-71c3b5f4169d@amd.com>
 <20220103141705.6hqflhwykqmtfim6@black.fi.intel.com>
 <YdMIWAT42el4D6wJ@zn.tnic>
 <20220103151516.pfcz2pap5l7r2rzv@box.shutemov.name>
 <b4b54116-1cd7-468a-0889-d497268cbfb2@intel.com>
 <20220103181059.ui5eloufw5gsojcb@box.shutemov.name>
 <20220104191424.oly2gqm4ltzj5wo3@box.shutemov.name>
 <0e0c38e2-67ad-1f51-c44b-d3c3d505e40a@intel.com>
 <20220105003108.mr7zyd5oyaaxmnmv@box.shutemov.name>
 <50dfa0db-fcd1-3c54-d982-237d2c9df431@intel.com>
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In-Reply-To: <50dfa0db-fcd1-3c54-d982-237d2c9df431@intel.com>
Precedence: bulk

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