linux-kernel - Re: [PATCH v1 08/11] x86/mm/pat: remove strict_prot parameter from reserve_pfn

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Message-ID: <fd641237-e412-4f32-98a6-b7d733e6819b@lucifer.local>
Date: Mon, 28 Apr 2025 21:18:39 +0100
From: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
To: David Hildenbrand <david@...hat.com>
Cc: linux-kernel@...r.kernel.org, linux-mm@...ck.org, x86@...nel.org,
        intel-gfx@...ts.freedesktop.org, dri-devel@...ts.freedesktop.org,
        linux-trace-kernel@...r.kernel.org,
        Dave Hansen <dave.hansen@...ux.intel.com>,
        Andy Lutomirski <luto@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Thomas Gleixner <tglx@...utronix.de>, Ingo Molnar <mingo@...hat.com>,
        Borislav Petkov <bp@...en8.de>, "H. Peter Anvin" <hpa@...or.com>,
        Jani Nikula <jani.nikula@...ux.intel.com>,
        Joonas Lahtinen <joonas.lahtinen@...ux.intel.com>,
        Rodrigo Vivi <rodrigo.vivi@...el.com>,
        Tvrtko Ursulin <tursulin@...ulin.net>,
        David Airlie <airlied@...il.com>, Simona Vetter <simona@...ll.ch>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Steven Rostedt <rostedt@...dmis.org>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Mathieu Desnoyers <mathieu.desnoyers@...icios.com>,
        "Liam R. Howlett" <Liam.Howlett@...cle.com>,
        Vlastimil Babka <vbabka@...e.cz>, Jann Horn <jannh@...gle.com>,
        Pedro Falcato <pfalcato@...e.de>, Peter Xu <peterx@...hat.com>
Subject: Re: [PATCH v1 08/11] x86/mm/pat: remove strict_prot parameter from
 reserve_pfn_range()

On Fri, Apr 25, 2025 at 10:17:12AM +0200, David Hildenbrand wrote:
> Always set to 0, so let's remove it.
>
> Signed-off-by: David Hildenbrand <david@...hat.com>

Ah yes here is where you remove it :)

Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>

> ---
>  arch/x86/mm/pat/memtype.c | 12 +++---------
>  1 file changed, 3 insertions(+), 9 deletions(-)
>
> diff --git a/arch/x86/mm/pat/memtype.c b/arch/x86/mm/pat/memtype.c
> index 668ebf0065157..57e3ced4c28cb 100644
> --- a/arch/x86/mm/pat/memtype.c
> +++ b/arch/x86/mm/pat/memtype.c
> @@ -858,8 +858,7 @@ int memtype_kernel_map_sync(u64 base, unsigned long size,
>   * Reserved non RAM regions only and after successful memtype_reserve,
>   * this func also keeps identity mapping (if any) in sync with this new prot.
>   */
> -static int reserve_pfn_range(u64 paddr, unsigned long size, pgprot_t *vma_prot,
> -				int strict_prot)
> +static int reserve_pfn_range(u64 paddr, unsigned long size, pgprot_t *vma_prot)
>  {
>  	int is_ram = 0;
>  	int ret;
> @@ -895,8 +894,7 @@ static int reserve_pfn_range(u64 paddr, unsigned long size, pgprot_t *vma_prot,
>  		return ret;
>
>  	if (pcm != want_pcm) {
> -		if (strict_prot ||
> -		    !is_new_memtype_allowed(paddr, size, want_pcm, pcm)) {
> +		if (!is_new_memtype_allowed(paddr, size, want_pcm, pcm)) {
>  			memtype_free(paddr, paddr + size);
>  			pr_err("x86/PAT: %s:%d map pfn expected mapping type %s for [mem %#010Lx-%#010Lx], got %s\n",
>  			       current->comm, current->pid,
> @@ -906,10 +904,6 @@ static int reserve_pfn_range(u64 paddr, unsigned long size, pgprot_t *vma_prot,
>  			       cattr_name(pcm));
>  			return -EINVAL;
>  		}
> -		/*
> -		 * We allow returning different type than the one requested in
> -		 * non strict case.
> -		 */
>  		pgprot_set_cachemode(vma_prot, pcm);
>  	}
>
> @@ -959,7 +953,7 @@ int pfnmap_track(unsigned long pfn, unsigned long size, pgprot_t *prot)
>  {
>  	const resource_size_t paddr = (resource_size_t)pfn << PAGE_SHIFT;
>
> -	return reserve_pfn_range(paddr, size, prot, 0);
> +	return reserve_pfn_range(paddr, size, prot);
>  }
>
>  void pfnmap_untrack(unsigned long pfn, unsigned long size)
> --
> 2.49.0
>