linux-kernel - Re: [PATCH] x86/efi: Always map boot service regions into new EFI page tables

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Date:	Mon, 14 Mar 2016 11:30:19 +0100
From:	Ingo Molnar <mingo@...nel.org>
To:	Matt Fleming <matt@...eblueprint.co.uk>
Cc:	Scott Ashcroft <scott.ashcroft@...k21.com>,
	"H . Peter Anvin" <hpa@...or.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ard Biesheuvel <ard.biesheuvel@...aro.org>,
	linux-kernel@...r.kernel.org, linux-efi@...r.kernel.org,
	Maarten Lankhorst <maarten.lankhorst@...ux.intel.com>,
	Matthew Garrett <mjg59@...f.ucam.org>,
	Borislav Petkov <bp@...en8.de>,
	Ben Hutchings <ben@...adent.org.uk>,
	Raphael Hertzog <hertzog@...ian.org>,
	Roger Shimizu <rogershimizu@...il.com>,
	Alexis Murzeau <amurzeau@...il.com>
Subject: Re: [PATCH] x86/efi: Always map boot service regions into new EFI
 page tables


* Matt Fleming <matt@...eblueprint.co.uk> wrote:

> diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c
> index 8fee5b6f8f66..af74849e8c0f 100644
> --- a/arch/x86/mm/pageattr.c
> +++ b/arch/x86/mm/pageattr.c
> @@ -1055,7 +1055,7 @@ static int populate_pud(struct cpa_data *cpa, unsigned long start, pgd_t *pgd,
>  	/*
>  	 * Map everything starting from the Gb boundary, possibly with 1G pages
>  	 */
> -	while (end - start >= PUD_SIZE) {
> +	while (cpu_has_gbpages && end - start >= PUD_SIZE) {
>  		set_pud(pud, __pud(cpa->pfn << PAGE_SHIFT | _PAGE_PSE |
>  				   massage_pgprot(pud_pgprot)));

Btw., can 'cpa->pfn << PAGE_SHIFT' possibly work on 32-bit systems?

cpa->pfn is unsigned long, so the result gets truncated to 32 bits ...

cpa->pfn should be u64.

Thanks,

	Ingo