ACK: [SRU][Trusty][PATCH 1/1] x86/mm: Fix slow_virt_to_phys() for X86_PAE again

[Brad Figg]

On Wed, Mar 09, 2016 at 12:50:53PM -0500, Joseph Salisbury wrote:
> From: Dexuan Cui <decui at microsoft.com>
> 
> BugLink: http://bugs.launchpad.net/bugs/1549601
> 
> "d1cd12108346: x86, pageattr: Prevent overflow in slow_virt_to_phys() for
> X86_PAE" was unintentionally removed by the recent "34437e67a672: x86/mm: Fix
> slow_virt_to_phys() to handle large PAT bit".
> 
> And, the variable 'phys_addr' was defined as "unsigned long" by mistake -- it should
> be "phys_addr_t".
> 
> As a result, Hyper-V network driver in 32-PAE Linux guest can't work again.
> 
> Fixes: commit 34437e67a672: "x86/mm: Fix slow_virt_to_phys() to handle large PAT bit"
> Signed-off-by: Dexuan Cui <decui at microsoft.com>
> Reviewed-by: Toshi Kani <toshi.kani at hpe.com>
> Cc: olaf at aepfle.de
> Cc: gregkh at linuxfoundation.org
> Cc: jasowang at redhat.com
> Cc: driverdev-devel at linuxdriverproject.org
> Cc: linux-mm at kvack.org
> Cc: apw at canonical.com
> Cc: Andrew Morton <akpm at linux-foundation.org>
> Cc: K. Y. Srinivasan <kys at microsoft.com>
> Cc: Haiyang Zhang <haiyangz at microsoft.com>
> Link: http://lkml.kernel.org/r/1456394292-9030-1-git-send-email-decui@microsoft.com
> Signed-off-by: Thomas Gleixner <tglx at linutronix.de>
> (backported from commit bf70e5513dfea29c3682e7eb3dbb45f0723bac09)
> Signed-off-by: Joseph Salisbury <joseph.salisbury at canonical.com>
> ---
>  arch/x86/include/asm/page_types.h |  9 ++++++---
>  arch/x86/mm/pageattr.c            | 26 +++++++++++++++++++++-----
>  2 files changed, 27 insertions(+), 8 deletions(-)
> 
> diff --git a/arch/x86/include/asm/page_types.h b/arch/x86/include/asm/page_types.h
> index f97fbe3..53193b7 100644
> --- a/arch/x86/include/asm/page_types.h
> +++ b/arch/x86/include/asm/page_types.h
> @@ -9,6 +9,12 @@
>  #define PAGE_SIZE	(_AC(1,UL) << PAGE_SHIFT)
>  #define PAGE_MASK	(~(PAGE_SIZE-1))
>  
> +#define PMD_PAGE_SIZE		(_AC(1, UL) << PMD_SHIFT)
> +#define PMD_PAGE_MASK		(~(PMD_PAGE_SIZE-1))
> +
> +#define PUD_PAGE_SIZE           (_AC(1, UL) << PUD_SHIFT)
> +#define PUD_PAGE_MASK           (~(PUD_PAGE_SIZE-1))
> +
>  #define __PHYSICAL_MASK		((phys_addr_t)((1ULL << __PHYSICAL_MASK_SHIFT) - 1))
>  #define __VIRTUAL_MASK		((1UL << __VIRTUAL_MASK_SHIFT) - 1)
>  
> @@ -17,9 +23,6 @@
>     (ie, 32-bit PAE). */
>  #define PHYSICAL_PAGE_MASK	(((signed long)PAGE_MASK) & __PHYSICAL_MASK)
>  
> -#define PMD_PAGE_SIZE		(_AC(1, UL) << PMD_SHIFT)
> -#define PMD_PAGE_MASK		(~(PMD_PAGE_SIZE-1))
> -
>  #define HPAGE_SHIFT		PMD_SHIFT
>  #define HPAGE_SIZE		(_AC(1,UL) << HPAGE_SHIFT)
>  #define HPAGE_MASK		(~(HPAGE_SIZE - 1))
> diff --git a/arch/x86/mm/pageattr.c b/arch/x86/mm/pageattr.c
> index d528ae3..bbaea09 100644
> --- a/arch/x86/mm/pageattr.c
> +++ b/arch/x86/mm/pageattr.c
> @@ -402,11 +402,27 @@ phys_addr_t slow_virt_to_phys(void *__virt_addr)
>  
>  	pte = lookup_address(virt_addr, &level);
>  	BUG_ON(!pte);
> -	psize = page_level_size(level);
> -	pmask = page_level_mask(level);
> -	offset = virt_addr & ~pmask;
> -	phys_addr = (phys_addr_t)pte_pfn(*pte) << PAGE_SHIFT;
> -	return (phys_addr | offset);
> +
> +	/*
> +	 * pXX_pfn() returns unsigned long, which must be cast to phys_addr_t
> +	 * before being left-shifted PAGE_SHIFT bits -- this trick is to
> +	 * make 32-PAE kernel work correctly.
> +	 */
> +	switch (level) {
> +	case PG_LEVEL_1G:
> +		phys_addr = (phys_addr_t)pud_pfn(*(pud_t *)pte) << PAGE_SHIFT;
> +		offset = virt_addr & ~PUD_PAGE_MASK;
> +		break;
> +	case PG_LEVEL_2M:
> +		phys_addr = (phys_addr_t)pmd_pfn(*(pmd_t *)pte) << PAGE_SHIFT;
> +		offset = virt_addr & ~PMD_PAGE_MASK;
> +		break;
> +	default:
> +		phys_addr = (phys_addr_t)pte_pfn(*pte) << PAGE_SHIFT;
> +		offset = virt_addr & ~PAGE_MASK;
> +	}
> +
> +	return (phys_addr_t)(phys_addr | offset);
>  }
>  EXPORT_SYMBOL_GPL(slow_virt_to_phys);
>  
> -- 
> 1.9.1
> 
> 
> -- 
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Looks good.

-- 
Brad Figg brad.figg at canonical.com http://www.canonical.com