linux-kernel - Re: [Xen-devel] [PATCH] xen-swiotlb: use actually allocated size on check physical contiguous

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Date:   Fri, 7 Sep 2018 15:47:50 -0700
From:   Joe Jin <joe.jin@...cle.com>
To:     Dongli Zhang <dongli.zhang@...cle.com>,
        "xen-devel@...ts.xenproject.org" <xen-devel@...ts.xenproject.org>
Cc:     Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
        John Sobecki <john.sobecki@...cle.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [Xen-devel] [PATCH] xen-swiotlb: use actually allocated size on
 check physical contiguous

Anybody would like to help review this patch?

Thanks,
Joe

On 09/05/2018 02:16 AM, Joe Jin wrote                                           
> xen_swiotlb_{alloc,free}_coherent() actually allocate/free size by order      
> but used the required size to check if address is physical contiguous,        
> if first pages are physical contiguous also passed                            
> range_straddles_page_boundary() check, but others were not it will            
> lead kernel panic.                                                            
>                                                                               
> Signed-off-by: Joe Jin <joe.jin@...cle.com>                                   
> Cc: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>                            
> ---                                                                           
>  drivers/xen/swiotlb-xen.c | 6 ++++++                                         
>  1 file changed, 6 insertions(+)                                              
>                                                                               
> diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c            
> index a6f9ba85dc4b..aa081f806728 100644                                       
> --- a/drivers/xen/swiotlb-xen.c                                               
> +++ b/drivers/xen/swiotlb-xen.c                                               
> @@ -303,6 +303,9 @@ xen_swiotlb_alloc_coherent(struct device *hwdev, size_t size,
>       */                                                                      
>       flags &= ~(__GFP_DMA | __GFP_HIGHMEM);                                  
>                                                                               
> +     /* Convert the size to actually allocated. */                           
> +     size = 1UL << (order + XEN_PAGE_SHIFT);                                 
> +                                                                             
>       /* On ARM this function returns an ioremap'ped virtual address for      
>        * which virt_to_phys doesn't return the corresponding physical         
>        * address. In fact on ARM virt_to_phys only works for kernel direct    
> @@ -351,6 +354,9 @@ xen_swiotlb_free_coherent(struct device *hwdev, size_t size, void *vaddr,
>        * physical address */                                                  
>       phys = xen_bus_to_phys(dev_addr);                                       
>                                                                               
> +     /* Convert the size to actually allocated. */                           
> +     size = 1UL << (order + XEN_PAGE_SHIFT);                                 
> +                                                                             
>       if (((dev_addr + size - 1 <= dma_mask)) ||                              
>           range_straddles_page_boundary(phys, size))                          
>               xen_destroy_contiguous_region(phys, order);                     
>