[Xen-devel] RE: [PATCH 1/6] vtd: Refactor iotlb flush code

["Kay, Allen M" <allen.m.kay@xxxxxxxxx>]

The fourth parameter, currently 0,  is supposed to be the AM field.  It is 
named order now.

+            if ( iommu_flush_iotlb_psi(iommu, iommu_domid,
+                        (paddr_t)gfn << PAGE_SHIFT_4K, 0,
+                        !dma_old_pte_present, flush_dev_iotlb) )

-----Original Message-----
From: Kay, Allen M 
Sent: Tuesday, November 08, 2011 6:42 PM
To: 'Jean Guyader'
Cc: Jean Guyader; xen-devel@xxxxxxxxxxxxxxxxxxx; Tim (Xen.org)
Subject: RE: [PATCH 1/6] vtd: Refactor iotlb flush code

Jean,

Page 122 of VT-d spec indicates you can invalidate multiple pages by setting 
the Address Mask (AM) field.  Will this achieve what you wanted to do?

http://download.intel.com/technology/computing/vptech/Intel(r)_VT_for_Direct_IO.pdf

Allen

-----Original Message-----
From: Jean Guyader [mailto:jean.guyader@xxxxxxxxxxxxx] 
Sent: Monday, November 07, 2011 11:42 PM
To: Kay, Allen M
Cc: Jean Guyader; xen-devel@xxxxxxxxxxxxxxxxxxx; Tim (Xen.org)
Subject: Re: [PATCH 1/6] vtd: Refactor iotlb flush code


Allen,

You are probably talking about __intel_iommu_iotlb_flush.
This function takes a range of address to flush. I haven't found a function in 
the vtd code to invalidate a range on address without doing a loop of 
flush_iotlb_psi, so I thought that the most efficient and quick way to flush a 
range would be to use a domain selective invalidation.

Jean

On 08/11 03:10, Kay, Allen M wrote:
> Jean,
> 
> The original code does not call iommu_flush_iotlb_dsi().  What is the reason 
> the refractored code need to use domain selective invalidation?
> 
> Allen
> -----
> 
> +        if ( page_count > 1 || gfn == -1 )
> +        {
> +            if ( iommu_flush_iotlb_dsi(iommu, iommu_domid,
> +                        0, flush_dev_iotlb) )
> +                iommu_flush_write_buffer(iommu);
> +        }
> +        else
> +        {
> +            if ( iommu_flush_iotlb_psi(iommu, iommu_domid,
> +                        (paddr_t)gfn << PAGE_SHIFT_4K, 0,
> +                        !dma_old_pte_present, flush_dev_iotlb) )
> +                iommu_flush_write_buffer(iommu);
> 
> -----Original Message-----
> From: Jean Guyader [mailto:jean.guyader@xxxxxxxxxxxxx]
> Sent: Monday, November 07, 2011 10:25 AM
> To: xen-devel@xxxxxxxxxxxxxxxxxxx
> Cc: tim@xxxxxxx; Kay, Allen M; Jean Guyader
> Subject: [PATCH 1/6] vtd: Refactor iotlb flush code
> 
> 
> Factorize the iotlb flush code from map_page and unmap_page into it's own 
> function.
> 
> Signed-off-by: Jean Guyader <jean.guyader@xxxxxxxxxxxxx>
> ---
>  xen/drivers/passthrough/vtd/iommu.c |   86 +++++++++++++++++-----------------
>  1 files changed, 43 insertions(+), 43 deletions(-)
> 

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