linux-kernel - Re: [PATCH kernel v9 30/32] vfio: powerpc/spapr: Use 32bit DMA window properties from table

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Message-ID: <1430173102.4472.118.camel@redhat.com>
Date:	Mon, 27 Apr 2015 16:18:22 -0600
From:	Alex Williamson <alex.williamson@...hat.com>
To:	Alexey Kardashevskiy <aik@...abs.ru>
Cc:	linuxppc-dev@...ts.ozlabs.org,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Paul Mackerras <paulus@...ba.org>,
	Gavin Shan <gwshan@...ux.vnet.ibm.com>,
	David Gibson <david@...son.dropbear.id.au>,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH kernel v9 30/32] vfio: powerpc/spapr: Use 32bit DMA
 window properties from table_group

On Sat, 2015-04-25 at 22:14 +1000, Alexey Kardashevskiy wrote:
> A table group might not have a table but it always has the default 32bit
> window parameters so use these.
> 
> No change in behavior is expected.
> 
> Signed-off-by: Alexey Kardashevskiy <aik@...abs.ru>
> ---
> Changes:
> v9:
> * new in the series - to make the next patch simpler
> ---
>  drivers/vfio/vfio_iommu_spapr_tce.c | 19 +++++++++++--------
>  1 file changed, 11 insertions(+), 8 deletions(-)


Acked-by: Alex Williamson <alex.williamson@...hat.com>


> diff --git a/drivers/vfio/vfio_iommu_spapr_tce.c b/drivers/vfio/vfio_iommu_spapr_tce.c
> index 4cfc2c1..a7d6729 100644
> --- a/drivers/vfio/vfio_iommu_spapr_tce.c
> +++ b/drivers/vfio/vfio_iommu_spapr_tce.c
> @@ -185,7 +185,6 @@ static int tce_iommu_enable(struct tce_container *container)
>  {
>  	int ret = 0;
>  	unsigned long locked;
> -	struct iommu_table *tbl;
>  	struct iommu_table_group *table_group;
>  
>  	if (!container->grp)
> @@ -221,13 +220,19 @@ static int tce_iommu_enable(struct tce_container *container)
>  	 * this is that we cannot tell here the amount of RAM used by the guest
>  	 * as this information is only available from KVM and VFIO is
>  	 * KVM agnostic.
> +	 *
> +	 * So we do not allow enabling a container without a group attached
> +	 * as there is no way to know how much we should increment
> +	 * the locked_vm counter.
>  	 */
>  	table_group = iommu_group_get_iommudata(container->grp);
>  	if (!table_group)
>  		return -ENODEV;
>  
> -	tbl = &table_group->tables[0];
> -	locked = (tbl->it_size << tbl->it_page_shift) >> PAGE_SHIFT;
> +	if (!table_group->tce32_size)
> +		return -EPERM;
> +
> +	locked = table_group->tce32_size >> PAGE_SHIFT;
>  	ret = try_increment_locked_vm(locked);
>  	if (ret)
>  		return ret;
> @@ -504,7 +509,6 @@ static long tce_iommu_ioctl(void *iommu_data,
>  
>  	case VFIO_IOMMU_SPAPR_TCE_GET_INFO: {
>  		struct vfio_iommu_spapr_tce_info info;
> -		struct iommu_table *tbl;
>  		struct iommu_table_group *table_group;
>  
>  		if (WARN_ON(!container->grp))
> @@ -512,8 +516,7 @@ static long tce_iommu_ioctl(void *iommu_data,
>  
>  		table_group = iommu_group_get_iommudata(container->grp);
>  
> -		tbl = &table_group->tables[0];
> -		if (WARN_ON_ONCE(!tbl))
> +		if (!table_group)
>  			return -ENXIO;
>  
>  		minsz = offsetofend(struct vfio_iommu_spapr_tce_info,
> @@ -525,8 +528,8 @@ static long tce_iommu_ioctl(void *iommu_data,
>  		if (info.argsz < minsz)
>  			return -EINVAL;
>  
> -		info.dma32_window_start = tbl->it_offset << tbl->it_page_shift;
> -		info.dma32_window_size = tbl->it_size << tbl->it_page_shift;
> +		info.dma32_window_start = table_group->tce32_start;
> +		info.dma32_window_size = table_group->tce32_size;
>  		info.flags = 0;
>  
>  		if (copy_to_user((void __user *)arg, &info, minsz))



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