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SubjectRe: [RFC v3 05/10] iommu: Do not map reserved regions
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On 15/11/16 13:09, Eric Auger wrote:
> As we introduced IOMMU_RESV_NOMAP and IOMMU_RESV_MSI regions,
> let's prevent those new regions from being mapped.
>
> Signed-off-by: Eric Auger <eric.auger@redhat.com>
> ---
> drivers/iommu/iommu.c | 3 +++
> 1 file changed, 3 insertions(+)
>
> diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
> index 6ee529f..a4530ad 100644
> --- a/drivers/iommu/iommu.c
> +++ b/drivers/iommu/iommu.c
> @@ -343,6 +343,9 @@ static int iommu_group_create_direct_mappings(struct iommu_group *group,
> start = ALIGN(entry->start, pg_size);
> end = ALIGN(entry->start + entry->length, pg_size);
>
> + if (entry->prot & IOMMU_RESV_MASK)

This seems to be the only place that this mask is used, and frankly I
think it's less clear than simply "(IOMMU_RESV_NOMAP | IOMMU_RESV_MSI)"
would be, at which point we may as well drop the mask and special value
trickery altogether. Plus, per my previous comment, if it were to be "if
(entry->type != <direct mapped type>)" instead, that's about as obvious
as it can get.

Robin.

> + continue;
> +
> for (addr = start; addr < end; addr += pg_size) {
> phys_addr_t phys_addr;
>
>

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