Hi Isaac,
On 4/3/21 1:25 AM, [email protected] wrote:
On 2021-03-30 22:39, Lu Baolu wrote:
On 3/31/21 1:36 PM, [email protected] wrote:
On 2021-03-30 21:47, Lu Baolu wrote:
On 3/31/21 11:00 AM, Isaac J. Manjarres wrote:
Add a callback for IOMMU drivers to provide a path for the
IOMMU framework to call into an IOMMU driver, which can call
into the io-pgtable code, to unmap a virtually contiguous
range of pages of the same size.
For IOMMU drivers that do not specify an unmap_pages() callback,
the existing logic of unmapping memory one page block at a time
will be used.
Signed-off-by: Isaac J. Manjarres <[email protected]>
Suggested-by: Will Deacon <[email protected]>
---
include/linux/iommu.h | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/include/linux/iommu.h b/include/linux/iommu.h
index 5e7fe519430a..9cf81242581a 100644
--- a/include/linux/iommu.h
+++ b/include/linux/iommu.h
@@ -193,6 +193,7 @@ struct iommu_iotlb_gather {
* @detach_dev: detach device from an iommu domain
* @map: map a physically contiguous memory region to an iommu
domain
* @unmap: unmap a physically contiguous memory region from an
iommu domain
+ * @unmap_pages: unmap a number of pages of the same size from an
iommu domain
* @flush_iotlb_all: Synchronously flush all hardware TLBs for
this domain
* @iotlb_sync_map: Sync mappings created recently using @map to
the hardware
* @iotlb_sync: Flush all queued ranges from the hardware TLBs
and empty flush
@@ -245,6 +246,9 @@ struct iommu_ops {
phys_addr_t paddr, size_t size, int prot, gfp_t gfp);
size_t (*unmap)(struct iommu_domain *domain, unsigned long iova,
size_t size, struct iommu_iotlb_gather *iotlb_gather);
+ size_t (*unmap_pages)(struct iommu_domain *domain, unsigned
long iova,
+ size_t pgsize, size_t pgcount,
+ struct iommu_iotlb_gather *iotlb_gather);
Is it possible to add an equivalent map_pages() callback?
Yes, map_pages() can be implemented and can leverage a lot of the
implementation
of unmap_pages(). The problem is that if you map several pages in one
call, and then
encounter an error and have to rollback, you should do TLB
maintenance, as iommu_map
does when it encounters an error. However, we can't call iommu_unmap
from io-pgtable-arm
for example. We can call arm_lpae_unmap_pages() from the later
patches, but that doesn't
solve the TLB maintenance issue. Do you have any thoughts on how to
address this?
Call unmap_pages() with the same pages and size to roll back. Does it
work?
Best regards,
baolu
Hi Lu,
I've given map_pages() a shot. Here's the second version of the RFC
series:
https://lore.kernel.org/linux-iommu/[email protected]/T/#t.
Thanks for doing that. I will look into it and try it with a VT-d
implementation.
Best regards,
baolu
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