Hi,
Replying again, as there was some issue with mailer last time.
On 3/21/2017 11:47 PM, Will Deacon wrote:
On Tue, Mar 21, 2017 at 05:46:29PM +0000, Robin Murphy wrote:
On 21/03/17 17:21, Will Deacon wrote:
On Tue, Mar 21, 2017 at 04:45:27PM +0100, Joerg Roedel wrote:
On Fri, Mar 10, 2017 at 08:49:36PM +0000, Will Deacon wrote:
@@ -1014,8 +1027,8 @@ struct iommu_group *iommu_group_get_for_dev(struct device
*dev)
* IOMMU driver.
*/
if (!group->default_domain) {
- group->default_domain = __iommu_domain_alloc(dev->bus,
- IOMMU_DOMAIN_DMA);
+ group->default_domain =
+ __iommu_domain_alloc(dev->bus, iommu_def_domain_type);
It would be good to have a fall-back here if we are talking to an IOMMU
driver that uses default domains, but does not support identity-mapped
domains (yet). Exynos and Rockchip IOMMU drivers seem to fall into this
category. A dev_warn() also makes sense in case allocating a identity
domain fails.
Sure, something like the diff below?
Will
--->8
diff --git a/drivers/iommu/iommu.c b/drivers/iommu/iommu.c
index 42a842e3f95f..f787626a745d 100644
--- a/drivers/iommu/iommu.c
+++ b/drivers/iommu/iommu.c
@@ -1027,10 +1027,19 @@ struct iommu_group *iommu_group_get_for_dev(struct
device *dev)
* IOMMU driver.
*/
if (!group->default_domain) {
- group->default_domain =
- __iommu_domain_alloc(dev->bus, iommu_def_domain_type);
+ struct iommu_domain *dom;
+
+ dom = __iommu_domain_alloc(dev->bus, iommu_def_domain_type);
+ if (!dom) {
+ dev_warn(dev,
+ "failed to allocate default IOMMU domain of type
%u; falling back to IOMMU_DOMAIN_DMA",
+ iommu_def_domain_type);
Conversely, that's going to be noisy if iommu_def_domain_type was
IOMMU_DOMAIN_DMA to begin with. I think it makes sense to warn if the
user asked for a specific default domain type on the command line and
that didn't work, but maybe not to bother otherwise. Plus, if they asked
for passthrough, then not allocating a default domain at all is probably
closer to the desired result than installing a DMA ops domain would be.
You're right -- I'll hack this about to check if the default type isn't
DOMAIN_DMA before warning about the allocation failure.
if some master devices want 'IDENTITY_DOMAIN' as default (because
those devices do not want any iommu resources to be used/dma_ops to be
set) and some 'DMA_DOMAIN' as default, then should the default be
'DMA_DOMAIN' and then masters needing IDENTITY_DOMAIN explicitly do an
detach_dev later. This [1] was adding the support for detach_dev
of the default DMA_DOMAINs.
[1] https://patchwork.codeaurora.org/patch/164933/
Regards,
Sricharan
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