On 23/01/2019 17:53, Andrii Anisov wrote:
Hello Julien,
Hi,
On 22.01.19 16:31, Julien Grall wrote:
IMO, the pure fixes, like patch 2, and the first hunk of patch 1 should be OK
for 4.12.
The first hunk of patch 1 aside, we never supported the new IOMMU bindings nor
unsharing the P2M. So what do you actually fix?
Supporting unshared P2M will require more work given because the code relies
on mfn_to_gmfn that is not implemented on Arm. So accepting this patch
standalone would be misleading as the rest of the series is not going to be
merged in Xen 4.12.
I'm not saying I want something from non-shared p2m push into 4.12.
I know and this is not what I implied in my previous e-mail. I pointed out that
the rest of the series is not planned for Xen 4.12, hence it does not make sense
to get that patch merged.
I would strip the first patch to its first chunk.
I can queue the first hunk for Xen 4.13.
Similarly, we don't support new IOMMU bindings. The patch #2 alone is going to
add more trouble as now Dom0 would not be able to use the IOMMU if it were not
hidden.
Are you sure we should pass IOMMU devices or related info to Dom0 if they are
not supported by hypervisor?
The commit message states "We don't passthrough IOMMU device to DOM0 even if it
is not used by Xen.", and you agreed that some time ago. Could you please
clarify why you have changed your mind?
This statement is only correct if the IOMMU has been actively blacklisted by
Xen. In the case of the SMMU driver, this is done by arm_smmu_dt_init(). The
function is only called when the IOMMU has been enabled.
So if you pass "iommu=disabled" to Xen commandline, the SMMU will be accessible
by Dom0.
When there are no drivers for the IOMMU used, then you end up to assign the
IOMMU to Dom0. This means that Dom0 can use them.
It does not make sense to remove the properties "iommus", "iommu-map",
"iommu-map-mask" if Dom0 is already touching the IOMMU. It is either everything
or nothing.
Cheers,
--
Julien Grall
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