From: Joao Martins joao.m.martins@oracle.com Sent: Friday, February 9, 2024 6:36 PM
On 08/02/2024 10:31, Joao Martins wrote:
On 08/02/2024 09:14, Yi Liu wrote:
Should set the SSADE (Second Stage Access/Dirty bit Enable) bit of the pasid entry when attaching a device to a nested domain if its parent has already enabled dirty tracking.
Fixes: 111bf85c68f6 ("iommu/vt-d: Add helper to setup pasid nested
translation")
Signed-off-by: Yi Liu yi.l.liu@intel.com
Reviewed-by: Joao Martins joao.m.martins@oracle.com
On a second thought, while the patch looks fine if this is what we wanna do, just a quick clarification on the why (that's also applicable to the last patch of your other series[0]). I am sure I am missing something :)
Shouldn't the nested domain be subdued to whatever features guest idea of ecap/cap instead of host's view? Or is this because guest first-stage page table on Intel is supposed to be always-enabled dirty tracking (per SDM) ? If it's the latter, it probably should be sprinkled in the commit message(s).
[0] https://lore.kernel.org/linux-iommu/20240208082307.15759-9- yi.l.liu@intel.com/
first-stage dirty tracking is always enabled. but the real point here is that the host has enabled dirty-tracking in second-stage so when a device is attached to a nested domain on top of that second-stage we should set SSADE in the pasid entry for that device.
even if there is a guest ecap/cap for first-stage dirty tracking that shouldn't affect the host setting for second-stage which is invisible to the guest.