Re: [PATCH 03/12] iommu/vt-d: Remove clearing translation data in disable_dmar_iommu()
On 2022/5/27 23:01, Jason Gunthorpe wrote: On Fri, May 27, 2022 at 02:30:10PM +0800, Lu Baolu wrote: The disable_dmar_iommu() is called when IOMMU initialzation fails or the IOMMU is hot-removed from the system. In both cases, there is no need to clear the IOMMU translation data structures for devices. On the initialization path, the device probing only happens after the IOMMU is initialized successfully, hence there're no translation data structures. On the hot-remove path, there is no real use case where the IOMMU is hot-removed, but the devices that it manages are still alive in the system. The translation data structures were torn down during device release, hence there's no need to repeat it in IOMMU hot-remove path either. Can you leave behind a 1 statement WARN_ON of some kind to check this? Sure. As the default domain is the first domain allocated for a device and the last one freed. We can WARN_ON the case where there's still domain IDs in use. How do you like this? + /* +* All iommu domains must have been detached from the devices, +* hence there should be no domain IDs in use. +*/ + if (WARN_ON(bitmap_weight(iommu->domain_ids, cap_ndoms(iommu->cap)) + != NUM_RESERVED_DID)) + return; Best regards, baolu ___ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu
Re: [PATCH 03/12] iommu/vt-d: Remove clearing translation data in disable_dmar_iommu()
On Fri, May 27, 2022 at 02:30:10PM +0800, Lu Baolu wrote: > The disable_dmar_iommu() is called when IOMMU initialzation fails or > the IOMMU is hot-removed from the system. In both cases, there is no > need to clear the IOMMU translation data structures for devices. > > On the initialization path, the device probing only happens after the > IOMMU is initialized successfully, hence there're no translation data > structures. > > On the hot-remove path, there is no real use case where the IOMMU is > hot-removed, but the devices that it manages are still alive in the > system. The translation data structures were torn down during device > release, hence there's no need to repeat it in IOMMU hot-remove path > either. Can you leave behind a 1 statement WARN_ON of some kind to check this? Jason ___ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu
[PATCH 03/12] iommu/vt-d: Remove clearing translation data in disable_dmar_iommu()
The disable_dmar_iommu() is called when IOMMU initialzation fails or
the IOMMU is hot-removed from the system. In both cases, there is no
need to clear the IOMMU translation data structures for devices.
On the initialization path, the device probing only happens after the
IOMMU is initialized successfully, hence there're no translation data
structures.
On the hot-remove path, there is no real use case where the IOMMU is
hot-removed, but the devices that it manages are still alive in the
system. The translation data structures were torn down during device
release, hence there's no need to repeat it in IOMMU hot-remove path
either.
So, let's remove this unnecessary code.
Signed-off-by: Lu Baolu
---
drivers/iommu/intel/iommu.c | 15 ---
1 file changed, 15 deletions(-)
diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c
index 6549b09d7f32..25d4c5200526 100644
--- a/drivers/iommu/intel/iommu.c
+++ b/drivers/iommu/intel/iommu.c
@@ -1715,24 +1715,9 @@ static int iommu_init_domains(struct intel_iommu *iommu)
static void disable_dmar_iommu(struct intel_iommu *iommu)
{
- struct device_domain_info *info, *tmp;
- unsigned long flags;
-
if (!iommu->domain_ids)
return;
- spin_lock_irqsave(&device_domain_lock, flags);
- list_for_each_entry_safe(info, tmp, &device_domain_list, global) {
- if (info->iommu != iommu)
- continue;
-
- if (!info->dev || !info->domain)
- continue;
-
- __dmar_remove_one_dev_info(info);
- }
- spin_unlock_irqrestore(&device_domain_lock, flags);
-
if (iommu->gcmd & DMA_GCMD_TE)
iommu_disable_translation(iommu);
}
--
2.25.1
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