Messages in this thread | | | From | "Tian, Kevin" <> | Subject | RE: [PATCH 07/12] iommu/vt-d: Cleanup use of iommu_flush_iotlb_psi() | Date | Mon, 8 Apr 2024 02:57:26 +0000 |
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> From: Baolu Lu <baolu.lu@linux.intel.com> > Sent: Sunday, April 7, 2024 3:06 PM > > On 3/28/24 3:50 PM, Tian, Kevin wrote: > >> From: Lu Baolu <baolu.lu@linux.intel.com> > >> Sent: Monday, March 25, 2024 10:17 AM > >> > >> Use cache_tag_flush_range() in switch_to_super_page() to invalidate the > >> necessary caches when switching mappings from normal to super pages. > The > >> iommu_flush_iotlb_psi() call in intel_iommu_memory_notifier() is > >> unnecessary since there should be no cache invalidation for the identity > >> domain. > >> > > > > what about a software identity domain? > > Software identity domain is used to fake the hardware passthrough > capability, on early VT-d hardware which doesn't implement the > passthrough mode. It's not any kind of protection domain, hence the OS > is not required to manage the cache synchronization. > > Although I hope we can remove it someday and force the DMA domain > instead, we still need to carry it nowadays. However, we need to make it > consistent with the hardware passthrough. That is, hardware passthrough > doesn't require any cache invalidation in memory hot-plug paths, the > software passthrough should not either. >
yes, that makes sense.
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