Messages in this thread | | | From | "Tian, Kevin" <> | Subject | RE: [PATCH 1/1] iommu/vt-d: Omit devTLB invalidation requests when TES=0 | Date | Tue, 14 Nov 2023 04:45:40 +0000 |
| |
> From: Baolu Lu <baolu.lu@linux.intel.com> > Sent: Tuesday, November 14, 2023 11:14 AM > > On 11/14/23 11:14 AM, Tian, Kevin wrote: > >> From: Lu Baolu<baolu.lu@linux.intel.com> > >> Sent: Tuesday, November 14, 2023 9:11 AM > >> > >> The latest VT-d spec indicates that when remapping hardware is disabled > >> (TES=0 in Global Status Register), upstream ATS Invalidation Completion > >> requests are treated as UR (Unsupported Request). > >> > >> Consequently, the spec recommends in section 4.3 Handling of Device-TLB > >> Invalidations that software refrain from submitting any Device-TLB > >> invalidation requests when address remapping hardware is disabled. > >> > >> Verify address remapping hardware is enabled prior to submitting Device- > >> TLB invalidation requests. > >> > >> Fixes: 792fb43ce2c9 ("iommu/vt-d: Enable Intel IOMMU scalable mode by > >> default") > >> Signed-off-by: Lu Baolu<baolu.lu@linux.intel.com> > >> --- > >> drivers/iommu/intel/dmar.c | 18 ++++++++++++++++++ > >> 1 file changed, 18 insertions(+) > >> > >> diff --git a/drivers/iommu/intel/dmar.c b/drivers/iommu/intel/dmar.c > >> index a3414afe11b0..23cb80d62a9a 100644 > >> --- a/drivers/iommu/intel/dmar.c > >> +++ b/drivers/iommu/intel/dmar.c > >> @@ -1522,6 +1522,15 @@ void qi_flush_dev_iotlb(struct intel_iommu > >> *iommu, u16 sid, u16 pfsid, > >> { > >> struct qi_desc desc; > >> > >> + /* > >> + * VT-d spec, section 4.3: > >> + * > >> + * Software is recommended to not submit any Device-TLB > >> invalidation > >> + * requests while address remapping hardware is disabled. > >> + */ > >> + if (!(iommu->gcmd & DMA_GCMD_TE)) > >> + return; > >> + > > Is it a valid case to see such request when the iommu is disabled? > > If not then let's add a WARN. > > There might be valid cases. The VT-d translation is turned on after all > devices get probed. >
but I didn't get why there will be actual mapping changes before vtd translation is enabled...
| |