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* Question about domain_init (v5.3-v5.7)
@ 2020-11-25 20:27 Jerry Snitselaar
  2020-11-26 11:01 ` Lu Baolu
  0 siblings, 1 reply; 8+ messages in thread
From: Jerry Snitselaar @ 2020-11-25 20:27 UTC (permalink / raw)
  To: Lu Baolu, Joerg Roedel, iommu, linux-kernel, stable


Is there a reason we check the requested guest address width against the
iommu's mgaw, instead of the agaw that we already know for the iommu?
I've run into a case with a new system where the mgaw reported is 57,
but if they set PAE to 46 instead of 52 in the bios, then sagaw reports
the highest supported agaw is 48 and the domain_init code fails here. In
other places like prepare_domain_attach_device, the dmar domain agaw
gets adjusted down to the iommu agaw. The agaw of the iommu gets
determined based off what is reported for sagaw. I'm wondering if it
can't instead do:

---
 drivers/iommu/intel-iommu.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c
index 6ca5c92ef2e5..a8e41ec36d9e 100644
--- a/drivers/iommu/intel-iommu.c
+++ b/drivers/iommu/intel-iommu.c
@@ -1862,8 +1862,8 @@ static int domain_init(struct dmar_domain *domain, struct intel_iommu *iommu,
 	domain_reserve_special_ranges(domain);

 	/* calculate AGAW */
-	if (guest_width > cap_mgaw(iommu->cap))
-	        guest_width = cap_mgaw(iommu->cap);
+	if (guest_width > agaw_to_width(iommu->agaw))
+	        guest_width = agaw_to_width(iommu->agaw);
 	domain->gaw = guest_width;
 	adjust_width = guestwidth_to_adjustwidth(guest_width);
 	agaw = width_to_agaw(adjust_width);
--
2.27.0


Thoughts? With the former code the ehci device for the ilo fails when
trying to get a private domain.

Thanks,
Jerry


^ permalink raw reply related	[flat|nested] 8+ messages in thread

end of thread, other threads:[~2020-12-01  2:46 UTC | newest]

Thread overview: 8+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2020-11-25 20:27 Question about domain_init (v5.3-v5.7) Jerry Snitselaar
2020-11-26 11:01 ` Lu Baolu
2020-11-26 21:35   ` Jerry Snitselaar
2020-11-27  2:12     ` Lu Baolu
2020-11-27  7:48       ` Jerry Snitselaar
2020-11-30 17:50       ` Jerry Snitselaar
2020-11-30 18:03         ` Jerry Snitselaar
2020-12-01  2:37         ` Lu Baolu

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