Messages in this thread |  | | From | Jerry Snitselaar <> | Subject | Re: Question about domain_init (v5.3-v5.7) | Date | Thu, 26 Nov 2020 14:35:30 -0700 |
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Lu Baolu @ 2020-11-26 04:01 MST:
> Hi Jerry, > > On 2020/11/26 4:27, Jerry Snitselaar wrote: >> 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 > > Isn't this a platform bug? If it's too late to fix it in the BIOS, you > maybe have to add a platform specific quirk to set mgaw to the highest > supported agaw? > > Best regards, > baolu
Is there somewhere you can point me to that discusses how they should be setting the mgaw? I misunderstood when I previously asked you about whether the mgaw could be a value that was greater than any of sagaw. If it is a bios issue, then they should fix it there.
> >> 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 >>
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