Messages in this thread | | | Subject | Re: [PATCH 5.4 v2 1/1] iommu/vt-d: Fix agaw for a supported 48 bit guest address width | From | Lu Baolu <> | Date | Thu, 8 Apr 2021 08:25:19 +0800 |
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On 4/8/21 2:40 AM, Saeed Mirzamohammadi wrote: > The IOMMU driver calculates the guest addressability for a DMA request > based on the value of the mgaw reported from the IOMMU. However, this > is a fused value and as mentioned in the spec, the guest width > should be calculated based on the minimum of supported adjusted guest > address width (SAGAW) and MGAW. > > This is from specification: > "Guest addressability for a given DMA request is limited to the > minimum of the value reported through this field and the adjusted > guest address width of the corresponding page-table structure. > (Adjusted guest address widths supported by hardware are reported > through the SAGAW field)." > > This causes domain initialization to fail and following > errors appear for EHCI PCI driver: > > [ 2.486393] ehci-pci 0000:01:00.4: EHCI Host Controller > [ 2.486624] ehci-pci 0000:01:00.4: new USB bus registered, assigned bus > number 1 > [ 2.489127] ehci-pci 0000:01:00.4: DMAR: Allocating domain failed > [ 2.489350] ehci-pci 0000:01:00.4: DMAR: 32bit DMA uses non-identity > mapping > [ 2.489359] ehci-pci 0000:01:00.4: can't setup: -12 > [ 2.489531] ehci-pci 0000:01:00.4: USB bus 1 deregistered > [ 2.490023] ehci-pci 0000:01:00.4: init 0000:01:00.4 fail, -12 > [ 2.490358] ehci-pci: probe of 0000:01:00.4 failed with error -12 > > This issue happens when the value of the sagaw corresponds to a > 48-bit agaw. This fix updates the calculation of the agaw based on > the minimum of IOMMU's sagaw value and MGAW. > > Signed-off-by: Saeed Mirzamohammadi <saeed.mirzamohammadi@oracle.com> > Tested-by: Camille Lu <camille.lu@hpe.com> > --- > > Change in v2: > - Added cap_width to calculate AGAW based on the minimum value of MGAW and AGAW. > --- > drivers/iommu/intel-iommu.c | 7 ++++--- > 1 file changed, 4 insertions(+), 3 deletions(-) > > diff --git a/drivers/iommu/intel-iommu.c b/drivers/iommu/intel-iommu.c > index 953d86ca6d2b..a2a03df97704 100644 > --- a/drivers/iommu/intel-iommu.c > +++ b/drivers/iommu/intel-iommu.c > @@ -1853,7 +1853,7 @@ static inline int guestwidth_to_adjustwidth(int gaw) > static int domain_init(struct dmar_domain *domain, struct intel_iommu *iommu, > int guest_width) > { > - int adjust_width, agaw; > + int adjust_width, agaw, cap_width; > unsigned long sagaw; > int err; > > @@ -1867,8 +1867,9 @@ 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); > + cap_width = min_t(int, cap_mgaw(iommu->cap), agaw_to_width(iommu->agaw)); > + if (guest_width > cap_width) > + guest_width = cap_width; > domain->gaw = guest_width; > adjust_width = guestwidth_to_adjustwidth(guest_width); > agaw = width_to_agaw(adjust_width); >
Reviewed-by: Lu Baolu <baolu.lu@linux.intel.com>
Best regards, baolu
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