Hi Greg, This patch fixes an issue with the IOMMU driver and it only applies to 5.4, 4.19, and 4.14 stable kernels. May I know when this patch would be available in the stable kernels? Subject: iommu/vt-d: Fix agaw for a supported 48 bit guest address width Thanks, Saeed > On Apr 11, 2021, at 4:49 PM, Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx> wrote: > > I guess you need to ask Greg KH <gregkh@xxxxxxxxxxxxxxxxxxx> with this > Cc-ing to stable@xxxxxxxxxxxxxxx. > > Best regards, > baolu > > On 2021/4/12 3:36, Saeed Mirzamohammadi wrote: >> Hi Lu, >> Thanks for the review. May I know when do we expect this to be applied to 5.4? >> Thanks, >> Saeed >>> On Apr 7, 2021, at 5:25 PM, Lu Baolu <baolu.lu@xxxxxxxxxxxxxxx <mailto:baolu.lu@xxxxxxxxxxxxxxx>> wrote: >>> >>> 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@xxxxxxxxxx <mailto:saeed.mirzamohammadi@xxxxxxxxxx>> >>>> Tested-by: Camille Lu <camille.lu@xxxxxxx <mailto:camille.lu@xxxxxxx>> >>>> --- >>>> 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@xxxxxxxxxxxxxxx <mailto:baolu.lu@xxxxxxxxxxxxxxx>> >>> >>> Best regards, >>> baolu
