> -----Original Message----- > From: Jon Nettleton [mailto:jon@xxxxxxxxxxxxx] > Sent: 09 October 2021 07:58 > To: Robin Murphy <robin.murphy@xxxxxxx> > Cc: Shameerali Kolothum Thodi <shameerali.kolothum.thodi@xxxxxxxxxx>; > linux-arm-kernel <linux-arm-kernel@xxxxxxxxxxxxxxxxxxx>; ACPI Devel Maling > List <linux-acpi@xxxxxxxxxxxxxxx>; Linux IOMMU > <iommu@xxxxxxxxxxxxxxxxxxxxxxxxxx>; Linuxarm <linuxarm@xxxxxxxxxx>; > Steven Price <steven.price@xxxxxxx>; Guohanjun (Hanjun Guo) > <guohanjun@xxxxxxxxxx>; yangyicong <yangyicong@xxxxxxxxxx>; Sami > Mujawar <Sami.Mujawar@xxxxxxx>; Will Deacon <will@xxxxxxxxxx>; > wanghuiqiang <wanghuiqiang@xxxxxxxxxx> > Subject: Re: [PATCH v7 1/9] iommu: Introduce a union to struct > iommu_resv_region > > On Fri, Oct 8, 2021 at 2:14 PM Robin Murphy <robin.murphy@xxxxxxx> > wrote: > > > > On 2021-08-05 09:07, Shameer Kolothum wrote: > > > A union is introduced to struct iommu_resv_region to hold any > > > firmware specific data. This is in preparation to add support for > > > IORT RMR reserve regions and the union now holds the RMR specific > > > information. > > > > > > Signed-off-by: Shameer Kolothum > > > <shameerali.kolothum.thodi@xxxxxxxxxx> > > > --- > > > include/linux/iommu.h | 11 +++++++++++ > > > 1 file changed, 11 insertions(+) > > > > > > diff --git a/include/linux/iommu.h b/include/linux/iommu.h index > > > 32d448050bf7..bd0e4641c569 100644 > > > --- a/include/linux/iommu.h > > > +++ b/include/linux/iommu.h > > > @@ -114,6 +114,13 @@ enum iommu_resv_type { > > > IOMMU_RESV_SW_MSI, > > > }; > > > > > > +struct iommu_iort_rmr_data { > > > +#define IOMMU_RMR_REMAP_PERMITTED (1 << 0) > > > + u32 flags; > > > + u32 sid; /* Stream Id associated with RMR entry */ > > > + void *smmu; /* Associated IORT SMMU node pointer */ > > > +}; > > > > Do we really need to duplicate all this data? AFAICS we could just > > save the acpi_iort_rmr pointer in the iommu_resv_region (with a > > forward declaration here if necessary) and defer parsing its actual > > mappings until the point where we can directly consume the results. > > From earlier discussions on this patchset, the original goal was also for > device-tree mechanisms to be able to hook into this code to support similar > RMR's and SMMU initialization, just not through the ACPI / IORT path. Yes. IIRC, there were some earlier attempts to have DT support for reserved regions and there was a suggestion to provide generic interfaces so that when DT solution comes up it is easier to add the support. Thanks, Shameer > > > > Robin. > > > > > + > > > /** > > > * struct iommu_resv_region - descriptor for a reserved memory region > > > * @list: Linked list pointers > > > @@ -121,6 +128,7 @@ enum iommu_resv_type { > > > * @length: Length of the region in bytes > > > * @prot: IOMMU Protection flags (READ/WRITE/...) > > > * @type: Type of the reserved region > > > + * @rmr: ACPI IORT RMR specific data > > > */ > > > struct iommu_resv_region { > > > struct list_head list; > > > @@ -128,6 +136,9 @@ struct iommu_resv_region { > > > size_t length; > > > int prot; > > > enum iommu_resv_type type; > > > + union { > > > + struct iommu_iort_rmr_data rmr; > > > + } fw_data; > > > }; > > > > > > /** > > >
