[PATCH v5 3/8] ACPI/IORT: Add a helper to retrieve RMR memory regions
Jon Nettleton
jon at solid-run.com
Sun Jul 4 00:38:38 PDT 2021
On Tue, Jun 29, 2021 at 7:34 PM Jon Nettleton <jon at solid-run.com> wrote:
>
> On Mon, Jun 14, 2021 at 2:49 PM Shameerali Kolothum Thodi
> <shameerali.kolothum.thodi at huawei.com> wrote:
> >
> >
> >
> > > -----Original Message-----
> > > From: Robin Murphy [mailto:robin.murphy at arm.com]
> > > Sent: 14 June 2021 12:23
> > > To: Shameerali Kolothum Thodi <shameerali.kolothum.thodi at huawei.com>;
> > > linux-arm-kernel at lists.infradead.org; linux-acpi at vger.kernel.org;
> > > iommu at lists.linux-foundation.org
> > > Cc: jon at solid-run.com; Linuxarm <linuxarm at huawei.com>;
> > > steven.price at arm.com; Guohanjun (Hanjun Guo) <guohanjun at huawei.com>;
> > > yangyicong <yangyicong at huawei.com>; Sami.Mujawar at arm.com;
> > > wanghuiqiang <wanghuiqiang at huawei.com>
> > > Subject: Re: [PATCH v5 3/8] ACPI/IORT: Add a helper to retrieve RMR memory
> > > regions
> > >
> > > On 2021-05-24 12:02, Shameer Kolothum wrote:
> > > > Add a helper function that retrieves RMR memory descriptors
> > > > associated with a given IOMMU. This will be used by IOMMU
> > > > drivers to setup necessary mappings.
> > > >
> > > > Now that we have this, invoke it from the generic helper
> > > > interface.
> > > >
> > > > Signed-off-by: Shameer Kolothum
> > > <shameerali.kolothum.thodi at huawei.com>
> > > > ---
> > > > drivers/acpi/arm64/iort.c | 50
> > > +++++++++++++++++++++++++++++++++++++++
> > > > drivers/iommu/dma-iommu.c | 4 ++++
> > > > include/linux/acpi_iort.h | 7 ++++++
> > > > 3 files changed, 61 insertions(+)
> > > >
> > > > diff --git a/drivers/acpi/arm64/iort.c b/drivers/acpi/arm64/iort.c
> > > > index fea1ffaedf3b..01917caf58de 100644
> > > > --- a/drivers/acpi/arm64/iort.c
> > > > +++ b/drivers/acpi/arm64/iort.c
> > > > @@ -12,6 +12,7 @@
> > > >
> > > > #include <linux/acpi_iort.h>
> > > > #include <linux/bitfield.h>
> > > > +#include <linux/dma-iommu.h>
> > > > #include <linux/iommu.h>
> > > > #include <linux/kernel.h>
> > > > #include <linux/list.h>
> > > > @@ -837,6 +838,53 @@ static inline int iort_add_device_replay(struct
> > > device *dev)
> > > > return err;
> > > > }
> > > >
> > > > +/**
> > > > + * iort_iommu_get_rmrs - Helper to retrieve RMR info associated with
> > > IOMMU
> > > > + * @iommu: fwnode for the IOMMU
> > > > + * @head: RMR list head to be populated
> > > > + *
> > > > + * Returns: 0 on success, <0 failure
> > > > + */
> > > > +int iort_iommu_get_rmrs(struct fwnode_handle *iommu_fwnode,
> > > > + struct list_head *head)
> > > > +{
> > > > + struct iort_rmr_entry *e;
> > > > + struct acpi_iort_node *iommu;
> > > > + int rmrs = 0;
> > > > +
> > > > + iommu = iort_get_iort_node(iommu_fwnode);
> > > > + if (!iommu || list_empty(&iort_rmr_list))
> > > > + return -ENODEV;
> > > > +
> > > > + list_for_each_entry(e, &iort_rmr_list, list) {
> > > > + int prot = IOMMU_READ | IOMMU_WRITE | IOMMU_NOEXEC |
> > > IOMMU_MMIO;
> > > > + struct iommu_resv_region *region;
> > > > + enum iommu_resv_type type;
> > > > + struct acpi_iort_rmr_desc *rmr_desc;
> > > > +
> > > > + if (e->smmu != iommu)
> > > > + continue;
> > > > +
> > > > + rmr_desc = e->rmr_desc;
> > > > + if (e->flags & IOMMU_RMR_REMAP_PERMITTED)
> > > > + type = IOMMU_RESV_DIRECT_RELAXABLE;
> > > > + else
> > > > + type = IOMMU_RESV_DIRECT;
> > >
>
> I have been looking at this a bit more and looking at the history of
> RMR_REMAP_PERMITTED. Based on the history I have found it
> seems to me like this would be the better options for prot.
>
> @@ -840,7 +840,7 @@ int iort_iommu_get_rmrs(struct fwnode_handle *iommu_fwnode,
> return -ENODEV;
>
> list_for_each_entry(e, &iort_rmr_list, list) {
> - int prot = IOMMU_READ | IOMMU_WRITE | IOMMU_NOEXEC | IOMMU_MMIO;
> + int prot = IOMMU_READ | IOMMU_WRITE;
> struct iommu_resv_region *region;
> enum iommu_resv_type type;
> struct acpi_iort_rmr_desc *rmr_desc;
> @@ -849,10 +849,13 @@ int iort_iommu_get_rmrs(struct fwnode_handle
> *iommu_fwnode,
> continue;
>
> rmr_desc = e->rmr_desc;
> - if (e->flags & IOMMU_RMR_REMAP_PERMITTED)
> + if (e->flags & IOMMU_RMR_REMAP_PERMITTED) {
> type = IOMMU_RESV_DIRECT_RELAXABLE;
> - else
> + prot |= IOMMU_CACHE;
> + } else {
> type = IOMMU_RESV_DIRECT;
> + prot |= IOMMU_MMIO;
> + }
>
> region = iommu_alloc_resv_region(rmr_desc->base_address,
> rmr_desc->length,
>
> any input on this? My reasoning is that IOMMU_RESV_DIRECT is specifically
> referenced for things like MSI doorbell and in all the examples needs
> IOMMU_MMIO, while REMAP_PERMITTED seems to be used for allocated
> system memory that is then used for device specific reserved regions which
> commits say would be like a GPU or USB device.
>
> -Jon
>
> > > Wasn't the idea that we can do all this during the initial parsing, i.e.
> > > we don't even have iort_rmr_entry, we store them as iommu_resv_regions
> > > and simply kmemdup() or whatever at this point?
> >
> >
> > Hmm... Not yet. I removed struct iommu_rmr() from v4. But yes, it looks like
> > we can get rid of iort_rmr_entry as well. Will give it a go in next.
> >
> > Thanks,
> > Shameer
> >
> > > Robin.
> > >
> > > > +
> > > > + region = iommu_alloc_resv_region(rmr_desc->base_address,
> > > > + rmr_desc->length,
> > > > + prot, type);
> > > > + if (region) {
> > > > + region->fw_data.rmr.flags = e->flags;
> > > > + region->fw_data.rmr.sid = e->sid;
> > > > + list_add_tail(®ion->list, head);
> > > > + rmrs++;
> > > > + }
> > > > + }
> > > > +
> > > > + return (rmrs == 0) ? -ENODEV : 0;
> > > > +}
> > > > +
> > > > /**
> > > > * iort_iommu_msi_get_resv_regions - Reserved region driver helper
> > > > * @dev: Device from iommu_get_resv_regions()
> > > > @@ -1108,6 +1156,8 @@ int iort_iommu_msi_get_resv_regions(struct
> > > device *dev, struct list_head *head)
> > > > const struct iommu_ops *iort_iommu_configure_id(struct device *dev,
> > > > const u32 *input_id)
> > > > { return NULL; }
> > > > +int iort_iommu_get_rmrs(struct fwnode_handle *fwnode, struct list_head
> > > *head)
> > > > +{ return -ENODEV; }
> > > > #endif
> > > >
> > > > static int nc_dma_get_range(struct device *dev, u64 *size)
> > > > diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
> > > > index 229ec65d98be..f893d460cfa4 100644
> > > > --- a/drivers/iommu/dma-iommu.c
> > > > +++ b/drivers/iommu/dma-iommu.c
> > > > @@ -185,6 +185,9 @@ EXPORT_SYMBOL(iommu_put_dma_cookie);
> > > > int iommu_dma_get_rmrs(struct fwnode_handle *iommu_fwnode,
> > > > struct list_head *list)
> > > > {
> > > > + if (!is_of_node(iommu_fwnode))
> > > > + return iort_iommu_get_rmrs(iommu_fwnode, list);
> > > > +
> > > > return -EINVAL;
> > > > }
> > > > EXPORT_SYMBOL(iommu_dma_get_rmrs);
> > > > @@ -200,6 +203,7 @@ EXPORT_SYMBOL(iommu_dma_get_rmrs);
> > > > void iommu_dma_put_rmrs(struct fwnode_handle *iommu_fwnode,
> > > > struct list_head *list)
> > > > {
> > > > + generic_iommu_put_resv_regions(iommu_fwnode->dev, list);
> > > > }
> > > > EXPORT_SYMBOL(iommu_dma_put_rmrs);
> > > >
> > > > diff --git a/include/linux/acpi_iort.h b/include/linux/acpi_iort.h
> > > > index 1a12baa58e40..e8c45fa59531 100644
> > > > --- a/include/linux/acpi_iort.h
> > > > +++ b/include/linux/acpi_iort.h
> > > > @@ -39,6 +39,8 @@ const struct iommu_ops
> > > *iort_iommu_configure_id(struct device *dev,
> > > > const u32 *id_in);
> > > > int iort_iommu_msi_get_resv_regions(struct device *dev, struct list_head
> > > *head);
> > > > phys_addr_t acpi_iort_dma_get_max_cpu_address(void);
> > > > +int iort_iommu_get_rmrs(struct fwnode_handle *iommu_fwnode,
> > > > + struct list_head *list);
> > > > #else
> > > > static inline void acpi_iort_init(void) { }
> > > > static inline u32 iort_msi_map_id(struct device *dev, u32 id)
> > > > @@ -59,6 +61,11 @@ int iort_iommu_msi_get_resv_regions(struct device
> > > *dev, struct list_head *head)
> > > >
> > > > static inline phys_addr_t acpi_iort_dma_get_max_cpu_address(void)
> > > > { return PHYS_ADDR_MAX; }
> > > > +
> > > > +static inline
> > > > +int iort_iommu_get_rmrs(struct fwnode_handle *iommu_fwnode,
> > > > + struct list_head *list)
> > > > +{ return -ENODEV; }
> > > > #endif
> > > >
> > > > #endif /* __ACPI_IORT_H__ */
> > > >
Ping. Any comments on this?
-Jon
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