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Re: [Xen-devel] [PATCH v5 5/8] xen/arm: assign devices to boot domains
On 26.09.19 00:12, Julien Grall wrote:
Hi Stefano,
Hi Stefano, Julien
On 25/09/2019 19:49, Stefano Stabellini wrote:
Scan the user provided dtb fragment at boot. For each device node, map
memory to guests, and route interrupts and setup the iommu.
The memory region to remap is specified by the "xen,reg" property.
The iommu is setup by passing the node of the device to assign on the
host device tree. The path is specified in the device tree fragment as
the "xen,path" string property.
The interrupts are remapped based on the information from the
corresponding node on the host device tree. Call
handle_device_interrupts to remap interrupts. Interrupts related device
tree properties are copied from the device tree fragment, same as all
the other properties.
Also add the new flag XEN_DOMCTL_CDF_iommu to that dom0less domU can use
the IOMMU.
Signed-off-by: Stefano Stabellini <stefanos@xxxxxxxxxx>
---
Changes in v5:
- use local variable for name
- use map_regions_p2mt
- add warning for not page aligned addresses/sizes
- introduce handle_passthrough_prop
Changes in v4:
- use unsigned
- improve commit message
- code style
- use dt_prop_cmp
- use device_tree_get_reg
- don't copy over xen,reg and xen,path
- don't create special interrupt properties for domU: copy them from the
fragment
- in-code comment
Changes in v3:
- improve commit message
- remove superfluous cast
- merge code with the copy code
- add interrup-parent
- demove depth > 2 check
- reuse code from handle_device_interrupts
- copy interrupts from host dt
Changes in v2:
- rename "path" to "xen,path"
- grammar fix
- use gaddr_to_gfn and maddr_to_mfn
- remove depth <= 2 limitation in scanning the dtb fragment
- introduce and parse xen,reg
- code style
- support more than one interrupt per device
- specify only the GIC is supported
---
xen/arch/arm/domain_build.c | 101 ++++++++++++++++++++++++++++++++++--
1 file changed, 97 insertions(+), 4 deletions(-)
diff --git a/xen/arch/arm/domain_build.c b/xen/arch/arm/domain_build.c
index 9d985d3bbe..414893bc24 100644
--- a/xen/arch/arm/domain_build.c
+++ b/xen/arch/arm/domain_build.c
@@ -1701,6 +1701,85 @@ static int __init make_vpl011_uart_node(struct
kernel_info *kinfo)
}
#endif
+/*
+ * Scan device tree properties for passthrough specific information.
+ * Returns -ENOENT when no passthrough properties are found
+ * < 0 on error
+ * 0 on success
+ */
+static int __init handle_passthrough_prop(struct kernel_info *kinfo,
+ const struct fdt_property *prop,
+ const char *name,
+ uint32_t address_cells, uint32_t
size_cells)
+{
+ const __be32 *cell;
+ unsigned int i, len;
+ struct dt_device_node *node;
+ int res;
+
+ /* xen,reg specifies where to map the MMIO region */
+ if ( dt_prop_cmp("xen,reg", name) == 0 )
+ {
+ paddr_t mstart, size, gstart;
+ cell = (const __be32 *)prop->data;
+ len = fdt32_to_cpu(prop->len) /
+ ((address_cells * 2 + size_cells) * sizeof(uint32_t));
+
+ for ( i = 0; i < len; i++ )
+ {
+ device_tree_get_reg(&cell, address_cells, size_cells,
+ &mstart, &size);
+ gstart = dt_next_cell(address_cells, &cell);
+
+ if ( gstart & ~PAGE_MASK || mstart & ~PAGE_MASK || size &
~PAGE_MASK )
+ dprintk(XENLOG_WARNING,
+ "DomU passthrough config has not page aligned
addresses/sizes\n");
I don't think this is wise to continue, the more this is a printk that
can only happen in debug build. So someone using a release build may not
notice the error.
So I think this wants to be a printk(XENLOG_ERR,...) and also return an
error.
+
+ res = map_regions_p2mt(kinfo->d,
+ gaddr_to_gfn(gstart),
+ PFN_DOWN(size),
+ maddr_to_mfn(mstart),
+ p2m_mmio_direct_dev);
Coding style.
+ if ( res < 0 )
+ {
+ dprintk(XENLOG_ERR,
+ "Failed to map %"PRIpaddr" to the guest
at%"PRIpaddr"\n",
+ mstart, gstart);
Similarly, this wants to be a printk.
+ return -EFAULT;
+ }
+ }
+
+ return 0;
+ }
+ /*
+ * xen,path specifies the corresponding node in the host DT.
+ * Both interrupt mappings and IOMMU settings are based on it,
+ * as they are done based on the corresponding host DT node.
+ */
+ else if ( dt_prop_cmp("xen,path", name) == 0 )
+ {
+ node = dt_find_node_by_path(prop->data);
+ if ( node == NULL )
+ {
+ dprintk(XENLOG_ERR, "Couldn't find node %s in host_dt!\n",
+ (char *)prop->data);
Same here.
+ return -EINVAL;
+ }
I have to admit that I don't know about dom0less feature enough ...
But, shouldn't we check if the device is behind the IOMMU and try to add
it (iommu_add_dt_device) before assigning it (this is needed for drivers
which support generic IOMMU DT bindings in the first place).
[please take a look at
https://lists.xenproject.org/archives/html/xen-devel/2019-09/msg02714.html
if so]
Julien, what do you think?
+
+ res = iommu_assign_dt_device(kinfo->d, node);
+ if ( res < 0 )
+ return res;
+
+ res = handle_device_interrupts(kinfo->d, node, true);
+ if ( res < 0 )
+ return res;
+
+ return 0;
+ }
+
+ return -ENOENT;
+}
+
static int __init handle_prop_pfdt(struct kernel_info *kinfo,
const void *pfdt, int nodeoff,
uint32_t address_cells, uint32_t
size_cells,
@@ -1709,6 +1788,7 @@ static int __init handle_prop_pfdt(struct kernel_info
*kinfo,
void *fdt = kinfo->fdt;
int propoff, nameoff, res;
const struct fdt_property *prop;
+ const char *name;
for ( propoff = fdt_first_property_offset(pfdt, nodeoff);
propoff >= 0;
@@ -1717,11 +1797,23 @@ static int __init handle_prop_pfdt(struct kernel_info
*kinfo,
if ( !(prop = fdt_get_property_by_offset(pfdt, propoff, NULL)) )
return -FDT_ERR_INTERNAL;
+ res = 0;
nameoff = fdt32_to_cpu(prop->nameoff);
- res = fdt_property(fdt, fdt_string(pfdt, nameoff),
- prop->data, fdt32_to_cpu(prop->len));
- if ( res )
+ name = fdt_string(pfdt, nameoff);
+
+ if ( scan_passthrough_prop )
+ res = handle_passthrough_prop(kinfo, prop, name,
+ address_cells, size_cells);
+ if ( res < 0 && res != -ENOENT )
return res;
+
+ /* copy all other properties */
+ if ( !scan_passthrough_prop || res == -ENOENT )
+ {
+ res = fdt_property(fdt, name, prop->data, fdt32_to_cpu(prop->len));
+ if ( res )
+ return res;
+ }
}
/* FDT_ERR_NOTFOUND => There is no more properties for this node */
@@ -2254,7 +2346,8 @@ void __init create_domUs(void)
struct xen_domctl_createdomain d_cfg = {
.arch.gic_version = XEN_DOMCTL_CONFIG_GIC_NATIVE,
.arch.nr_spis = 0,
- .flags = XEN_DOMCTL_CDF_hvm | XEN_DOMCTL_CDF_hap,
+ .flags = XEN_DOMCTL_CDF_hvm | XEN_DOMCTL_CDF_hap |
+ XEN_DOMCTL_CDF_iommu,
This will break dom0less on platform without an IOMMU because setting
CDF_iommu for them will be invalid.
I also don't think this is wise to always enable the IOMMU. This should
only be done if there is a partial device-tree present (most likely it
means passthrough will be used).
.max_evtchn_port = -1,
.max_grant_frames = 64,
.max_maptrack_frames = 1024,
Cheers,
--
Regards,
Oleksandr Tyshchenko
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