On Wed, 24 Nov 2021, Oleksandr Tyshchenko wrote: > From: Oleksandr Tyshchenko <oleksandr_tyshchenko@xxxxxxxx> > > Xen on Arm has gained new support recently to calculate and report > extended regions (unused address space) safe to use for external > mappings. These regions are reported via "reg" property under > "hypervisor" node in the guest device-tree. As region 0 is reserved > for grant table space (always present), the indexes for extended > regions are 1...N. > > No device-tree bindings update is needed (except clarifying the text) > as guest infers the presence of extended regions from the number > of regions in "reg" property. > > Signed-off-by: Oleksandr Tyshchenko <oleksandr_tyshchenko@xxxxxxxx> > --- > According to the recent update to Xen's guest.txt: > https://xenbits.xen.org/gitweb/?p=xen.git;a=blob_plain;f=docs/misc/arm/device-tree/guest.txt;hb=refs/heads/master > > Changes V2 -> V3: > - new patch > --- > Documentation/devicetree/bindings/arm/xen.txt | 12 ++++++++---- > 1 file changed, 8 insertions(+), 4 deletions(-) > > diff --git a/Documentation/devicetree/bindings/arm/xen.txt b/Documentation/devicetree/bindings/arm/xen.txt > index db5c56d..156fe10b 100644 > --- a/Documentation/devicetree/bindings/arm/xen.txt > +++ b/Documentation/devicetree/bindings/arm/xen.txt > @@ -7,10 +7,14 @@ the following properties: > compatible = "xen,xen-<version>", "xen,xen"; > where <version> is the version of the Xen ABI of the platform. > > -- reg: specifies the base physical address and size of a region in > - memory where the grant table should be mapped to, using an > - HYPERVISOR_memory_op hypercall. The memory region is large enough to map > - the whole grant table (it is larger or equal to gnttab_max_grant_frames()). > +- reg: specifies the base physical address and size of the regions in memory > + where the special resources should be mapped to, using an HYPERVISOR_memory_op > + hypercall. > + Region 0 is reserved for mapping grant table, it must be always present. > + The memory region is large enough to map the whole grant table (it is larger > + or equal to gnttab_max_grant_frames()). > + Regions 1...N are extended regions (unused address space) for mapping foreign > + GFNs and grants, they might be absent if there is nothing to expose. > This property is unnecessary when booting Dom0 using ACPI. I would remove the last sentence about ACPI as the initialization is not done via the xen,xen device tree node in that case anyway. With that change: Reviewed-by: Stefano Stabellini <sstabellini@xxxxxxxxxx>
