[v8] Add support for 32-bit physical address

[XEN v8 0/5] Add support for 32-bit physical address

Posted by Ayan Kumar Halder 10 months, 3 weeks ago

Hi All,

Please have a look at https://lists.xenproject.org/archives/html/xen-devel/2022-11/msg01465.html
for the context.

The benefits of using 32 bit physical addresses are as follows :-

1. It helps to use Xen on platforms (for eg R52) which supports 32-bit
physical addresses and has no support for large physical address extension.
On 32-bit MPU systems which supports flat-mapping (for eg R52), it helps
to translate 32 bit VA into 32 bit PA.

2. It also helps in code optimization when the underlying platform does not
use large physical address extension.

The following points are to be noted :-
1. Device tree always use uint64_t for address and size. The caller needs to
translate between uint64_t and unsigned long (when 32 bit physical addressing is used).
2. Currently, we have enabled this option for Arm_32 as the MMU for Arm_64
uses 48-bit physical addressing.

Changes from :

v1 - 1. Reordered the patches such that the first three patches fixes issues in
the existing codebase. These can be applied independent of the remaining patches
in this serie.

2. Dropped translate_dt_address_size() for the address/size translation between
paddr_t and u64 (as parsed from the device tree). Also, dropped the check for
truncation (while converting u64 to paddr_t).
Instead now we have modified device_tree_get_reg() and typecasted the return for
dt_read_number(), to obtain paddr_t. Also, introduced wrappers for
fdt_get_mem_rsv() and dt_device_get_address() for the same purpose. These can be
found in patch 4/11 and patch 6/11.

3. Split "Other adaptations required to support 32bit paddr" into the following
individual patches for each adaptation :
xen/arm: smmu: Use writeq_relaxed_non_atomic() for writing to
SMMU_CBn_TTBR0
xen/arm: guest_walk: LPAE specific bits should be enclosed within
"ifndef CONFIG_ARM_PA_32"

4. Introduced "xen/arm: p2m: Enable support for 32bit IPA".

v2 - 1. Dropped patches 1/11, 2/11 and 3/11 from the v2 as it has already been
committed (except 2/11 - "[XEN v5] xen/arm: Use the correct format specifier"
which is waiting to be committed).

2. Introduced a new patch "xen/drivers: ns16550: Use paddr_t for io_base/io_size".

v3 - 1. Combined the patches from https://lists.xenproject.org/archives/html/xen-devel/2023-02/msg00656.html in this series.

v4 - 1. Dropped "xen/drivers: ns16550: Use paddr_t for io_base/io_size" from the patch series.

2. Introduced "xen/arm: domain_build: Check if the address fits the range of physical address".

3. "xen/arm: Use the correct format specifier" has been committed in v4.

v5 - 1. Based on the comments on "[XEN v5 08/10] xen/arm: domain_build: Check if the address fits the range of physical address",
the patch has been modified and split into the following :-

a. xen: dt: Replace u64 with uint64_t as the callback function parameters
for dt_for_each_range()
b. xen/arm: pci: Use 'uint64_t' as the datatype for the function
parameters.
c. xen/arm: domain_build: Check if the address fits the range of physical
address

v6 - 1. Reordered the patches such that only the patches which are dependent on
"CONFIG_PHYS_ADDR_T_32" appear after the Kconfig option is introduced.

v7 - 1. Changes from "[XEN v7 01/11] xen/arm: domain_build: Track unallocated pages using the frame number
" till "[XEN v7 06/11] xen: dt: Replace u64 with uint64_t as the callback function parameters for dt_for_each_range()"
have been committed. So the remaining 5 patches are sent out.

Ayan Kumar Halder (5):
xen/arm: p2m: Use the pa_range_info table to support ARM_32 and ARM_64
xen/arm: Introduce choice to enable 64/32 bit physical addressing
xen/arm: guest_walk: LPAE specific bits should be enclosed within
"ifndef CONFIG_PHYS_ADDR_T_32"
xen/arm: Restrict zeroeth_table_offset for ARM_64
xen/arm: p2m: Enable support for 32bit IPA for ARM_32

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2.17.1