[XEN v6 12/12] xen/arm: p2m: Enable support for 32bit IPA for ARM_32

[Ayan Kumar Halder <ayan.kumar.halder@xxxxxxx>]

Refer ARM DDI 0406C.d ID040418, B3-1345,

"A stage 2 translation with an input address range of 31-34 bits can
start the translation either:

- With a first-level lookup, accessing a first-level translation
  table with 2-16 entries.

- With a second-level lookup, accessing a set of concatenated
  second-level translation tables"

Thus, for 32 bit IPA, there will be no concatenated root level tables.
So, the root-order is 0.

Also, Refer ARM DDI 0406C.d ID040418, B3-1348
"Determining the required first lookup level for stage 2 translations

For a stage 2 translation, the output address range from the stage 1
translations determines the required input address range for the stage 2
translation. The permitted values of VTCR.SL0 are:
0b00 Stage 2 translation lookup must start at the second level.
0b01 Stage 2 translation lookup must start at the first level.

VTCR.T0SZ must indicate the required input address range. The size of
the input address region is 2^(32-T0SZ) bytes."

Thus VTCR.SL0 = 1 (maximum value) and VTCR.T0SZ = 0 when the size of
input address region is 2^32 bytes.

Signed-off-by: Ayan Kumar Halder <ayan.kumar.halder@xxxxxxx>
---
Changes from -

v1 - New patch.

v2 - 1. Added Ack.

v3 - 1. Dropped Ack. 
2. Rebased the patch based on the previous change.

v4 - 1. t0sz is 0 for 32-bit IPA on Arm32.
2. Updated the commit message to explain t0sz, sl0 and root_order.

v5 - 1. Rebased on top of the changes in the previous patch.

 xen/arch/arm/p2m.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/xen/arch/arm/p2m.c b/xen/arch/arm/p2m.c
index 1fe3cccf46..6e13772cbc 100644
--- a/xen/arch/arm/p2m.c
+++ b/xen/arch/arm/p2m.c
@@ -2265,7 +2265,7 @@ void __init setup_virt_paging(void)
         [6] = { 52,      12/*12*/,  4,          2 },
         [7] = { 0 }  /* Invalid */
 #else
-        [0] = { 0 },  /* Invalid */
+        [0] = { 32,      0/*0*/,    0,          1 },
         [1] = { 0 },  /* Invalid */
         [3] = { 0 }  /* Invalid */
 #endif
-- 
2.17.1