Vladimir Kondratiev 331dae1bc1 platform: generic: mips eyeq7h: prohibit accessing memory beyond DRAM ...

SBI code arranges domain PMP regions in a way that last entry is
all-inclusive "0..~0 RWX" and the rest of entries are not programmed.
This causes a problem for the eyeq7h.

CPU can issue speculative prefetches to non-existent addresses. If this
access goes to the system NOC, it is mis-interpreted as an access
violation and error is reported, forcing system reset.

To prevent such a speculative transaction to leave a CPU cluster,
block it using PMP, by restricting memory region to physically present
memory. To achieve this, on early init:

- update flags for the last all-inclusive "0..~0 RWX" entry to be
  inaccessible MMIO. MMIO serves to set up PMA attributes to uncached
  non-prefetchable, preventing transactions to reach system NOC
- add an all-permissive entry matching DRAM.

Resulting memory regions:

Domain0 Region00            : 0x0000000800100000-0x000000080013ffff M: (F,R,X) S/U: ()
Domain0 Region01            : 0x0000000800100000-0x00000008001fffff M: (F,R,W) S/U: ()
Domain0 Region02            : 0x0000000048700000-0x000000004870ffff M: (I,R,W) S/U: ()
Domain0 Region03            : 0x0000000067480000-0x000000006748ffff M: (I,R,W) S/U: ()
Domain0 Region04            : 0x0000000067500000-0x000000006750ffff M: (I,R,W) S/U: ()
Domain0 Region05            : 0x0000000048740000-0x000000004875ffff M: (I,R,W) S/U: ()
Domain0 Region06            : 0x00000000674c0000-0x00000000674dffff M: (I,R,W) S/U: ()
Domain0 Region07            : 0x0000000067540000-0x000000006755ffff M: (I,R,W) S/U: ()
Domain0 Region08            : 0x0000000000000000-0x000000007fffffff M: (I,R,W) S/U: (R,W)
Domain0 Region09            : 0x0000000800000000-0x00000008ffffffff M: () S/U: (R,W,X)
Domain0 Region10            : 0x0000001000000000-0x0000001fffffffff M: (I) S/U: (R,W)
Domain0 Region11            : 0x0000000000000000-0xffffffffffffffff M: (I) S/U: ()

Here Region09 covers DRAM, region 11 set to non-accessible
uncached no-prefetch for the entire address range

Signed-off-by: Vladimir Kondratiev <vladimir.kondratiev@mobileye.com>
Reviewed-by: Anup Patel <anup@brainfault.org>
Link: https://lore.kernel.org/r/20260223-for-upstream-eyeq7h-v3-21-621d004d1a21@mobileye.com
Signed-off-by: Anup Patel <anup@brainfault.org>

2026-02-25 18:49:03 +05:30

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