Subject: Re: [PATCH v2 1/3] arm64: mm: Fix rodata=full block mapping support for realm guests

From: Catalin Marinas <[email-masked]>
Date: Fri, 3 Apr 2026 11:31:18 +0100

On Thu, Apr 02, 2026 at 09:43:59PM +0100, Catalin Marinas wrote:
> Another thing I couldn't get my head around - IIUC is_realm_world()
> won't return true for map_mem() yet (if in a realm). Can we have realms
> on hardware that does not support BBML2_NOABORT? We may not have
> configuration with rodata_full set (it should be complementary to realm
> support).

With rodata_full==false, can_set_direct_map() returns false initially
but after arm64_rsi_init() it starts returning true if is_realm_world().
The side-effect is that map_mem() goes for block mappings and
linear_map_requires_bbml2 set to false. Later on,
linear_map_maybe_split_to_ptes() will skip the splitting.

Unless I'm missing something, is_realm_world() calls in
force_pte_mapping() and can_set_direct_map() are useless. I'd remove
them and either require BBML2_NOABORT with CCA or get the user to force
rodata_full when running in realms. Or move arm64_rsi_init() even
earlier?

-- 
Catalin