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From: Catalin Marinas <catalin.marinas@arm.com>
To: Ryan Roberts <ryan.roberts@arm.com>
Cc: Will Deacon <will@kernel.org>,
	"David Hildenbrand (Arm)" <david@kernel.org>,
	Dev Jain <dev.jain@arm.com>,
	Yang Shi <yang@os.amperecomputing.com>,
	Suzuki K Poulose <suzuki.poulose@arm.com>,
	Jinjiang Tu <tujinjiang@huawei.com>,
	Kevin Brodsky <kevin.brodsky@arm.com>,
	linux-arm-kernel@lists.infradead.org,
	linux-kernel@vger.kernel.org, stable@vger.kernel.org
Subject: Re: [PATCH v2 1/3] arm64: mm: Fix rodata=full block mapping support for realm guests
Date: Fri, 3 Apr 2026 11:31:18 +0100	[thread overview]
Message-ID: <ac-W9oNM_O5RTtaf@arm.com> (raw)
In-Reply-To: <ac7VD4Z85nS30GCp@arm.com>

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


  reply	other threads:[~2026-04-03 10:31 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-03-30 16:17 [PATCH v2 0/3] Fix bugs for realm guest plus BBML2_NOABORT Ryan Roberts
2026-03-30 16:17 ` [PATCH v2 1/3] arm64: mm: Fix rodata=full block mapping support for realm guests Ryan Roberts
2026-03-31 14:35   ` Suzuki K Poulose
2026-04-02 20:43   ` Catalin Marinas
2026-04-03 10:31     ` Catalin Marinas [this message]
2026-03-30 16:17 ` [PATCH v2 2/3] arm64: mm: Handle invalid large leaf mappings correctly Ryan Roberts
2026-03-30 16:17 ` [PATCH v2 3/3] arm64: mm: Remove pmd_sect() and pud_sect() Ryan Roberts
2026-04-02 21:11 ` [PATCH v2 0/3] Fix bugs for realm guest plus BBML2_NOABORT Catalin Marinas

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