From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 54F2A3BED70; Mon, 23 Mar 2026 17:20:40 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=217.140.110.172 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774286441; cv=none; b=RFWiu4c4+VSSTUv2wmZQhzlufJUSxcfy6+/SYnYqUHdV07tYmB/5sZaRnHZ4g2F1R4OukWR3T8iPBMbHkb+1Lsy4CxjYLxQeBSPEci/T0YGn5lfCtxLhHG63IKapDh1QoPNvQ00H7ztQJLRRn7WaE8kHuRCnjro0UJFAViNuTgk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1774286441; c=relaxed/simple; bh=cGwdQXbx4HQmSXzfvzrDVIxS8sciA0V0xGoMWgKtZzA=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=INa2cT9uegrBIHG0309p/Xui7mfpnW/WywwaO2KFNRJjmw5LI5YDYWlatbJCyoY9Bb5i/mlNrjrC/409sfgZz/WxPsc+zG92K4XUSM0Zl6lF+RqBoIIB0Uz2LvJavpz0H5OuIa8LEU4cRKMWLUlo34D9FEd1VfjMSnDb6ZBn+wU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com; spf=pass smtp.mailfrom=arm.com; arc=none smtp.client-ip=217.140.110.172 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=arm.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=arm.com Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 84B2014BF; Mon, 23 Mar 2026 10:20:33 -0700 (PDT) Received: from [10.57.83.179] (unknown [10.57.83.179]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 0DAD53F694; Mon, 23 Mar 2026 10:20:37 -0700 (PDT) Message-ID: <4b514b8b-c999-44f7-a7b1-12bd301b007f@arm.com> Date: Mon, 23 Mar 2026 17:20:36 +0000 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v1 1/3] arm64: mm: Fix rodata=full block mapping support for realm guests Content-Language: en-GB To: Kevin Brodsky , Catalin Marinas , Will Deacon , "David Hildenbrand (Arm)" , Dev Jain , Yang Shi , Suzuki K Poulose , Jinjiang Tu Cc: linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org References: <20260323130317.1737522-1-ryan.roberts@arm.com> <20260323130317.1737522-2-ryan.roberts@arm.com> <71261065-7895-492f-8457-998901391530@arm.com> From: Ryan Roberts In-Reply-To: <71261065-7895-492f-8457-998901391530@arm.com> Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit On 23/03/2026 16:52, Kevin Brodsky wrote: > On 23/03/2026 14:03, Ryan Roberts wrote: >> [...] >> >> diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c >> index 96711b8578fd0..b9b248d24fd10 100644 >> --- a/arch/arm64/mm/init.c >> +++ b/arch/arm64/mm/init.c >> @@ -350,7 +350,6 @@ void __init arch_mm_preinit(void) >> } >> >> swiotlb_init(swiotlb, flags); >> - swiotlb_update_mem_attributes(); >> >> /* >> * Check boundaries twice: Some fundamental inconsistencies can be >> @@ -377,6 +376,14 @@ void __init arch_mm_preinit(void) >> } >> } >> >> +bool page_alloc_available __ro_after_init; >> + >> +void __init mem_init(void) >> +{ >> + page_alloc_available = true; >> + swiotlb_update_mem_attributes(); > > The move seems reasonable, x86 calls this function even later (from > arch_cpu_finalize_init()). > >> +} >> + >> void free_initmem(void) >> { >> void *lm_init_begin = lm_alias(__init_begin); >> diff --git a/arch/arm64/mm/mmu.c b/arch/arm64/mm/mmu.c >> index a6a00accf4f93..5b6a8d53e64b7 100644 >> --- a/arch/arm64/mm/mmu.c >> +++ b/arch/arm64/mm/mmu.c >> @@ -773,14 +773,33 @@ int split_kernel_leaf_mapping(unsigned long start, unsigned long end) >> { >> int ret; >> >> - /* >> - * !BBML2_NOABORT systems should not be trying to change permissions on >> - * anything that is not pte-mapped in the first place. Just return early >> - * and let the permission change code raise a warning if not already >> - * pte-mapped. >> - */ >> - if (!system_supports_bbml2_noabort()) >> - return 0; >> + if (!system_supports_bbml2_noabort()) { >> + /* >> + * !BBML2_NOABORT systems should not be trying to change >> + * permissions on anything that is not pte-mapped in the first >> + * place. Just return early and let the permission change code >> + * raise a warning if not already pte-mapped. >> + */ >> + if (system_capabilities_finalized() || >> + !cpu_supports_bbml2_noabort()) >> + return 0; >> + >> + /* >> + * Boot-time: split_kernel_leaf_mapping_locked() allocates from >> + * page allocator. Can't split until it's available. >> + */ >> + extern bool page_alloc_available; > > Could we at least have the declaration in say ? x86 defines a > similar global so we could eventually have a generic global (defined > before mem_init() is called). Yeah, fair enough. I was being lazy. I'll move it to the header for v2. > > Looks good otherwise: > > Reviewed-by: Kevin Brodsky > >> + if (WARN_ON(!page_alloc_available)) >> + return -EBUSY; >> + >> + /* >> + * Boot-time: Started secondary cpus but don't know if they >> + * support BBML2_NOABORT yet. Can't allow splitting in this >> + * window in case they don't. >> + */ >> + if (WARN_ON(num_online_cpus() > 1)) >> + return -EBUSY; >> + } >> >> /* >> * If the region is within a pte-mapped area, there is no need to try to