From nobody Thu Oct 2 02:12:35 2025 Received: from mail-wm1-f73.google.com (mail-wm1-f73.google.com [209.85.128.73]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 5035930FF25 for ; Wed, 24 Sep 2025 15:00:23 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.128.73 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758726025; cv=none; b=dUvJzVetjJ3QqptdcTamglTPGAPzuQ6rdCSrjwUoQ5PTUuZympnkmWW49FvXqitaQhbH0oKeDgiYbFNeALJY/fS0Mr+oHddS0JMOZGLcy0MnDN2jU89fO54J3hh5BDPTz+TcttgJJjzu1YCROuxUEB20ZKrEiZcnrJXuKrhV3Wo= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1758726025; c=relaxed/simple; bh=BlPWJVLTizBu3rBmLZteoElQSh8cUGz0SgfTUTNxP+U=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=aRYJrWawqcvmmrtBvdQzoOmXe3BnfBEPWc9rOXM/YZ00AJdkNlLaHF1Ad/PAkFG8qzEB60Jpew/f7an+o/wSKxICRRkP32AQNUfh+bQhoGplOieGEKsZmq6JdWsI113Xd/4eSy2YcNSppArirRc5rXYa5jS05p4t2XS/LPLmX4w= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--jackmanb.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=Xtau7mql; arc=none smtp.client-ip=209.85.128.73 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--jackmanb.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="Xtau7mql" Received: by mail-wm1-f73.google.com with SMTP id 5b1f17b1804b1-45b98de0e34so65918275e9.0 for ; Wed, 24 Sep 2025 08:00:23 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20230601; t=1758726022; x=1759330822; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:from:to:cc:subject:date:message-id:reply-to; bh=Dzh5+kDID1KhkCxx5TAU7iczEzF1E7tPp3j9MouQ4wI=; b=Xtau7mql6ix214wG0kWx5jZUnNgUoqpyTDkjFKKMMT0VJPqVA4+le3UpDtiBKuJjRE Ndmk9St9VNV/bXUgx1eALzppooG3r/izYY/8PumXqoad8AuTDCROMSAzIV+sUNWZZr7g Uvc3HlL7Dhk1PI7r+aVGrW6+vwj98+HMrJZyGGT7E1xpkiz29oaxBmHcLv3hIxrWzl9X 1RnopMwjX+gZ/9o+ozNbFA8cLdN70TSn7tuC4Q7brFKc5lSzRb4LdtJfOV8LPs8X8Vwt 1F3mizOhKxR7EHAxLquO7KxyKLQI8ju1Pjn8UK29t7RZ1KYITMtWCizzXWQBdxGNMSZl Hk0Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1758726022; x=1759330822; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=Dzh5+kDID1KhkCxx5TAU7iczEzF1E7tPp3j9MouQ4wI=; b=uoepEC8WSStPLRQs41IOhDvjTNQbS8/nm2R5DPqlkbh/TQFQKAyyXwLIDFdj+1IIIU XS5Lsk9qvytXldm8lbXa+6pho/qS/ZMuXLrzwO0JbbVMqlzBtuN2YGEc0jJcqJr5vQvm 2KsYgGFiNxLz+7II+O1FsnVZjkVLYG8VI9jWLsn2FifbQ+qKgVEUqeX0fxRzHD00jCDE RpFIxDL43um6pdV5OrN/7ztoJ5itJluQdP7+fxabxdNLfrCliF9PWOOgUcR/N2bA6KB2 jYYzMo5n4yPbAJ3Lhdc02RBVpdkSTHEIDlbVjYFIc+lgbwwtTmmQfatvM/bxXORz4UFq 9A8A== X-Forwarded-Encrypted: i=1; AJvYcCXUtOztPd/5EZf0UH5dvjajFfcJmvU4TS7p+v9pJ6SveVhL9CHq83SF8BaZey0PAMo626nX/R/m4K0sU3Y=@vger.kernel.org X-Gm-Message-State: AOJu0YxNU6/LwkqSwZfBZK96eAsr8q34buRyHTpO2cCmJdpt1tm/kloS P6hUk/nxcSZnF7y8qfbzzLfsdwbnBB2j08KAAx213bOhp6nAQKjr/o8LOULl1pa6XjemEvRI+ha Udq/WJYJtOzzklQ== X-Google-Smtp-Source: AGHT+IEsHROXBlX8gPQ5wff3adn8/PrmanibVw/L6EsgdA0zSkoUR9p6G5MTbXSwhHIl6BOnzg1VAmDD3yV6Wg== X-Received: from wmbeu9.prod.google.com ([2002:a05:600c:81c9:b0:45f:2859:5428]) (user=jackmanb job=prod-delivery.src-stubby-dispatcher) by 2002:a05:600c:608c:b0:46e:2f74:2b9a with SMTP id 5b1f17b1804b1-46e32a1a097mr1793855e9.30.1758726021991; Wed, 24 Sep 2025 08:00:21 -0700 (PDT) Date: Wed, 24 Sep 2025 14:59:49 +0000 In-Reply-To: <20250924-b4-asi-page-alloc-v1-0-2d861768041f@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20250924-b4-asi-page-alloc-v1-0-2d861768041f@google.com> X-Mailer: b4 0.14.2 Message-ID: <20250924-b4-asi-page-alloc-v1-14-2d861768041f@google.com> Subject: [PATCH 14/21] x86/mm/pat: introduce cpa_fault option From: Brendan Jackman To: jackmanb@google.com, Andy Lutomirski , Lorenzo Stoakes , "Liam R. Howlett" , Suren Baghdasaryan , Michal Hocko , Johannes Weiner , Zi Yan , Axel Rasmussen , Yuanchu Xie , Roman Gushchin Cc: peterz@infradead.org, bp@alien8.de, dave.hansen@linux.intel.com, mingo@redhat.com, tglx@linutronix.de, akpm@linux-foundation.org, david@redhat.com, derkling@google.com, junaids@google.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, reijiw@google.com, rientjes@google.com, rppt@kernel.org, vbabka@suse.cz, x86@kernel.org, yosry.ahmed@linux.dev Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Different usecases for the CPA code have different needs for the behaviour when encountering an unmapped address. Currently this is encoded by using the presence of the .pgd as a side-channel. Subsequent ASI changes won't get the correct behaviour based on this side-channel, so add an explicit enum to request the different behaviours that might be needed. Note this is now making explicit a couple of causes that populate the pagetables when encountering holes, until now this was implicit: 1. kernel_unmap_pages_in_pgd() Calling this function without a corresponding kernel_map_pages_in_pgd() seems like a bug, so the "correct" behaviour here might actually be CPA_FAULT_ERROR. 2. Ditto for __set_memory_enc_pgtable(). It seems the comment in __cpa_process_fault() (deleted in this patch) may have been stale with regard to the coco usecases here (including point 2). Anyway, if these need to be updated that will be a separate patch, no functional change is intended with this one. Signed-off-by: Brendan Jackman --- arch/x86/mm/pat/set_memory.c | 27 ++++++++++++++++++++------- 1 file changed, 20 insertions(+), 7 deletions(-) diff --git a/arch/x86/mm/pat/set_memory.c b/arch/x86/mm/pat/set_memory.c index 53c3ac0ba55d6b6992db6f6761ffdfbd52bf3688..2a50844515e81913fed32d5b6d1= ec19e8e249533 100644 --- a/arch/x86/mm/pat/set_memory.c +++ b/arch/x86/mm/pat/set_memory.c @@ -36,6 +36,16 @@ =20 #include "../mm_internal.h" =20 +/* What should CPA do if encountering an unmapped address? */ +enum cpa_fault { + /* Default depending on address. */ + CPA_FAULT_DEFAULT =3D 0, + /* Populate cpa_data.pgd using cpa_data.pfn. */ + CPA_FAULT_POPULATE, + /* Warn and return an error. */ + CPA_FAULT_ERROR, +}; + /* * The current flushing context - we pass it instead of 5 arguments: */ @@ -51,6 +61,7 @@ struct cpa_data { unsigned int force_split : 1, force_static_prot : 1, force_flush_all : 1; + enum cpa_fault on_fault : 2; struct page **pages; }; =20 @@ -1790,14 +1801,13 @@ static inline bool is_direct_map(unsigned long vadd= r) static int __cpa_process_fault(struct cpa_data *cpa, unsigned long vaddr, int primary) { - if (cpa->pgd) { - /* - * Right now, we only execute this code path when mapping - * the EFI virtual memory map regions, no other users - * provide a ->pgd value. This may change in the future. - */ + if (cpa->on_fault =3D=3D CPA_FAULT_POPULATE) return populate_pgd(cpa, vaddr); - } + + if (WARN_ON(cpa->on_fault =3D=3D CPA_FAULT_ERROR)) + return -EFAULT; + + /* CPA_FAULT_DEFAULT: */ =20 /* * Ignore all non primary paths. @@ -2417,6 +2427,7 @@ static int __set_memory_enc_pgtable(unsigned long add= r, int numpages, bool enc) cpa.mask_set =3D enc ? pgprot_encrypted(empty) : pgprot_decrypted(empty); cpa.mask_clr =3D enc ? pgprot_decrypted(empty) : pgprot_encrypted(empty); cpa.pgd =3D init_mm.pgd; + cpa.on_fault =3D CPA_FAULT_POPULATE; =20 /* Must avoid aliasing mappings in the highmem code */ kmap_flush_unused(); @@ -2743,6 +2754,7 @@ int __init kernel_map_pages_in_pgd(pgd_t *pgd, u64 pf= n, unsigned long address, .mask_set =3D __pgprot(0), .mask_clr =3D __pgprot(~page_flags & (_PAGE_NX|_PAGE_RW|_PAGE_DIRTY)), .flags =3D CPA_NO_CHECK_ALIAS, + .on_fault =3D CPA_FAULT_POPULATE, }; =20 WARN_ONCE(num_online_cpus() > 1, "Don't call after initializing SMP"); @@ -2786,6 +2798,7 @@ int __init kernel_unmap_pages_in_pgd(pgd_t *pgd, unsi= gned long address, .mask_set =3D __pgprot(0), .mask_clr =3D __pgprot(_PAGE_PRESENT | _PAGE_RW | _PAGE_DIRTY), .flags =3D CPA_NO_CHECK_ALIAS, + .on_fault =3D CPA_FAULT_POPULATE, }; =20 WARN_ONCE(num_online_cpus() > 1, "Don't call after initializing SMP"); --=20 2.50.1