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Fri, 12 Sep 2025 09:17:34 +0000 (UTC) X-Farcaster-Flow-ID: a91e1d85-e397-46af-94b1-48a53ba9e43e Received: from EX19D015EUB001.ant.amazon.com (10.252.51.114) by EX19MTAEUA002.ant.amazon.com (10.252.50.126) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA) id 15.2.2562.20; Fri, 12 Sep 2025 09:17:33 +0000 Received: from EX19D015EUB004.ant.amazon.com (10.252.51.13) by EX19D015EUB001.ant.amazon.com (10.252.51.114) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA) id 15.2.2562.20; Fri, 12 Sep 2025 09:17:33 +0000 Received: from EX19D015EUB004.ant.amazon.com ([fe80::2dc9:7aa9:9cd3:fc8a]) by EX19D015EUB004.ant.amazon.com ([fe80::2dc9:7aa9:9cd3:fc8a%3]) with mapi id 15.02.2562.020; Fri, 12 Sep 2025 09:17:33 +0000 From: "Roy, Patrick" CC: "Thomson, Jack" , "Kalyazin, Nikita" , "Cali, Marco" , "derekmn@amazon.co.uk" , "Roy, Patrick" , "willy@infradead.org" , "corbet@lwn.net" , "pbonzini@redhat.com" , "maz@kernel.org" , "oliver.upton@linux.dev" , "joey.gouly@arm.com" , "suzuki.poulose@arm.com" , "yuzenghui@huawei.com" , "catalin.marinas@arm.com" , "will@kernel.org" , "chenhuacai@kernel.org" , "kernel@xen0n.name" , "paul.walmsley@sifive.com" , "palmer@dabbelt.com" , "aou@eecs.berkeley.edu" , "alex@ghiti.fr" , "agordeev@linux.ibm.com" , "gerald.schaefer@linux.ibm.com" , "hca@linux.ibm.com" , "gor@linux.ibm.com" , "borntraeger@linux.ibm.com" , "svens@linux.ibm.com" , "dave.hansen@linux.intel.com" , "luto@kernel.org" , "peterz@infradead.org" , "tglx@linutronix.de" , "mingo@redhat.com" , "bp@alien8.de" , "x86@kernel.org" , "hpa@zytor.com" , "trondmy@kernel.org" , "anna@kernel.org" , "hubcap@omnibond.com" , "martin@omnibond.com" , "viro@zeniv.linux.org.uk" , "brauner@kernel.org" , "jack@suse.cz" , "akpm@linux-foundation.org" , "david@redhat.com" , "lorenzo.stoakes@oracle.com" , "Liam.Howlett@oracle.com" , "vbabka@suse.cz" , "rppt@kernel.org" , "surenb@google.com" , "mhocko@suse.com" , "ast@kernel.org" , "daniel@iogearbox.net" , "andrii@kernel.org" , "martin.lau@linux.dev" , "eddyz87@gmail.com" , "song@kernel.org" , "yonghong.song@linux.dev" , "john.fastabend@gmail.com" , "kpsingh@kernel.org" , "sdf@fomichev.me" , "haoluo@google.com" , "jolsa@kernel.org" , "jgg@ziepe.ca" , "jhubbard@nvidia.com" , "peterx@redhat.com" , "jannh@google.com" , "pfalcato@suse.de" , "axelrasmussen@google.com" , "yuanchu@google.com" , "weixugc@google.com" , "hannes@cmpxchg.org" , "zhengqi.arch@bytedance.com" , "shakeel.butt@linux.dev" , "shuah@kernel.org" , "seanjc@google.com" , "linux-fsdevel@vger.kernel.org" , "linux-doc@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "kvm@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "kvmarm@lists.linux.dev" , "loongarch@lists.linux.dev" , "linux-riscv@lists.infradead.org" , "linux-s390@vger.kernel.org" , "linux-nfs@vger.kernel.org" , "devel@lists.orangefs.org" , "linux-mm@kvack.org" , "bpf@vger.kernel.org" , "linux-kselftest@vger.kernel.org" , "Fuad Tabba" Subject: [PATCH v6 02/11] arch: export set_direct_map_valid_noflush to KVM module Thread-Topic: [PATCH v6 02/11] arch: export set_direct_map_valid_noflush to KVM module Thread-Index: AQHcI8YSgiTpMeKXGkS2hhvLGeEJDA== Date: Fri, 12 Sep 2025 09:17:32 +0000 Message-ID: <20250912091708.17502-3-roypat@amazon.co.uk> References: <20250912091708.17502-1-roypat@amazon.co.uk> In-Reply-To: <20250912091708.17502-1-roypat@amazon.co.uk> Accept-Language: en-US Content-Language: en-US X-MS-Has-Attach: X-MS-TNEF-Correlator: Content-Transfer-Encoding: quoted-printable Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Use the new per-module export functionality to allow KVM (and only KVM) access to set_direct_map_valid_noflush(). This allows guest_memfd to remove its memory from the direct map, even if KVM is built as a module. Direct map removal gives guest_memfd the same protection that memfd_secret enjoys, such as hardening against Spectre-like attacks through in-kernel gadgets. Reviewed-by: Fuad Tabba Signed-off-by: Patrick Roy --- arch/arm64/mm/pageattr.c | 1 + arch/loongarch/mm/pageattr.c | 1 + arch/riscv/mm/pageattr.c | 1 + arch/s390/mm/pageattr.c | 1 + arch/x86/mm/pat/set_memory.c | 1 + 5 files changed, 5 insertions(+) diff --git a/arch/arm64/mm/pageattr.c b/arch/arm64/mm/pageattr.c index 04d4a8f676db..4f3cddfab9b0 100644 --- a/arch/arm64/mm/pageattr.c +++ b/arch/arm64/mm/pageattr.c @@ -291,6 +291,7 @@ int set_direct_map_valid_noflush(struct page *page, uns= igned nr, bool valid) =20 return set_memory_valid(addr, nr, valid); } +EXPORT_SYMBOL_FOR_MODULES(set_direct_map_valid_noflush, "kvm"); =20 #ifdef CONFIG_DEBUG_PAGEALLOC /* diff --git a/arch/loongarch/mm/pageattr.c b/arch/loongarch/mm/pageattr.c index f5e910b68229..458f5ae6a89b 100644 --- a/arch/loongarch/mm/pageattr.c +++ b/arch/loongarch/mm/pageattr.c @@ -236,3 +236,4 @@ int set_direct_map_valid_noflush(struct page *page, uns= igned nr, bool valid) =20 return __set_memory(addr, 1, set, clear); } +EXPORT_SYMBOL_FOR_MODULES(set_direct_map_valid_noflush, "kvm"); diff --git a/arch/riscv/mm/pageattr.c b/arch/riscv/mm/pageattr.c index 3f76db3d2769..6db31040cd66 100644 --- a/arch/riscv/mm/pageattr.c +++ b/arch/riscv/mm/pageattr.c @@ -400,6 +400,7 @@ int set_direct_map_valid_noflush(struct page *page, uns= igned nr, bool valid) =20 return __set_memory((unsigned long)page_address(page), nr, set, clear); } +EXPORT_SYMBOL_FOR_MODULES(set_direct_map_valid_noflush, "kvm"); =20 #ifdef CONFIG_DEBUG_PAGEALLOC static int debug_pagealloc_set_page(pte_t *pte, unsigned long addr, void *= data) diff --git a/arch/s390/mm/pageattr.c b/arch/s390/mm/pageattr.c index 348e759840e7..8ffd9ef09bc6 100644 --- a/arch/s390/mm/pageattr.c +++ b/arch/s390/mm/pageattr.c @@ -413,6 +413,7 @@ int set_direct_map_valid_noflush(struct page *page, uns= igned nr, bool valid) =20 return __set_memory((unsigned long)page_to_virt(page), nr, flags); } +EXPORT_SYMBOL_FOR_MODULES(set_direct_map_valid_noflush, "kvm"); =20 bool kernel_page_present(struct page *page) { diff --git a/arch/x86/mm/pat/set_memory.c b/arch/x86/mm/pat/set_memory.c index 8834c76f91c9..87e9c7d2dcdc 100644 --- a/arch/x86/mm/pat/set_memory.c +++ b/arch/x86/mm/pat/set_memory.c @@ -2661,6 +2661,7 @@ int set_direct_map_valid_noflush(struct page *page, u= nsigned nr, bool valid) =20 return __set_pages_np(page, nr); } +EXPORT_SYMBOL_FOR_MODULES(set_direct_map_valid_noflush, "kvm"); =20 #ifdef CONFIG_DEBUG_PAGEALLOC void __kernel_map_pages(struct page *page, int numpages, int enable) --=20 2.50.1