From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id D92DFFCC9A2 for ; Tue, 10 Mar 2026 00:00:52 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:From:References:Cc:To: Subject:MIME-Version:Date:Message-ID:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=i2s1ZKrT0odZbcQMPSUAq9ZmS8GrDH5iC2zXThGxWhs=; b=iO7s0uXUG6IAH9 ei3XfK2ulBaz9FAbmtX8ssnLGXAHOM9O6j+p8W4KEymeUo08tmAkR1U1w45doMBepP+3dr78G6XMu shEnUwh8zZbeplbZi3MXZAXHjK7eFxv2qWv+Tj7VyVgmw1VBx/bYD+v5FNvea/1dzdMPlC3rd2sha P3RwArx4LDDJsLGHxOmHSMJvuOdW8MMNZ0rMuTf5VugMyrT7U86HEHybxQauGeLm71ALNMu2XJfJH OXpug0x7pkFU0ZSjCqsAYFIQW4VJk5GYwaIkPqJUbbvqlkGnFMWDq6SulT756IeSwBit2Jj4TOcWu T29/voNWU6ocntOasTUQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1vzkWT-00000008KUX-2jTV; Tue, 10 Mar 2026 00:00:30 +0000 Received: from sea.source.kernel.org ([2600:3c0a:e001:78e:0:1991:8:25]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1vyCbG-00000002Jcm-14V9 for linux-riscv@lists.infradead.org; Thu, 05 Mar 2026 17:35:03 +0000 Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by sea.source.kernel.org (Postfix) with ESMTP id 72EF64042F; Thu, 5 Mar 2026 17:35:01 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id AFEACC19425; Thu, 5 Mar 2026 17:34:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1772732101; bh=56aRoAVzPeQ+dwVrdE3T5LIBh/tHK5LhrXeg2GPGARY=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=SNJUfyAa+pOGSpSVWJhLtY5AZnRO7etbHovFucUT8TXtqWY9985XSqGU8RMWCDSMd 1ZFYbjOd3UTSfkRHwfCNAbUOR8czgn3AP5sdfd3NDuMTwlejtHcBQywUKbAkce4nTe dEwNcN9AYGiADUff+P0WNpX+woEHoHermioN+npeoYqsCJHEP5pDpw9nhdmbj8i1n9 S8ZG8tpuRHozTfhieeF2eQimOT3Mr+dJeCNLypIAETyKi3durz59wMY2erlZRNGn7t n1IaS6Ru9j6oE8qY8qN5jctLVXgDfFP9P0eHUpDtsiPtIGlce9evGXASnm9NnTQCF0 DnFXPOqZ3moTA== Message-ID: Date: Thu, 5 Mar 2026 18:34:35 +0100 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v10 02/15] set_memory: add folio_{zap,restore}_direct_map helpers To: "Kalyazin, Nikita" , "kvm@vger.kernel.org" , "linux-doc@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "kvmarm@lists.linux.dev" , "linux-fsdevel@vger.kernel.org" , "linux-mm@kvack.org" , "bpf@vger.kernel.org" , "linux-kselftest@vger.kernel.org" , "kernel@xen0n.name" , "linux-riscv@lists.infradead.org" , "linux-s390@vger.kernel.org" , "loongarch@lists.linux.dev" Cc: "pbonzini@redhat.com" , "corbet@lwn.net" , "maz@kernel.org" , "oupton@kernel.org" , "joey.gouly@arm.com" , "suzuki.poulose@arm.com" , "yuzenghui@huawei.com" , "catalin.marinas@arm.com" , "will@kernel.org" , "seanjc@google.com" , "tglx@kernel.org" , "mingo@redhat.com" , "bp@alien8.de" , "dave.hansen@linux.intel.com" , "x86@kernel.org" , "hpa@zytor.com" , "luto@kernel.org" , "peterz@infradead.org" , "willy@infradead.org" , "akpm@linux-foundation.org" , "lorenzo.stoakes@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" , "shuah@kernel.org" , "riel@surriel.com" , "ryan.roberts@arm.com" , "jgross@suse.com" , "yu-cheng.yu@intel.com" , "kas@kernel.org" , "coxu@redhat.com" , "kevin.brodsky@arm.com" , "ackerleytng@google.com" , "maobibo@loongson.cn" , "prsampat@amd.com" , "mlevitsk@redhat.com" , "jmattson@google.com" , "jthoughton@google.com" , "agordeev@linux.ibm.com" , "alex@ghiti.fr" , "aou@eecs.berkeley.edu" , "borntraeger@linux.ibm.com" , "chenhuacai@kernel.org" , "dev.jain@arm.com" , "gor@linux.ibm.com" , "hca@linux.ibm.com" , "palmer@dabbelt.com" , "pjw@kernel.org" , "shijie@os.amperecomputing.com" , "svens@linux.ibm.com" , "thuth@redhat.com" , "wyihan@google.com" , "yang@os.amperecomputing.com" , "Jonathan.Cameron@huawei.com" , "Liam.Howlett@oracle.com" , "urezki@gmail.com" , "zhengqi.arch@bytedance.com" , "gerald.schaefer@linux.ibm.com" , "jiayuan.chen@shopee.com" , "lenb@kernel.org" , "osalvador@suse.de" , "pavel@kernel.org" , "rafael@kernel.org" , "vannapurve@google.com" , "jackmanb@google.com" , "aneesh.kumar@kernel.org" , "patrick.roy@linux.dev" , "Thomson, Jack" , "Itazuri, Takahiro" , "Manwaring, Derek" , "Cali, Marco" References: <20260126164445.11867-1-kalyazin@amazon.com> <20260126164445.11867-3-kalyazin@amazon.com> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org On 1/26/26 17:47, Kalyazin, Nikita wrote: > From: Nikita Kalyazin > > These allow guest_memfd to remove its memory from the direct map. > Only implement them for architectures that have direct map. > In folio_zap_direct_map(), flush TLB on architectures where > set_direct_map_valid_noflush() does not flush it internally. "Let's provide folio_{zap,restore}_direct_map helpers as preparation for supporting removal of the direct map for guest_memfd folios. ... > > The new helpers need to be accessible to KVM on architectures that > support guest_memfd (x86 and arm64). Since arm64 does not support > building KVM as a module, only export them on x86. > > Direct map removal gives guest_memfd the same protection that > memfd_secret does, such as hardening against Spectre-like attacks > through in-kernel gadgets. Would it be possible to convert mm/secretmem.c as well? There, we use set_direct_map_invalid_noflush(folio_page(folio, 0)); and set_direct_map_default_noflush(folio_page(folio, 0)); Which is a bit different to below code. At least looking at the x86 variants, I wonder why we don't simply use set_direct_map_valid_noflush(). If so, can you add a patch to do the conversion, pleeeeassse ? :) > > Reviewed-by: Ackerley Tng > Signed-off-by: Nikita Kalyazin > --- > arch/arm64/include/asm/set_memory.h | 2 ++ > arch/arm64/mm/pageattr.c | 12 ++++++++++++ > arch/loongarch/include/asm/set_memory.h | 2 ++ > arch/loongarch/mm/pageattr.c | 12 ++++++++++++ > arch/riscv/include/asm/set_memory.h | 2 ++ > arch/riscv/mm/pageattr.c | 12 ++++++++++++ > arch/s390/include/asm/set_memory.h | 2 ++ > arch/s390/mm/pageattr.c | 12 ++++++++++++ > arch/x86/include/asm/set_memory.h | 2 ++ > arch/x86/mm/pat/set_memory.c | 20 ++++++++++++++++++++ > include/linux/set_memory.h | 10 ++++++++++ > 11 files changed, 88 insertions(+) > > diff --git a/arch/arm64/include/asm/set_memory.h b/arch/arm64/include/asm/set_memory.h > index c71a2a6812c4..49fd54f3c265 100644 > --- a/arch/arm64/include/asm/set_memory.h > +++ b/arch/arm64/include/asm/set_memory.h > @@ -15,6 +15,8 @@ int set_direct_map_invalid_noflush(const void *addr); > int set_direct_map_default_noflush(const void *addr); > int set_direct_map_valid_noflush(const void *addr, unsigned long numpages, > bool valid); > +int folio_zap_direct_map(struct folio *folio); > +int folio_restore_direct_map(struct folio *folio); > bool kernel_page_present(struct page *page); > > int set_memory_encrypted(unsigned long addr, int numpages); > diff --git a/arch/arm64/mm/pageattr.c b/arch/arm64/mm/pageattr.c > index e2bdc3c1f992..0b88b0344499 100644 > --- a/arch/arm64/mm/pageattr.c > +++ b/arch/arm64/mm/pageattr.c > @@ -356,6 +356,18 @@ int set_direct_map_valid_noflush(const void *addr, unsigned long numpages, > return set_memory_valid((unsigned long)addr, numpages, valid); > } > > +int folio_zap_direct_map(struct folio *folio) > +{ > + return set_direct_map_valid_noflush(folio_address(folio), > + folio_nr_pages(folio), false); > +} > + > +int folio_restore_direct_map(struct folio *folio) > +{ > + return set_direct_map_valid_noflush(folio_address(folio), > + folio_nr_pages(folio), true); > +} Is there a good reason why we cannot have two generic inline functions that simply call set_direct_map_valid_noflush() ? Is it because of some flushing behavior? (which we could figure out) In particular, a single set of functions could have a beautiful centralized kerneldoc, right?! :) -- Cheers, David _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv