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X-CSE-ConnectionGUID: 6nY8BPMfRD+gUUyjO4gS8Q== X-CSE-MsgGUID: /M9e4AW7Tnq+niNtBUZyWQ== X-IronPort-AV: E=McAfee;i="6800,10657,11633"; a="77612336" X-IronPort-AV: E=Sophos;i="6.20,252,1758610800"; d="scan'208";a="77612336" Received: from orviesa010.jf.intel.com ([10.64.159.150]) by fmvoesa105.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 05 Dec 2025 09:26:58 -0800 X-CSE-ConnectionGUID: F9P4sbSUS1agtmmb/ST5Xg== X-CSE-MsgGUID: RM8P4RCTRyq268Qov786Aw== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.20,252,1758610800"; d="scan'208";a="194646785" Received: from vverma7-desk1.amr.corp.intel.com (HELO [10.125.108.173]) ([10.125.108.173]) by orviesa010-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 05 Dec 2025 09:26:57 -0800 Message-ID: <9409531b-589b-4a54-b122-06a3cf0846f3@intel.com> Date: Fri, 5 Dec 2025 09:26:56 -0800 Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v8 01/13] x86: export set_direct_map_valid_noflush to KVM module To: "Kalyazin, Nikita" , "kvm@vger.kernel.org" , "linux-doc@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "kvmarm@lists.linux.dev" , "linux-fsdevel@vger.kernel.org" , "linux-mm@kvack.org" , "bpf@vger.kernel.org" , "linux-kselftest@vger.kernel.org" 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@linutronix.de" , "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" , "david@kernel.org" , "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" , "shuah@kernel.org" , "riel@surriel.com" , "baohua@kernel.org" , "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" , "isaku.yamahata@intel.com" , "jmattson@google.com" , "jthoughton@google.com" , "linux-arm-kernel@lists.infradead.org" , "vannapurve@google.com" , "jackmanb@google.com" , "aneesh.kumar@kernel.org" , "patrick.roy@linux.dev" , "Thomson, Jack" , "Itazuri, Takahiro" , "Manwaring, Derek" , "Cali, Marco" References: <20251205165743.9341-1-kalyazin@amazon.com> <20251205165743.9341-2-kalyazin@amazon.com> From: Dave Hansen Content-Language: en-US Autocrypt: addr=dave.hansen@intel.com; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 12/5/25 08:57, Kalyazin, Nikita wrote: ... > +EXPORT_SYMBOL_FOR_MODULES(set_direct_map_valid_noflush, "kvm"); I think this export is a bad idea. The interface is abhorrent enough, but exporting it just invites abuse and bugs. I think what this really needs is a pair of helpers that are just: folio_zap_direct_map() and folio_restore_direct_map() that take a folio. *Those* can get exported to modules and those should internally flush the TLB and not expect callers to do it.