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b=QKNzmbfk137GH9cQf861KFuI/s73C1BD2S3Hmbu7L4olXN8PPEoplOGPC3Dn+Fghq d7NNig4oWCpOSIeBtNStaJwz3bg7aVQZat7qFuMIPU0kjjV1Zxa7gbFsWnix0oDnv7 ZRKHmxfl/AQ8POyX8V98RhNoPE/yFC0oqIg1E0MtXDoMOAKelQtsVvb3FGZixoZivK Rp7oq4fmbL4nC88WdaO1cINXanI8SNdp86XjdW3uyKEa9nEnZpVBxgV/GT7DBxWNJz MGAMiMltUcK9PHqa/Jgmr9mFgqF0Q1rQRYaIL9ClhIG7TJqwK/Gl5opvhFbV6wah/U wsGtLw2eFS8rQ== Received: by mail-ej1-f44.google.com with SMTP id a640c23a62f3a-b7cf4a975d2so148872866b.2 for ; Thu, 15 Jan 2026 02:54:38 -0800 (PST) X-Forwarded-Encrypted: i=1; AJvYcCW7EWdz1pzM7d/eA70YIqU3GsOYvDt+6+oy4Ziv/GIispN7IBpkjoX/GNQeN1DVLSOZUif3b0yuyQ==@kvack.org X-Gm-Message-State: AOJu0YzFAmKSeDjfXtVfOHd6Ox/dTkW7STUS4X3tiFtru9kHawCUh10j a33wSkT4TNgQfwLvXCaR9pC/VFDH4c8ZmuF8aT0t0FHgPY6UINV6RKs+ISNLVFMtA28AA8hA7aF bUabS4AFKlTgDcKTGvktsO/N+o54Myag= X-Received: by 2002:a17:907:742:b0:b80:4103:537e with SMTP id a640c23a62f3a-b87614066e3mr530726366b.53.1768474476869; Thu, 15 Jan 2026 02:54:36 -0800 (PST) MIME-Version: 1.0 References: <20260114134510.1835-1-kalyazin@amazon.com> <20260114134510.1835-2-kalyazin@amazon.com> In-Reply-To: <20260114134510.1835-2-kalyazin@amazon.com> From: Huacai Chen Date: Thu, 15 Jan 2026 18:54:27 +0800 X-Gmail-Original-Message-ID: X-Gm-Features: AZwV_QhNEeWPSp4pau3pJiv_muGT_zHnXI7A5fP4Fz_wHAvUMBfJQxrRqBdZrqI Message-ID: Subject: Re: [PATCH v9 01/13] set_memory: add folio_{zap,restore}_direct_map helpers To: "Kalyazin, Nikita" Cc: "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" , "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" , "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" , "dev.jain@arm.com" , "gor@linux.ibm.com" , "hca@linux.ibm.com" , "Jonathan.Cameron@huawei.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" , "vannapurve@google.com" , "jackmanb@google.com" , "aneesh.kumar@kernel.org" , "patrick.roy@linux.dev" , "Thomson, Jack" , "Itazuri, Takahiro" , "Manwaring, Derek" , "Cali, Marco" Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Stat-Signature: hn5j8cyzenjwmdt79ryfs97b3483iufi X-Rspam-User: X-Rspamd-Queue-Id: C2AB3180009 X-Rspamd-Server: rspam08 X-HE-Tag: 1768474479-328164 X-HE-Meta: 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 U8BEBIl5 gC7Y5I+1rflM8ZV2VxCufu0JnM1Rv/iAKppPPoYavHPl6Lz/3NsolWzfO6bKpCfp3ToVbR2E7KcIwgJZf56bZ5kcm7nGOmF2bqV/ClFUnmJSqEceRX2BKDta0e7GfDksi0/6peIC0MtJTUa+/Hjm93z323tkqi9RZepNo0J9bmRRCgAeRo3+igsYEW6HFCbRmJ3/r+ck2oCzza/1LTxWS8bTa4I8NktLTePM0nNBqniiYHjiAPACofxub2zUXGJ8Ub3c0aj/Kb9UZR2o2EOBR+1I6LLFF9L/sicb4Ny4qdSNVcLa3i5JvLUkbS7a5F2x0T6b2dB2yiE6BqS+Fmv7TC8Iopw/6T+NjvV5G6oK9mrwf9idrLu/mP/LdSI4xs/2G2oTTbmuU1Z/nLUxFPG8bOy9PgdTz/W3X0abZJKxhSo2cx0fSjRvtgN3emkHHm6zAEr9vTPTNKBsPeC4VN23iX8SWrG96M5ijXuEgyI9E3Ov38UA= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Hi, Nikita, On Wed, Jan 14, 2026 at 9:45=E2=80=AFPM 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. > > 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. > > 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 | 16 ++++++++++++++++ > arch/riscv/include/asm/set_memory.h | 2 ++ > arch/riscv/mm/pageattr.c | 16 ++++++++++++++++ > arch/s390/include/asm/set_memory.h | 2 ++ > arch/s390/mm/pageattr.c | 18 ++++++++++++++++++ > 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, 102 insertions(+) > > diff --git a/arch/arm64/include/asm/set_memory.h b/arch/arm64/include/asm= /set_memory.h > index 90f61b17275e..d949f1deb701 100644 > --- a/arch/arm64/include/asm/set_memory.h > +++ b/arch/arm64/include/asm/set_memory.h > @@ -14,6 +14,8 @@ int set_memory_valid(unsigned long addr, int numpages, = int enable); > int set_direct_map_invalid_noflush(struct page *page); > int set_direct_map_default_noflush(struct page *page); > int set_direct_map_valid_noflush(struct page *page, unsigned nr, bool va= lid); > +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 f0e784b963e6..a94eff324dda 100644 > --- a/arch/arm64/mm/pageattr.c > +++ b/arch/arm64/mm/pageattr.c > @@ -357,6 +357,18 @@ int set_direct_map_valid_noflush(struct page *page, = unsigned nr, bool valid) > return set_memory_valid(addr, nr, valid); > } > > +int folio_zap_direct_map(struct folio *folio) > +{ > + return set_direct_map_valid_noflush(folio_page(folio, 0), > + folio_nr_pages(folio), false)= ; > +} > + > +int folio_restore_direct_map(struct folio *folio) > +{ > + return set_direct_map_valid_noflush(folio_page(folio, 0), > + folio_nr_pages(folio), true); > +} > + > #ifdef CONFIG_DEBUG_PAGEALLOC > /* > * This is - apart from the return value - doing the same > diff --git a/arch/loongarch/include/asm/set_memory.h b/arch/loongarch/inc= lude/asm/set_memory.h > index 55dfaefd02c8..9bc80ac420a9 100644 > --- a/arch/loongarch/include/asm/set_memory.h > +++ b/arch/loongarch/include/asm/set_memory.h > @@ -18,5 +18,7 @@ bool kernel_page_present(struct page *page); > int set_direct_map_default_noflush(struct page *page); > int set_direct_map_invalid_noflush(struct page *page); > int set_direct_map_valid_noflush(struct page *page, unsigned nr, bool va= lid); > +int folio_zap_direct_map(struct folio *folio); > +int folio_restore_direct_map(struct folio *folio); > > #endif /* _ASM_LOONGARCH_SET_MEMORY_H */ > diff --git a/arch/loongarch/mm/pageattr.c b/arch/loongarch/mm/pageattr.c > index f5e910b68229..14bd322dd112 100644 > --- a/arch/loongarch/mm/pageattr.c > +++ b/arch/loongarch/mm/pageattr.c > @@ -236,3 +236,19 @@ int set_direct_map_valid_noflush(struct page *page, = unsigned nr, bool valid) > > return __set_memory(addr, 1, set, clear); > } > + > +int folio_zap_direct_map(struct folio *folio) > +{ > + int ret; > + > + ret =3D set_direct_map_valid_noflush(folio_page(folio, 0), > + folio_nr_pages(folio), false); > + > + return ret; Why not use a single statement which is the same as the ARM64 version? The RISCV version has the same problem. Huacai > +} > + > +int folio_restore_direct_map(struct folio *folio) > +{ > + return set_direct_map_valid_noflush(folio_page(folio, 0), > + folio_nr_pages(folio), true); > +} > diff --git a/arch/riscv/include/asm/set_memory.h b/arch/riscv/include/asm= /set_memory.h > index 87389e93325a..16557b70c830 100644 > --- a/arch/riscv/include/asm/set_memory.h > +++ b/arch/riscv/include/asm/set_memory.h > @@ -43,6 +43,8 @@ static inline int set_kernel_memory(char *startp, char = *endp, > int set_direct_map_invalid_noflush(struct page *page); > int set_direct_map_default_noflush(struct page *page); > int set_direct_map_valid_noflush(struct page *page, unsigned nr, bool va= lid); > +int folio_zap_direct_map(struct folio *folio); > +int folio_restore_direct_map(struct folio *folio); > bool kernel_page_present(struct page *page); > > #endif /* __ASSEMBLER__ */ > diff --git a/arch/riscv/mm/pageattr.c b/arch/riscv/mm/pageattr.c > index 3f76db3d2769..2c218868114b 100644 > --- a/arch/riscv/mm/pageattr.c > +++ b/arch/riscv/mm/pageattr.c > @@ -401,6 +401,22 @@ int set_direct_map_valid_noflush(struct page *page, = unsigned nr, bool valid) > return __set_memory((unsigned long)page_address(page), nr, set, c= lear); > } > > +int folio_zap_direct_map(struct folio *folio) > +{ > + int ret; > + > + ret =3D set_direct_map_valid_noflush(folio_page(folio, 0), > + folio_nr_pages(folio), false); > + > + return ret; > +} > + > +int folio_restore_direct_map(struct folio *folio) > +{ > + return set_direct_map_valid_noflush(folio_page(folio, 0), > + folio_nr_pages(folio), true); > +} > + > #ifdef CONFIG_DEBUG_PAGEALLOC > static int debug_pagealloc_set_page(pte_t *pte, unsigned long addr, void= *data) > { > diff --git a/arch/s390/include/asm/set_memory.h b/arch/s390/include/asm/s= et_memory.h > index 94092f4ae764..fc73652e5715 100644 > --- a/arch/s390/include/asm/set_memory.h > +++ b/arch/s390/include/asm/set_memory.h > @@ -63,6 +63,8 @@ __SET_MEMORY_FUNC(set_memory_4k, SET_MEMORY_4K) > int set_direct_map_invalid_noflush(struct page *page); > int set_direct_map_default_noflush(struct page *page); > int set_direct_map_valid_noflush(struct page *page, unsigned nr, bool va= lid); > +int folio_zap_direct_map(struct folio *folio); > +int folio_restore_direct_map(struct folio *folio); > bool kernel_page_present(struct page *page); > > #endif > diff --git a/arch/s390/mm/pageattr.c b/arch/s390/mm/pageattr.c > index d3ce04a4b248..df4a487b484d 100644 > --- a/arch/s390/mm/pageattr.c > +++ b/arch/s390/mm/pageattr.c > @@ -412,6 +412,24 @@ int set_direct_map_valid_noflush(struct page *page, = unsigned nr, bool valid) > return __set_memory((unsigned long)page_to_virt(page), nr, flags)= ; > } > > +int folio_zap_direct_map(struct folio *folio) > +{ > + unsigned long addr =3D (unsigned long)folio_address(folio); > + int ret; > + > + ret =3D set_direct_map_valid_noflush(folio_page(folio, 0), > + folio_nr_pages(folio), false); > + flush_tlb_kernel_range(addr, addr + folio_size(folio)); > + > + return ret; > +} > + > +int folio_restore_direct_map(struct folio *folio) > +{ > + return set_direct_map_valid_noflush(folio_page(folio, 0), > + folio_nr_pages(folio), true); > +} > + > bool kernel_page_present(struct page *page) > { > unsigned long addr; > diff --git a/arch/x86/include/asm/set_memory.h b/arch/x86/include/asm/set= _memory.h > index 61f56cdaccb5..7208af609121 100644 > --- a/arch/x86/include/asm/set_memory.h > +++ b/arch/x86/include/asm/set_memory.h > @@ -90,6 +90,8 @@ int set_pages_rw(struct page *page, int numpages); > int set_direct_map_invalid_noflush(struct page *page); > int set_direct_map_default_noflush(struct page *page); > int set_direct_map_valid_noflush(struct page *page, unsigned nr, bool va= lid); > +int folio_zap_direct_map(struct folio *folio); > +int folio_restore_direct_map(struct folio *folio); > bool kernel_page_present(struct page *page); > > extern int kernel_set_to_readonly; > diff --git a/arch/x86/mm/pat/set_memory.c b/arch/x86/mm/pat/set_memory.c > index 6c6eb486f7a6..3f0fc30eb320 100644 > --- a/arch/x86/mm/pat/set_memory.c > +++ b/arch/x86/mm/pat/set_memory.c > @@ -2656,6 +2656,26 @@ int set_direct_map_valid_noflush(struct page *page= , unsigned nr, bool valid) > return __set_pages_np(page, nr); > } > > +int folio_zap_direct_map(struct folio *folio) > +{ > + unsigned long addr =3D (unsigned long)folio_address(folio); > + int ret; > + > + ret =3D set_direct_map_valid_noflush(folio_page(folio, 0), > + folio_nr_pages(folio), false); > + flush_tlb_kernel_range(addr, addr + folio_size(folio)); > + > + return ret; > +} > +EXPORT_SYMBOL_FOR_MODULES(folio_zap_direct_map, "kvm"); > + > +int folio_restore_direct_map(struct folio *folio) > +{ > + return set_direct_map_valid_noflush(folio_page(folio, 0), > + folio_nr_pages(folio), true); > +} > +EXPORT_SYMBOL_FOR_MODULES(folio_restore_direct_map, "kvm"); > + > #ifdef CONFIG_DEBUG_PAGEALLOC > void __kernel_map_pages(struct page *page, int numpages, int enable) > { > diff --git a/include/linux/set_memory.h b/include/linux/set_memory.h > index 3030d9245f5a..8d1c8a7f7d79 100644 > --- a/include/linux/set_memory.h > +++ b/include/linux/set_memory.h > @@ -40,6 +40,16 @@ static inline int set_direct_map_valid_noflush(struct = page *page, > return 0; > } > > +static inline int folio_zap_direct_map(struct folio *folio) > +{ > + return 0; > +} > + > +static inline int folio_restore_direct_map(struct folio *folio) > +{ > + return 0; > +} > + > static inline bool kernel_page_present(struct page *page) > { > return true; > -- > 2.50.1 > >