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charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Precedence: bulk X-Mailing-List: linux-s390@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 From: Nikita Kalyazin =0A= =0A= These allow guest_memfd to remove its memory from the direct map.=0A= Only implement them for architectures that have direct map.=0A= In folio_zap_direct_map(), flush TLB on architectures where=0A= set_direct_map_valid_noflush() does not flush it internally.=0A= =0A= The new helpers need to be accessible to KVM on architectures that=0A= support guest_memfd (x86 and arm64). Since arm64 does not support=0A= building KVM as a module, only export them on x86.=0A= =0A= Direct map removal gives guest_memfd the same protection that=0A= memfd_secret does, such as hardening against Spectre-like attacks=0A= through in-kernel gadgets.=0A= =0A= Signed-off-by: Nikita Kalyazin =0A= ---=0A= arch/arm64/include/asm/set_memory.h | 2 ++=0A= arch/arm64/mm/pageattr.c | 12 ++++++++++++=0A= arch/loongarch/include/asm/set_memory.h | 2 ++=0A= arch/loongarch/mm/pageattr.c | 16 ++++++++++++++++=0A= arch/riscv/include/asm/set_memory.h | 2 ++=0A= arch/riscv/mm/pageattr.c | 16 ++++++++++++++++=0A= arch/s390/include/asm/set_memory.h | 2 ++=0A= arch/s390/mm/pageattr.c | 18 ++++++++++++++++++=0A= arch/x86/include/asm/set_memory.h | 2 ++=0A= arch/x86/mm/pat/set_memory.c | 20 ++++++++++++++++++++=0A= include/linux/set_memory.h | 10 ++++++++++=0A= 11 files changed, 102 insertions(+)=0A= =0A= diff --git a/arch/arm64/include/asm/set_memory.h b/arch/arm64/include/asm/s= et_memory.h=0A= index 90f61b17275e..d949f1deb701 100644=0A= --- a/arch/arm64/include/asm/set_memory.h=0A= +++ b/arch/arm64/include/asm/set_memory.h=0A= @@ -14,6 +14,8 @@ int set_memory_valid(unsigned long addr, int numpages, in= t enable);=0A= int set_direct_map_invalid_noflush(struct page *page);=0A= int set_direct_map_default_noflush(struct page *page);=0A= int set_direct_map_valid_noflush(struct page *page, unsigned nr, bool vali= d);=0A= +int folio_zap_direct_map(struct folio *folio);=0A= +int folio_restore_direct_map(struct folio *folio);=0A= bool kernel_page_present(struct page *page);=0A= =0A= int set_memory_encrypted(unsigned long addr, int numpages);=0A= diff --git a/arch/arm64/mm/pageattr.c b/arch/arm64/mm/pageattr.c=0A= index f0e784b963e6..a94eff324dda 100644=0A= --- a/arch/arm64/mm/pageattr.c=0A= +++ b/arch/arm64/mm/pageattr.c=0A= @@ -357,6 +357,18 @@ int set_direct_map_valid_noflush(struct page *page, un= signed nr, bool valid)=0A= return set_memory_valid(addr, nr, valid);=0A= }=0A= =0A= +int folio_zap_direct_map(struct folio *folio)=0A= +{=0A= + return set_direct_map_valid_noflush(folio_page(folio, 0),=0A= + folio_nr_pages(folio), false);=0A= +}=0A= +=0A= +int folio_restore_direct_map(struct folio *folio)=0A= +{=0A= + return set_direct_map_valid_noflush(folio_page(folio, 0),=0A= + folio_nr_pages(folio), true);=0A= +}=0A= +=0A= #ifdef CONFIG_DEBUG_PAGEALLOC=0A= /*=0A= * This is - apart from the return value - doing the same=0A= diff --git a/arch/loongarch/include/asm/set_memory.h b/arch/loongarch/inclu= de/asm/set_memory.h=0A= index 55dfaefd02c8..9bc80ac420a9 100644=0A= --- a/arch/loongarch/include/asm/set_memory.h=0A= +++ b/arch/loongarch/include/asm/set_memory.h=0A= @@ -18,5 +18,7 @@ bool kernel_page_present(struct page *page);=0A= int set_direct_map_default_noflush(struct page *page);=0A= int set_direct_map_invalid_noflush(struct page *page);=0A= int set_direct_map_valid_noflush(struct page *page, unsigned nr, bool vali= d);=0A= +int folio_zap_direct_map(struct folio *folio);=0A= +int folio_restore_direct_map(struct folio *folio);=0A= =0A= #endif /* _ASM_LOONGARCH_SET_MEMORY_H */=0A= diff --git a/arch/loongarch/mm/pageattr.c b/arch/loongarch/mm/pageattr.c=0A= index f5e910b68229..14bd322dd112 100644=0A= --- a/arch/loongarch/mm/pageattr.c=0A= +++ b/arch/loongarch/mm/pageattr.c=0A= @@ -236,3 +236,19 @@ int set_direct_map_valid_noflush(struct page *page, un= signed nr, bool valid)=0A= =0A= return __set_memory(addr, 1, set, clear);=0A= }=0A= +=0A= +int folio_zap_direct_map(struct folio *folio)=0A= +{=0A= + int ret;=0A= +=0A= + ret =3D set_direct_map_valid_noflush(folio_page(folio, 0),=0A= + folio_nr_pages(folio), false);=0A= +=0A= + return ret;=0A= +}=0A= +=0A= +int folio_restore_direct_map(struct folio *folio)=0A= +{=0A= + return set_direct_map_valid_noflush(folio_page(folio, 0),=0A= + folio_nr_pages(folio), true);=0A= +}=0A= diff --git a/arch/riscv/include/asm/set_memory.h b/arch/riscv/include/asm/s= et_memory.h=0A= index 87389e93325a..16557b70c830 100644=0A= --- a/arch/riscv/include/asm/set_memory.h=0A= +++ b/arch/riscv/include/asm/set_memory.h=0A= @@ -43,6 +43,8 @@ static inline int set_kernel_memory(char *startp, char *e= ndp,=0A= int set_direct_map_invalid_noflush(struct page *page);=0A= int set_direct_map_default_noflush(struct page *page);=0A= int set_direct_map_valid_noflush(struct page *page, unsigned nr, bool vali= d);=0A= +int folio_zap_direct_map(struct folio *folio);=0A= +int folio_restore_direct_map(struct folio *folio);=0A= bool kernel_page_present(struct page *page);=0A= =0A= #endif /* __ASSEMBLER__ */=0A= diff --git a/arch/riscv/mm/pageattr.c b/arch/riscv/mm/pageattr.c=0A= index 3f76db3d2769..2c218868114b 100644=0A= --- a/arch/riscv/mm/pageattr.c=0A= +++ b/arch/riscv/mm/pageattr.c=0A= @@ -401,6 +401,22 @@ int set_direct_map_valid_noflush(struct page *page, un= signed nr, bool valid)=0A= return __set_memory((unsigned long)page_address(page), nr, set, clear);= =0A= }=0A= =0A= +int folio_zap_direct_map(struct folio *folio)=0A= +{=0A= + int ret;=0A= +=0A= + ret =3D set_direct_map_valid_noflush(folio_page(folio, 0),=0A= + folio_nr_pages(folio), false);=0A= +=0A= + return ret;=0A= +}=0A= +=0A= +int folio_restore_direct_map(struct folio *folio)=0A= +{=0A= + return set_direct_map_valid_noflush(folio_page(folio, 0),=0A= + folio_nr_pages(folio), true);=0A= +}=0A= +=0A= #ifdef CONFIG_DEBUG_PAGEALLOC=0A= static int debug_pagealloc_set_page(pte_t *pte, unsigned long addr, void *= data)=0A= {=0A= diff --git a/arch/s390/include/asm/set_memory.h b/arch/s390/include/asm/set= _memory.h=0A= index 94092f4ae764..fc73652e5715 100644=0A= --- a/arch/s390/include/asm/set_memory.h=0A= +++ b/arch/s390/include/asm/set_memory.h=0A= @@ -63,6 +63,8 @@ __SET_MEMORY_FUNC(set_memory_4k, SET_MEMORY_4K)=0A= int set_direct_map_invalid_noflush(struct page *page);=0A= int set_direct_map_default_noflush(struct page *page);=0A= int set_direct_map_valid_noflush(struct page *page, unsigned nr, bool vali= d);=0A= +int folio_zap_direct_map(struct folio *folio);=0A= +int folio_restore_direct_map(struct folio *folio);=0A= bool kernel_page_present(struct page *page);=0A= =0A= #endif=0A= diff --git a/arch/s390/mm/pageattr.c b/arch/s390/mm/pageattr.c=0A= index d3ce04a4b248..df4a487b484d 100644=0A= --- a/arch/s390/mm/pageattr.c=0A= +++ b/arch/s390/mm/pageattr.c=0A= @@ -412,6 +412,24 @@ int set_direct_map_valid_noflush(struct page *page, un= signed nr, bool valid)=0A= return __set_memory((unsigned long)page_to_virt(page), nr, flags);=0A= }=0A= =0A= +int folio_zap_direct_map(struct folio *folio)=0A= +{=0A= + unsigned long addr =3D (unsigned long)folio_address(folio);=0A= + int ret;=0A= +=0A= + ret =3D set_direct_map_valid_noflush(folio_page(folio, 0),=0A= + folio_nr_pages(folio), false);=0A= + flush_tlb_kernel_range(addr, addr + folio_size(folio));=0A= +=0A= + return ret;=0A= +}=0A= +=0A= +int folio_restore_direct_map(struct folio *folio)=0A= +{=0A= + return set_direct_map_valid_noflush(folio_page(folio, 0),=0A= + folio_nr_pages(folio), true);=0A= +}=0A= +=0A= bool kernel_page_present(struct page *page)=0A= {=0A= unsigned long addr;=0A= diff --git a/arch/x86/include/asm/set_memory.h b/arch/x86/include/asm/set_m= emory.h=0A= index 61f56cdaccb5..7208af609121 100644=0A= --- a/arch/x86/include/asm/set_memory.h=0A= +++ b/arch/x86/include/asm/set_memory.h=0A= @@ -90,6 +90,8 @@ int set_pages_rw(struct page *page, int numpages);=0A= int set_direct_map_invalid_noflush(struct page *page);=0A= int set_direct_map_default_noflush(struct page *page);=0A= int set_direct_map_valid_noflush(struct page *page, unsigned nr, bool vali= d);=0A= +int folio_zap_direct_map(struct folio *folio);=0A= +int folio_restore_direct_map(struct folio *folio);=0A= bool kernel_page_present(struct page *page);=0A= =0A= extern int kernel_set_to_readonly;=0A= diff --git a/arch/x86/mm/pat/set_memory.c b/arch/x86/mm/pat/set_memory.c=0A= index 6c6eb486f7a6..3f0fc30eb320 100644=0A= --- a/arch/x86/mm/pat/set_memory.c=0A= +++ b/arch/x86/mm/pat/set_memory.c=0A= @@ -2656,6 +2656,26 @@ int set_direct_map_valid_noflush(struct page *page, = unsigned nr, bool valid)=0A= return __set_pages_np(page, nr);=0A= }=0A= =0A= +int folio_zap_direct_map(struct folio *folio)=0A= +{=0A= + unsigned long addr =3D (unsigned long)folio_address(folio);=0A= + int ret;=0A= +=0A= + ret =3D set_direct_map_valid_noflush(folio_page(folio, 0),=0A= + folio_nr_pages(folio), false);=0A= + flush_tlb_kernel_range(addr, addr + folio_size(folio));=0A= +=0A= + return ret;=0A= +}=0A= +EXPORT_SYMBOL_FOR_MODULES(folio_zap_direct_map, "kvm");=0A= +=0A= +int folio_restore_direct_map(struct folio *folio)=0A= +{=0A= + return set_direct_map_valid_noflush(folio_page(folio, 0),=0A= + folio_nr_pages(folio), true);=0A= +}=0A= +EXPORT_SYMBOL_FOR_MODULES(folio_restore_direct_map, "kvm");=0A= +=0A= #ifdef CONFIG_DEBUG_PAGEALLOC=0A= void __kernel_map_pages(struct page *page, int numpages, int enable)=0A= {=0A= diff --git a/include/linux/set_memory.h b/include/linux/set_memory.h=0A= index 3030d9245f5a..8d1c8a7f7d79 100644=0A= --- a/include/linux/set_memory.h=0A= +++ b/include/linux/set_memory.h=0A= @@ -40,6 +40,16 @@ static inline int set_direct_map_valid_noflush(struct pa= ge *page,=0A= return 0;=0A= }=0A= =0A= +static inline int folio_zap_direct_map(struct folio *folio)=0A= +{=0A= + return 0;=0A= +}=0A= +=0A= +static inline int folio_restore_direct_map(struct folio *folio)=0A= +{=0A= + return 0;=0A= +}=0A= +=0A= static inline bool kernel_page_present(struct page *page)=0A= {=0A= return true;=0A= -- =0A= 2.50.1=0A= =0A=