| Message ID | 20220422224508.440670-3-jane.chu@oracle.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | DAX poison recovery | expand |
On Fri, Apr 22, 2022 at 04:45:03PM -0600, Jane Chu wrote: > Relocate the twin mce functions to arch/x86/mm/pat/set_memory.c > file where they belong. > > While at it, fixup a function name in a comment. > > Reviewed-by: Christoph Hellwig <hch@lst.de> > Reviewed-by: Dan Williams <dan.j.williams@intel.com> > Signed-off-by: Jane Chu <jane.chu@oracle.com> > --- > arch/x86/include/asm/set_memory.h | 52 ------------------------------- > arch/x86/mm/pat/set_memory.c | 49 ++++++++++++++++++++++++++++- > include/linux/set_memory.h | 8 ++--- > 3 files changed, 52 insertions(+), 57 deletions(-) Acked-by: Borislav Petkov <bp@suse.de>
On Fri, Apr 22, 2022 at 3:46 PM Jane Chu <jane.chu@oracle.com> wrote: > > Relocate the twin mce functions to arch/x86/mm/pat/set_memory.c > file where they belong. > > While at it, fixup a function name in a comment. > > Reviewed-by: Christoph Hellwig <hch@lst.de> > Reviewed-by: Dan Williams <dan.j.williams@intel.com> > Signed-off-by: Jane Chu <jane.chu@oracle.com> > --- > arch/x86/include/asm/set_memory.h | 52 ------------------------------- > arch/x86/mm/pat/set_memory.c | 49 ++++++++++++++++++++++++++++- > include/linux/set_memory.h | 8 ++--- > 3 files changed, 52 insertions(+), 57 deletions(-) > > diff --git a/arch/x86/include/asm/set_memory.h b/arch/x86/include/asm/set_memory.h > index 78ca53512486..b45c4d27fd46 100644 > --- a/arch/x86/include/asm/set_memory.h > +++ b/arch/x86/include/asm/set_memory.h > @@ -86,56 +86,4 @@ bool kernel_page_present(struct page *page); > > extern int kernel_set_to_readonly; > > -#ifdef CONFIG_X86_64 > -/* > - * Prevent speculative access to the page by either unmapping > - * it (if we do not require access to any part of the page) or > - * marking it uncacheable (if we want to try to retrieve data > - * from non-poisoned lines in the page). > - */ > -static inline int set_mce_nospec(unsigned long pfn, bool unmap) > -{ > - unsigned long decoy_addr; > - int rc; > - > - /* SGX pages are not in the 1:1 map */ > - if (arch_is_platform_page(pfn << PAGE_SHIFT)) > - return 0; > - /* > - * We would like to just call: > - * set_memory_XX((unsigned long)pfn_to_kaddr(pfn), 1); > - * but doing that would radically increase the odds of a > - * speculative access to the poison page because we'd have > - * the virtual address of the kernel 1:1 mapping sitting > - * around in registers. > - * Instead we get tricky. We create a non-canonical address > - * that looks just like the one we want, but has bit 63 flipped. > - * This relies on set_memory_XX() properly sanitizing any __pa() > - * results with __PHYSICAL_MASK or PTE_PFN_MASK. > - */ > - decoy_addr = (pfn << PAGE_SHIFT) + (PAGE_OFFSET ^ BIT(63)); > - > - if (unmap) > - rc = set_memory_np(decoy_addr, 1); > - else > - rc = set_memory_uc(decoy_addr, 1); > - if (rc) > - pr_warn("Could not invalidate pfn=0x%lx from 1:1 map\n", pfn); > - return rc; > -} > -#define set_mce_nospec set_mce_nospec > - > -/* Restore full speculative operation to the pfn. */ > -static inline int clear_mce_nospec(unsigned long pfn) > -{ > - return set_memory_wb((unsigned long) pfn_to_kaddr(pfn), 1); > -} > -#define clear_mce_nospec clear_mce_nospec > -#else > -/* > - * Few people would run a 32-bit kernel on a machine that supports > - * recoverable errors because they have too much memory to boot 32-bit. > - */ > -#endif > - > #endif /* _ASM_X86_SET_MEMORY_H */ > diff --git a/arch/x86/mm/pat/set_memory.c b/arch/x86/mm/pat/set_memory.c > index abf5ed76e4b7..978cf5bd2ab6 100644 > --- a/arch/x86/mm/pat/set_memory.c > +++ b/arch/x86/mm/pat/set_memory.c > @@ -1816,7 +1816,7 @@ static inline int cpa_clear_pages_array(struct page **pages, int numpages, > } > > /* > - * _set_memory_prot is an internal helper for callers that have been passed > + * __set_memory_prot is an internal helper for callers that have been passed > * a pgprot_t value from upper layers and a reservation has already been taken. > * If you want to set the pgprot to a specific page protocol, use the > * set_memory_xx() functions. > @@ -1925,6 +1925,53 @@ int set_memory_wb(unsigned long addr, int numpages) > } > EXPORT_SYMBOL(set_memory_wb); > > +/* > + * Prevent speculative access to the page by either unmapping > + * it (if we do not require access to any part of the page) or > + * marking it uncacheable (if we want to try to retrieve data > + * from non-poisoned lines in the page). > + */ > +int set_mce_nospec(unsigned long pfn, bool unmap) > +{ > + unsigned long decoy_addr; > + int rc; > + > + if (!IS_ENABLED(CONFIG_64BIT)) > + return 0; > + > + /* SGX pages are not in the 1:1 map */ > + if (arch_is_platform_page(pfn << PAGE_SHIFT)) > + return 0; > + /* > + * We would like to just call: > + * set_memory_XX((unsigned long)pfn_to_kaddr(pfn), 1); > + * but doing that would radically increase the odds of a > + * speculative access to the poison page because we'd have > + * the virtual address of the kernel 1:1 mapping sitting > + * around in registers. > + * Instead we get tricky. We create a non-canonical address > + * that looks just like the one we want, but has bit 63 flipped. > + * This relies on set_memory_XX() properly sanitizing any __pa() > + * results with __PHYSICAL_MASK or PTE_PFN_MASK. > + */ > + decoy_addr = (pfn << PAGE_SHIFT) + (PAGE_OFFSET ^ BIT(63)); > + > + if (unmap) > + rc = set_memory_np(decoy_addr, 1); > + else > + rc = set_memory_uc(decoy_addr, 1); > + if (rc) > + pr_warn("Could not invalidate pfn=0x%lx from 1:1 map\n", pfn); > + return rc; > +} > + > +/* Restore full speculative operation to the pfn. */ > +int clear_mce_nospec(unsigned long pfn) > +{ > + return set_memory_wb((unsigned long) pfn_to_kaddr(pfn), 1); > +} > +EXPORT_SYMBOL_GPL(clear_mce_nospec); > + > int set_memory_x(unsigned long addr, int numpages) > { > if (!(__supported_pte_mask & _PAGE_NX)) > diff --git a/include/linux/set_memory.h b/include/linux/set_memory.h > index f36be5166c19..683a6c3f7179 100644 > --- a/include/linux/set_memory.h > +++ b/include/linux/set_memory.h > @@ -42,14 +42,14 @@ static inline bool can_set_direct_map(void) > #endif > #endif /* CONFIG_ARCH_HAS_SET_DIRECT_MAP */ > > -#ifndef set_mce_nospec > +#ifdef CONFIG_X86_64 Jane, I just noticed that this makes set_mce_nospec() and clear_mce_nospec() x86_64-only. If / when more architectures add support for these helpers they will need to go back to the "#ifndef $symbol" scheme to allow asm/set_memory.h to indicate the availability of the arch-local helper.
diff --git a/arch/x86/include/asm/set_memory.h b/arch/x86/include/asm/set_memory.h index 78ca53512486..b45c4d27fd46 100644 --- a/arch/x86/include/asm/set_memory.h +++ b/arch/x86/include/asm/set_memory.h @@ -86,56 +86,4 @@ bool kernel_page_present(struct page *page); extern int kernel_set_to_readonly; -#ifdef CONFIG_X86_64 -/* - * Prevent speculative access to the page by either unmapping - * it (if we do not require access to any part of the page) or - * marking it uncacheable (if we want to try to retrieve data - * from non-poisoned lines in the page). - */ -static inline int set_mce_nospec(unsigned long pfn, bool unmap) -{ - unsigned long decoy_addr; - int rc; - - /* SGX pages are not in the 1:1 map */ - if (arch_is_platform_page(pfn << PAGE_SHIFT)) - return 0; - /* - * We would like to just call: - * set_memory_XX((unsigned long)pfn_to_kaddr(pfn), 1); - * but doing that would radically increase the odds of a - * speculative access to the poison page because we'd have - * the virtual address of the kernel 1:1 mapping sitting - * around in registers. - * Instead we get tricky. We create a non-canonical address - * that looks just like the one we want, but has bit 63 flipped. - * This relies on set_memory_XX() properly sanitizing any __pa() - * results with __PHYSICAL_MASK or PTE_PFN_MASK. - */ - decoy_addr = (pfn << PAGE_SHIFT) + (PAGE_OFFSET ^ BIT(63)); - - if (unmap) - rc = set_memory_np(decoy_addr, 1); - else - rc = set_memory_uc(decoy_addr, 1); - if (rc) - pr_warn("Could not invalidate pfn=0x%lx from 1:1 map\n", pfn); - return rc; -} -#define set_mce_nospec set_mce_nospec - -/* Restore full speculative operation to the pfn. */ -static inline int clear_mce_nospec(unsigned long pfn) -{ - return set_memory_wb((unsigned long) pfn_to_kaddr(pfn), 1); -} -#define clear_mce_nospec clear_mce_nospec -#else -/* - * Few people would run a 32-bit kernel on a machine that supports - * recoverable errors because they have too much memory to boot 32-bit. - */ -#endif - #endif /* _ASM_X86_SET_MEMORY_H */ diff --git a/arch/x86/mm/pat/set_memory.c b/arch/x86/mm/pat/set_memory.c index abf5ed76e4b7..978cf5bd2ab6 100644 --- a/arch/x86/mm/pat/set_memory.c +++ b/arch/x86/mm/pat/set_memory.c @@ -1816,7 +1816,7 @@ static inline int cpa_clear_pages_array(struct page **pages, int numpages, } /* - * _set_memory_prot is an internal helper for callers that have been passed + * __set_memory_prot is an internal helper for callers that have been passed * a pgprot_t value from upper layers and a reservation has already been taken. * If you want to set the pgprot to a specific page protocol, use the * set_memory_xx() functions. @@ -1925,6 +1925,53 @@ int set_memory_wb(unsigned long addr, int numpages) } EXPORT_SYMBOL(set_memory_wb); +/* + * Prevent speculative access to the page by either unmapping + * it (if we do not require access to any part of the page) or + * marking it uncacheable (if we want to try to retrieve data + * from non-poisoned lines in the page). + */ +int set_mce_nospec(unsigned long pfn, bool unmap) +{ + unsigned long decoy_addr; + int rc; + + if (!IS_ENABLED(CONFIG_64BIT)) + return 0; + + /* SGX pages are not in the 1:1 map */ + if (arch_is_platform_page(pfn << PAGE_SHIFT)) + return 0; + /* + * We would like to just call: + * set_memory_XX((unsigned long)pfn_to_kaddr(pfn), 1); + * but doing that would radically increase the odds of a + * speculative access to the poison page because we'd have + * the virtual address of the kernel 1:1 mapping sitting + * around in registers. + * Instead we get tricky. We create a non-canonical address + * that looks just like the one we want, but has bit 63 flipped. + * This relies on set_memory_XX() properly sanitizing any __pa() + * results with __PHYSICAL_MASK or PTE_PFN_MASK. + */ + decoy_addr = (pfn << PAGE_SHIFT) + (PAGE_OFFSET ^ BIT(63)); + + if (unmap) + rc = set_memory_np(decoy_addr, 1); + else + rc = set_memory_uc(decoy_addr, 1); + if (rc) + pr_warn("Could not invalidate pfn=0x%lx from 1:1 map\n", pfn); + return rc; +} + +/* Restore full speculative operation to the pfn. */ +int clear_mce_nospec(unsigned long pfn) +{ + return set_memory_wb((unsigned long) pfn_to_kaddr(pfn), 1); +} +EXPORT_SYMBOL_GPL(clear_mce_nospec); + int set_memory_x(unsigned long addr, int numpages) { if (!(__supported_pte_mask & _PAGE_NX)) diff --git a/include/linux/set_memory.h b/include/linux/set_memory.h index f36be5166c19..683a6c3f7179 100644 --- a/include/linux/set_memory.h +++ b/include/linux/set_memory.h @@ -42,14 +42,14 @@ static inline bool can_set_direct_map(void) #endif #endif /* CONFIG_ARCH_HAS_SET_DIRECT_MAP */ -#ifndef set_mce_nospec +#ifdef CONFIG_X86_64 +int set_mce_nospec(unsigned long pfn, bool unmap); +int clear_mce_nospec(unsigned long pfn); +#else static inline int set_mce_nospec(unsigned long pfn, bool unmap) { return 0; } -#endif - -#ifndef clear_mce_nospec static inline int clear_mce_nospec(unsigned long pfn) { return 0;