diff options
Diffstat (limited to 'arch/x86/mm/pat')
| -rw-r--r-- | arch/x86/mm/pat/set_memory.c | 49 |
1 files changed, 47 insertions, 2 deletions
diff --git a/arch/x86/mm/pat/set_memory.c b/arch/x86/mm/pat/set_memory.c index 0656db33574d..1abd5438f126 100644 --- a/arch/x86/mm/pat/set_memory.c +++ b/arch/x86/mm/pat/set_memory.c @@ -19,6 +19,7 @@ #include <linux/vmstat.h> #include <linux/kernel.h> #include <linux/cc_platform.h> +#include <linux/set_memory.h> #include <asm/e820/api.h> #include <asm/processor.h> @@ -29,7 +30,6 @@ #include <asm/pgalloc.h> #include <asm/proto.h> #include <asm/memtype.h> -#include <asm/set_memory.h> #include <asm/hyperv-tlfs.h> #include <asm/mshyperv.h> @@ -1805,7 +1805,7 @@ 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. @@ -1914,6 +1914,51 @@ int set_memory_wb(unsigned long addr, int numpages) } EXPORT_SYMBOL(set_memory_wb); +/* Prevent speculative access to a page by marking it not-present */ +#ifdef CONFIG_X86_64 +int set_mce_nospec(unsigned long pfn) +{ + 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)); + + rc = set_memory_np(decoy_addr, 1); + if (rc) + pr_warn("Could not invalidate pfn=0x%lx from 1:1 map\n", pfn); + return rc; +} + +static int set_memory_present(unsigned long *addr, int numpages) +{ + return change_page_attr_set(addr, numpages, __pgprot(_PAGE_PRESENT), 0); +} + +/* Restore full speculative operation to the pfn. */ +int clear_mce_nospec(unsigned long pfn) +{ + unsigned long addr = (unsigned long) pfn_to_kaddr(pfn); + + return set_memory_present(&addr, 1); +} +EXPORT_SYMBOL_GPL(clear_mce_nospec); +#endif /* CONFIG_X86_64 */ + int set_memory_x(unsigned long addr, int numpages) { if (!(__supported_pte_mask & _PAGE_NX)) |