diff options
Diffstat (limited to 'arch/x86/mm/pat/set_memory.c')
-rw-r--r-- | arch/x86/mm/pat/set_memory.c | 139 |
1 files changed, 108 insertions, 31 deletions
diff --git a/arch/x86/mm/pat/set_memory.c b/arch/x86/mm/pat/set_memory.c index 80c9037ffadf..44f7b2ea6a07 100644 --- a/arch/x86/mm/pat/set_memory.c +++ b/arch/x86/mm/pat/set_memory.c @@ -619,7 +619,8 @@ static inline pgprot_t static_protections(pgprot_t prot, unsigned long start, * Validate strict W^X semantics. */ static inline pgprot_t verify_rwx(pgprot_t old, pgprot_t new, unsigned long start, - unsigned long pfn, unsigned long npg) + unsigned long pfn, unsigned long npg, + bool nx, bool rw) { unsigned long end; @@ -641,6 +642,10 @@ static inline pgprot_t verify_rwx(pgprot_t old, pgprot_t new, unsigned long star if ((pgprot_val(new) & (_PAGE_RW | _PAGE_NX)) != _PAGE_RW) return new; + /* Non-leaf translation entries can disable writing or execution. */ + if (!rw || nx) + return new; + end = start + npg * PAGE_SIZE - 1; WARN_ONCE(1, "CPA detected W^X violation: %016llx -> %016llx range: 0x%016lx - 0x%016lx PFN %lx\n", (unsigned long long)pgprot_val(old), @@ -657,56 +662,82 @@ static inline pgprot_t verify_rwx(pgprot_t old, pgprot_t new, unsigned long star /* * Lookup the page table entry for a virtual address in a specific pgd. - * Return a pointer to the entry and the level of the mapping. + * Return a pointer to the entry (or NULL if the entry does not exist), + * the level of the entry, and the effective NX and RW bits of all + * page table levels. */ -pte_t *lookup_address_in_pgd(pgd_t *pgd, unsigned long address, - unsigned int *level) +pte_t *lookup_address_in_pgd_attr(pgd_t *pgd, unsigned long address, + unsigned int *level, bool *nx, bool *rw) { p4d_t *p4d; pud_t *pud; pmd_t *pmd; - *level = PG_LEVEL_NONE; + *level = PG_LEVEL_256T; + *nx = false; + *rw = true; if (pgd_none(*pgd)) return NULL; + *level = PG_LEVEL_512G; + *nx |= pgd_flags(*pgd) & _PAGE_NX; + *rw &= pgd_flags(*pgd) & _PAGE_RW; + p4d = p4d_offset(pgd, address); if (p4d_none(*p4d)) return NULL; - *level = PG_LEVEL_512G; if (p4d_leaf(*p4d) || !p4d_present(*p4d)) return (pte_t *)p4d; + *level = PG_LEVEL_1G; + *nx |= p4d_flags(*p4d) & _PAGE_NX; + *rw &= p4d_flags(*p4d) & _PAGE_RW; + pud = pud_offset(p4d, address); if (pud_none(*pud)) return NULL; - *level = PG_LEVEL_1G; if (pud_leaf(*pud) || !pud_present(*pud)) return (pte_t *)pud; + *level = PG_LEVEL_2M; + *nx |= pud_flags(*pud) & _PAGE_NX; + *rw &= pud_flags(*pud) & _PAGE_RW; + pmd = pmd_offset(pud, address); if (pmd_none(*pmd)) return NULL; - *level = PG_LEVEL_2M; if (pmd_leaf(*pmd) || !pmd_present(*pmd)) return (pte_t *)pmd; *level = PG_LEVEL_4K; + *nx |= pmd_flags(*pmd) & _PAGE_NX; + *rw &= pmd_flags(*pmd) & _PAGE_RW; return pte_offset_kernel(pmd, address); } /* + * Lookup the page table entry for a virtual address in a specific pgd. + * Return a pointer to the entry and the level of the mapping. + */ +pte_t *lookup_address_in_pgd(pgd_t *pgd, unsigned long address, + unsigned int *level) +{ + bool nx, rw; + + return lookup_address_in_pgd_attr(pgd, address, level, &nx, &rw); +} + +/* * Lookup the page table entry for a virtual address. Return a pointer * to the entry and the level of the mapping. * - * Note: We return pud and pmd either when the entry is marked large - * or when the present bit is not set. Otherwise we would return a - * pointer to a nonexisting mapping. + * Note: the function returns p4d, pud or pmd either when the entry is marked + * large or when the present bit is not set. Otherwise it returns NULL. */ pte_t *lookup_address(unsigned long address, unsigned int *level) { @@ -715,13 +746,16 @@ pte_t *lookup_address(unsigned long address, unsigned int *level) EXPORT_SYMBOL_GPL(lookup_address); static pte_t *_lookup_address_cpa(struct cpa_data *cpa, unsigned long address, - unsigned int *level) + unsigned int *level, bool *nx, bool *rw) { - if (cpa->pgd) - return lookup_address_in_pgd(cpa->pgd + pgd_index(address), - address, level); + pgd_t *pgd; + + if (!cpa->pgd) + pgd = pgd_offset_k(address); + else + pgd = cpa->pgd + pgd_index(address); - return lookup_address(address, level); + return lookup_address_in_pgd_attr(pgd, address, level, nx, rw); } /* @@ -849,12 +883,13 @@ static int __should_split_large_page(pte_t *kpte, unsigned long address, pgprot_t old_prot, new_prot, req_prot, chk_prot; pte_t new_pte, *tmp; enum pg_level level; + bool nx, rw; /* * Check for races, another CPU might have split this page * up already: */ - tmp = _lookup_address_cpa(cpa, address, &level); + tmp = _lookup_address_cpa(cpa, address, &level, &nx, &rw); if (tmp != kpte) return 1; @@ -965,7 +1000,8 @@ static int __should_split_large_page(pte_t *kpte, unsigned long address, new_prot = static_protections(req_prot, lpaddr, old_pfn, numpages, psize, CPA_DETECT); - new_prot = verify_rwx(old_prot, new_prot, lpaddr, old_pfn, numpages); + new_prot = verify_rwx(old_prot, new_prot, lpaddr, old_pfn, numpages, + nx, rw); /* * If there is a conflict, split the large page. @@ -1046,6 +1082,7 @@ __split_large_page(struct cpa_data *cpa, pte_t *kpte, unsigned long address, pte_t *pbase = (pte_t *)page_address(base); unsigned int i, level; pgprot_t ref_prot; + bool nx, rw; pte_t *tmp; spin_lock(&pgd_lock); @@ -1053,7 +1090,7 @@ __split_large_page(struct cpa_data *cpa, pte_t *kpte, unsigned long address, * Check for races, another CPU might have split this page * up for us already: */ - tmp = _lookup_address_cpa(cpa, address, &level); + tmp = _lookup_address_cpa(cpa, address, &level, &nx, &rw); if (tmp != kpte) { spin_unlock(&pgd_lock); return 1; @@ -1082,8 +1119,8 @@ __split_large_page(struct cpa_data *cpa, pte_t *kpte, unsigned long address, lpinc = PMD_SIZE; /* * Clear the PSE flags if the PRESENT flag is not set - * otherwise pmd_present/pmd_huge will return true - * even on a non present pmd. + * otherwise pmd_present() will return true even on a non + * present pmd. */ if (!(pgprot_val(ref_prot) & _PAGE_PRESENT)) pgprot_val(ref_prot) &= ~_PAGE_PSE; @@ -1594,10 +1631,11 @@ static int __change_page_attr(struct cpa_data *cpa, int primary) int do_split, err; unsigned int level; pte_t *kpte, old_pte; + bool nx, rw; address = __cpa_addr(cpa, cpa->curpage); repeat: - kpte = _lookup_address_cpa(cpa, address, &level); + kpte = _lookup_address_cpa(cpa, address, &level, &nx, &rw); if (!kpte) return __cpa_process_fault(cpa, address, primary); @@ -1619,7 +1657,8 @@ repeat: new_prot = static_protections(new_prot, address, pfn, 1, 0, CPA_PROTECT); - new_prot = verify_rwx(old_prot, new_prot, address, pfn, 1); + new_prot = verify_rwx(old_prot, new_prot, address, pfn, 1, + nx, rw); new_prot = pgprot_clear_protnone_bits(new_prot); @@ -2156,7 +2195,8 @@ static int __set_memory_enc_pgtable(unsigned long addr, int numpages, bool enc) cpa_flush(&cpa, x86_platform.guest.enc_cache_flush_required()); /* Notify hypervisor that we are about to set/clr encryption attribute. */ - if (!x86_platform.guest.enc_status_change_prepare(addr, numpages, enc)) + ret = x86_platform.guest.enc_status_change_prepare(addr, numpages, enc); + if (ret) goto vmm_fail; ret = __change_page_attr_set_clr(&cpa, 1); @@ -2174,24 +2214,61 @@ static int __set_memory_enc_pgtable(unsigned long addr, int numpages, bool enc) return ret; /* Notify hypervisor that we have successfully set/clr encryption attribute. */ - if (!x86_platform.guest.enc_status_change_finish(addr, numpages, enc)) + ret = x86_platform.guest.enc_status_change_finish(addr, numpages, enc); + if (ret) goto vmm_fail; return 0; vmm_fail: - WARN_ONCE(1, "CPA VMM failure to convert memory (addr=%p, numpages=%d) to %s.\n", - (void *)addr, numpages, enc ? "private" : "shared"); + WARN_ONCE(1, "CPA VMM failure to convert memory (addr=%p, numpages=%d) to %s: %d\n", + (void *)addr, numpages, enc ? "private" : "shared", ret); + + return ret; +} + +/* + * The lock serializes conversions between private and shared memory. + * + * It is taken for read on conversion. A write lock guarantees that no + * concurrent conversions are in progress. + */ +static DECLARE_RWSEM(mem_enc_lock); + +/* + * Stop new private<->shared conversions. + * + * Taking the exclusive mem_enc_lock waits for in-flight conversions to complete. + * The lock is not released to prevent new conversions from being started. + */ +bool set_memory_enc_stop_conversion(void) +{ + /* + * In a crash scenario, sleep is not allowed. Try to take the lock. + * Failure indicates that there is a race with the conversion. + */ + if (oops_in_progress) + return down_write_trylock(&mem_enc_lock); - return -EIO; + down_write(&mem_enc_lock); + + return true; } static int __set_memory_enc_dec(unsigned long addr, int numpages, bool enc) { - if (cc_platform_has(CC_ATTR_MEM_ENCRYPT)) - return __set_memory_enc_pgtable(addr, numpages, enc); + int ret = 0; - return 0; + if (cc_platform_has(CC_ATTR_MEM_ENCRYPT)) { + if (!down_read_trylock(&mem_enc_lock)) + return -EBUSY; + + ret = __set_memory_enc_pgtable(addr, numpages, enc); + + up_read(&mem_enc_lock); + } + + return ret; } int set_memory_encrypted(unsigned long addr, int numpages) |