From: Lai Jiangshan <laijs@xxxxxxxxxxxxxxxxx> Check combined access when guest shares pagetables. For example, here is a shared pagetable: pgd[] pud[] pmd[] virtual address pointers /->pmd1(u--)->pte1(uw-)->page1 <- ptr1 (u--) /->pud1(uw-)--->pmd2(uw-)->pte2(uw-)->page2 <- ptr2 (uw-) pgd-| (shared pmd[] as above) \->pud2(u--)--->pmd1(u--)->pte1(uw-)->page1 <- ptr3 (u--) \->pmd2(uw-)->pte2(uw-)->page2 <- ptr4 (u--) pud1 and pud2 point to the same pmd table The test is usefull when TDP is not enabled. Co-Developed-by: Hou Wenlong <houwenlong.hwl@xxxxxxxxxxxx> Signed-off-by: Lai Jiangshan <laijs@xxxxxxxxxxxxxxxxx> --- x86/access.c | 99 ++++++++++++++++++++++++++++++++++++++++++++++++---- 1 file changed, 93 insertions(+), 6 deletions(-) diff --git a/x86/access.c b/x86/access.c index 7dc9eb6..6dbe6e5 100644 --- a/x86/access.c +++ b/x86/access.c @@ -60,6 +60,8 @@ enum { AC_PDE_BIT36_BIT, AC_PDE_BIT13_BIT, + AC_PUDE_NO_WRITABLE_BIT, // special test case to disable write bit on PUD entry + AC_PKU_AD_BIT, AC_PKU_WD_BIT, AC_PKU_PKEY_BIT, @@ -97,6 +99,8 @@ enum { #define AC_PDE_BIT36_MASK (1 << AC_PDE_BIT36_BIT) #define AC_PDE_BIT13_MASK (1 << AC_PDE_BIT13_BIT) +#define AC_PUDE_NO_WRITABLE_MASK (1 << AC_PUDE_NO_WRITABLE_BIT) + #define AC_PKU_AD_MASK (1 << AC_PKU_AD_BIT) #define AC_PKU_WD_MASK (1 << AC_PKU_WD_BIT) #define AC_PKU_PKEY_MASK (1 << AC_PKU_PKEY_BIT) @@ -326,6 +330,7 @@ static pt_element_t ac_test_alloc_pt(ac_pool_t *pool) { pt_element_t ret = pool->pt_pool + pool->pt_pool_current; pool->pt_pool_current += PAGE_SIZE; + memset(va(ret), 0, PAGE_SIZE); return ret; } @@ -408,7 +413,8 @@ static void ac_emulate_access(ac_test_t *at, unsigned flags) goto fault; } - writable = F(AC_PDE_WRITABLE); + writable = !F(AC_PUDE_NO_WRITABLE); + writable &= F(AC_PDE_WRITABLE); user = F(AC_PDE_USER); executable = !F(AC_PDE_NX); @@ -471,7 +477,7 @@ static void ac_set_expected_status(ac_test_t *at) ac_emulate_access(at, at->flags); } -static void __ac_setup_specific_pages(ac_test_t *at, ac_pool_t *pool, +static void __ac_setup_specific_pages(ac_test_t *at, ac_pool_t *pool, bool reuse, u64 pd_page, u64 pt_page) { @@ -496,13 +502,26 @@ static void __ac_setup_specific_pages(ac_test_t *at, ac_pool_t *pool, goto next; } skip = false; + if (reuse && vroot[index]) { + switch (i) { + case 2: + at->pdep = &vroot[index]; + break; + case 1: + at->ptep = &vroot[index]; + break; + } + goto next; + } switch (i) { case 5: case 4: case 3: - pte = pd_page ? pd_page : ac_test_alloc_pt(pool); + pte = (i==3 && pd_page) ? pd_page : ac_test_alloc_pt(pool); pte |= PT_PRESENT_MASK | PT_WRITABLE_MASK | PT_USER_MASK; + if (F(AC_PUDE_NO_WRITABLE)) + pte &= ~PT_WRITABLE_MASK; break; case 2: if (!F(AC_PDE_PSE)) { @@ -568,13 +587,13 @@ static void __ac_setup_specific_pages(ac_test_t *at, ac_pool_t *pool, static void ac_test_setup_pte(ac_test_t *at, ac_pool_t *pool) { - __ac_setup_specific_pages(at, pool, 0, 0); + __ac_setup_specific_pages(at, pool, false, 0, 0); } static void ac_setup_specific_pages(ac_test_t *at, ac_pool_t *pool, u64 pd_page, u64 pt_page) { - return __ac_setup_specific_pages(at, pool, pd_page, pt_page); + return __ac_setup_specific_pages(at, pool, false, pd_page, pt_page); } static void dump_mapping(ac_test_t *at) @@ -930,6 +949,73 @@ err: return 0; } +static int check_combined_protection(ac_pool_t *pool) +{ + ac_test_t at1, at2, at3, at4; + int err_read_at1, err_write_at2; + int err_read_at3, err_write_at4; + pt_element_t pmd = ac_test_alloc_pt(pool); + unsigned long ptr1 = 0x123480000000; + unsigned long ptr2 = ptr1 + 2 * 1024 * 1024; + unsigned long ptr3 = ptr1 + 1 * 1024 * 1024 * 1024; + unsigned long ptr4 = ptr3 + 2 * 1024 * 1024; + + /* + * pgd[] pud[] pmd[] virtual address pointers + * /->pmd1(u--)->pte1(uw-)->page1 <- ptr1 (u--) + * /->pud1(uw-)--->pmd2(uw-)->pte2(uw-)->page2 <- ptr2 (uw-) + * pgd-| (shared pmd[] as above) + * \->pud2(u--)--->pmd1(u--)->pte1(uw-)->page1 <- ptr3 (u--) + * \->pmd2(uw-)->pte2(uw-)->page2 <- ptr4 (u--) + * pud1 and pud2 point to the same pmd page. + */ + + ac_test_init(&at1, (void *)(ptr1)); + at1.flags = AC_PDE_PRESENT_MASK | AC_PTE_PRESENT_MASK | + AC_PDE_USER_MASK | AC_PTE_USER_MASK | + AC_PDE_ACCESSED_MASK | AC_PTE_ACCESSED_MASK | + AC_PTE_WRITABLE_MASK | AC_ACCESS_USER_MASK; + __ac_setup_specific_pages(&at1, pool, false, pmd, 0); + + ac_test_init(&at2, (void *)(ptr2)); + at2.flags = at1.flags | AC_PDE_WRITABLE_MASK | AC_PTE_DIRTY_MASK | AC_ACCESS_WRITE_MASK; + __ac_setup_specific_pages(&at2, pool, true, pmd, 0); + + ac_test_init(&at3, (void *)(ptr3)); + at3.flags = AC_PUDE_NO_WRITABLE_MASK | at1.flags; + __ac_setup_specific_pages(&at3, pool, true, pmd, 0); + + ac_test_init(&at4, (void *)(ptr4)); + at4.flags = AC_PUDE_NO_WRITABLE_MASK | at2.flags; + __ac_setup_specific_pages(&at4, pool, true, pmd, 0); + + err_read_at1 = ac_test_do_access(&at1); + if (!err_read_at1) { + printf("%s: read access at1 fail\n", __FUNCTION__); + return 0; + } + + err_write_at2 = ac_test_do_access(&at2); + if (!err_write_at2) { + printf("%s: write access at2 fail\n", __FUNCTION__); + return 0; + } + + err_read_at3 = ac_test_do_access(&at3); + if (!err_read_at3) { + printf("%s: read access at3 fail\n", __FUNCTION__); + return 0; + } + + err_write_at4 = ac_test_do_access(&at4); + if (!err_write_at4) { + printf("%s: write access at4 should fail\n", __FUNCTION__); + return 0; + } + + return 1; +} + static int ac_test_exec(ac_test_t *at, ac_pool_t *pool) { int r; @@ -948,7 +1034,8 @@ const ac_test_fn ac_test_cases[] = corrupt_hugepage_triger, check_pfec_on_prefetch_pte, check_large_pte_dirty_for_nowp, - check_smep_andnot_wp + check_smep_andnot_wp, + check_combined_protection }; static int ac_test_run(void) -- 2.19.1.6.gb485710b