From: Lai Jiangshan <laijs@xxxxxxxxxxxxxxxxx>
Add a test to verify that KVM correctly handles the case where two or
more non-leaf page table entries point at the same table gfn, but with
different parent access permissions.
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 useful when TDP is not enabled.
Co-Developed-by: Hou Wenlong <houwenlong.hwl@xxxxxxxxxxxx>
Signed-off-by: Hou Wenlong <houwenlong.hwl@xxxxxxxxxxxx>
Signed-off-by: Lai Jiangshan <laijs@xxxxxxxxxxxxxxxxx>
---
x86/access.c | 106 ++++++++++++++++++++++++++++++++++++++++++++++++---
1 file changed, 100 insertions(+), 6 deletions(-)
diff --git a/x86/access.c b/x86/access.c
index 7dc9eb6..0ad677e 100644
--- a/x86/access.c
+++ b/x86/access.c
@@ -60,6 +60,12 @@ enum {
AC_PDE_BIT36_BIT,
AC_PDE_BIT13_BIT,
+ /*
+ * special test case to DISABLE writable bit on page directory
+ * pointer table entry.
+ */
+ AC_PDPTE_NO_WRITABLE_BIT,
+
AC_PKU_AD_BIT,
AC_PKU_WD_BIT,
AC_PKU_PKEY_BIT,
@@ -97,6 +103,8 @@ enum {
#define AC_PDE_BIT36_MASK (1 << AC_PDE_BIT36_BIT)
#define AC_PDE_BIT13_MASK (1 << AC_PDE_BIT13_BIT)
+#define AC_PDPTE_NO_WRITABLE_MASK (1 << AC_PDPTE_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)
@@ -130,6 +138,7 @@ const char *ac_names[] = {
[AC_PDE_BIT51_BIT] = "pde.51",
[AC_PDE_BIT36_BIT] = "pde.36",
[AC_PDE_BIT13_BIT] = "pde.13",
+ [AC_PDPTE_NO_WRITABLE_BIT] = "pdpte.ro",
[AC_PKU_AD_BIT] = "pkru.ad",
[AC_PKU_WD_BIT] = "pkru.wd",
[AC_PKU_PKEY_BIT] = "pkey=1",
@@ -326,6 +335,7 @@ 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 +418,7 @@ static void ac_emulate_access(ac_test_t *at, unsigned flags)
goto fault;
}
- writable = F(AC_PDE_WRITABLE);
+ writable = !F(AC_PDPTE_NO_WRITABLE) && F(AC_PDE_WRITABLE);
user = F(AC_PDE_USER);
executable = !F(AC_PDE_NX);
@@ -471,7 +481,7 @@ 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 +506,29 @@ 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:
+ pte = ac_test_alloc_pt(pool);
+ pte |= PT_PRESENT_MASK | PT_WRITABLE_MASK | PT_USER_MASK;
+ break;
case 3:
pte = pd_page ? pd_page : ac_test_alloc_pt(pool);
- pte |= PT_PRESENT_MASK | PT_WRITABLE_MASK | PT_USER_MASK;
+ pte |= PT_PRESENT_MASK | PT_USER_MASK;
+ if (!F(AC_PDPTE_NO_WRITABLE))
+ pte |= PT_WRITABLE_MASK;
break;
case 2:
if (!F(AC_PDE_PSE)) {
@@ -568,13 +594,13 @@ 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 +956,73 @@ err:
return 0;
}
+static int check_effective_sp_permissions(ac_pool_t *pool)
+{
+ unsigned long ptr1 = 0x123480000000;
+ unsigned long ptr2 = ptr1 + SZ_2M;
+ unsigned long ptr3 = ptr1 + SZ_1G;
+ unsigned long ptr4 = ptr3 + SZ_2M;
+ pt_element_t pmd = ac_test_alloc_pt(pool);
+ ac_test_t at1, at2, at3, at4;
+ int err_read_at1, err_write_at2;
+ int err_read_at3, err_write_at4;
+
+ /*
+ * 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_PDPTE_NO_WRITABLE_MASK | at1.flags;
+ __ac_setup_specific_pages(&at3, pool, true, pmd, 0);
+
+ ac_test_init(&at4, (void *)(ptr4));
+ at4.flags = AC_PDPTE_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 +1041,8 @@ 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_effective_sp_permissions,
};
static int ac_test_run(void)
