[kvm-unit-tests PATCH] x86: test combined access

[kvm-unit-tests PATCH] x86: test combined access

[Lai Jiangshan]

From: Lai Jiangshan <laijs@linux.alibaba.com>

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@antgroup.com>
Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com>
---
 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

Re: [kvm-unit-tests PATCH] x86: test combined access

[Sean Christopherson]

On Thu, Jun 03, 2021, Lai Jiangshan wrote:
> From: Lai Jiangshan <laijs@linux.alibaba.com>
> 
> Check combined access when guest shares pagetables.

Can we avoid "combined"?  Purely because of Intel using "combined" to refer to
the full IA32+EPT translation.  It'd also be helpful to provide a bit more
detail.  E.g. 

  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 usefull when TDP is not enabled.
              ^^^^^^^
	      useful

> Co-Developed-by: Hou Wenlong <houwenlong.hwl@antgroup.com>

Co-developed-by, and this needs Hou Wenlong's SoB as well.

> Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com>
> ---
>  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

Part of me thinks we should use AC_PDPTE_WRITABLE_BIT to be consistent with the
PDE and PTE bits, but I think I agree that special casing this one-off tests is
cleaner overall.

For better or worse, this test uses x86 legacy paging terminology for the entry
bits, not Linux's generic PTE/PMD/PUD/PGD.  I.e. for consistency, I think it
makes sense to use AC_PDPTE_NO_WRITABLE_BIT.

This new bit also needs an entry in ac_names[], otherwise it'll print garbage on
failure.  I'm thinking:

@@ -134,6 +134,7 @@ 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",


> +
>      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);

These can be combined, e.g.

       writable = !F(AC_PDPTE_NO_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

This will seemingly clear the WRITABLE bit for PML4 and PML5, but due to reuse
behavior, that may not be reflected in the actual page tables depending on
whether or not the first test clears the writable bit.

For robustness and clarity, I think it'd be better to do:

        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_USER_MASK;
            if (!F(AC_PDPTE_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)

To avoid the "combined" verbiage, how about check_effective_sp_permissions()?

[kvm-unit-tests PATCH V2] x86: Add a test to check effective permissions

[Lai Jiangshan]

From: Lai Jiangshan <laijs@linux.alibaba.com>

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@antgroup.com>
Signed-off-by: Hou Wenlong <houwenlong.hwl@antgroup.com>
Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com>
---
 x86/access.c | 106 ++++++++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 100 insertions(+), 6 deletions(-)

diff --git a/x86/access.c b/x86/access.c
index 7dc9eb6..98b8545 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 + 2 * 1024 * 1024;
+	unsigned long ptr3 = ptr1 + 1 * 1024 * 1024 * 1024;
+	unsigned long ptr4 = ptr3 + 2 * 1024 * 1024;
+	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)
-- 
2.19.1.6.gb485710b

Re: [kvm-unit-tests PATCH V2] x86: Add a test to check effective permissions

[Sean Christopherson]

On Fri, Jun 04, 2021, Lai Jiangshan wrote:
> @@ -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);

Should this go in a separate patch?  This seems like a bug fix.

>      return ret;
>  }
>  
> +static int check_effective_sp_permissions(ac_pool_t *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;

I belatedly remembered we have SZ_2M and SZ_1G, I think we can use those here
instead of open coding the math.

[kvm-unit-tests PATCH V3] x86: Add a test to check effective permissions

[Lai Jiangshan]

From: Lai Jiangshan <laijs@linux.alibaba.com>

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@antgroup.com>
Signed-off-by: Hou Wenlong <houwenlong.hwl@antgroup.com>
Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com>
---
 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)
-- 
2.19.1.6.gb485710b

Re: [kvm-unit-tests PATCH V2] x86: Add a test to check effective permissions

[Lai Jiangshan]

On 2021/6/5 05:40, Sean Christopherson wrote:
> On Fri, Jun 04, 2021, Lai Jiangshan wrote:
>> @@ -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);
> 
> Should this go in a separate patch?  This seems like a bug fix.

I don't think we need to separate the patch. It is a patch for the testing
repository in which there is no real bug.

I prefer to add the test in a single patch with everything the test needs.

> 
>>       return ret;
>>   }
>>   
>> +static int check_effective_sp_permissions(ac_pool_t *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;
> 
> I belatedly remembered we have SZ_2M and SZ_1G, I think we can use those here
> instead of open coding the math.
> 

Will do.

Thanks
Lai

Re: [kvm-unit-tests PATCH V3] x86: Add a test to check effective permissions

[Sean Christopherson]

On Sun, Jun 06, 2021, Lai Jiangshan wrote:
> From: Lai Jiangshan <laijs@linux.alibaba.com>
> 
> 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@antgroup.com>
> Signed-off-by: Hou Wenlong <houwenlong.hwl@antgroup.com>
> Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com>
> ---

Awesome, thanks!

Reviewed-by: Sean Christopherson <seanjc@google.com>

Re: [kvm-unit-tests PATCH V3] x86: Add a test to check effective permissions

[Paolo Bonzini]

On 05/06/21 19:49, Lai Jiangshan wrote:
> From: Lai Jiangshan <laijs@linux.alibaba.com>
> 
> 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@antgroup.com>
> Signed-off-by: Hou Wenlong <houwenlong.hwl@antgroup.com>
> Signed-off-by: Lai Jiangshan <laijs@linux.alibaba.com>
> ---
>   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)
> 

Applied, thanks.

Paolo