linux-kernel - [kvm-unit-tests PATCH] x86: access: Add tests for reserved bits of guest physical address

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Message-Id: <20200227172826.22004-1-mgamal@redhat.com>
Date:   Thu, 27 Feb 2020 19:28:26 +0200
From:   Mohammed Gamal <mgamal@...hat.com>
To:     kvm@...r.kernel.org, pbonzini@...hat.com
Cc:     sean.j.christopherson@...el.com, vkuznets@...hat.com,
        wanpengli@...cent.com, jmattson@...gle.com, joro@...tes.org,
        linux-kernel@...r.kernel.org, Mohammed Gamal <mgamal@...hat.com>
Subject: [kvm-unit-tests PATCH] x86: access: Add tests for reserved bits of guest physical address

This extends the access tests to also test for reserved bits
in guest physical addresses.

Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
Signed-off-by: Mohammed Gamal <mgamal@...hat.com>
---
 x86/access.c | 31 +++++++++++++++++++++++++++++--
 1 file changed, 29 insertions(+), 2 deletions(-)

diff --git a/x86/access.c b/x86/access.c
index 7303fc3..b98b403 100644
--- a/x86/access.c
+++ b/x86/access.c
@@ -47,6 +47,7 @@ enum {
     AC_PTE_DIRTY_BIT,
     AC_PTE_NX_BIT,
     AC_PTE_BIT51_BIT,
+    AC_PTE_BIT40_BIT,
 
     AC_PDE_PRESENT_BIT,
     AC_PDE_WRITABLE_BIT,
@@ -56,6 +57,7 @@ enum {
     AC_PDE_PSE_BIT,
     AC_PDE_NX_BIT,
     AC_PDE_BIT51_BIT,
+    AC_PDE_BIT40_BIT,
     AC_PDE_BIT13_BIT,
 
     AC_PKU_AD_BIT,
@@ -82,6 +84,7 @@ enum {
 #define AC_PTE_DIRTY_MASK     (1 << AC_PTE_DIRTY_BIT)
 #define AC_PTE_NX_MASK        (1 << AC_PTE_NX_BIT)
 #define AC_PTE_BIT51_MASK     (1 << AC_PTE_BIT51_BIT)
+#define AC_PTE_BIT40_MASK     (1 << AC_PTE_BIT40_BIT)
 
 #define AC_PDE_PRESENT_MASK   (1 << AC_PDE_PRESENT_BIT)
 #define AC_PDE_WRITABLE_MASK  (1 << AC_PDE_WRITABLE_BIT)
@@ -91,6 +94,7 @@ enum {
 #define AC_PDE_PSE_MASK       (1 << AC_PDE_PSE_BIT)
 #define AC_PDE_NX_MASK        (1 << AC_PDE_NX_BIT)
 #define AC_PDE_BIT51_MASK     (1 << AC_PDE_BIT51_BIT)
+#define AC_PDE_BIT40_MASK     (1 << AC_PDE_BIT40_BIT)
 #define AC_PDE_BIT13_MASK     (1 << AC_PDE_BIT13_BIT)
 
 #define AC_PKU_AD_MASK        (1 << AC_PKU_AD_BIT)
@@ -115,6 +119,7 @@ const char *ac_names[] = {
     [AC_PTE_DIRTY_BIT] = "pte.d",
     [AC_PTE_NX_BIT] = "pte.nx",
     [AC_PTE_BIT51_BIT] = "pte.51",
+    [AC_PTE_BIT40_BIT] = "pte.40",
     [AC_PDE_PRESENT_BIT] = "pde.p",
     [AC_PDE_ACCESSED_BIT] = "pde.a",
     [AC_PDE_WRITABLE_BIT] = "pde.rw",
@@ -123,6 +128,7 @@ const char *ac_names[] = {
     [AC_PDE_PSE_BIT] = "pde.pse",
     [AC_PDE_NX_BIT] = "pde.nx",
     [AC_PDE_BIT51_BIT] = "pde.51",
+    [AC_PDE_BIT40_BIT] = "pde.40",
     [AC_PDE_BIT13_BIT] = "pde.13",
     [AC_PKU_AD_BIT] = "pkru.ad",
     [AC_PKU_WD_BIT] = "pkru.wd",
@@ -289,6 +295,14 @@ static _Bool ac_test_legal(ac_test_t *at)
     if (!F(AC_PDE_PSE) && F(AC_PDE_BIT13))
         return false;
 
+    /*
+     * Shorten the test by avoiding testing too many reserved bit combinations
+     */
+    if ((F(AC_PDE_BIT51) + F(AC_PDE_BIT40) + F(AC_PDE_BIT13)) > 1)
+        return false;
+    if ((F(AC_PTE_BIT51) + F(AC_PTE_BIT40)) > 1)
+        return false;
+
     return true;
 }
 
@@ -375,7 +389,7 @@ static void ac_emulate_access(ac_test_t *at, unsigned flags)
         at->ignore_pde = PT_ACCESSED_MASK;
 
     pde_valid = F(AC_PDE_PRESENT)
-        && !F(AC_PDE_BIT51) && !F(AC_PDE_BIT13)
+        && !F(AC_PDE_BIT51) && !F(AC_PDE_BIT40) && !F(AC_PDE_BIT13)
         && !(F(AC_PDE_NX) && !F(AC_CPU_EFER_NX));
 
     if (!pde_valid) {
@@ -401,7 +415,7 @@ static void ac_emulate_access(ac_test_t *at, unsigned flags)
     at->expected_pde |= PT_ACCESSED_MASK;
 
     pte_valid = F(AC_PTE_PRESENT)
-        && !F(AC_PTE_BIT51)
+        && !F(AC_PTE_BIT51) && !F(AC_PTE_BIT40)
         && !(F(AC_PTE_NX) && !F(AC_CPU_EFER_NX));
 
     if (!pte_valid) {
@@ -510,6 +524,8 @@ static void __ac_setup_specific_pages(ac_test_t *at, ac_pool_t *pool,
 		pte |= PT64_NX_MASK;
 	    if (F(AC_PDE_BIT51))
 		pte |= 1ull << 51;
+	    if (F(AC_PDE_BIT40))
+                pte |= 1ull << 40;
 	    if (F(AC_PDE_BIT13))
 		pte |= 1ull << 13;
 	    at->pdep = &vroot[index];
@@ -532,6 +548,8 @@ static void __ac_setup_specific_pages(ac_test_t *at, ac_pool_t *pool,
 		pte |= PT64_NX_MASK;
 	    if (F(AC_PTE_BIT51))
 		pte |= 1ull << 51;
+	    if (F(AC_PTE_BIT40))
+                pte |= 1ull << 40;
 	    at->ptep = &vroot[index];
 	    break;
 	}
@@ -935,6 +953,15 @@ static int ac_test_run(void)
     printf("run\n");
     tests = successes = 0;
 
+    if (cpuid_maxphyaddr() >= 52) {
+        invalid_mask |= AC_PDE_BIT51_MASK;
+        invalid_mask |= AC_PTE_BIT51_MASK;
+    }
+    if (cpuid_maxphyaddr() >= 41) {
+        invalid_mask |= AC_PDE_BIT40_MASK;
+        invalid_mask |= AC_PTE_BIT40_MASK;
+    }
+
     if (this_cpu_has(X86_FEATURE_PKU)) {
         set_cr4_pke(1);
         set_cr4_pke(0);
-- 
2.21.1