[kvm-unit-tests PATCH] x86/access: Fixed test stuck issue on new 52bit machine

[Yang Weijiang <weijiang.yang@xxxxxxxxx>]

When the application is tested on a machine with 52bit-physical-address, the
synthesized 52bit GPA triggers EPT(4-Level) fast_page_fault infinitely. On the
other hand, there's no reserved bits in 51:max_physical_address on machines with
52bit-physical-address.

Signed-off-by: Yang Weijiang <weijiang.yang@xxxxxxxxx>
---
 x86/access.c | 20 +++++++++++---------
 1 file changed, 11 insertions(+), 9 deletions(-)

diff --git a/x86/access.c b/x86/access.c
index 7dc9eb6..bec1c4d 100644
--- a/x86/access.c
+++ b/x86/access.c
@@ -15,6 +15,7 @@ static _Bool verbose = false;
 typedef unsigned long pt_element_t;
 static int invalid_mask;
 static int page_table_levels;
+static int max_phyaddr;
 
 #define PT_BASE_ADDR_MASK ((pt_element_t)((((pt_element_t)1 << 36) - 1) & PAGE_MASK))
 #define PT_PSE_BASE_ADDR_MASK (PT_BASE_ADDR_MASK & ~(1ull << 21))
@@ -394,9 +395,10 @@ static void ac_emulate_access(ac_test_t *at, unsigned flags)
     if (!F(AC_PDE_ACCESSED))
         at->ignore_pde = PT_ACCESSED_MASK;
 
-    pde_valid = F(AC_PDE_PRESENT)
-        && !F(AC_PDE_BIT51) && !F(AC_PDE_BIT36) && !F(AC_PDE_BIT13)
+    pde_valid = F(AC_PDE_PRESENT) && !F(AC_PDE_BIT36) && !F(AC_PDE_BIT13)
         && !(F(AC_PDE_NX) && !F(AC_CPU_EFER_NX));
+    if (max_phyaddr < 52)
+        pde_valid &= !F(AC_PDE_BIT51);
 
     if (!pde_valid) {
         at->expected_fault = 1;
@@ -420,9 +422,10 @@ 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_BIT36)
+    pte_valid = F(AC_PTE_PRESENT) && !F(AC_PTE_BIT36)
         && !(F(AC_PTE_NX) && !F(AC_CPU_EFER_NX));
+    if (max_phyaddr < 52)
+        pte_valid &= !F(AC_PTE_BIT51);
 
     if (!pte_valid) {
         at->expected_fault = 1;
@@ -964,13 +967,11 @@ static int ac_test_run(void)
     shadow_cr4 = read_cr4();
     shadow_efer = rdmsr(MSR_EFER);
 
-    if (cpuid_maxphyaddr() >= 52) {
-        invalid_mask |= AC_PDE_BIT51_MASK;
-        invalid_mask |= AC_PTE_BIT51_MASK;
-    }
-    if (cpuid_maxphyaddr() >= 37) {
+    if (max_phyaddr  >= 37 && max_phyaddr < 52) {
         invalid_mask |= AC_PDE_BIT36_MASK;
         invalid_mask |= AC_PTE_BIT36_MASK;
+        invalid_mask |= AC_PDE_BIT51_MASK;
+        invalid_mask |= AC_PTE_BIT51_MASK;
     }
 
     if (this_cpu_has(X86_FEATURE_PKU)) {
@@ -1038,6 +1039,7 @@ int main(void)
     int r;
 
     printf("starting test\n\n");
+    max_phyaddr = cpuid_maxphyaddr();
     page_table_levels = 4;
     r = ac_test_run();
 
-- 
2.17.2