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[Xen-devel] [PATCH] enforce EPT paging structure memory type and page-walk length check


  • To: "xen-devel@xxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxx>
  • From: "Li, Xin" <xin.li@xxxxxxxxx>
  • Date: Thu, 10 Jun 2010 16:09:59 +0800
  • Accept-language: zh-CN, en-US
  • Acceptlanguage: zh-CN, en-US
  • Delivery-date: Thu, 10 Jun 2010 01:11:52 -0700
  • List-id: Xen developer discussion <xen-devel.lists.xensource.com>
  • Thread-index: AcsIdFHaAaqWlHaSQraOgKSjvMq7Pg==
  • Thread-topic: [PATCH] enforce EPT paging structure memory type and page-walk length check

VMX: enforce EPT paging structure memory type and page-walk length check.

Also use a micro to get EPT walk length.

signed-off-by: Xin Li <xin.li@xxxxxxxxx>

diff -r b522d6148f44 xen/arch/x86/hvm/vmx/vmcs.c
--- a/xen/arch/x86/hvm/vmx/vmcs.c       Thu Jun 10 08:31:36 2010 +0100
+++ b/xen/arch/x86/hvm/vmx/vmcs.c       Wed Jun 09 19:37:38 2010 -0700
@@ -192,6 +192,26 @@ static int vmx_init_vmcs_config(void)
             MSR_IA32_VMX_PROCBASED_CTLS2, &mismatch);
     }
 
+    /* The IA32_VMX_EPT_VPID_CAP MSR exists only when EPT or VPID available */
+    if ( _vmx_secondary_exec_control & (SECONDARY_EXEC_ENABLE_EPT |
+                                        SECONDARY_EXEC_ENABLE_VPID) )
+    {
+        rdmsrl(MSR_IA32_VMX_EPT_VPID_CAP, _vmx_ept_vpid_cap);
+
+        /*
+         * Additional sanity checking before using EPT:
+         * 1) the CPU we are running on must support EPT WB, as we will set
+         *    ept paging structures memory type to WB;
+         * 2) the CPU must support the EPT page-walk length of 4 according to
+         *    Intel SDM 25.2.2.
+         *
+         * Or we just don't use EPT.
+         */
+        if ( !(_vmx_ept_vpid_cap & VMX_EPT_MEMORY_TYPE_WB) ||
+             !(_vmx_ept_vpid_cap & VMX_EPT_WALK_LENGTH_4_SUPPORTED) )
+            _vmx_secondary_exec_control &= ~SECONDARY_EXEC_ENABLE_EPT;
+    }
+
     if ( _vmx_secondary_exec_control & SECONDARY_EXEC_ENABLE_EPT )
     {
         /*
@@ -209,11 +229,6 @@ static int vmx_init_vmcs_config(void)
                 ~(SECONDARY_EXEC_ENABLE_EPT |
                   SECONDARY_EXEC_UNRESTRICTED_GUEST);
     }
-
-    /* The IA32_VMX_EPT_VPID_CAP MSR exists only when EPT or VPID available */
-    if ( _vmx_secondary_exec_control &
-          (SECONDARY_EXEC_ENABLE_EPT | SECONDARY_EXEC_ENABLE_VPID) )
-        rdmsrl(MSR_IA32_VMX_EPT_VPID_CAP, _vmx_ept_vpid_cap);
 
     if ( (_vmx_secondary_exec_control & SECONDARY_EXEC_PAUSE_LOOP_EXITING) &&
           ple_gap == 0 )
diff -r b522d6148f44 xen/arch/x86/hvm/vmx/vmx.c
--- a/xen/arch/x86/hvm/vmx/vmx.c        Thu Jun 10 08:31:36 2010 +0100
+++ b/xen/arch/x86/hvm/vmx/vmx.c        Wed Jun 09 19:37:39 2010 -0700
@@ -78,11 +78,14 @@ static int vmx_domain_initialise(struct 
 {
     int rc;
 
-    d->arch.hvm_domain.vmx.ept_control.etmt = EPT_DEFAULT_MT;
-    d->arch.hvm_domain.vmx.ept_control.gaw  = EPT_DEFAULT_GAW;
+    /* Set the memory type used when accessing EPT paging structures. */
+    d->arch.hvm_domain.vmx.ept_control.ept_mt = EPT_DEFAULT_MT;
+
+    /* set EPT page-walk length, now it's actual walk length - 1, i.e. 3 */
+    d->arch.hvm_domain.vmx.ept_control.ept_wl = 3;
+
     d->arch.hvm_domain.vmx.ept_control.asr  =
         pagetable_get_pfn(p2m_get_pagetable(p2m_get_hostp2m(d)));
-
 
     if ( (rc = vmx_alloc_vlapic_mapping(d)) != 0 )
         return rc;
diff -r b522d6148f44 xen/arch/x86/mm/hap/p2m-ept.c
--- a/xen/arch/x86/mm/hap/p2m-ept.c     Thu Jun 10 08:31:36 2010 +0100
+++ b/xen/arch/x86/mm/hap/p2m-ept.c     Wed Jun 09 19:37:39 2010 -0700
@@ -253,7 +253,7 @@ ept_set_entry(struct domain *d, unsigned
 
     ASSERT(table != NULL);
 
-    for ( i = EPT_DEFAULT_GAW; i > walk_level; i-- )
+    for ( i = ept_get_wl(d); i > walk_level; i-- )
     {
         ret = ept_next_level(d, 0, &table, &gfn_remainder, i * 
EPT_TABLE_ORDER);
         if ( !ret )
@@ -402,7 +402,7 @@ static mfn_t ept_get_entry(struct domain
 
     /* Should check if gfn obeys GAW here. */
 
-    for ( i = EPT_DEFAULT_GAW; i > 0; i-- )
+    for ( i = ept_get_wl(d); i > 0; i-- )
     {
     retry:
         ret = ept_next_level(d, 1, &table, &gfn_remainder,
@@ -492,7 +492,7 @@ static ept_entry_t ept_get_entry_content
     if ( gfn > d->arch.p2m->max_mapped_pfn )
         goto out;
 
-    for ( i = EPT_DEFAULT_GAW; i > 0; i-- )
+    for ( i = ept_get_wl(d); i > 0; i-- )
     {
         ret = ept_next_level(d, 1, &table, &gfn_remainder,
                              i * EPT_TABLE_ORDER);
@@ -531,7 +531,7 @@ void ept_walk_table(struct domain *d, un
         goto out;
     }
 
-    for ( i = EPT_DEFAULT_GAW; i >= 0; i-- )
+    for ( i = ept_get_wl(d); i >= 0; i-- )
     {
         ept_entry_t *ept_entry, *next;
         u32 index;
@@ -658,8 +658,6 @@ static void ept_change_entry_type_global
     if ( pagetable_get_pfn(p2m_get_pagetable(p2m_get_hostp2m(d))) == 0 )
         return;
 
-    BUG_ON(EPT_DEFAULT_GAW != 3);
-
     l4e = 
map_domain_page(mfn_x(pagetable_get_mfn(p2m_get_pagetable(p2m_get_hostp2m(d)))));
     for (i4 = 0; i4 < EPT_PAGETABLE_ENTRIES; i4++ )
     {
@@ -751,7 +749,7 @@ static void ept_dump_p2m_table(unsigned 
     int order;
     int i;
     int is_pod;
-    int ret;
+    int ret = 0;
     unsigned long index;
     unsigned long gfn, gfn_remainder;
     unsigned long record_counter = 0;
@@ -772,7 +770,7 @@ static void ept_dump_p2m_table(unsigned 
             table =
                 
map_domain_page(mfn_x(pagetable_get_mfn(p2m_get_pagetable(p2m))));
 
-            for ( i = EPT_DEFAULT_GAW; i > 0; i-- )
+            for ( i = ept_get_wl(d); i > 0; i-- )
             {
                 ret = ept_next_level(d, 1, &table, &gfn_remainder,
                                      i * EPT_TABLE_ORDER);
diff -r b522d6148f44 xen/include/asm-x86/hvm/vmx/vmcs.h
--- a/xen/include/asm-x86/hvm/vmx/vmcs.h        Thu Jun 10 08:31:36 2010 +0100
+++ b/xen/include/asm-x86/hvm/vmx/vmcs.h        Wed Jun 09 19:37:39 2010 -0700
@@ -55,22 +55,24 @@ struct vmx_msr_state {
     unsigned long msrs[VMX_MSR_COUNT];
 };
 
-#define EPT_DEFAULT_MT      6
-#define EPT_DEFAULT_GAW     3
+#define EPT_DEFAULT_MT      MTRR_TYPE_WRBACK
 
 struct vmx_domain {
     unsigned long apic_access_mfn;
     union {
         struct {
-            u64 etmt :3,
-                gaw  :3,
-                rsvd :6,
-                asr  :52;
+            u64 ept_mt :3,
+                ept_wl :3,
+                rsvd   :6,
+                asr    :52;
         };
         u64 eptp;
     } ept_control;
     cpumask_t ept_synced;
 };
+
+#define ept_get_wl(d)  \
+    ((d)->arch.hvm_domain.vmx.ept_control.ept_wl)
 
 struct arch_vmx_struct {
     /* Virtual address of VMCS. */
@@ -174,8 +176,9 @@ extern u32 vmx_secondary_exec_control;
 
 extern bool_t cpu_has_vmx_ins_outs_instr_info;
 
-extern u64 vmx_ept_vpid_cap;
-
+#define VMX_EPT_WALK_LENGTH_4_SUPPORTED         0x00000040
+#define VMX_EPT_MEMORY_TYPE_UC                  0x00000100
+#define VMX_EPT_MEMORY_TYPE_WB                  0x00004000
 #define VMX_EPT_SUPERPAGE_2MB                   0x00010000
 #define VMX_EPT_SUPERPAGE_1GB                   0x00020000
 
@@ -193,10 +196,6 @@ extern u64 vmx_ept_vpid_cap;
     (vmx_cpu_based_exec_control & CPU_BASED_ACTIVATE_SECONDARY_CONTROLS)
 #define cpu_has_vmx_ept \
     (vmx_secondary_exec_control & SECONDARY_EXEC_ENABLE_EPT)
-#define cpu_has_vmx_ept_1gb \
-    (vmx_ept_vpid_cap & VMX_EPT_SUPERPAGE_1GB)
-#define cpu_has_vmx_ept_2mb \
-    (vmx_ept_vpid_cap & VMX_EPT_SUPERPAGE_2MB)
 #define cpu_has_vmx_vpid \
     (vmx_secondary_exec_control & SECONDARY_EXEC_ENABLE_VPID)
 #define cpu_has_monitor_trap_flag \
diff -r b522d6148f44 xen/include/asm-x86/hvm/vmx/vmx.h
--- a/xen/include/asm-x86/hvm/vmx/vmx.h Thu Jun 10 08:31:36 2010 +0100
+++ b/xen/include/asm-x86/hvm/vmx/vmx.h Wed Jun 09 19:37:39 2010 -0700
@@ -183,6 +183,20 @@ void vmx_update_debug_state(struct vcpu 
 #define MODRM_EAX_06    ".byte 0x30\n" /* [EAX], with reg/opcode: /6 */
 #define MODRM_EAX_07    ".byte 0x38\n" /* [EAX], with reg/opcode: /7 */
 #define MODRM_EAX_ECX   ".byte 0xc1\n" /* EAX, ECX */
+
+extern u64 vmx_ept_vpid_cap;
+
+#define cpu_has_vmx_ept_wl4_supported           \
+    (vmx_ept_vpid_cap & VMX_EPT_WALK_LENGTH_4_SUPPORTED)
+#define cpu_has_vmx_ept_mt_uc                   \
+    (vmx_ept_vpid_cap & VMX_EPT_MEMORY_TYPE_UC)
+#define cpu_has_vmx_ept_mt_wb                   \
+    (vmx_ept_vpid_cap & VMX_EPT_MEMORY_TYPE_WB)
+#define cpu_has_vmx_ept_1gb                     \
+    (vmx_ept_vpid_cap & VMX_EPT_SUPERPAGE_1GB)
+#define cpu_has_vmx_ept_2mb                     \
+    (vmx_ept_vpid_cap & VMX_EPT_SUPERPAGE_2MB)
+
 
 static inline void __vmptrld(u64 addr)
 {

Attachment: ept_mt_wl_check.patch
Description: ept_mt_wl_check.patch

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