[Xen-devel] [PATCH 2/2] Xen: Fix VMCS setting for x2APIC mode guest while enabling APICV

["Li, Jiongxi" <jiongxi.li@xxxxxxxxx>]

The "APIC-register virtualization" and "virtual-interrupt deliver"
VM-execution control has no effect on the behavior of RDMSR/WRMSR if
the "virtualize x2APIC mode" VM-execution control is 0.
When guest uses x2APIC mode, we should enable "virtualize x2APIC mode"
for APICV first.

Signed-off-by: Jiongxi Li <jiongxi.li@xxxxxxxxx>

diff --git a/xen/arch/x86/hvm/vmx/vmcs.c b/xen/arch/x86/hvm/vmx/vmcs.c
index de22e03..f6d69d6 100644
--- a/xen/arch/x86/hvm/vmx/vmcs.c
+++ b/xen/arch/x86/hvm/vmx/vmcs.c
@@ -190,7 +190,8 @@ static int vmx_init_vmcs_config(void)
          */
         if ( _vmx_cpu_based_exec_control & CPU_BASED_TPR_SHADOW )
             opt |= SECONDARY_EXEC_APIC_REGISTER_VIRT |
-                   SECONDARY_EXEC_VIRTUAL_INTR_DELIVERY;
+                   SECONDARY_EXEC_VIRTUAL_INTR_DELIVERY |
+                   SECONDARY_EXEC_VIRTUALIZE_X2APIC_MODE;
 
 
         _vmx_secondary_exec_control = adjust_vmx_controls(
@@ -673,6 +674,36 @@ void vmx_disable_intercept_for_msr(struct vcpu *v, u32 
msr, int type)
     }
 }
 
+void vmx_enable_intercept_for_msr(struct vcpu *v, u32 msr, int type)
+{
+    unsigned long *msr_bitmap = v->arch.hvm_vmx.msr_bitmap;
+
+    /* VMX MSR bitmap supported? */
+    if ( msr_bitmap == NULL )
+        return;
+
+    /*
+     * See Intel PRM Vol. 3, 20.6.9 (MSR-Bitmap Address). Early manuals
+     * have the write-low and read-high bitmap offsets the wrong way round.
+     * We can control MSRs 0x00000000-0x00001fff and 0xc0000000-0xc0001fff.
+     */
+    if ( msr <= 0x1fff )
+    {
+        if (type & MSR_TYPE_R)
+            __set_bit(msr, msr_bitmap + 0x000/BYTES_PER_LONG); /* read-low */
+        if (type & MSR_TYPE_W)
+            __set_bit(msr, msr_bitmap + 0x800/BYTES_PER_LONG); /* write-low */
+    }
+    else if ( (msr >= 0xc0000000) && (msr <= 0xc0001fff) )
+    {
+        msr &= 0x1fff;
+        if (type & MSR_TYPE_R)
+            __set_bit(msr, msr_bitmap + 0x400/BYTES_PER_LONG); /* read-high */
+        if (type & MSR_TYPE_W)
+            __set_bit(msr, msr_bitmap + 0xc00/BYTES_PER_LONG); /* write-high */
+    }
+}
+
 /*
  * access_type: read == 0, write == 1
  */
@@ -764,6 +795,9 @@ static int construct_vmcs(struct vcpu *v)
         vmentry_ctl &= ~VM_ENTRY_LOAD_GUEST_PAT;
     }
 
+    /* Disable Virtualize x2APIC mode by default. */
+    v->arch.hvm_vmx.secondary_exec_control &= 
~SECONDARY_EXEC_VIRTUALIZE_X2APIC_MODE;
+
     /* Do not enable Monitor Trap Flag unless start single step debug */
     v->arch.hvm_vmx.exec_control &= ~CPU_BASED_MONITOR_TRAP_FLAG;
 
@@ -800,18 +834,6 @@ static int construct_vmcs(struct vcpu *v)
         vmx_disable_intercept_for_msr(v, MSR_IA32_SYSENTER_EIP, MSR_TYPE_R | 
MSR_TYPE_W);
         if ( cpu_has_vmx_pat && paging_mode_hap(d) )
             vmx_disable_intercept_for_msr(v, MSR_IA32_CR_PAT, MSR_TYPE_R | 
MSR_TYPE_W);
-        if ( cpu_has_vmx_apic_reg_virt )
-        {
-            int msr;
-            for (msr = MSR_IA32_APICBASE_MSR; msr <= MSR_IA32_APICBASE_MSR + 
0xff; msr++)
-                vmx_disable_intercept_for_msr(v, msr, MSR_TYPE_R);
-        }
-        if ( cpu_has_vmx_virtual_intr_delivery )
-        {
-            vmx_disable_intercept_for_msr(v, MSR_IA32_APICTPR_MSR, MSR_TYPE_W);
-            vmx_disable_intercept_for_msr(v, MSR_IA32_APICEOI_MSR, MSR_TYPE_W);
-            vmx_disable_intercept_for_msr(v, MSR_IA32_APICSELF_MSR, 
MSR_TYPE_W);
-        }
     }
 
     /* I/O access bitmap. */
diff --git a/xen/arch/x86/hvm/vmx/vmx.c b/xen/arch/x86/hvm/vmx/vmx.c
index 2949782..e0977b8 100644
--- a/xen/arch/x86/hvm/vmx/vmx.c
+++ b/xen/arch/x86/hvm/vmx/vmx.c
@@ -1886,18 +1886,54 @@ static void vmx_install_vlapic_mapping(struct vcpu *v)
 
 void vmx_vlapic_msr_changed(struct vcpu *v)
 {
+    int virtualize_x2apic_mode;
     struct vlapic *vlapic = vcpu_vlapic(v);
 
-    if ( !cpu_has_vmx_virtualize_apic_accesses )
+    virtualize_x2apic_mode = ( (cpu_has_vmx_apic_reg_virt ||
+                                cpu_has_vmx_virtual_intr_delivery) &&
+                               cpu_has_vmx_virtualize_x2apic_mode );
+
+    if ( !cpu_has_vmx_virtualize_apic_accesses &&
+         !virtualize_x2apic_mode )
         return;
 
     vmx_vmcs_enter(v);
     v->arch.hvm_vmx.secondary_exec_control &=
-        ~SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES;
+        ~(SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES |
+          SECONDARY_EXEC_VIRTUALIZE_X2APIC_MODE);
     if ( !vlapic_hw_disabled(vlapic) &&
          (vlapic_base_address(vlapic) == APIC_DEFAULT_PHYS_BASE) )
-        v->arch.hvm_vmx.secondary_exec_control |=
-            SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES;
+    {
+        if ( virtualize_x2apic_mode &&
+             vlapic_x2apic_mode(vlapic) )
+        {
+            v->arch.hvm_vmx.secondary_exec_control |=
+                SECONDARY_EXEC_VIRTUALIZE_X2APIC_MODE;
+            if ( cpu_has_vmx_apic_reg_virt )
+            {
+                for (int msr = MSR_IA32_APICBASE_MSR; msr <= 
MSR_IA32_APICBASE_MSR + 0xff; msr++)
+                    vmx_disable_intercept_for_msr(v, msr, MSR_TYPE_R);
+            }
+            if ( cpu_has_vmx_virtual_intr_delivery )
+            {
+                vmx_disable_intercept_for_msr(v, MSR_IA32_APICTPR_MSR, 
MSR_TYPE_W);
+                vmx_disable_intercept_for_msr(v, MSR_IA32_APICEOI_MSR, 
MSR_TYPE_W);
+                vmx_disable_intercept_for_msr(v, MSR_IA32_APICSELF_MSR, 
MSR_TYPE_W);
+            }
+        }
+        else
+        {
+            v->arch.hvm_vmx.secondary_exec_control |=
+                SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES;
+            for (int msr = MSR_IA32_APICBASE_MSR; msr <= MSR_IA32_APICBASE_MSR 
+ 0xff; msr++)
+                vmx_enable_intercept_for_msr(v, msr, MSR_TYPE_R);
+
+            vmx_enable_intercept_for_msr(v, MSR_IA32_APICTPR_MSR, MSR_TYPE_W);
+            vmx_enable_intercept_for_msr(v, MSR_IA32_APICEOI_MSR, MSR_TYPE_W);
+            vmx_enable_intercept_for_msr(v, MSR_IA32_APICSELF_MSR, MSR_TYPE_W);
+
+        }
+    }
     vmx_update_secondary_exec_control(v);
     vmx_vmcs_exit(v);
 }
diff --git a/xen/include/asm-x86/hvm/vmx/vmcs.h 
b/xen/include/asm-x86/hvm/vmx/vmcs.h
index 51df81e..a909a5a 100644
--- a/xen/include/asm-x86/hvm/vmx/vmcs.h
+++ b/xen/include/asm-x86/hvm/vmx/vmcs.h
@@ -184,6 +184,7 @@ extern u32 vmx_vmentry_control;
 #define SECONDARY_EXEC_ENABLE_EPT               0x00000002
 #define SECONDARY_EXEC_DESCRIPTOR_TABLE_EXITING 0x00000004
 #define SECONDARY_EXEC_ENABLE_RDTSCP            0x00000008
+#define SECONDARY_EXEC_VIRTUALIZE_X2APIC_MODE   0x00000010
 #define SECONDARY_EXEC_ENABLE_VPID              0x00000020
 #define SECONDARY_EXEC_WBINVD_EXITING           0x00000040
 #define SECONDARY_EXEC_UNRESTRICTED_GUEST       0x00000080
@@ -244,6 +245,8 @@ extern bool_t cpu_has_vmx_ins_outs_instr_info;
     (vmx_secondary_exec_control & SECONDARY_EXEC_APIC_REGISTER_VIRT)
 #define cpu_has_vmx_virtual_intr_delivery \
     (vmx_secondary_exec_control & SECONDARY_EXEC_VIRTUAL_INTR_DELIVERY)
+#define cpu_has_vmx_virtualize_x2apic_mode \
+    (vmx_secondary_exec_control & SECONDARY_EXEC_VIRTUALIZE_X2APIC_MODE)
 
 /* GUEST_INTERRUPTIBILITY_INFO flags. */
 #define VMX_INTR_SHADOW_STI             0x00000001
@@ -430,6 +433,7 @@ enum vmcs_field {
 #define MSR_TYPE_R 1
 #define MSR_TYPE_W 2
 void vmx_disable_intercept_for_msr(struct vcpu *v, u32 msr, int type);
+void vmx_enable_intercept_for_msr(struct vcpu *v, u32 msr, int type);
 int vmx_read_guest_msr(u32 msr, u64 *val);
 int vmx_write_guest_msr(u32 msr, u64 val);
 int vmx_add_guest_msr(u32 msr);
-- 
1.7.12.1


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