[Xen-devel] [PATCH RESEND 2/4] x86: MPX IA32_BNDCFGS msr handle

["Jan Beulich" <JBeulich@xxxxxxxx>]

When MPX supported, a new guest-state field for IA32_BNDCFGS
is added to the VMCS. In addition, two new controls are added:
 - a VM-exit control called "clear BNDCFGS"
 - a VM-entry control called "load BNDCFGS."
VM exits always save IA32_BNDCFGS into BNDCFGS field of VMCS.

Signed-off-by: Xudong Hao <xudong.hao@xxxxxxxxx>
Reviewed-by: Liu Jinsong <jinsong.liu@xxxxxxxxx>

Unlikely, but in case VMX support is not available, not expose
MPX to hvm guest.

Suggested-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
Suggested-by: Jan Beulich <jbeulich@xxxxxxxx>
Signed-off-by: Liu Jinsong <jinsong.liu@xxxxxxxxx>
Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>

--- a/xen/arch/x86/hvm/hvm.c
+++ b/xen/arch/x86/hvm/hvm.c
@@ -2909,6 +2909,12 @@ void hvm_cpuid(unsigned int input, unsig
         if ( (count == 0) && !cpu_has_smep )
             *ebx &= ~cpufeat_mask(X86_FEATURE_SMEP);
 
+        /* Don't expose MPX to hvm when VMX support is not available */
+        if ( (count == 0) &&
+             (!(vmx_vmexit_control & VM_EXIT_CLEAR_BNDCFGS) ||
+              !(vmx_vmentry_control & VM_ENTRY_LOAD_BNDCFGS)) )
+            *ebx &= ~cpufeat_mask(X86_FEATURE_MPX);
+
         /* Don't expose INVPCID to non-hap hvm. */
         if ( (count == 0) && !hap_enabled(d) )
             *ebx &= ~cpufeat_mask(X86_FEATURE_INVPCID);
--- a/xen/arch/x86/hvm/vmx/vmcs.c
+++ b/xen/arch/x86/hvm/vmx/vmcs.c
@@ -269,7 +269,8 @@ static int vmx_init_vmcs_config(void)
     }
 
     min = VM_EXIT_ACK_INTR_ON_EXIT;
-    opt = VM_EXIT_SAVE_GUEST_PAT | VM_EXIT_LOAD_HOST_PAT;
+    opt = VM_EXIT_SAVE_GUEST_PAT | VM_EXIT_LOAD_HOST_PAT |
+          VM_EXIT_CLEAR_BNDCFGS;
     min |= VM_EXIT_IA32E_MODE;
     _vmx_vmexit_control = adjust_vmx_controls(
         "VMExit Control", min, opt, MSR_IA32_VMX_EXIT_CTLS, &mismatch);
@@ -283,7 +284,7 @@ static int vmx_init_vmcs_config(void)
         _vmx_pin_based_exec_control  &= ~ PIN_BASED_POSTED_INTERRUPT;
 
     min = 0;
-    opt = VM_ENTRY_LOAD_GUEST_PAT;
+    opt = VM_ENTRY_LOAD_GUEST_PAT | VM_ENTRY_LOAD_BNDCFGS;
     _vmx_vmentry_control = adjust_vmx_controls(
         "VMEntry Control", min, opt, MSR_IA32_VMX_ENTRY_CTLS, &mismatch);
 
@@ -955,6 +956,9 @@ static int construct_vmcs(struct vcpu *v
         vmx_disable_intercept_for_msr(v, MSR_IA32_SYSENTER_EIP, MSR_TYPE_R | 
MSR_TYPE_W);
         if ( paging_mode_hap(d) && (!iommu_enabled || iommu_snoop) )
             vmx_disable_intercept_for_msr(v, MSR_IA32_CR_PAT, MSR_TYPE_R | 
MSR_TYPE_W);
+        if ( (vmexit_ctl & VM_EXIT_CLEAR_BNDCFGS) &&
+             (vmentry_ctl & VM_ENTRY_LOAD_BNDCFGS) )
+            vmx_disable_intercept_for_msr(v, MSR_IA32_BNDCFGS, MSR_TYPE_R | 
MSR_TYPE_W);
     }
 
     /* I/O access bitmap. */
--- a/xen/include/asm-x86/cpufeature.h
+++ b/xen/include/asm-x86/cpufeature.h
@@ -148,6 +148,7 @@
 #define X86_FEATURE_INVPCID    (7*32+10) /* Invalidate Process Context ID */
 #define X86_FEATURE_RTM        (7*32+11) /* Restricted Transactional Memory */
 #define X86_FEATURE_NO_FPU_SEL         (7*32+13) /* FPU CS/DS stored as zero */
+#define X86_FEATURE_MPX                (7*32+14) /* Memory Protection 
Extensions */
 #define X86_FEATURE_SMAP       (7*32+20) /* Supervisor Mode Access Prevention 
*/
 
 #define cpu_has(c, bit)                test_bit(bit, (c)->x86_capability)
@@ -197,6 +198,7 @@
 #define cpu_has_xsave           boot_cpu_has(X86_FEATURE_XSAVE)
 #define cpu_has_avx             boot_cpu_has(X86_FEATURE_AVX)
 #define cpu_has_lwp             boot_cpu_has(X86_FEATURE_LWP)
+#define cpu_has_mpx             boot_cpu_has(X86_FEATURE_MPX)
 
 #define cpu_has_arch_perfmon    boot_cpu_has(X86_FEATURE_ARCH_PERFMON)
 
--- a/xen/include/asm-x86/hvm/vmx/vmcs.h
+++ b/xen/include/asm-x86/hvm/vmx/vmcs.h
@@ -186,6 +186,7 @@ extern u32 vmx_pin_based_exec_control;
 #define VM_EXIT_SAVE_GUEST_EFER         0x00100000
 #define VM_EXIT_LOAD_HOST_EFER          0x00200000
 #define VM_EXIT_SAVE_PREEMPT_TIMER      0x00400000
+#define VM_EXIT_CLEAR_BNDCFGS           0x00800000
 extern u32 vmx_vmexit_control;
 
 #define VM_ENTRY_IA32E_MODE             0x00000200
@@ -194,6 +195,7 @@ extern u32 vmx_vmexit_control;
 #define VM_ENTRY_LOAD_PERF_GLOBAL_CTRL  0x00002000
 #define VM_ENTRY_LOAD_GUEST_PAT         0x00004000
 #define VM_ENTRY_LOAD_GUEST_EFER        0x00008000
+#define VM_ENTRY_LOAD_BNDCFGS           0x00010000
 extern u32 vmx_vmentry_control;
 
 #define SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES 0x00000001
--- a/xen/include/asm-x86/msr-index.h
+++ b/xen/include/asm-x86/msr-index.h
@@ -56,6 +56,8 @@
 #define MSR_IA32_DS_AREA               0x00000600
 #define MSR_IA32_PERF_CAPABILITIES     0x00000345
 
+#define MSR_IA32_BNDCFGS               0x00000D90
+
 #define MSR_MTRRfix64K_00000           0x00000250
 #define MSR_MTRRfix16K_80000           0x00000258
 #define MSR_MTRRfix16K_A0000           0x00000259

Attachment: x86-MPX.patch
Description: Text document

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