[Xen-devel] [PATCH v4 05/11] x86/vmx: expose LMCE feature via guest MSR_IA32_FEATURE_CONTROL

[Haozhong Zhang <haozhong.zhang@xxxxxxxxx>]

If MCG_LMCE_P is present in guest MSR_IA32_MCG_CAP, then set LMCE and
LOCK bits in guest MSR_IA32_FEATURE_CONTROL. Intel SDM requires those
bits are set before SW can enable LMCE.

Signed-off-by: Haozhong Zhang <haozhong.zhang@xxxxxxxxx>
Reviewed-by: Kevin Tian <kevin.tian@xxxxxxxxx>
Reviewed-by: Jan Beulich <jbeulich@xxxxxxxx>
---
Cc: Jan Beulich <jbeulich@xxxxxxxx>
Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
Cc: Jun Nakajima <jun.nakajima@xxxxxxxxx>
Cc: Kevin Tian <kevin.tian@xxxxxxxxx>
---
 xen/arch/x86/cpu/mcheck/mce_intel.c | 4 ++++
 xen/arch/x86/hvm/vmx/vmx.c          | 9 +++++++++
 xen/arch/x86/hvm/vmx/vvmx.c         | 4 ----
 xen/include/asm-x86/mce.h           | 1 +
 4 files changed, 14 insertions(+), 4 deletions(-)

diff --git a/xen/arch/x86/cpu/mcheck/mce_intel.c 
b/xen/arch/x86/cpu/mcheck/mce_intel.c
index 020b02deff..5cb49ca697 100644
--- a/xen/arch/x86/cpu/mcheck/mce_intel.c
+++ b/xen/arch/x86/cpu/mcheck/mce_intel.c
@@ -946,3 +946,7 @@ int vmce_intel_rdmsr(const struct vcpu *v, uint32_t msr, 
uint64_t *val)
     return 1;
 }
 
+bool vmce_has_lmce(const struct vcpu *v)
+{
+    return v->arch.vmce.mcg_cap & MCG_LMCE_P;
+}
diff --git a/xen/arch/x86/hvm/vmx/vmx.c b/xen/arch/x86/hvm/vmx/vmx.c
index c53b24955a..6a193ef9d4 100644
--- a/xen/arch/x86/hvm/vmx/vmx.c
+++ b/xen/arch/x86/hvm/vmx/vmx.c
@@ -55,6 +55,7 @@
 #include <asm/hvm/nestedhvm.h>
 #include <asm/altp2m.h>
 #include <asm/event.h>
+#include <asm/mce.h>
 #include <asm/monitor.h>
 #include <public/arch-x86/cpuid.h>
 
@@ -2856,6 +2857,8 @@ static int is_last_branch_msr(u32 ecx)
 
 static int vmx_msr_read_intercept(unsigned int msr, uint64_t *msr_content)
 {
+    const struct vcpu *curr = current;
+
     HVM_DBG_LOG(DBG_LEVEL_MSR, "ecx=%#x", msr);
 
     switch ( msr )
@@ -2873,6 +2876,12 @@ static int vmx_msr_read_intercept(unsigned int msr, 
uint64_t *msr_content)
         __vmread(GUEST_IA32_DEBUGCTL, msr_content);
         break;
     case MSR_IA32_FEATURE_CONTROL:
+        *msr_content = IA32_FEATURE_CONTROL_LOCK;
+        if ( vmce_has_lmce(curr) )
+            *msr_content |= IA32_FEATURE_CONTROL_LMCE_ON;
+        if ( nestedhvm_enabled(curr->domain) )
+            *msr_content |= IA32_FEATURE_CONTROL_ENABLE_VMXON_OUTSIDE_SMX;
+        break;
     case MSR_IA32_VMX_BASIC...MSR_IA32_VMX_VMFUNC:
         if ( !nvmx_msr_read_intercept(msr, msr_content) )
             goto gp_fault;
diff --git a/xen/arch/x86/hvm/vmx/vvmx.c b/xen/arch/x86/hvm/vmx/vvmx.c
index 3560faec6d..f451935ea6 100644
--- a/xen/arch/x86/hvm/vmx/vvmx.c
+++ b/xen/arch/x86/hvm/vmx/vvmx.c
@@ -2084,10 +2084,6 @@ int nvmx_msr_read_intercept(unsigned int msr, u64 
*msr_content)
         data = gen_vmx_msr(data, VMX_ENTRY_CTLS_DEFAULT1, host_data);
         break;
 
-    case MSR_IA32_FEATURE_CONTROL:
-        data = IA32_FEATURE_CONTROL_LOCK |
-               IA32_FEATURE_CONTROL_ENABLE_VMXON_OUTSIDE_SMX;
-        break;
     case MSR_IA32_VMX_VMCS_ENUM:
         /* The max index of VVMCS encoding is 0x1f. */
         data = 0x1f << 1;
diff --git a/xen/include/asm-x86/mce.h b/xen/include/asm-x86/mce.h
index 549bef3ebe..56ad1f92dd 100644
--- a/xen/include/asm-x86/mce.h
+++ b/xen/include/asm-x86/mce.h
@@ -36,6 +36,7 @@ extern void vmce_init_vcpu(struct vcpu *);
 extern int vmce_restore_vcpu(struct vcpu *, const struct hvm_vmce_vcpu *);
 extern int vmce_wrmsr(uint32_t msr, uint64_t val);
 extern int vmce_rdmsr(uint32_t msr, uint64_t *val);
+extern bool vmce_has_lmce(const struct vcpu *v);
 
 extern unsigned int nr_mce_banks;
 
-- 
2.11.0


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