[PATCH v3 4/9] x86/vmce: emulate MSR_IA32_MCG_EXT_CTL

[Haozhong Zhang <haozhong.zhang@intel.com>]

If MCG_LMCE_P is present in guest MSR_IA32_MCG_CAP, then allow guest
to read/write MSR_IA32_MCG_EXT_CTL.

Signed-off-by: Haozhong Zhang <haozhong.zhang@intel.com>
---
Cc: Jan Beulich <jbeulich@suse.com>
Cc: Andrew Cooper <andrew.cooper3@citrix.com>

Changes in v3:
 * Replace lmce_enabled in struct hvm_vmce_vcpu and struct vmce by
   mcg_ext_ctl.
 * Drop the change to XEN_DOMCTL_INTERFACE_VERSION, as it was changed
   by c/s 33e5c325 recently.
---
 xen/arch/x86/cpu/mcheck/vmce.c         | 34 +++++++++++++++++++++++++++++++++-
 xen/include/asm-x86/mce.h              |  1 +
 xen/include/public/arch-x86/hvm/save.h |  1 +
 3 files changed, 35 insertions(+), 1 deletion(-)

diff --git a/xen/arch/x86/cpu/mcheck/vmce.c b/xen/arch/x86/cpu/mcheck/vmce.c
index d591d31..2106706 100644
--- a/xen/arch/x86/cpu/mcheck/vmce.c
+++ b/xen/arch/x86/cpu/mcheck/vmce.c
@@ -90,6 +90,7 @@ int vmce_restore_vcpu(struct vcpu *v, const struct hvm_vmce_vcpu *ctxt)
     v->arch.vmce.mcg_cap = ctxt->caps;
     v->arch.vmce.bank[0].mci_ctl2 = ctxt->mci_ctl2_bank0;
     v->arch.vmce.bank[1].mci_ctl2 = ctxt->mci_ctl2_bank1;
+    v->arch.vmce.mcg_ext_ctl = ctxt->mcg_ext_ctl;
 
     return 0;
 }
@@ -199,6 +200,26 @@ int vmce_rdmsr(uint32_t msr, uint64_t *val)
         mce_printk(MCE_VERBOSE, "MCE: %pv: rd MCG_CTL %#"PRIx64"\n", cur, *val);
         break;
 
+    case MSR_IA32_MCG_EXT_CTL:
+        /*
+         * If MCG_LMCE_P is present in guest MSR_IA32_MCG_CAP, the LMCE and LOCK
+         * bits are always set in guest MSR_IA32_FEATURE_CONTROL by Xen, so it
+         * does not need to check them here.
+         */
+        if ( cur->arch.vmce.mcg_cap & MCG_LMCE_P )
+        {
+            *val = cur->arch.vmce.mcg_ext_ctl;
+            mce_printk(MCE_VERBOSE, "MCE: %pv: rd MCG_EXT_CTL %#"PRIx64"\n",
+                       cur, *val);
+        }
+        else
+        {
+            ret = -1;
+            mce_printk(MCE_VERBOSE, "MCE: %pv: rd MCG_EXT_CTL, not supported\n",
+                       cur);
+        }
+        break;
+
     default:
         ret = mce_bank_msr(cur, msr) ? bank_mce_rdmsr(cur, msr, val) : 0;
         break;
@@ -308,6 +329,16 @@ int vmce_wrmsr(uint32_t msr, uint64_t val)
         mce_printk(MCE_VERBOSE, "MCE: %pv: MCG_CAP is r/o\n", cur);
         break;
 
+    case MSR_IA32_MCG_EXT_CTL:
+        if ( (cur->arch.vmce.mcg_cap & MCG_LMCE_P) &&
+             !(val & ~MCG_EXT_CTL_LMCE_EN) )
+            cur->arch.vmce.mcg_ext_ctl = val;
+        else
+            ret = -1;
+        mce_printk(MCE_VERBOSE, "MCE: %pv: wr MCG_EXT_CTL %"PRIx64"%s\n",
+                   cur, val, (ret == -1) ? ", not supported" : "");
+        break;
+
     default:
         ret = mce_bank_msr(cur, msr) ? bank_mce_wrmsr(cur, msr, val) : 0;
         break;
@@ -326,7 +357,8 @@ static int vmce_save_vcpu_ctxt(struct domain *d, hvm_domain_context_t *h)
         struct hvm_vmce_vcpu ctxt = {
             .caps = v->arch.vmce.mcg_cap,
             .mci_ctl2_bank0 = v->arch.vmce.bank[0].mci_ctl2,
-            .mci_ctl2_bank1 = v->arch.vmce.bank[1].mci_ctl2
+            .mci_ctl2_bank1 = v->arch.vmce.bank[1].mci_ctl2,
+            .mcg_ext_ctl = v->arch.vmce.mcg_ext_ctl,
         };
 
         err = hvm_save_entry(VMCE_VCPU, v->vcpu_id, h, &ctxt);
diff --git a/xen/include/asm-x86/mce.h b/xen/include/asm-x86/mce.h
index 56ad1f9..35f9962 100644
--- a/xen/include/asm-x86/mce.h
+++ b/xen/include/asm-x86/mce.h
@@ -27,6 +27,7 @@ struct vmce_bank {
 struct vmce {
     uint64_t mcg_cap;
     uint64_t mcg_status;
+    uint64_t mcg_ext_ctl;
     spinlock_t lock;
     struct vmce_bank bank[GUEST_MC_BANK_NUM];
 };
diff --git a/xen/include/public/arch-x86/hvm/save.h b/xen/include/public/arch-x86/hvm/save.h
index 66ae1a2..ec581cc 100644
--- a/xen/include/public/arch-x86/hvm/save.h
+++ b/xen/include/public/arch-x86/hvm/save.h
@@ -599,6 +599,7 @@ struct hvm_vmce_vcpu {
     uint64_t caps;
     uint64_t mci_ctl2_bank0;
     uint64_t mci_ctl2_bank1;
+    uint64_t mcg_ext_ctl;
 };
 
 DECLARE_HVM_SAVE_TYPE(VMCE_VCPU, 18, struct hvm_vmce_vcpu);
-- 
2.10.1


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