[Xen-devel] [PATCH v2 07/12] x86/vmce: emulate MSR_IA32_MCG_EXT_CTL

[Haozhong Zhang <haozhong.zhang@xxxxxxxxx>]

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@xxxxxxxxx>
---
Cc: Jan Beulich <jbeulich@xxxxxxxx>
Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>

Changes in v2:
 * Remove stray blank in the code comment.
 * Move the success branch to the front when handling MSR_IA32_MCG_EXT_CTL.
 * Move lmce_enabled before bank[] in struct vmce.
 * Increase XEN_DOMCTL_INTERFACE_VERSION by 1.
---
 xen/arch/x86/cpu/mcheck/vmce.c         | 34 +++++++++++++++++++++++++++++++++-
 xen/include/asm-x86/mce.h              |  1 +
 xen/include/public/arch-x86/hvm/save.h |  2 ++
 xen/include/public/domctl.h            |  2 +-
 4 files changed, 37 insertions(+), 2 deletions(-)

diff --git a/xen/arch/x86/cpu/mcheck/vmce.c b/xen/arch/x86/cpu/mcheck/vmce.c
index 058bb91..c396d07 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.lmce_enabled = ctxt->lmce_enabled;
 
     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.lmce_enabled ? MCG_EXT_CTL_LMCE_EN : 0;
+            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.lmce_enabled = (val & MCG_EXT_CTL_LMCE_EN);
+        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,
+            .lmce_enabled = v->arch.vmce.lmce_enabled,
         };
 
         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 6b827ef..dee66b3 100644
--- a/xen/include/asm-x86/mce.h
+++ b/xen/include/asm-x86/mce.h
@@ -28,6 +28,7 @@ struct vmce {
     uint64_t mcg_cap;
     uint64_t mcg_status;
     spinlock_t lock;
+    bool lmce_enabled; /* guest MSR_IA32_MCG_EXT_CTL.LMCE_EN (bit 0) */
     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 419a3b2..76374fc 100644
--- a/xen/include/public/arch-x86/hvm/save.h
+++ b/xen/include/public/arch-x86/hvm/save.h
@@ -599,6 +599,8 @@ struct hvm_vmce_vcpu {
     uint64_t caps;
     uint64_t mci_ctl2_bank0;
     uint64_t mci_ctl2_bank1;
+    uint8_t  lmce_enabled;
+    uint8_t  pad[7];
 };
 
 DECLARE_HVM_SAVE_TYPE(VMCE_VCPU, 18, struct hvm_vmce_vcpu);
diff --git a/xen/include/public/domctl.h b/xen/include/public/domctl.h
index 85cbb7c..2842589 100644
--- a/xen/include/public/domctl.h
+++ b/xen/include/public/domctl.h
@@ -37,7 +37,7 @@
 #include "hvm/save.h"
 #include "memory.h"
 
-#define XEN_DOMCTL_INTERFACE_VERSION 0x0000000c
+#define XEN_DOMCTL_INTERFACE_VERSION 0x0000000d
 
 /*
  * NB. xen_domctl.domain is an IN/OUT parameter for this operation.
-- 
2.10.1


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