[Xen-devel] RE: [PATCH] Don't enable irq for machine check vmexit

["Jiang, Yunhong" <yunhong.jiang@xxxxxxxxx>]

Keir/Tim, here is attached patch. Please have a look onit.

Thanks
Yunhong Jiang

# HG changeset patch
# User Yunhong Jiang <yunhong.jiang@xxxxxxxxx>
# Date 1265363638 -28800
# Node ID 01b2ce3f2cc95dd2e9c6defe2cee8a892e867187
# Parent  7b751b0e6f1bc7485b0718e634ed7cb9ce9ab68c
We should not enable irq for machine check VMExit

In changeset 18658:824892134573, IRQ is enabled during VMExit except external 
interrupt. The exception should apply for machine check also, because :
a) The mce_logout_lock should be held in irq_disabled context.
b) The machine check event should be handled as quickly as possible, enable irq 
will increase the period greatly.

Signed-off-by: Jiang, Yunhong <yunhong.jiang@xxxxxxxxx>

diff -r 7b751b0e6f1b -r 01b2ce3f2cc9 xen/arch/x86/hvm/vmx/vmx.c
--- a/xen/arch/x86/hvm/vmx/vmx.c        Thu Feb 04 19:40:19 2010 +0000
+++ b/xen/arch/x86/hvm/vmx/vmx.c        Fri Feb 05 17:53:58 2010 +0800
@@ -2168,7 +2168,7 @@ static void vmx_failed_vmentry(unsigned 
     case EXIT_REASON_MCE_DURING_VMENTRY:
         printk("caused by machine check.\n");
         HVMTRACE_0D(MCE);
-        do_machine_check(regs);
+        /* Handled already */
         break;
     default:
         printk("reason not known yet!");
@@ -2259,6 +2259,23 @@ err:
 err:
     vmx_inject_hw_exception(TRAP_gp_fault, 0);
     return -1;
+}
+
+int vmx_mce_exit(int exit_reason)
+{
+    if ( unlikely(exit_reason & VMX_EXIT_REASONS_FAILED_VMENTRY &&
+        (uint16_t)exit_reason == EXIT_REASON_MCE_DURING_VMENTRY) )
+            return 1;
+    else if (unlikely(exit_reason == EXIT_REASON_EXCEPTION_NMI))
+    {
+        uint32_t vector;
+
+        vector = __vmread(VM_EXIT_INTR_INFO) & INTR_INFO_VECTOR_MASK;
+        if (vector == TRAP_machine_check)
+            return 1;
+    }
+
+    return 0;
 }
 
 asmlinkage void vmx_vmexit_handler(struct cpu_user_regs *regs)
@@ -2287,6 +2304,9 @@ asmlinkage void vmx_vmexit_handler(struc
     /* Handle the interrupt we missed before allowing any more in. */
     if ( exit_reason == EXIT_REASON_EXTERNAL_INTERRUPT )
         vmx_do_extint(regs);
+
+    if ( vmx_mce_exit(exit_reason) )
+        do_machine_check(regs);
 
     /* Now enable interrupts so it's safe to take locks. */
     local_irq_enable();
@@ -2447,8 +2467,9 @@ asmlinkage void vmx_vmexit_handler(struc
             self_nmi(); /* Real NMI, vector 2: normal processing. */
             break;
         case TRAP_machine_check:
+            dprintk(XENLOG_INFO, "VMexit for machine check\n");
             HVMTRACE_0D(MCE);
-            do_machine_check(regs);
+            /* Handled already */
             break;
         case TRAP_invalid_op:
             vmx_vmexit_ud_intercept(regs);

Attachment: vmexit_mca_irq.patch
Description: vmexit_mca_irq.patch

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