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

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

Sorry forgot the patch.

--jyh

diff -r 857d7b2dd8c7 xen/arch/x86/hvm/vmx/vmx.c
--- a/xen/arch/x86/hvm/vmx/vmx.c        Fri Jan 29 08:59:46 2010 +0000
+++ b/xen/arch/x86/hvm/vmx/vmx.c        Sun Jan 31 18:40:34 2010 +0800
@@ -2153,6 +2153,7 @@ static void vmx_failed_vmentry(unsigned 
         printk("caused by machine check.\n");
         HVMTRACE_0D(MCE);
         do_machine_check(regs);
+        local_irq_enable();
         break;
     default:
         printk("reason not known yet!");
@@ -2243,6 +2244,23 @@ 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)
@@ -2273,7 +2291,8 @@ asmlinkage void vmx_vmexit_handler(struc
         vmx_do_extint(regs);
 
     /* Now enable interrupts so it's safe to take locks. */
-    local_irq_enable();
+    if ( !(vmx_mce_exit(exit_reason)) )
+        local_irq_enable();
 
     if ( unlikely(exit_reason & VMX_EXIT_REASONS_FAILED_VMENTRY) )
         return vmx_failed_vmentry(exit_reason, regs);
@@ -2433,6 +2452,7 @@ asmlinkage void vmx_vmexit_handler(struc
         case TRAP_machine_check:
             HVMTRACE_0D(MCE);
             do_machine_check(regs);
+            local_irq_enable();
             break;
         case TRAP_invalid_op:
             vmx_vmexit_ud_intercept(regs);



>-----Original Message-----
>From: Jiang, Yunhong
>Sent: Monday, February 01, 2010 4:48 PM
>To: Keir Fraser; Tim.Deegan@xxxxxxxxxx
>Cc: xen-devel@xxxxxxxxxxxxxxxxxxx
>Subject: [PATCH] Don't enable irq for machine check vmexit
>
>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>
>
>This is in hotspot code path, I try to use unlikely, hope to reduce the 
>performance
>impact
>
>Thanks
>Yunhong Jiang

Attachment: hvm_vmexit.patch
Description: hvm_vmexit.patch

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