Keir, any comments to this patch?
Thanks
Yunhong Jiang
>-----Original Message-----
>From: Jiang, Yunhong
>Sent: Monday, February 01, 2010 5:18 PM
>To: Jiang, Yunhong; Keir Fraser; Tim.Deegan@xxxxxxxxxx
>Cc: xen-devel@xxxxxxxxxxxxxxxxxxx
>Subject: RE: [PATCH] Don't enable irq for machine check vmexit
>
>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
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