[PATCH 2/3][PARAVIRT] Make IO delay a NOP

From: Anthony Liguori <aliguori@us.ibm.com>
To: kvm-devel <kvm-devel@lists.sourceforge.net>
Cc: virtualization <virtualization@lists.osdl.org>,
	Ingo Molnar <mingo@elte.hu>
Subject: [PATCH 2/3][PARAVIRT] Make IO delay a NOP
Date: Wed, 30 May 2007 09:53:02 -0500	[thread overview]
Message-ID: <465D8FCE.1000409@us.ibm.com> (raw)
In-Reply-To: <465D8F03.7000201@us.ibm.com>

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Regards,

Anthony Liguori

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Subject: [PATCH][PARAVIRT] Make IO delay a NOP for paravirt guests

No delay is required in between PIO operations under KVM guests so make IO
delay a NOP.  This was originally part of Ingo Molnar's paravirt series.

Signed-off-by: Anthony Liguori <aliguori@us.ibm.com>

Index: kvm/arch/i386/kernel/kvm.c
===================================================================

--- kvm.orig/arch/i386/kernel/kvm.c	2007-05-30 09:30:42.000000000 -0500
+++ kvm/arch/i386/kernel/kvm.c	2007-05-30 09:31:46.000000000 -0500
@@ -28,9 +28,17 @@
 static DEFINE_PER_CPU(struct kvm_vcpu_para_state, para_state);
 extern unsigned char hypercall_addr[4];
 
+/*
+ * No need for any "IO delay" on KVM
+ */
+static void kvm_io_delay(void)
+{
+}
+
 static void kvm_guest_setup(void)
 {
 	paravirt_ops.name = "KVM";
+	paravirt_ops.io_delay = kvm_io_delay;
 	paravirt_ops.paravirt_enabled = 1;
 }
 

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