Currently we use pv-ops to tell linux not to do anything on io_delay.
While the basic idea is good IMHO, I don't see why we would need pv-ops
for that. The io delay function already has a switch that can do nothing
if you're so inclined.
So here's a patch (stacked on top of the previous pv-ops series) that
removes the io delay pv-ops hook and just sets the native io delay
variable instead.
Signed-off-by: Alexander Graf <agraf@xxxxxxx>
---
arch/x86/Kconfig | 14 --------------
arch/x86/kernel/kvm.c | 16 +++-------------
2 files changed, 3 insertions(+), 27 deletions(-)
diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
index 97d4f92..ebed686 100644
--- a/arch/x86/Kconfig
+++ b/arch/x86/Kconfig
@@ -527,20 +527,6 @@ config KVM_GUEST
This option enables various optimizations for running under the KVM
hypervisor.
-config KVM_IODELAY
- bool "KVM IO-delay support"
- depends on KVM_GUEST
- select PARAVIRT_CPU
- ---help---
- Usually we wait for PIO access to complete. When inside KVM there's
- no need to do that, as we know that we're not going through a bus,
- but process PIO requests instantly.
-
- This option disables PIO waits, but drags in CPU-bound pv-ops. Thus
- you will probably get more speed loss than speedup using this option.
-
- If in doubt, say N.
-
config KVM_MMU
bool "KVM PV MMU support"
depends on KVM_GUEST
diff --git a/arch/x86/kernel/kvm.c b/arch/x86/kernel/kvm.c
index 7e0207f..be182e6 100644
--- a/arch/x86/kernel/kvm.c
+++ b/arch/x86/kernel/kvm.c
@@ -29,15 +29,6 @@
#include <linux/hardirq.h>
#include <asm/timer.h>
-#ifdef CONFIG_KVM_IODELAY
-/*
- * No need for any "IO delay" on KVM
- */
-static void kvm_io_delay(void)
-{
-}
-#endif /* CONFIG_KVM_IODELAY */
-
#ifdef CONFIG_KVM_MMU
#define MMU_QUEUE_SIZE 1024
@@ -201,13 +192,12 @@ static void kvm_leave_lazy_mmu(void)
static void __init paravirt_ops_setup(void)
{
+ extern int io_delay_type;
pv_info.name = "KVM";
pv_info.paravirt_enabled = 1;
-#ifdef CONFIG_KVM_IODELAY
- if (kvm_para_has_feature(KVM_FEATURE_NOP_IO_DELAY))
- pv_cpu_ops.io_delay = kvm_io_delay;
-#endif
+ /* Disable IO delay */
+ io_delay_type = CONFIG_IO_DELAY_TYPE_NONE;
#ifdef CONFIG_KVM_MMU
if (kvm_para_has_feature(KVM_FEATURE_MMU_OP)) {
--
1.6.0.2
--
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