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KVM: vmx: Emulate MSR IA32_UMWAIT_CONTROL

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UMWAIT and TPAUSE instructions use 32bit IA32_UMWAIT_CONTROL at MSR index
E1H to determines the maximum time in TSC-quanta that the processor can
reside in either C0.1 or C0.2.

This patch emulates MSR IA32_UMWAIT_CONTROL in guest and differentiate
IA32_UMWAIT_CONTROL between host and guest. The variable
mwait_control_cached in arch/x86/kernel/cpu/umwait.c caches the MSR value,
so this patch uses it to avoid frequently rdmsr of IA32_UMWAIT_CONTROL.

Co-developed-by: Jingqi Liu <jingqi.liu@intel.com>
Signed-off-by: Jingqi Liu <jingqi.liu@intel.com>
Signed-off-by: Tao Xu <tao3.xu@intel.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Tao Xu
2019-07-16 14:55:50 +08:00
committed by Paolo Bonzini
parent e69e72faa3
commit 6e3ba4abce
4 changed files with 53 additions and 0 deletions
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6
arch/x86/kernel/cpu/umwait.c
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@ -17,6 +17,12 @@
*/
static u32 umwait_control_cached = UMWAIT_CTRL_VAL(100000, UMWAIT_C02_ENABLE);
u32 get_umwait_control_msr(void)
{
return umwait_control_cached;
}
EXPORT_SYMBOL_GPL(get_umwait_control_msr);
/*
* Cache the original IA32_UMWAIT_CONTROL MSR value which is configured by
* hardware or BIOS before kernel boot.