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| author |   Tao Xu <tao3.xu@intel.com> | 2019-07-16 14:55:50 +0800 |
|---|---|---|
| committer |   Paolo Bonzini <pbonzini@redhat.com> | 2019-09-24 14:34:36 +0200 |
| commit | 6e3ba4abcea5681eebbfc10f1b56c9fbe80b6685 (patch) | |
| tree | 98719f3f207dfe3d8ef0b8125c56b6ea2dca02de /arch/x86/kernel | |
| parent | KVM: x86: Add support for user wait instructions (diff) | |
| download | linux-dev-6e3ba4abcea5681eebbfc10f1b56c9fbe80b6685.tar.xz linux-dev-6e3ba4abcea5681eebbfc10f1b56c9fbe80b6685.zip | |
KVM: vmx: Emulate MSR IA32_UMWAIT_CONTROL
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>
Diffstat (limited to 'arch/x86/kernel')
| -rw-r--r-- | arch/x86/kernel/cpu/umwait.c | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/arch/x86/kernel/cpu/umwait.c b/arch/x86/kernel/cpu/umwait.c index 32b4dc9030aa..c222f283b456 100644 --- a/arch/x86/kernel/cpu/umwait.c +++ b/arch/x86/kernel/cpu/umwait.c @@ -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. |