When TSC frequency is known (retrieved from hypervisor), we should skip
TSC refined calibration by setting X86_FEATURE_TSC_KNOWN_FREQ.
Signed-off-by: Alexey Makhalov <amakhalov at vmware.com>
---
arch/x86/kernel/cpu/vmware.c | 2 ++
1 file changed, 2 insertions(+)
diff --git a/arch/x86/kernel/cpu/vmware.c b/arch/x86/kernel/cpu/vmware.c
index c6ede3b3d302..83164110ccc5 100644
--- a/arch/x86/kernel/cpu/vmware.c
+++ b/arch/x86/kernel/cpu/vmware.c
@@ -378,6 +378,8 @@ static void __init vmware_set_capabilities(void)
{
setup_force_cpu_cap(X86_FEATURE_CONSTANT_TSC);
setup_force_cpu_cap(X86_FEATURE_TSC_RELIABLE);
+ if (vmware_tsc_khz)
+ setup_force_cpu_cap(X86_FEATURE_TSC_KNOWN_FREQ);
if (vmware_hypercall_mode == CPUID_VMWARE_FEATURES_ECX_VMCALL)
setup_force_cpu_cap(X86_FEATURE_VMCALL);
else if (vmware_hypercall_mode == CPUID_VMWARE_FEATURES_ECX_VMMCALL)
--
2.11.0
Alexey Makhalov <amakhalov at vmware.com> writes:> When TSC frequency is known (retrieved from hypervisor), we should skip > TSC refined calibration by setting X86_FEATURE_TSC_KNOWN_FREQ. > > Signed-off-by: Alexey Makhalov <amakhalov at vmware.com> > --- > arch/x86/kernel/cpu/vmware.c | 2 ++ > 1 file changed, 2 insertions(+) > > diff --git a/arch/x86/kernel/cpu/vmware.c b/arch/x86/kernel/cpu/vmware.c > index c6ede3b3d302..83164110ccc5 100644 > --- a/arch/x86/kernel/cpu/vmware.c > +++ b/arch/x86/kernel/cpu/vmware.c > @@ -378,6 +378,8 @@ static void __init vmware_set_capabilities(void) > { > setup_force_cpu_cap(X86_FEATURE_CONSTANT_TSC); > setup_force_cpu_cap(X86_FEATURE_TSC_RELIABLE); > + if (vmware_tsc_khz) > + setup_force_cpu_cap(X86_FEATURE_TSC_KNOWN_FREQ); > if (vmware_hypercall_mode == CPUID_VMWARE_FEATURES_ECX_VMCALL) > setup_force_cpu_cap(X86_FEATURE_VMCALL); > else if (vmware_hypercall_mode == CPUID_VMWARE_FEATURES_ECX_VMMCALL)The same trick is being used in Xen/Jailhouse/KVM code already and Hyper-V overwrites x86_platform.calibrate_tsc/x86_platform.calibrate_cpu hooks to basically achive the same goal. Should we maybe introduce a flag in 'struct hypervisor_x86' or something like that to unify all this? Just a suggestion. -- Vitaly