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KVM: x86: SVM: fix tsc scaling when the host doesn't support it 

It was decided that when TSC scaling is not supported,
the virtual MSR_AMD64_TSC_RATIO should still have the default '1.0'
value.

However in this case kvm_max_tsc_scaling_ratio is not set,
which breaks various assumptions.

Fix this by always calculating kvm_max_tsc_scaling_ratio regardless of
host support.  For consistency, do the same for VMX.

Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Maxim Levitsky <mlevitsk@redhat.com>
Message-Id: <20220322172449.235575-8-mlevitsk@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Maxim Levitsky 2022-03-22 19:24:48 +02:00 committed by Paolo Bonzini
parent f37b735e31
commit 8809931383
3 changed files with 6 additions and 9 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
arch/x86/kvm/svm/svm.c
View File

@ -4752,10 +4752,10 @@ static __init int svm_hardware_setup(void)
} else {
pr_info("TSC scaling supported\n");
kvm_has_tsc_control = true;
kvm_max_tsc_scaling_ratio = SVM_TSC_RATIO_MAX;
kvm_tsc_scaling_ratio_frac_bits = 32;
}
}
kvm_max_tsc_scaling_ratio = SVM_TSC_RATIO_MAX;
kvm_tsc_scaling_ratio_frac_bits = 32;
tsc_aux_uret_slot = kvm_add_user_return_msr(MSR_TSC_AUX);

7
arch/x86/kvm/vmx/vmx.c
View File

@ -7980,12 +7980,11 @@ static __init int hardware_setup(void)
if (!enable_apicv)
vmx_x86_ops.sync_pir_to_irr = NULL;
if (cpu_has_vmx_tsc_scaling()) {
if (cpu_has_vmx_tsc_scaling())
kvm_has_tsc_control = true;
kvm_max_tsc_scaling_ratio = KVM_VMX_TSC_MULTIPLIER_MAX;
kvm_tsc_scaling_ratio_frac_bits = 48;
}
kvm_max_tsc_scaling_ratio = KVM_VMX_TSC_MULTIPLIER_MAX;
kvm_tsc_scaling_ratio_frac_bits = 48;
kvm_has_bus_lock_exit = cpu_has_vmx_bus_lock_detection();
set_bit(0, vmx_vpid_bitmap); /* 0 is reserved for host */

4
arch/x86/kvm/x86.c
View File

@ -11602,10 +11602,8 @@ int kvm_arch_hardware_setup(void *opaque)
u64 max = min(0x7fffffffULL,
__scale_tsc(kvm_max_tsc_scaling_ratio, tsc_khz));
kvm_max_guest_tsc_khz = max;
kvm_default_tsc_scaling_ratio = 1ULL << kvm_tsc_scaling_ratio_frac_bits;
}
kvm_default_tsc_scaling_ratio = 1ULL << kvm_tsc_scaling_ratio_frac_bits;
kvm_init_msr_list();
return 0;
}