From 880993138396f8f0be620c425d08f84490c35251 Mon Sep 17 00:00:00 2001
From: Maxim Levitsky <mlevitsk@redhat.com>
Date: Tue, 22 Mar 2022 19:24:48 +0200
Subject: [PATCH] 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>
---
arch/x86/kvm/svm/svm.c | 4 ++--
arch/x86/kvm/vmx/vmx.c | 7 +++----
arch/x86/kvm/x86.c | 4 +---
3 files changed, 6 insertions(+), 9 deletions(-)
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c
index cff941989431b..bd4c64b362d24 100644
--- a/arch/x86/kvm/svm/svm.c
+++ b/arch/x86/kvm/svm/svm.c
@@ -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);
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c
index fb8d5b6d05f70..1bbd3e97694c2 100644
--- a/arch/x86/kvm/vmx/vmx.c
+++ b/arch/x86/kvm/vmx/vmx.c
@@ -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 */
diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index bc63ba52c4d63..498cd4aaa2cb3 100644
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -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;
}
--
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