[PATCH v4 10/47] x86/tsc: Consolidate forcing of X86_FEATURE_TSC_KNOWN_FREQ for PV code

[Sean Christopherson <seanjc@xxxxxxxxxx>]

Now that all paravirt code that explicitly specifies the TSC frequency
also sets X86_FEATURE_TSC_KNOWN_FREQ, replace all of the one-off code
and simply set X86_FEATURE_TSC_KNOWN_FREQ if the TSC frequency is known.

Do NOT force set TSC_KNOWN_FREQ if the "known" TSC frequency was provided
by the user.  Per commit bd35c77e32e4 ("x86/tsc: Add tsc_early_khz command
line parameter"), one of the goals of the param is to allow the refined
calibration work "to do meaningful error checking".

Note, preferring the user-provided TSC frequency over the frequency from
the hypervisor or trusted firmware, while simultaneously not treating the
user-provided frequency as gospel, is obviously incongruous.  Sweep the
problem under the rug for now to avoid opening a big can of worms that
likely doesn't have a great answer.

No functional change intended.

Signed-off-by: Sean Christopherson <seanjc@xxxxxxxxxx>
---
 arch/x86/coco/sev/core.c       | 1 -
 arch/x86/coco/tdx/tdx.c        | 1 -
 arch/x86/kernel/cpu/acrn.c     | 2 --
 arch/x86/kernel/cpu/mshyperv.c | 1 -
 arch/x86/kernel/cpu/vmware.c   | 2 --
 arch/x86/kernel/jailhouse.c    | 1 -
 arch/x86/kernel/kvmclock.c     | 1 -
 arch/x86/kernel/tsc.c          | 9 +++++++++
 arch/x86/xen/time.c            | 1 -
 9 files changed, 9 insertions(+), 10 deletions(-)

diff --git a/arch/x86/coco/sev/core.c b/arch/x86/coco/sev/core.c
index bc5ae9ef74da..72313b36b6f5 100644
--- a/arch/x86/coco/sev/core.c
+++ b/arch/x86/coco/sev/core.c
@@ -2027,7 +2027,6 @@ unsigned int __init snp_secure_tsc_init(void)
 
        secrets = (__force struct snp_secrets_page *)mem;
 
-       setup_force_cpu_cap(X86_FEATURE_TSC_KNOWN_FREQ);
        setup_force_cpu_cap(X86_FEATURE_TSC_RELIABLE);
 
        rdmsrq(MSR_AMD64_GUEST_TSC_FREQ, tsc_freq_mhz);
diff --git a/arch/x86/coco/tdx/tdx.c b/arch/x86/coco/tdx/tdx.c
index 5d7976359220..ab463c2b2dab 100644
--- a/arch/x86/coco/tdx/tdx.c
+++ b/arch/x86/coco/tdx/tdx.c
@@ -1205,7 +1205,6 @@ unsigned int __init tdx_tsc_init(void)
 
        /* TSC is the only reliable clock in TDX guest */
        setup_force_cpu_cap(X86_FEATURE_TSC_RELIABLE);
-       setup_force_cpu_cap(X86_FEATURE_TSC_KNOWN_FREQ);
 
        return info.tsc_khz;
 }
diff --git a/arch/x86/kernel/cpu/acrn.c b/arch/x86/kernel/cpu/acrn.c
index 0303fe6a2efa..ad8f2da8003b 100644
--- a/arch/x86/kernel/cpu/acrn.c
+++ b/arch/x86/kernel/cpu/acrn.c
@@ -33,8 +33,6 @@ static void __init acrn_init_platform(void)
 {
        /* Install system interrupt handler for ACRN hypervisor callback */
        sysvec_install(HYPERVISOR_CALLBACK_VECTOR, sysvec_acrn_hv_callback);
-
-       setup_force_cpu_cap(X86_FEATURE_TSC_KNOWN_FREQ);
 }
 
 static bool acrn_x2apic_available(void)
diff --git a/arch/x86/kernel/cpu/mshyperv.c b/arch/x86/kernel/cpu/mshyperv.c
index 733e12d5a7dd..f8653fc05a40 100644
--- a/arch/x86/kernel/cpu/mshyperv.c
+++ b/arch/x86/kernel/cpu/mshyperv.c
@@ -575,7 +575,6 @@ static void __init ms_hyperv_init_platform(void)
            ms_hyperv.misc_features & HV_FEATURE_FREQUENCY_MSRS_AVAILABLE) {
                x86_init.hyper.get_tsc_khz = hv_get_tsc_khz;
                x86_init.hyper.get_cpu_khz = hv_get_tsc_khz;
-               setup_force_cpu_cap(X86_FEATURE_TSC_KNOWN_FREQ);
        }
 
        if (ms_hyperv.priv_high & HV_ISOLATION) {
diff --git a/arch/x86/kernel/cpu/vmware.c b/arch/x86/kernel/cpu/vmware.c
index 7c8cf4885e82..2d0624c66799 100644
--- a/arch/x86/kernel/cpu/vmware.c
+++ b/arch/x86/kernel/cpu/vmware.c
@@ -390,8 +390,6 @@ 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)
diff --git a/arch/x86/kernel/jailhouse.c b/arch/x86/kernel/jailhouse.c
index 4034e08c5f11..e4d7d9e2cd69 100644
--- a/arch/x86/kernel/jailhouse.c
+++ b/arch/x86/kernel/jailhouse.c
@@ -255,7 +255,6 @@ static void __init jailhouse_init_platform(void)
        pr_debug("Jailhouse: PM-Timer IO Port: %#x\n", pmtmr_ioport);
 
        precalibrated_tsc_khz = setup_data.v1.tsc_khz;
-       setup_force_cpu_cap(X86_FEATURE_TSC_KNOWN_FREQ);
 
        pci_probe = 0;
 
diff --git a/arch/x86/kernel/kvmclock.c b/arch/x86/kernel/kvmclock.c
index ec888eef74aa..69752b170e0a 100644
--- a/arch/x86/kernel/kvmclock.c
+++ b/arch/x86/kernel/kvmclock.c
@@ -117,7 +117,6 @@ static inline void kvm_sched_clock_init(bool stable)
  */
 static unsigned int __init kvm_get_tsc_khz(void)
 {
-       setup_force_cpu_cap(X86_FEATURE_TSC_KNOWN_FREQ);
        return pvclock_tsc_khz(this_cpu_pvti());
 }
 
diff --git a/arch/x86/kernel/tsc.c b/arch/x86/kernel/tsc.c
index 362596612442..8cef918486db 100644
--- a/arch/x86/kernel/tsc.c
+++ b/arch/x86/kernel/tsc.c
@@ -1569,6 +1569,15 @@ void __init tsc_early_init(void)
        if (!known_tsc_khz && x86_init.hyper.get_tsc_khz)
                known_tsc_khz = x86_init.hyper.get_tsc_khz();
 
+       /*
+        * Mark the TSC frequency as known if it was obtained from a hypervisor
+        * or trusted firmware.  Don't mark the frequency as known if the user
+        * specified the frequency, as the user-provided frequency is intended
+        * as a "starting point", not a known, guaranteed frequency.
+        */
+       if (known_tsc_khz && !tsc_early_khz)
+               setup_force_cpu_cap(X86_FEATURE_TSC_KNOWN_FREQ);
+
        if (!determine_cpu_tsc_frequencies(true, known_cpu_khz, known_tsc_khz))
                return;
        tsc_enable_sched_clock();
diff --git a/arch/x86/xen/time.c b/arch/x86/xen/time.c
index 1adb44fdddb2..487ad838c441 100644
--- a/arch/x86/xen/time.c
+++ b/arch/x86/xen/time.c
@@ -43,7 +43,6 @@ static unsigned int __init xen_tsc_khz(void)
        struct pvclock_vcpu_time_info *info =
                &HYPERVISOR_shared_info->vcpu_info[0].time;
 
-       setup_force_cpu_cap(X86_FEATURE_TSC_KNOWN_FREQ);
        return pvclock_tsc_khz(info);
 }
 
-- 
2.54.0.823.g6e5bcc1fc9-goog