From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pl1-f201.google.com (mail-pl1-f201.google.com [209.85.214.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 093E03F4DF8 for ; Fri, 29 May 2026 14:45:04 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.214.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780065906; cv=none; b=Na2R2tDhC3ZQYD56cG8gXwccEBzbitFVsLQbE8EC54hWCLMlZ2AGf2XC5HWQTZ++ypugk6tshmxw7aZQ7/INrIIlQ7jP9YZzJA5YAIKyeW9Hxl0j+IhAmuUpX1g+ucVbmssQzBMu35J+gYrD8ALclCuzJz51jEmFvfb6tkYcD4A= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780065906; c=relaxed/simple; bh=bU4yyxwDONnh6/m4AIrBZuy9EH4am/4yreSoKbC9BSs=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=nBckhclEw0hwoQTof9OpE/bPFh2a2RhtsudNaZdrU+B3mccQ9zMkXGqvuPiJRGL79KutXmfAAMnHV+je/oFvPEfzNuw2micd7S4Quf24t+Cc/IM7xRtzjCYe3XW83UfQjfUhK2kVOhH3AWueiCt2vMbmlg/Mz3qEbbF9NPLU8ec= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com; spf=pass smtp.mailfrom=flex--seanjc.bounces.google.com; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b=tizPqjee; arc=none smtp.client-ip=209.85.214.201 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=reject dis=none) header.from=google.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=flex--seanjc.bounces.google.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="tizPqjee" Received: by mail-pl1-f201.google.com with SMTP id d9443c01a7336-2beff6b6e74so27940255ad.1 for ; Fri, 29 May 2026 07:45:04 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1780065903; x=1780670703; darn=vger.kernel.org; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:reply-to:from:to:cc:subject:date:message-id:reply-to; bh=H0GwXhoguEvRGovrleKtlxRg6q5h/dMOER9+6opKAAY=; b=tizPqjeerMvAs1ipgETZNtmHwAPNyb0OuuwcGmcmrLVP5tcY4t1Ma+H4qi9/+IRBfe sUHkIdCgODWqmDTaCvQcHxOA4Axu2txonWQYjJF6nrYkgVLoXdc+bTHQ4lC2edjgqSc1 KSy6YMLNiqXTlPSF8GRXkpMjVjJ2eMdoOTlL9H51QOGATdd+8rBvfW7MrNPeNCbZGZLN p/XdXaIXIHFuR0U/5fztbbouoLKkv8o2tvfF2eOKeuuNfk41pO/8NtP+0ICwDI5fUnGI Mz9QL5bejl9IRID5KilhLAeUQXC9mAgAXBHUlnSyG7xmyt2R2/cC6h1lTV9Bs0kdF+9U ehiQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1780065903; x=1780670703; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:reply-to:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=H0GwXhoguEvRGovrleKtlxRg6q5h/dMOER9+6opKAAY=; b=oBRX+Gbc3LISBIxPmiQ13LAfb5WlHkzhWOf6YQUxpSRhrUpWhut6ZMZYkp1HytfvrE Ni3MGI/wK89abpUvkJp4ovTUYBW+tfKynCrDQWTnrGb9fKlpJnBk8Remvb7x8/KW13hI huwItVUSojRNVxE0Oc3OBd3jBMfxGPGhoHnYezrag4Jdl1qVIvwEue+RFyd6km9T5MiY ZytFu3LKmYDmkBsf3uwBszLCBh8Ka+9/TpelusBl1+MqmkDnjjYqzWsAdHF5Cduk/Y0i fkmA/1r1n82Kw3TlHIP1ezm8tmQiUG459SRmRuOfn8Lou1XdP9jxc/wOLvHoXrNWVf6s guHw== X-Forwarded-Encrypted: i=1; AFNElJ/76ZjIcrDJHUZpLaKkM6SqZ7DqwvaDq7Iy9ergaXgoqscx6AP5f58RV5DiMAL55D9iJA6N5BiNko8RIOk=@vger.kernel.org X-Gm-Message-State: AOJu0YzGjqWP4GXQwqSLlUJAtbufr95F8gR2iNz8IKw799qF+eBGsmK3 /XkSwrz0SEA8R2XlyGlbq0YDIZgHVOYKF+mNjO5V4P6QM05w10fn1lJYYL6ouOmSFs0jnzeFbXs jbmBHMg== X-Received: from pgc24.prod.google.com ([2002:a05:6a02:2f98:b0:c80:192c:51ff]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a17:902:c94c:b0:2b2:be01:5532 with SMTP id d9443c01a7336-2bf3686d1dcmr856725ad.35.1780065903103; Fri, 29 May 2026 07:45:03 -0700 (PDT) Reply-To: Sean Christopherson Date: Fri, 29 May 2026 07:43:57 -0700 In-Reply-To: <20260529144435.704127-1-seanjc@google.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260529144435.704127-1-seanjc@google.com> X-Mailer: git-send-email 2.54.0.823.g6e5bcc1fc9-goog Message-ID: <20260529144435.704127-11-seanjc@google.com> Subject: [PATCH v4 10/47] x86/tsc: Consolidate forcing of X86_FEATURE_TSC_KNOWN_FREQ for PV code From: Sean Christopherson To: Paolo Bonzini , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, Kiryl Shutsemau , Sean Christopherson , "K. Y. Srinivasan" , Haiyang Zhang , Wei Liu , Dexuan Cui , Long Li , Ajay Kaher , Alexey Makhalov , Jan Kiszka , Andy Lutomirski , Peter Zijlstra , Juergen Gross , Daniel Lezcano , John Stultz Cc: "H. Peter Anvin" , Rick Edgecombe , Vitaly Kuznetsov , Broadcom internal kernel review list , Boris Ostrovsky , Stephen Boyd , kvm@vger.kernel.org, linux-kernel@vger.kernel.org, linux-coco@lists.linux.dev, linux-hyperv@vger.kernel.org, virtualization@lists.linux.dev, xen-devel@lists.xenproject.org, David Woodhouse , Tom Lendacky , Nikunj A Dadhania , David Woodhouse , Michael Kelley , Thomas Gleixner Content-Type: text/plain; charset="UTF-8" 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 --- 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