From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pj1-f74.google.com (mail-pj1-f74.google.com [209.85.216.74]) (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 6BFBA41C8C7 for ; Wed, 1 Jul 2026 19:33:00 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.216.74 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782934383; cv=none; b=E7zV/xVTVADx4jGSUEK4SgZ+mZIR+ZK5X1MNCJlvvN5FW9bYTXCHNWwr2hle4TeTCNXefo/3dGScPV3sYBDm+L+Br7zEaZ9ObPl802CKdLX70fHM065119RgjgOlMz0EC9f1QpLkz/vkgyKeQuJIie2E/pWWxaaxcaLtlrygoCc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782934383; c=relaxed/simple; bh=tCV4PY2Cjyqd7ro3RVQKSLWulEUjgqTY5Nrfa61b3sE=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=VWnlNjHfD6UBWFPyvTNF+Rz3btMd2yw+yl/5vpWS8Y6gH1SWhCwTdtnrc6VlDT9wTpmbahwYtMpbm3UNiRDIHIMu90lQMH11taOtKMwMlvUJtejBm5MVleCmStkfZ/Dlh+3+bvkfTE7i9USi4pf+XFO8CujJEI5+niXnnUgrpVY= 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=PGEvX76y; arc=none smtp.client-ip=209.85.216.74 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="PGEvX76y" Received: by mail-pj1-f74.google.com with SMTP id 98e67ed59e1d1-380a638fb5bso818261a91.0 for ; Wed, 01 Jul 2026 12:33:00 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1782934379; x=1783539179; darn=lists.linux.dev; h=content-type:cc:to:from:subject:message-id:references:mime-version :in-reply-to:date:reply-to:from:to:cc:subject:date:message-id :reply-to:content-type; bh=D8RMEeRf8IO60ymrjMFeZrqFOqn/98Ma8JhKdrpIeKM=; b=PGEvX76ycGrAP8591v1qAbtSRpjBcesL/XgMOQ8E81ZmetTwgDjk6Jr7oONq7z+H3Q hzZ88KX/mvZDgJMpBCF20X6Ps1vhVbOnLs77jfgnlLw5EPChQOQNett0+HeAF6tS+5dT teb17CoAzQIqvGluTDP0eq00Dpb5vdsjaFaelI92mzG3yi45bj5nfqmB7ehSNKC8l9tY OzxdTxA+nm+VoqDSLWfJqrZ1hrXpDR1Iawki6bZiwKBpL79MBogjLfQ/15vJeHtx/26v kTLna2G7vfSfgzu6BFNS4EzCV/GknOO+HhV5cvYpf+IOabv3SATB8yR1Ye/UPz7w6P3w iyaA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1782934379; x=1783539179; h=content-type: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:content-type; bh=D8RMEeRf8IO60ymrjMFeZrqFOqn/98Ma8JhKdrpIeKM=; b=sT78ZmJCQAYWOHst4S1qfk9pUBGVar6gvDlpTvglnb8FFMXi/BcS0Udvta7TEdCmPY d5pyk+hg54hiMuIlhku5NrdeYaqu4Z9UDcLP8N79ggWljztx/In7uFQQtYiGibL74Yrj BOJZSHfJaOvNp7arsimO3WrJRDzhGEMW9qMmzlEHjjL51vsX6NPF/LEuSaLaLDYhUNtz V2niRsAevzdo9fx9SqZCbeDJnX4ZeQz2tf12xxXVi/pPSN4IIxxR72tmdhsO4jKRi4sm Da1ZBYpcYf2MPfDU3ugLkMcj7VGNuB+yIrrhiQUo4O2HX1jVsFkNVf4X3WS+Xq9qFlbZ 0PBw== X-Forwarded-Encrypted: i=1; AHgh+RpXHCVUHcbmX5skHmClPPLOU/Rs45C++BpvoFXgmkXcyxRzjZg15ZggdPXuguxYhdenkmoLN36Qq39V@lists.linux.dev X-Gm-Message-State: AOJu0YxKiKyTI5YYRul/x3jSjP6SIN6ARpycqXOv+1gngQkOlnULMltH PhAJSGRkr+vdL4n+vjvMsq/AviJ3PdL2ATbZrmPUWTKzAvtm1g6+avOiiJpvMJ4zd89ySG72jH9 3lnuVOw== X-Received: from plkp8.prod.google.com ([2002:a17:902:6b88:b0:2c7:ebed:f6e8]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a17:903:3ba4:b0:2c1:ee75:56bb with SMTP id d9443c01a7336-2ca9117aa06mr20678475ad.20.1782934379169; Wed, 01 Jul 2026 12:32:59 -0700 (PDT) Reply-To: Sean Christopherson Date: Wed, 1 Jul 2026 12:31:48 -0700 In-Reply-To: <20260701193212.749551-1-seanjc@google.com> Precedence: bulk X-Mailing-List: linux-coco@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 References: <20260701193212.749551-1-seanjc@google.com> X-Mailer: git-send-email 2.55.0.rc0.799.gd6f94ed593-goog Message-ID: <20260701193212.749551-28-seanjc@google.com> Subject: [PATCH v5 27/51] clocksource: hyper-v: Don't save/restore TSC offset when using HV sched_clock From: Sean Christopherson To: Jonathan Corbet , Paolo Bonzini , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, Kiryl Shutsemau , Rick Edgecombe , 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: Shuah Khan , "H. Peter Anvin" , Vitaly Kuznetsov , Broadcom internal kernel review list , Boris Ostrovsky , Stephen Boyd , linux-doc@vger.kernel.org, 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, Tom Lendacky , Nikunj A Dadhania , David Woodhouse , David Woodhouse , Michael Kelley , Thomas Gleixner Content-Type: text/plain; charset="UTF-8" Now that Hyper-V overrides the sched_clock save/restore hooks if and only sched_clock itself is set to the Hyper-V reference counter, drop the invocation of the "old" save/restore callbacks. When the registration of the PV sched_clock was done separately from overriding the save/restore hooks, it was possible for Hyper-V to clobber the TSC save/restore callbacks without actually switching to the Hyper-V refcounter. Enabling a PV sched_clock is a one-way street, i.e. the kernel will never revert to using TSC for sched_clock, and so there is no need to invoke the TSC save/restore hooks (and if there was, it belongs in common PV code). Reviewed-by: Michael Kelley Tested-by: Michael Kelley Reviewed-by: David Woodhouse Acked-by: Wei Liu Signed-off-by: Sean Christopherson --- drivers/clocksource/hyperv_timer.c | 10 ---------- 1 file changed, 10 deletions(-) diff --git a/drivers/clocksource/hyperv_timer.c b/drivers/clocksource/hyperv_timer.c index daa8cbfe61ee..220668207d19 100644 --- a/drivers/clocksource/hyperv_timer.c +++ b/drivers/clocksource/hyperv_timer.c @@ -544,9 +544,6 @@ static __always_inline void hv_setup_sched_clock(void *sched_clock) #include static u64 hv_ref_counter_at_suspend; -static void (*old_save_sched_clock_state)(void); -static void (*old_restore_sched_clock_state)(void); - /* * Hyper-V clock counter resets during hibernation. Save and restore clock * offset during suspend/resume, while also considering the time passed @@ -556,8 +553,6 @@ static void (*old_restore_sched_clock_state)(void); */ static void hv_save_sched_clock_state(void) { - old_save_sched_clock_state(); - hv_ref_counter_at_suspend = hv_read_reference_counter(); } @@ -570,8 +565,6 @@ static void hv_restore_sched_clock_state(void) * - reference counter (time) now. */ hv_sched_clock_offset -= (hv_ref_counter_at_suspend - hv_read_reference_counter()); - - old_restore_sched_clock_state(); } static __always_inline void hv_setup_sched_clock(void *sched_clock) @@ -579,10 +572,7 @@ static __always_inline void hv_setup_sched_clock(void *sched_clock) /* We're on x86/x64 *and* using PV ops */ paravirt_set_sched_clock(sched_clock); - old_save_sched_clock_state = x86_platform.save_sched_clock_state; x86_platform.save_sched_clock_state = hv_save_sched_clock_state; - - old_restore_sched_clock_state = x86_platform.restore_sched_clock_state; x86_platform.restore_sched_clock_state = hv_restore_sched_clock_state; } #else /* !CONFIG_GENERIC_SCHED_CLOCK && !CONFIG_PARAVIRT */ -- 2.55.0.rc0.799.gd6f94ed593-goog