From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pf1-f201.google.com (mail-pf1-f201.google.com [209.85.210.201]) (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 DEF414229C9 for ; Wed, 1 Jul 2026 19:33:08 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.210.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782934391; cv=none; b=qwzxnlLKj+IYRe5rirVdjpCS3L5994nw8T9QiT3p03ZDktATFPyNlJrGQNr4M+XlWq3u924IQPV2YByr2aVyCvzvnvTCv24U0ldE44aauSH5Cn1yUQWsGEy/RqZLV4mxjruF2EC6M2ZuUtveSzk5ERiM2DTlgQmfRiXV72b5K9A= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782934391; c=relaxed/simple; bh=odtTAw4qAyKVMoQOFS9NQKiMBl8SSPflZ8sexqq+tVc=; h=Date:In-Reply-To:Mime-Version:References:Message-ID:Subject:From: To:Cc:Content-Type; b=mJ6tlr1jc+CBtSAnum2ZYvKOI+j+FMjCoG4VwEH173haYV1VAX0Z9uz5+hfa1KABgSmb/imYvGiTSZrZwe16xo3fGvKUPre08PKj6OAtxvs2ZiIS9iBQ/c65yH+AN7OvhaIirW4V8rZqHcwOS7n6S4DSIxv5DjTjXAWk23vZMM0= 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=Z9pbLP8R; arc=none smtp.client-ip=209.85.210.201 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="Z9pbLP8R" Received: by mail-pf1-f201.google.com with SMTP id d2e1a72fcca58-845e3ede1f9so1072309b3a.0 for ; Wed, 01 Jul 2026 12:33:08 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20251104; t=1782934388; x=1783539188; 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=qFfbhUmYyCU6tRW/uev50JnnPJRuq59CtmTnO4qaTps=; b=Z9pbLP8RzwzuKuLzlfrm5Prb7daDS39w3We9CUaV2F7dzjc6vupfNsHYXJ/uNF7kwk 1/CQ7RZDZAMKJdACXon7ImfdCh18M3GAaYVJ5JUuOI2qob2Dsuvg2RDEYnbMsP1qHk1r V4r3aOAeOAmlVLsq3rExkfbeX/iZg7F1Jm7MNss9hgyXbbzPLh2YglTzpzAqm70HHsXr +r4oesTjqHEgu94n6ZOkXp5DK/LfSKpT5llxFjm0Grku+sZiy5fLD+XKQ5KE8xTenb// ibgdBS3M/qzvqtJO3yFXP8N2WZfIVjx5edXZeg/w3UvEpsLMZu3rC7y0CG4TbeTmQQzC 3bEg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1782934388; x=1783539188; 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=qFfbhUmYyCU6tRW/uev50JnnPJRuq59CtmTnO4qaTps=; b=pexCgWg7C+M0mhE1Cs3x1a58WI2/AsG+Y8AbRQ6+T6L+yVRLVEPPt3wlCA5CSo84Mn xQA+JSO28Zn2jDrObaAUHNRYpDp9OyrVBAV0/s78bcFw/LFYbBYyv16NiOjOOKN5Mpai +64AC+Cnb+mZnXKnGpiAPik1Xn0MpPJQvFpp4suQMa1l6OAyohTfISZV/fq5HuUYLUL0 wpU5txnjpjMAbA0bqp7mK9yfvXDhavHbNgQ6bHQJfDhBL4wv0AFaLANfH9SjBpVOks6s TBbftPn6329eGC//VktB8wceI6OGKkRv0XbcWuKLzenTpCxrFbbj4B0p/dXDihqCM/Qn 5GfQ== X-Forwarded-Encrypted: i=1; AFNElJ/DDaAm9mjbrOe+eCWEcN3IiW7hk5oqYjDCTE1s+mk675nOL1C4zyCdzr0KcDKFpnQ90Dn6raTpmdY=@vger.kernel.org X-Gm-Message-State: AOJu0YyQEyJHuEVVMIKk9jf6d05692RUl8s6oKyI+dEaYqoKFRNhI/lt U7/g6/jzW6oH4hCvfRAI1T/mIH5ydrteXFu733xAYocQ2cDhaw4rqve+OWIurLoQCpuqqqDsM75 X6dFDHA== X-Received: from pfvx7.prod.google.com ([2002:a05:6a00:2707:b0:847:8f34:1b76]) (user=seanjc job=prod-delivery.src-stubby-dispatcher) by 2002:a05:6a00:8f0a:b0:847:86d8:5937 with SMTP id d2e1a72fcca58-847c51e4a35mr1955201b3a.50.1782934387701; Wed, 01 Jul 2026 12:33:07 -0700 (PDT) Reply-To: Sean Christopherson Date: Wed, 1 Jul 2026 12:31:54 -0700 In-Reply-To: <20260701193212.749551-1-seanjc@google.com> Precedence: bulk X-Mailing-List: linux-doc@vger.kernel.org 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: <20260701193212.749551-34-seanjc@google.com> Subject: [PATCH v5 33/51] x86/xen/time: NOP-ify x86_platform's sched_clock save/restore hooks 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" NOP-ify the x86_platform sched_clock save/restore hooks when setting up Xen's PV clock to make it somewhat obvious the hooks aren't used when running as a Xen guest (Xen uses a paravirtualized suspend/resume flow). Reviewed-by: David Woodhouse Signed-off-by: Sean Christopherson --- arch/x86/xen/time.c | 6 ++++++ 1 file changed, 6 insertions(+) diff --git a/arch/x86/xen/time.c b/arch/x86/xen/time.c index 487ad838c441..477441752f40 100644 --- a/arch/x86/xen/time.c +++ b/arch/x86/xen/time.c @@ -567,6 +567,12 @@ static void __init xen_init_time_common(void) xen_sched_clock_offset = xen_clocksource_read(); static_call_update(pv_steal_clock, xen_steal_clock); paravirt_set_sched_clock(xen_sched_clock); + /* + * Xen has paravirtualized suspend/resume and so doesn't use the common + * x86 sched_clock save/restore hooks. + */ + x86_platform.save_sched_clock_state = x86_init_noop; + x86_platform.restore_sched_clock_state = x86_init_noop; x86_init.hyper.get_tsc_khz = xen_tsc_khz; x86_platform.get_wallclock = xen_get_wallclock; -- 2.55.0.rc0.799.gd6f94ed593-goog