From patchwork Thu Apr 18 19:34:47 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: David Woodhouse X-Patchwork-Id: 13635321 Received: from desiato.infradead.org (desiato.infradead.org [90.155.92.199]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 41857194C68; Thu, 18 Apr 2024 19:43:10 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=90.155.92.199 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1713469391; cv=none; b=hDjdm+FETTmwBsY9g463VlZD/L+HCv7ZCj2v+phnDlFcvjCYI1Q2pcLW+/PE6I4OqSwjkQTrdX8dkJEPO+hyfMWnLcvdP1g0JzYb+dR2t56G16UzZQrQTzEzcJHevvAFxBEgzu+X3+hZ01/FIZUW9OkjmwyWY0WFLP7CeuEFyK4= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1713469391; c=relaxed/simple; bh=sKiS3ZpuiMcyy6TXTSQWYzInni8lO/cauQ/w7u1huLg=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Zhi8i4fdODFIsWqqKNVnDCW1IwczHWEvnVtbZxq3IG/du3bUDyz1xWk64ck18CKJAiLkiIJ6RGiV/wLCCEkroic3AwS/64AnS6TCFmLff2csmQzVttRr3OR4iYMk75cbUBzLkMc0M1PZFn2lNpyiF9T2H4uRDJiIiWcm5ff2spc= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org; spf=none smtp.mailfrom=desiato.srs.infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=BejXjR1u; arc=none smtp.client-ip=90.155.92.199 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=desiato.srs.infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="BejXjR1u" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=desiato.20200630; h=Sender:Content-Transfer-Encoding: MIME-Version:References:In-Reply-To:Message-ID:Date:Subject:Cc:To:From: Reply-To:Content-Type:Content-ID:Content-Description; bh=i9sb97HlDBeFt7Dzk4l2/rP13VZEgB89kjbsK1Zc/xw=; b=BejXjR1uHxkx+p3/+TiibdhHXQ PtsKwTNFODrLbBlIryBYhdZz8oBvULnCeOHMk42fQYjBjX2reRUoZNYRvkk1sW4bJLw7cVGhiTgL4 m4ksz/rnYeONj+9lFYf0qIHsOLXEdGi+TauE+mp8qwniNvvNQ0vRKwZ8Oxu30EBrX0xJ+ay2jCYxm mxZS28tWvwzsmfI8IyXdkTDyR5EO8vqo+zYHlvDohOknWHJjggjBwMt0XQTBenJtObYAkjvFqrAFq RrJP3sm9iOGO8V08Wjt+Q7fpxVdEArKOImG6hcqqKOfc/ArtJVWwC9sh7XJj+dAW6JRHJOYFSG+Vt gDj3rBxA==; Received: from [2001:8b0:10b:1::ebe] (helo=i7.infradead.org) by desiato.infradead.org with esmtpsa (Exim 4.97.1 #2 (Red Hat Linux)) id 1rxXXf-0000000C8MO-2jYq; Thu, 18 Apr 2024 19:35:32 +0000 Received: from dwoodhou by i7.infradead.org with local (Exim 4.97.1 #2 (Red Hat Linux)) id 1rxXXf-00000000Asm-0LxX; Thu, 18 Apr 2024 20:35:31 +0100 From: David Woodhouse To: kvm@vger.kernel.org Cc: Paolo Bonzini , Jonathan Corbet , Sean Christopherson , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , Paul Durrant , Shuah Khan , linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org, Oliver Upton , Marcelo Tosatti , jalliste@amazon.co.uk, sveith@amazon.de Subject: [PATCH 08/10] KVM: x86: Remove periodic global clock updates Date: Thu, 18 Apr 2024 20:34:47 +0100 Message-ID: <20240418193528.41780-9-dwmw2@infradead.org> X-Mailer: git-send-email 2.44.0 In-Reply-To: <20240418193528.41780-1-dwmw2@infradead.org> References: <20240418193528.41780-1-dwmw2@infradead.org> Precedence: bulk X-Mailing-List: kvm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Sender: David Woodhouse X-SRS-Rewrite: SMTP reverse-path rewritten from by desiato.infradead.org. See http://www.infradead.org/rpr.html From: David Woodhouse This effectively reverts commit 332967a3eac0 ("x86: kvm: introduce periodic global clock updates"). The periodic update was introduced to propagate NTP corrections to the guest KVM clock, when the KVM clock was based on CLOCK_MONOTONIC. However, commit 53fafdbb8b21 ("KVM: x86: switch KVMCLOCK base to monotonic raw clock") switched to using CLOCK_MONOTONIC_RAW as the basis for the KVM clock, avoiding the NTP frequency skew altogether. So the periodic update serves no purpose. Remove it. Signed-off-by: David Woodhouse Reviewed-by: Paul Durrant --- arch/x86/kvm/x86.c | 25 ------------------------- 1 file changed, 25 deletions(-) diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index 44b3d2a0da5b..4ec4eb850c5b 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -155,9 +155,6 @@ EXPORT_SYMBOL_GPL(report_ignored_msrs); unsigned int min_timer_period_us = 200; module_param(min_timer_period_us, uint, 0644); -static bool __read_mostly kvmclock_periodic_sync = true; -module_param(kvmclock_periodic_sync, bool, 0444); - /* tsc tolerance in parts per million - default to 1/2 of the NTP threshold */ static u32 __read_mostly tsc_tolerance_ppm = 250; module_param(tsc_tolerance_ppm, uint, 0644); @@ -3434,20 +3431,6 @@ static void kvm_gen_kvmclock_update(struct kvm_vcpu *v) KVMCLOCK_UPDATE_DELAY); } -#define KVMCLOCK_SYNC_PERIOD (300 * HZ) - -static void kvmclock_sync_fn(struct work_struct *work) -{ - struct delayed_work *dwork = to_delayed_work(work); - struct kvm_arch *ka = container_of(dwork, struct kvm_arch, - kvmclock_sync_work); - struct kvm *kvm = container_of(ka, struct kvm, arch); - - schedule_delayed_work(&kvm->arch.kvmclock_update_work, 0); - schedule_delayed_work(&kvm->arch.kvmclock_sync_work, - KVMCLOCK_SYNC_PERIOD); -} - /* These helpers are safe iff @msr is known to be an MCx bank MSR. */ static bool is_mci_control_msr(u32 msr) { @@ -12416,8 +12399,6 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu) void kvm_arch_vcpu_postcreate(struct kvm_vcpu *vcpu) { - struct kvm *kvm = vcpu->kvm; - if (mutex_lock_killable(&vcpu->mutex)) return; vcpu_load(vcpu); @@ -12428,10 +12409,6 @@ void kvm_arch_vcpu_postcreate(struct kvm_vcpu *vcpu) vcpu->arch.msr_kvm_poll_control = 1; mutex_unlock(&vcpu->mutex); - - if (kvmclock_periodic_sync && vcpu->vcpu_idx == 0) - schedule_delayed_work(&kvm->arch.kvmclock_sync_work, - KVMCLOCK_SYNC_PERIOD); } void kvm_arch_vcpu_destroy(struct kvm_vcpu *vcpu) @@ -12804,7 +12781,6 @@ int kvm_arch_init_vm(struct kvm *kvm, unsigned long type) #endif INIT_DELAYED_WORK(&kvm->arch.kvmclock_update_work, kvmclock_update_fn); - INIT_DELAYED_WORK(&kvm->arch.kvmclock_sync_work, kvmclock_sync_fn); kvm_apicv_init(kvm); kvm_hv_init_vm(kvm); @@ -12844,7 +12820,6 @@ static void kvm_unload_vcpu_mmus(struct kvm *kvm) void kvm_arch_sync_events(struct kvm *kvm) { - cancel_delayed_work_sync(&kvm->arch.kvmclock_sync_work); cancel_delayed_work_sync(&kvm->arch.kvmclock_update_work); kvm_free_pit(kvm); }