From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.1 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8ABCCC282CE for ; Mon, 22 Apr 2019 19:42:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 4F9852175B for ; Mon, 22 Apr 2019 19:42:41 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1555962161; bh=a/tDOxXZmubAs3j/a20Am9PD6cFX24xUBC6esjBERXc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=aXC7L2sgWf/Rs612imWC3nreF+jluW5qAsr/leQtb8atP4JBhMlhFXJiKJUd9c0u0 rfYGBkMl/zThKJNBgBnB5Sca8Ib0eWeUleWx9MKuA3NvEy3uJYVqu2m0eXWVYZua7O OwzIN50oS97pe6PA+n5dqwNLPyAgm79vNBuX/1gU= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728906AbfDVTmk (ORCPT ); Mon, 22 Apr 2019 15:42:40 -0400 Received: from mail.kernel.org ([198.145.29.99]:43034 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728824AbfDVTmi (ORCPT ); Mon, 22 Apr 2019 15:42:38 -0400 Received: from sasha-vm.mshome.net (c-73-47-72-35.hsd1.nh.comcast.net [73.47.72.35]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 17BFE218DA; Mon, 22 Apr 2019 19:42:37 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1555962157; bh=a/tDOxXZmubAs3j/a20Am9PD6cFX24xUBC6esjBERXc=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=VkIIlmA3js6Z90kBQG4PBYx4CbDXAsxKaT8kH+G5uX6jmLPqDOKWb6buFyrEvH+BH Fz7JmeESmuo/9nFW3kOxuArhmKNxb+bv0VvyYiXEG443wXqQ1Cer+5fGhBWH+kT6MY Ms1zzYdsMy5tmO/jT4Sbkz7+M1UaeGuMuYtq0a1Y= From: Sasha Levin To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: Marc Zyngier , Sasha Levin , kvmarm@lists.cs.columbia.edu Subject: [PATCH AUTOSEL 5.0 25/98] KVM: arm64: Reset the PMU in preemptible context Date: Mon, 22 Apr 2019 15:40:52 -0400 Message-Id: <20190422194205.10404-25-sashal@kernel.org> X-Mailer: git-send-email 2.19.1 In-Reply-To: <20190422194205.10404-1-sashal@kernel.org> References: <20190422194205.10404-1-sashal@kernel.org> MIME-Version: 1.0 X-stable: review X-Patchwork-Hint: Ignore Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Marc Zyngier [ Upstream commit ebff0b0e3d3c862c16c487959db5e0d879632559 ] We've become very cautious to now always reset the vcpu when nothing is loaded on the physical CPU. To do so, we now disable preemption and do a kvm_arch_vcpu_put() to make sure we have all the state in memory (and that it won't be loaded behind out back). This now causes issues with resetting the PMU, which calls into perf. Perf itself uses mutexes, which clashes with the lack of preemption. It is worth realizing that the PMU is fully emulated, and that no PMU state is ever loaded on the physical CPU. This means we can perfectly reset the PMU outside of the non-preemptible section. Fixes: e761a927bc9a ("KVM: arm/arm64: Reset the VCPU without preemption and vcpu state loaded") Reported-by: Julien Grall Tested-by: Julien Grall Signed-off-by: Marc Zyngier Signed-off-by: Sasha Levin (Microsoft) --- arch/arm64/kvm/reset.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) diff --git a/arch/arm64/kvm/reset.c b/arch/arm64/kvm/reset.c index f16a5f8ff2b4..e2a0500cd7a2 100644 --- a/arch/arm64/kvm/reset.c +++ b/arch/arm64/kvm/reset.c @@ -123,6 +123,9 @@ int kvm_reset_vcpu(struct kvm_vcpu *vcpu) int ret = -EINVAL; bool loaded; + /* Reset PMU outside of the non-preemptible section */ + kvm_pmu_vcpu_reset(vcpu); + preempt_disable(); loaded = (vcpu->cpu != -1); if (loaded) @@ -170,9 +173,6 @@ int kvm_reset_vcpu(struct kvm_vcpu *vcpu) vcpu->arch.reset_state.reset = false; } - /* Reset PMU */ - kvm_pmu_vcpu_reset(vcpu); - /* Default workaround setup is enabled (if supported) */ if (kvm_arm_have_ssbd() == KVM_SSBD_KERNEL) vcpu->arch.workaround_flags |= VCPU_WORKAROUND_2_FLAG; -- 2.19.1