From patchwork Mon Mar 15 13:55:55 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 401147 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=-19.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, 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 9A38AC43381 for ; Mon, 15 Mar 2021 14:10:38 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 88A6A64F34 for ; Mon, 15 Mar 2021 14:10:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234037AbhCOOKH (ORCPT ); Mon, 15 Mar 2021 10:10:07 -0400 Received: from mail.kernel.org ([198.145.29.99]:52502 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234661AbhCOOEp (ORCPT ); Mon, 15 Mar 2021 10:04:45 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 88AE864EFD; Mon, 15 Mar 2021 14:04:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1615817084; bh=dLggE5UcIHdTZxiVTcRYvG1zoFKMcwZg9ZMurFrMvKQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=1ORzIRsAQjtwyEIy+HbiRzbowW9d2nGht4MqlvvTaTyrKBMbyQBAbUQNIfy6c0Pqp hHEQbhkeYxm/Df6wLK7LYpd+ZGgeyIyHmRpUdUu6HAOJjl0ZtquBKk1diqBWN8JxCX 4RxgaQXX4fXgDLhby/aDvei1hiGXlmdqKzrcgt+E= From: gregkh@linuxfoundation.org To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Sean Christopherson , Paolo Bonzini Subject: [PATCH 5.11 292/306] KVM: x86: Ensure deadline timer has truly expired before posting its IRQ Date: Mon, 15 Mar 2021 14:55:55 +0100 Message-Id: <20210315135517.556638562@linuxfoundation.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210315135507.611436477@linuxfoundation.org> References: <20210315135507.611436477@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Greg Kroah-Hartman From: Sean Christopherson commit beda430177f56656e7980dcce93456ffaa35676b upstream. When posting a deadline timer interrupt, open code the checks guarding __kvm_wait_lapic_expire() in order to skip the lapic_timer_int_injected() check in kvm_wait_lapic_expire(). The injection check will always fail since the interrupt has not yet be injected. Moving the call after injection would also be wrong as that wouldn't actually delay delivery of the IRQ if it is indeed sent via posted interrupt. Fixes: 010fd37fddf6 ("KVM: LAPIC: Reduce world switch latency caused by timer_advance_ns") Cc: stable@vger.kernel.org Signed-off-by: Sean Christopherson Message-Id: <20210305021808.3769732-1-seanjc@google.com> Signed-off-by: Paolo Bonzini Signed-off-by: Greg Kroah-Hartman --- arch/x86/kvm/lapic.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) --- a/arch/x86/kvm/lapic.c +++ b/arch/x86/kvm/lapic.c @@ -1641,7 +1641,16 @@ static void apic_timer_expired(struct kv } if (kvm_use_posted_timer_interrupt(apic->vcpu)) { - kvm_wait_lapic_expire(vcpu); + /* + * Ensure the guest's timer has truly expired before posting an + * interrupt. Open code the relevant checks to avoid querying + * lapic_timer_int_injected(), which will be false since the + * interrupt isn't yet injected. Waiting until after injecting + * is not an option since that won't help a posted interrupt. + */ + if (vcpu->arch.apic->lapic_timer.expired_tscdeadline && + vcpu->arch.apic->lapic_timer.timer_advance_ns) + __kvm_wait_lapic_expire(vcpu); kvm_apic_inject_pending_timer_irqs(apic); return; }