From patchwork Mon Mar 15 13:56:09 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg KH X-Patchwork-Id: 401149 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 72384C41620 for ; Mon, 15 Mar 2021 14:10:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 524A164F1A for ; Mon, 15 Mar 2021 14:10:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234790AbhCOOKB (ORCPT ); Mon, 15 Mar 2021 10:10:01 -0400 Received: from mail.kernel.org ([198.145.29.99]:52902 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234632AbhCOOEf (ORCPT ); Mon, 15 Mar 2021 10:04:35 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 1C0D764DAD; Mon, 15 Mar 2021 14:04:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1615817074; bh=dLggE5UcIHdTZxiVTcRYvG1zoFKMcwZg9ZMurFrMvKQ=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=zR61yK5Z0zYeWtMQCZ/K0GDdCq58+s3AYSjBKiL/tUQ4HFYObIotCZYg10eWvWn5U nxIPrDcVWwxFQoFHSS4RLMtI8IW3jqfb9kOaVfUbeKb9jyjdu4Op613fKukMbPJoPX M0M8ufdCl/W7siHYNmNYur/n2SRVB6xdkRvhCKIw= From: gregkh@linuxfoundation.org To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Sean Christopherson , Paolo Bonzini Subject: [PATCH 5.10 276/290] KVM: x86: Ensure deadline timer has truly expired before posting its IRQ Date: Mon, 15 Mar 2021 14:56:09 +0100 Message-Id: <20210315135551.359947615@linuxfoundation.org> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210315135541.921894249@linuxfoundation.org> References: <20210315135541.921894249@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; }