From nobody Sun Feb 8 14:10:51 2026 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1ECDCEB64DA for ; Tue, 18 Jul 2023 09:14:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232208AbjGRJOX (ORCPT ); Tue, 18 Jul 2023 05:14:23 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53192 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230230AbjGRJOK (ORCPT ); Tue, 18 Jul 2023 05:14:10 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C837EE60 for ; Tue, 18 Jul 2023 02:13:22 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1689671602; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=4WlIkr5Df/8dGsk772CbAon6bnUBTqjKXV9qoX9zRiI=; b=XuWIn0EFCjTct5C0MhoQUZ8EgY/Cqus0cPO7OCBjJ4YZjZtK8EhrJBCoWifu5jRJufvjww KR2F1S8yFBmuAvg274kvv+53b1zv6cz9nRjybyq5UO2XRWS2Gb7bUCvTS/MunGlX/LUOzR a6j3z8FsyaPYdHAIiBPu4Ysbmok1tCI= Received: from mimecast-mx02.redhat.com (66.187.233.73 [66.187.233.73]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-14-dSfb6Q6kOYqqc21jhdQidA-1; Tue, 18 Jul 2023 05:13:18 -0400 X-MC-Unique: dSfb6Q6kOYqqc21jhdQidA-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.rdu2.redhat.com [10.11.54.7]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 685113803916; Tue, 18 Jul 2023 09:13:18 +0000 (UTC) Received: from localhost.localdomain (unknown [10.45.224.28]) by smtp.corp.redhat.com (Postfix) with ESMTP id ECCAC1454143; Tue, 18 Jul 2023 09:13:15 +0000 (UTC) From: Maxim Levitsky To: kvm@vger.kernel.org Cc: "H. Peter Anvin" , Sean Christopherson , linux-kernel@vger.kernel.org, Thomas Gleixner , Paolo Bonzini , Ingo Molnar , Dave Hansen , x86@kernel.org, Borislav Petkov , Maxim Levitsky Subject: [PATCH 1/3] KVM: x86: VMX: __kvm_apic_update_irr must update the IRR atomically Date: Tue, 18 Jul 2023 12:13:08 +0300 Message-Id: <20230718091310.119672-2-mlevitsk@redhat.com> In-Reply-To: <20230718091310.119672-1-mlevitsk@redhat.com> References: <20230718091310.119672-1-mlevitsk@redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Scanned-By: MIMEDefang 3.1 on 10.11.54.7 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" If APICv is inhibited, then IPIs from peer vCPUs are done by atomically setting bits in IRR. This means, that when __kvm_apic_update_irr copies PIR to IRR, it has to modify IRR atomically as well. Signed-off-by: Maxim Levitsky --- arch/x86/kvm/lapic.c | 18 +++++++++++------- 1 file changed, 11 insertions(+), 7 deletions(-) diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c index e542cf285b5184..b3f57e0f0d64ae 100644 --- a/arch/x86/kvm/lapic.c +++ b/arch/x86/kvm/lapic.c @@ -627,15 +627,19 @@ bool __kvm_apic_update_irr(u32 *pir, void *regs, int = *max_irr) =20 for (i =3D vec =3D 0; i <=3D 7; i++, vec +=3D 32) { pir_val =3D READ_ONCE(pir[i]); - irr_val =3D *((u32 *)(regs + APIC_IRR + i * 0x10)); + irr_val =3D READ_ONCE(*((u32 *)(regs + APIC_IRR + i * 0x10))); + if (pir_val) { + pir_val =3D xchg(&pir[i], 0); + + while (!try_cmpxchg(((u32 *)(regs + APIC_IRR + i * 0x10)), + &irr_val, irr_val | pir_val)); + prev_irr_val =3D irr_val; - irr_val |=3D xchg(&pir[i], 0); - *((u32 *)(regs + APIC_IRR + i * 0x10)) =3D irr_val; - if (prev_irr_val !=3D irr_val) { - max_updated_irr =3D - __fls(irr_val ^ prev_irr_val) + vec; - } + irr_val |=3D pir_val; + + if (prev_irr_val !=3D irr_val) + max_updated_irr =3D __fls(irr_val ^ prev_irr_val) + vec; } if (irr_val) *max_irr =3D __fls(irr_val) + vec; --=20 2.26.3