From nobody Sun Feb 8 10:49:00 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 34190C3DA7A for ; Fri, 6 Jan 2023 01:14:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235836AbjAFBON (ORCPT ); Thu, 5 Jan 2023 20:14:13 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37316 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236738AbjAFBN3 (ORCPT ); Thu, 5 Jan 2023 20:13:29 -0500 Received: from mail-pg1-x54a.google.com (mail-pg1-x54a.google.com [IPv6:2607:f8b0:4864:20::54a]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id EAB6371FC2 for ; Thu, 5 Jan 2023 17:13:28 -0800 (PST) Received: by mail-pg1-x54a.google.com with SMTP id g32-20020a635660000000b00478c21b8095so208173pgm.10 for ; Thu, 05 Jan 2023 17:13:28 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:reply-to:from:to:cc:subject:date:message-id:reply-to; bh=vMUnRQfVbAJv33RqxFDNJJJTw+ranbI7U0SAs08XATU=; b=G0S4DPyFrd2Oopyroqh9Cz+8c5WqAKldFy75kkimMEIxV5yGuhY63/jc5SSl8Gm6ow h5k5dfPgQ6cySfnnFTdy3suRsCkubzhnft2Qb4DNgZ1K1z0/K4m86z1Olk1zTNEn+vcb Vvlp7boDP/jU4GYiHSbAB3/mC9kpQZp+L4sF80R2yV45vQnY3+3593a/0icBu71baSWr d2cGicwM/cN95qmenJDi+9o+Y3+/tOjD9WduMIyXiwssF32BUmqVMegBR+dcwcb7po3U 7ZqHfbVAX+YJKOPNoAaqKvi7dAO1uVxczzvvi+hh2CIBiLRoQ6u1fALpCpM1WolSrWs9 1Ntw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:from:subject:message-id:references:mime-version:in-reply-to :date:reply-to:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=vMUnRQfVbAJv33RqxFDNJJJTw+ranbI7U0SAs08XATU=; b=Y1tNan+K5930J1K4liXQeGJUmOncEz7txTs+wdQm9R+thv2Es2FgaHJY0vh2TvUopG +bgGzpK4sJmuqympl38SxMJ/ddjik5ESkQ9a8WxeO+pVnKOhM+7ZgIRu6j0dgfHw4McP xawzTapsEK65s25Ue5a68IMCIQEDaBlI8X92fflYRJjKcyATMItygMSdyieXmJwF623C edFK7d+U/l8nLhqo/60acYmy1nLRlICDTXNFDMrUL3kWQ3xYLj9QwTWQSOi5Wz2FbXCp lL6PPzd1nXiN34W3msEvxtePZ8Vdbkiv3aDHruUmcgh3j0nStRK70vVa2Y6yGs26hS5Q AWjQ== X-Gm-Message-State: AFqh2kqya7CKyvu2Z05YwjsPsc2nKeb7WedE7FtxWis9y8j+5mzWj4K6 YSp+7NSGB5Kaf+Njm3BlsKFkw/7G5Uk= X-Google-Smtp-Source: AMrXdXuudHup8qpImaQf0/5abeg0Y+xEfxUzUer6fZO+gAvhbkcBPXjm11rIZkOPqnYsqI6yl/Ume75/0NA= X-Received: from zagreus.c.googlers.com ([fda3:e722:ac3:cc00:7f:e700:c0a8:5c37]) (user=seanjc job=sendgmr) by 2002:a05:6a00:2451:b0:580:9b0b:4fde with SMTP id d17-20020a056a00245100b005809b0b4fdemr3392591pfj.49.1672967608513; Thu, 05 Jan 2023 17:13:28 -0800 (PST) Reply-To: Sean Christopherson Date: Fri, 6 Jan 2023 01:12:41 +0000 In-Reply-To: <20230106011306.85230-1-seanjc@google.com> Mime-Version: 1.0 References: <20230106011306.85230-1-seanjc@google.com> X-Mailer: git-send-email 2.39.0.314.g84b9a713c41-goog Message-ID: <20230106011306.85230-9-seanjc@google.com> Subject: [PATCH v5 08/33] KVM: x86: Handle APICv updates for APIC "mode" changes via request From: Sean Christopherson To: Sean Christopherson , Paolo Bonzini Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Alejandro Jimenez , Maxim Levitsky , Suravee Suthikulpanit , Li RongQing , Greg Edwards Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" Use KVM_REQ_UPDATE_APICV to react to APIC "mode" changes, i.e. to handle the APIC being hardware enabled/disabled and/or x2APIC being toggled. There is no need to immediately update APICv state, the only requirement is that APICv be updating prior to the next VM-Enter. Making a request will allow piggybacking KVM_REQ_UPDATE_APICV to "inhibit" the APICv memslot when x2APIC is enabled. Doing that directly from kvm_lapic_set_base() isn't feasible as KVM's SRCU must not be held when modifying memslots (to avoid deadlock), and may or may not be held when kvm_lapic_set_base() is called, i.e. KVM can't do the right thing without tracking that is rightly buried behind CONFIG_PROVE_RCU=3Dy. Suggested-by: Maxim Levitsky Reviewed-by: Maxim Levitsky Signed-off-by: Sean Christopherson --- arch/x86/kvm/lapic.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c index 2183a9b8efa5..3ed74ad60516 100644 --- a/arch/x86/kvm/lapic.c +++ b/arch/x86/kvm/lapic.c @@ -2401,7 +2401,7 @@ void kvm_lapic_set_base(struct kvm_vcpu *vcpu, u64 va= lue) kvm_apic_set_x2apic_id(apic, vcpu->vcpu_id); =20 if ((old_value ^ value) & (MSR_IA32_APICBASE_ENABLE | X2APIC_ENABLE)) { - kvm_vcpu_update_apicv(vcpu); + kvm_make_request(KVM_REQ_APICV_UPDATE, vcpu); static_call_cond(kvm_x86_set_virtual_apic_mode)(vcpu); } =20 --=20 2.39.0.314.g84b9a713c41-goog