From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 475EA2EFD9C; Tue, 12 Aug 2025 10:46:21 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=90.155.50.34 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1754995582; cv=none; b=CxK2SpZSFKJQixzySIozxu05frLt8cfd2a+h1MJWZ/vFAWq6e42Iq8W7dG0OA4Ixudjv636vb0MpUXsmozSeWx/8MiI2T3JJjBUnXHQeFguWihG4ldX+27rvzJrogr9aGW+jlNLzvIFJWNW15JMNbnkTaxJrNMuWcJDm47P4AoE= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1754995582; c=relaxed/simple; bh=pmMhsQf5CMo+3Ho8xP1cyZDCl4RaFaa9YcloHl2GNlU=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=rPMDgoBkezPYzTCpiyHVPfhTj1T/C5FiFEBAcslpGQvJ2PpIJeFEdMnLhfVh/LXo2Gu81BWvxTIrmnF7S851OaM/Nuh4gyZJ1BGjNPeeevmYAB2T14yq4mcP6fiC+stTCruOD4Ta4rSSQeS68lKlMy+lnkkaeGZSACAOpkytJcQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org; spf=none smtp.mailfrom=casper.srs.infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=O6yuFL46; arc=none smtp.client-ip=90.155.50.34 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=casper.srs.infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="O6yuFL46" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=MIME-Version:Content-Type:References: In-Reply-To:Date:Cc:To:From:Subject:Message-ID:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=pmMhsQf5CMo+3Ho8xP1cyZDCl4RaFaa9YcloHl2GNlU=; b=O6yuFL46KEs90BaXxyr9smvZJ7 68yAlcD2TrcBEM1BPIKoRxCnU9Put27vLrZuEoR0Fa4QiPk7HoztmUYCBP+GCWIfqp5d6xp3tIPIO dC2hp0GrW4Gomq1SHHYDzTEAdjaW9HAM32AuGCosi3OgpBJLizcuT+6T86mIR6JjasuZQUFxFMkYw 6Rql11xkpLItLpGIee0l6FyojvRSp44KWE6NAlQZZ1ksie31mN5bcELASDolRW2fiofi6XmA2sa9R lWmWz+9n5I662u2I/S5PAMLPPKAmHnP+ZIgb9TyiR2lfOEhdywU1THbwiZt/LMU0vUA++hHwZBAYU olJuyZMg==; Received: from [54.239.6.185] (helo=u09cd745991455d.ant.amazon.com) by casper.infradead.org with esmtpsa (Exim 4.98.2 #2 (Red Hat Linux)) id 1ulmW1-0000000FQVQ-2hjA; Tue, 12 Aug 2025 10:46:02 +0000 Message-ID: Subject: Re: [PATCH] KVM: x86: Synchronize APIC State with QEMU when irqchip=split From: David Woodhouse To: hugo lee , Sean Christopherson Cc: pbonzini@redhat.com, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, hpa@zytor.com, x86@kernel.org, kvm@vger.kernel.org, linux-kernel@vger.kernel.org, Yuguo Li Date: Tue, 12 Aug 2025 12:46:01 +0200 In-Reply-To: References: <20250806081051.3533470-1-hugoolli@tencent.com> Content-Type: multipart/signed; micalg="sha-256"; protocol="application/pkcs7-signature"; boundary="=-NYxdVI700yCS2X7ugkeQ" User-Agent: Evolution 3.52.3-0ubuntu1 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-SRS-Rewrite: SMTP reverse-path rewritten from by casper.infradead.org. See http://www.infradead.org/rpr.html --=-NYxdVI700yCS2X7ugkeQ Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Tue, 2025-08-12 at 18:08 +0800, hugo lee wrote: >=20 > On some legacy bios images using guests, they may disable PIT > after booting. Do you mean they may *not* disable the PIT after booting? Linux had that problem for a long time, until I fixed it with https://git.kernel.org/torvalds/c/70e6b7d9ae3 > When irqchip=3Dsplit is on, qemu will keep kicking the guest and try to > get the Big QEMU Lock. If it's the PIT, surely QEMU will keep stealing time pointlessly unless we actually disable the PIT itself? Not just the IRQ delivery? Or do you use this to realise that the IRQ output from the PIT isn't going anywhere and thus disable the event in QEMU completely?=20 --=-NYxdVI700yCS2X7ugkeQ Content-Type: application/pkcs7-signature; name="smime.p7s" Content-Disposition: attachment; filename="smime.p7s" Content-Transfer-Encoding: base64 MIAGCSqGSIb3DQEHAqCAMIACAQExDzANBglghkgBZQMEAgEFADCABgkqhkiG9w0BBwEAAKCCD9Aw ggSOMIIDdqADAgECAhAOmiw0ECVD4cWj5DqVrT9PMA0GCSqGSIb3DQEBCwUAMGUxCzAJBgNVBAYT AlVTMRUwEwYDVQQKEwxEaWdpQ2VydCBJbmMxGTAXBgNVBAsTEHd3dy5kaWdpY2VydC5jb20xJDAi BgNVBAMTG0RpZ2lDZXJ0IEFzc3VyZWQgSUQgUm9vdCBDQTAeFw0yNDAxMzAwMDAwMDBaFw0zMTEx MDkyMzU5NTlaMEExCzAJBgNVBAYTAkFVMRAwDgYDVQQKEwdWZXJva2V5MSAwHgYDVQQDExdWZXJv a2V5IFNlY3VyZSBFbWFpbCBHMjCCASIwDQYJKoZIhvcNAQEBBQADggEPADCCAQoCggEBAMjvgLKj jfhCFqxYyRiW8g3cNFAvltDbK5AzcOaR7yVzVGadr4YcCVxjKrEJOgi7WEOH8rUgCNB5cTD8N/Et GfZI+LGqSv0YtNa54T9D1AWJy08ZKkWvfGGIXN9UFAPMJ6OLLH/UUEgFa+7KlrEvMUupDFGnnR06 aDJAwtycb8yXtILj+TvfhLFhafxroXrflspavejQkEiHjNjtHnwbZ+o43g0/yxjwnarGI3kgcak7 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