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 A40EB223DDA; Wed, 13 Aug 2025 10:03:45 +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=1755079427; cv=none; b=tIfI2QSoi56Rxn+pS5BoctqhrhvfSBlVO5MLL6iYP4EZp+pcC1N7lY17Ekhc76Ovj9osdB/ayTNsy0kARHssju/52kR7R4B4czucWUhNRXM/pFra9BULd3j845e1ygTo1QnT3Uw3z25mC+Rbe/QzpOWilkh3O4bhM08friyH75Q= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1755079427; c=relaxed/simple; bh=L8kFq5n5DhigsqusajTj/qcpjGDaFAR2IlXT6u7ZH0k=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=jdjs+JjR7HfTtDj0oJcu13K7QIinwIKp+5HAkJXqVgt+NIXJ1iqmUpQljQuwGVEa0kJdshobSyQdNARPqX+zSwNQlRbp5BfeSHfiruYG7I9Wg1adU40xNB/sISyP97TIKTM+cX+DI+10KzC88q7nmTRHRivh2xjzkVKjuI9aTCw= 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=mC6CQ4Zg; 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="mC6CQ4Zg" 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=L8kFq5n5DhigsqusajTj/qcpjGDaFAR2IlXT6u7ZH0k=; b=mC6CQ4ZgDkj+YEbFwuSQQb9MYZ S1ewtVPLIjokHu5Iivy8swoE3oP1OXD6Cjh+X89s1hG5vD6ZNAgj46pkHFbVAiYuldnzq2PBgmJeI atmMu65eHHQwRs0NiIOgpen5iPWUHpId9NUFYmuXaSLl2vrxl5VsDfqoblgtWNgGnbk6MXxHS66qV 7izHIPr048vjbOtWoK5xlEJSHLrFtUHmIJwvNDqDKlPeASABplFVkzf8vVrHwP0rjox8W/jHwGYZh T/6Id8HoYFubNv2GYm6BSiHnk1PLyMVSYB3E02eSV1g7VaM4gjAE9nmnGlahAsvQ24WiBboTy3SM2 XM9LOIBw==; Received: from 54-240-197-231.amazon.com ([54.240.197.231] helo=u09cd745991455d.ant.amazon.com) by casper.infradead.org with esmtpsa (Exim 4.98.2 #2 (Red Hat Linux)) id 1um8KF-00000007e8Y-3MBI; Wed, 13 Aug 2025 10:03:20 +0000 Message-ID: Subject: Re: [PATCH] KVM: x86: Synchronize APIC State with QEMU when irqchip=split From: David Woodhouse To: hugo lee Cc: Sean Christopherson , 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: Wed, 13 Aug 2025 12:03:18 +0200 In-Reply-To: References: <20250806081051.3533470-1-hugoolli@tencent.com> Content-Type: multipart/signed; micalg="sha-256"; protocol="application/pkcs7-signature"; boundary="=-/YFUhZ6CjRGl5DLVOFsi" 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 --=-/YFUhZ6CjRGl5DLVOFsi Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Wed, 2025-08-13 at 17:30 +0800, hugo lee wrote: >=20 > Sorry for the misleading, what I was going to say is > do only cpu_synchroniza_state() in this new userspace exit reason > and do nothing on the PIT. > So QEMU will ignore the PIT as the guests do. >=20 > The resample is great and needed, but the synchronization > makes more sense to me on this question. So if the guest doesn't actually quiesce the PIT, QEMU will *still* keep waking up to waggle the PIT output pin, it's just that QEMU won't bother telling the kernel about it? --=-/YFUhZ6CjRGl5DLVOFsi 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 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