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 5047A2882A9; Mon, 23 Jun 2025 16:44:31 +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=1750697072; cv=none; b=IjWubmMkRBxr9KQnAYTlcgwPFR/V13g5hsVQ1yVThrekzWPXw1xn8typkkciwIFGJNOUcQPTg8JdtVYMpHQvCLX60xh0IYapXZH07hdmUE+pHt8Zn1KKLz4qP1tksrbxPXv8jj1oibaS0cSbIdoSKVL5B8YKQ1YBfp+0salmVAo= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1750697072; c=relaxed/simple; bh=Emiq1FV1ttr+CBNmWAmNnJ/s86V/e3girU5btU4QwPQ=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=dchZGYft+s/lYOtHJep0UupoOvPLRLo1Pb2FTn3GeIQz2I6hPzKQu9vu8ZMcWUWdUvU56CZrz5FKWzDWJhoUDH4jy4QdIJdp1wan7XY1IZebbqaYKGDZNP4QTsbRS/nuwej3YnBSCUlqqmP7bKd17mDsj4pWA/3YvfvVDvuf0zA= 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=UzMl5v4n; 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="UzMl5v4n" 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=Emiq1FV1ttr+CBNmWAmNnJ/s86V/e3girU5btU4QwPQ=; b=UzMl5v4nndQiWGcH2Bx6PJaF7I VZvQxcSDg0o0f8vqZ046n310EJ51F93F5fdG1CizxKYWqSgtzQF/T/KrCBqIKnFdkZcqxBYXfhqon AhHABBkMIijxRdTruKXXWjVbd9+aO0I9VCRfNT0WxuO/Sl44iNwo/ZuRbvf58pBdhh7V1oWLq1fW4 8oSy14zR6B754oZT4lYCNU8eduEdQIFifKL97YuS1ngVP39InKA3i7lmGW43RSD7IJP7mQw8F+WfB EZI3leGwAbz2wGgDPF8hP9hPhBaViDDgTJfO1deu0cRuql/CiI6/mOheBqWVwoSWjC6fFypX5lbRD yQD1Jy0g==; Received: from [54.239.6.189] (helo=edge-cache-144.e-fra50.amazon.com) by casper.infradead.org with esmtpsa (Exim 4.98.2 #2 (Red Hat Linux)) id 1uTkHU-0000000425N-08Yt; Mon, 23 Jun 2025 16:44:28 +0000 Message-ID: <7cc618b80681e8e1402c73886505f6247c810db8.camel@infradead.org> Subject: Re: KVM: x86/xen: Allow 'out of range' event channel ports in IRQ routing table. From: David Woodhouse To: paul@xen.org, kvm@vger.kernel.org, Sean Christopherson , "Orlov, Ivan" Cc: Paolo Bonzini , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , x86@kernel.org, "H. Peter Anvin" , linux-kernel@vger.kernel.org Date: Mon, 23 Jun 2025 18:44:26 +0200 In-Reply-To: <7fedbeac-300f-48a3-9860-e05b6d286cd1@xen.org> References: <7fedbeac-300f-48a3-9860-e05b6d286cd1@xen.org> Content-Type: multipart/signed; micalg="sha-256"; protocol="application/pkcs7-signature"; boundary="=-CCM+5jMfWnH/MfFJSdvZ" User-Agent: Evolution 3.52.3-0ubuntu1 Precedence: bulk X-Mailing-List: kvm@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 --=-CCM+5jMfWnH/MfFJSdvZ Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable On Mon, 2025-05-12 at 10:29 +0100, Paul Durrant wrote: > On 08/05/2025 21:30, David Woodhouse wrote: > > From: David Woodhouse > >=20 > > To avoid imposing an ordering constraint on userspace, allow 'invalid' > > event channel targets to be configured in the IRQ routing table. > >=20 > > This is the same as accepting interrupts targeted at vCPUs which don't > > exist yet, which is already the case for both Xen event channels *and* > > for MSIs (which don't do any filtering of permitted APIC ID targets at > > all). > >=20 > > If userspace actually *triggers* an IRQ with an invalid target, that > > will fail cleanly, as kvm_xen_set_evtchn_fast() also does the same rang= e > > check. > >=20 > > If KVM enforced that the IRQ target must be valid at the time it is > > *configured*, that would force userspace to create all vCPUs and do > > various other parts of setup (in this case, setting the Xen long_mode) > > before restoring the IRQ table. > >=20 > > Cc: stable@vger.kernel.org > > Signed-off-by: David Woodhouse > > --- > > =C2=A0 arch/x86/kvm/xen.c | 14 ++++++++++++-- > > =C2=A0 1 file changed, 12 insertions(+), 2 deletions(-) > >=20 >=20 > Reviewed-by: Paul Durrant Ping? --=-CCM+5jMfWnH/MfFJSdvZ Content-Type: application/pkcs7-signature; name="smime.p7s" Content-Disposition: attachment; filename="smime.p7s" Content-Transfer-Encoding: base64 MIAGCSqGSIb3DQEHAqCAMIACAQExDzANBglghkgBZQMEAgEFADCABgkqhkiG9w0BBwEAAKCCD9Aw ggSOMIIDdqADAgECAhAOmiw0ECVD4cWj5DqVrT9PMA0GCSqGSIb3DQEBCwUAMGUxCzAJBgNVBAYT AlVTMRUwEwYDVQQKEwxEaWdpQ2VydCBJbmMxGTAXBgNVBAsTEHd3dy5kaWdpY2VydC5jb20xJDAi BgNVBAMTG0RpZ2lDZXJ0IEFzc3VyZWQgSUQgUm9vdCBDQTAeFw0yNDAxMzAwMDAwMDBaFw0zMTEx MDkyMzU5NTlaMEExCzAJBgNVBAYTAkFVMRAwDgYDVQQKEwdWZXJva2V5MSAwHgYDVQQDExdWZXJv a2V5IFNlY3VyZSBFbWFpbCBHMjCCASIwDQYJKoZIhvcNAQEBBQADggEPADCCAQoCggEBAMjvgLKj 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