From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-7.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3F419C433EF for ; Thu, 23 Sep 2021 04:45:11 +0000 (UTC) Received: from lists.xenproject.org (lists.xenproject.org [192.237.175.120]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id DF24561090 for ; Thu, 23 Sep 2021 04:45:10 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org DF24561090 Authentication-Results: mail.kernel.org; dmarc=fail (p=quarantine dis=none) header.from=suse.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=lists.xenproject.org Received: from list by lists.xenproject.org with outflank-mailman.193411.344495 (Exim 4.92) (envelope-from ) id 1mTGbQ-0006tE-05; Thu, 23 Sep 2021 04:44:56 +0000 X-Outflank-Mailman: Message body and most headers restored to incoming version Received: by outflank-mailman (output) from mailman id 193411.344495; Thu, 23 Sep 2021 04:44:55 +0000 Received: from localhost ([127.0.0.1] helo=lists.xenproject.org) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1mTGbP-0006t7-T0; Thu, 23 Sep 2021 04:44:55 +0000 Received: by outflank-mailman (input) for mailman id 193411; Thu, 23 Sep 2021 04:44:54 +0000 Received: from all-amaz-eas1.inumbo.com ([34.197.232.57] helo=us1-amaz-eas2.inumbo.com) by lists.xenproject.org with esmtp (Exim 4.92) (envelope-from ) id 1mTGbO-0006t1-2d for xen-devel@lists.xenproject.org; Thu, 23 Sep 2021 04:44:54 +0000 Received: from smtp-out1.suse.de (unknown [195.135.220.28]) by us1-amaz-eas2.inumbo.com (Halon) with ESMTPS id fda70712-1c28-11ec-ba13-12813bfff9fa; Thu, 23 Sep 2021 04:44:52 +0000 (UTC) Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out1.suse.de (Postfix) with ESMTPS id C5C5822304; Thu, 23 Sep 2021 04:44:51 +0000 (UTC) Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id 7D2B113DBB; Thu, 23 Sep 2021 04:44:51 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id TWNPHUMGTGHlNwAAMHmgww (envelope-from ); Thu, 23 Sep 2021 04:44:51 +0000 X-BeenThere: xen-devel@lists.xenproject.org List-Id: Xen developer discussion List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Errors-To: xen-devel-bounces@lists.xenproject.org Precedence: list Sender: "Xen-devel" X-Inumbo-ID: fda70712-1c28-11ec-ba13-12813bfff9fa DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1632372291; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=6DS1OShxkN081ActC9VohxvjjWhXQsUmGfkvB+j0Sq4=; b=NxKyAbJyMgEPCr4dSNHUkVYCcpBq8h4ByundRC9cvA4lsE4KPrue+SiaBi7yzhPxl8HhrZ jITXbjboLxn7r1+fA/d5DKm+Zm0Xfc1CWQa4nDujoUZwGkWwpVQayUeMYhV+ZlPw+OjWsd TrSZkpkSTvUiO0G1dTM319PHna12LRo= Subject: Re: [PATCH v2 1/2] x86/xen: remove xen_have_vcpu_info_placement flag To: Boris Ostrovsky , xen-devel@lists.xenproject.org, x86@kernel.org, linux-kernel@vger.kernel.org Cc: peterz@infradead.org, Stefano Stabellini , Thomas Gleixner , Ingo Molnar , Borislav Petkov , "H. Peter Anvin" References: <20210922103102.3589-1-jgross@suse.com> <20210922103102.3589-2-jgross@suse.com> <212d31cd-650d-27c6-b523-fd4f686872d1@oracle.com> From: Juergen Gross Message-ID: <7de79902-e31b-899d-44bb-f9daabb2ecf0@suse.com> Date: Thu, 23 Sep 2021 06:44:50 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.12.0 MIME-Version: 1.0 In-Reply-To: <212d31cd-650d-27c6-b523-fd4f686872d1@oracle.com> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="7p42MbmcR2R1URc5b0nLq1zIkTD8u7F9m" This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --7p42MbmcR2R1URc5b0nLq1zIkTD8u7F9m Content-Type: multipart/mixed; boundary="IlXSuJXAwFX31QSGBlKtSGJwPbIgwtFQl"; protected-headers="v1" From: Juergen Gross To: Boris Ostrovsky , xen-devel@lists.xenproject.org, x86@kernel.org, linux-kernel@vger.kernel.org Cc: peterz@infradead.org, Stefano Stabellini , Thomas Gleixner , Ingo Molnar , Borislav Petkov , "H. Peter Anvin" Message-ID: <7de79902-e31b-899d-44bb-f9daabb2ecf0@suse.com> Subject: Re: [PATCH v2 1/2] x86/xen: remove xen_have_vcpu_info_placement flag References: <20210922103102.3589-1-jgross@suse.com> <20210922103102.3589-2-jgross@suse.com> <212d31cd-650d-27c6-b523-fd4f686872d1@oracle.com> In-Reply-To: <212d31cd-650d-27c6-b523-fd4f686872d1@oracle.com> --IlXSuJXAwFX31QSGBlKtSGJwPbIgwtFQl Content-Type: multipart/mixed; boundary="------------2D82B1FDA2C0BF04A0178389" Content-Language: en-US This is a multi-part message in MIME format. --------------2D82B1FDA2C0BF04A0178389 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: quoted-printable On 22.09.21 23:43, Boris Ostrovsky wrote: >=20 > On 9/22/21 6:31 AM, Juergen Gross wrote: >> =20 >> - if (xen_have_vcpu_info_placement) { >> - vcpup =3D &per_cpu(xen_vcpu_info, cpu); >> - info.mfn =3D arbitrary_virt_to_mfn(vcpup); >> - info.offset =3D offset_in_page(vcpup); >> + vcpup =3D &per_cpu(xen_vcpu_info, cpu); >> + info.mfn =3D arbitrary_virt_to_mfn(vcpup); >> + info.offset =3D offset_in_page(vcpup); >> =20 >> - /* >> - * Check to see if the hypervisor will put the vcpu_info >> - * structure where we want it, which allows direct access via >> - * a percpu-variable. >> - * N.B. This hypercall can _only_ be called once per CPU. >> - * Subsequent calls will error out with -EINVAL. This is due to >> - * the fact that hypervisor has no unregister variant and this >> - * hypercall does not allow to over-write info.mfn and >> - * info.offset. >> - */ >> - err =3D HYPERVISOR_vcpu_op(VCPUOP_register_vcpu_info, >> - xen_vcpu_nr(cpu), &info); >> - >> - if (err) { >> - pr_warn_once("register_vcpu_info failed: cpu=3D%d err=3D%d\n", >> - cpu, err); >> - xen_have_vcpu_info_placement =3D 0; >> - } else { >> - /* >> - * This cpu is using the registered vcpu info, even if >> - * later ones fail to. >> - */ >> - per_cpu(xen_vcpu, cpu) =3D vcpup; >> - } >> - } >> - >> - if (!xen_have_vcpu_info_placement) >> - xen_vcpu_info_reset(cpu); >> + /* >> + * N.B. This hypercall can _only_ be called once per CPU. >> + * Subsequent calls will error out with -EINVAL. This is due to >> + * the fact that hypervisor has no unregister variant and this >> + * hypercall does not allow to over-write info.mfn and >> + * info.offset. >> + */ >> + err =3D HYPERVISOR_vcpu_op(VCPUOP_register_vcpu_info, xen_vcpu_nr(cp= u), >> + &info); >> + if (err) >> + panic("register_vcpu_info failed: cpu=3D%d err=3D%d\n", cpu, err); >> =20 >=20 >=20 > This is change in behavior. Before if the hypercall failed we still try= to boot. I am not sure we need to worry about this (since it's not clear= it actually works)=C2=A0 but I'd at least mention this in the commit mes= sage. Hmm, maybe I should have been more explicit saying that the hypercall was introduced in Xen 3.4, and only reason of failure is either an illegal vcpu, an invalid mapping specification, or a try to reissue the hypercall for a vcpu. None of those should ever happen. Juergen --------------2D82B1FDA2C0BF04A0178389 Content-Type: application/pgp-keys; name="OpenPGP_0xB0DE9DD628BF132F.asc" Content-Transfer-Encoding: quoted-printable Content-Description: OpenPGP public key Content-Disposition: attachment; filename="OpenPGP_0xB0DE9DD628BF132F.asc" -----BEGIN PGP PUBLIC KEY BLOCK----- xsBNBFOMcBYBCACgGjqjoGvbEouQZw/ToiBg9W98AlM2QHV+iNHsEs7kxWhKMjrioyspZKOBy= cWx w3ie3j9uvg9EOB3aN4xiTv4qbnGiTr3oJhkB1gsb6ToJQZ8uxGq2kaV2KL9650I1SJvedYm8O= f8Z d621lSmoKOwlNClALZNew72NjJLEzTalU1OdT7/i1TXkH09XSSI8mEQ/ouNcMvIJNwQpd369y= 9bf IhWUiVXEK7MlRgUG6MvIj6Y3Am/BBLUVbDa4+gmzDC9ezlZkTZG2t14zWPvxXP3FAp2pkW0xq= G7/ 377qptDmrk42GlSKN4z76ELnLxussxc7I2hx18NUcbP8+uty4bMxABEBAAHNHEp1ZXJnZW4gR= 3Jv c3MgPGpnQHBmdXBmLm5ldD7CwHkEEwECACMFAlOMcBYCGwMHCwkIBwMCAQYVCAIJCgsEFgIDA= QIe AQIXgAAKCRCw3p3WKL8TL0KdB/93FcIZ3GCNwFU0u3EjNbNjmXBKDY4FUGNQH2lvWAUy+dnyT= hpw dtF/jQ6j9RwE8VP0+NXcYpGJDWlNb9/JmYqLiX2Q3TyevpB0CA3dbBQp0OW0fgCetToGIQrg0= MbD 1C/sEOv8Mr4NAfbauXjZlvTj30H2jO0u+6WGM6nHwbh2l5O8ZiHkH32iaSTfN7Eu5RnNVUJbv= oPH Z8SlM4KWm8rG+lIkGurqqu5gu8q8ZMKdsdGC4bBxdQKDKHEFExLJK/nRPFmAuGlId1E3fe10v= 5QL +qHI3EIPtyfE7i9Hz6rVwi7lWKgh7pe0ZvatAudZ+JNIlBKptb64FaiIOAWDCx1SzR9KdWVyZ= 2Vu IEdyb3NzIDxqZ3Jvc3NAc3VzZS5jb20+wsB5BBMBAgAjBQJTjHCvAhsDBwsJCAcDAgEGFQgCC= QoL BBYCAwECHgECF4AACgkQsN6d1ii/Ey/HmQf/RtI7kv5A2PS4RF7HoZhPVPogNVbC4YA6lW7Dr= Wf0 teC0RR3MzXfy6pJ+7KLgkqMlrAbN/8Dvjoz78X+5vhH/rDLa9BuZQlhFmvcGtCF8eR0T1v0nC= /nu AFVGy+67q2DH8As3KPu0344TBDpAvr2uYM4tSqxK4DURx5INz4ZZ0WNFHcqsfvlGJALDeE0Lh= ITT d9jLzdDad1pQSToCnLl6SBJZjDOX9QQcyUigZFtCXFst4dlsvddrxyqT1f17+2cFSdu7+ynLm= XBK 7abQ3rwJY8SbRO2iRulogc5vr/RLMMlscDAiDkaFQWLoqHHOdfO9rURssHNN8WkMnQfvUewRz= 80h SnVlcmdlbiBHcm9zcyA8amdyb3NzQG5vdmVsbC5jb20+wsB5BBMBAgAjBQJTjHDXAhsDBwsJC= AcD AgEGFQgCCQoLBBYCAwECHgECF4AACgkQsN6d1ii/Ey8PUQf/ehmgCI9jB9hlgexLvgOtf7PJn= FOX gMLdBQgBlVPO3/D9R8LtF9DBAFPNhlrsfIG/SqICoRCqUcJ96Pn3P7UUinFG/I0ECGF4EvTE1= jnD kfJZr6jrbjgyoZHiw/4BNwSTL9rWASyLgqlA8u1mf+c2yUwcGhgkRAd1gOwungxcwzwqgljf0= N51 N5JfVRHRtyfwq/ge+YEkDGcTU6Y0sPOuj4Dyfm8fJzdfHNQsWq3PnczLVELStJNdapwPOoE+l= otu fe3AM2vAEYJ9rTz3Cki4JFUsgLkHFqGZarrPGi1eyQcXeluldO3m91NK/1xMI3/+8jbO0tsn1= tqS EUGIJi7ox80eSnVlcmdlbiBHcm9zcyA8amdyb3NzQHN1c2UuZGU+wsB5BBMBAgAjBQJTjHDrA= hsD BwsJCAcDAgEGFQgCCQoLBBYCAwECHgECF4AACgkQsN6d1ii/Ey+LhQf9GL45eU5vOowA2u5N3= g3O ZUEBmDHVVbqMtzwlmNC4k9Kx39r5s2vcFl4tXqW7g9/ViXYuiDXb0RfUpZiIUW89siKrkzmQ5= dM7 wRqzgJpJwK8Bn2MIxAKArekWpiCKvBOB/Cc+3EXE78XdlxLyOi/NrmSGRIov0karw2RzMNOu5= D+j LRZQd1Sv27AR+IP3I8U4aqnhLpwhK7MEy9oCILlgZ1QZe49kpcumcZKORmzBTNh30FVKK1Evm= V2x AKDoaEOgQB4iFQLhJCdP1I5aSgM5IVFdn7v5YgEYuJYx37IoN1EblHI//x/e2AaIHpzK5h88N= Eaw QsaNRpNSrcfbFmAg987ATQRTjHAWAQgAyzH6AOODMBjgfWE9VeCgsrwH3exNAU32gLq2xvjpW= nHI s98ndPUDpnoxWQugJ6MpMncr0xSwFmHEgnSEjK/PAjppgmyc57BwKII3sV4on+gDVFJR6Y8ZR= wgn BC5mVM6JjQ5xDk8WRXljExRfUX9pNhdE5eBOZJrDRoLUmmjDtKzWaDhIg/+1Hzz93X4fCQkNV= bVF LELU9bMaLPBG/x5q4iYZ2k2ex6d47YE1ZFdMm6YBYMOljGkZKwYde5ldM9mo45mmwe0icXKLk= pEd IXKTZeKDO+Hdv1aqFuAcccTg9RXDQjmwhC3yEmrmcfl0+rPghO0Iv3OOImwTEe4co3c1mwARA= QAB wsBfBBgBAgAJBQJTjHAWAhsMAAoJELDendYovxMvQ/gH/1ha96vm4P/L+bQpJwrZ/dneZcmEw= Tbe 8YFsw2V/Buv6Z4Mysln3nQK5ZadD534CF7TDVft7fC4tU4PONxF5D+/tvgkPfDAfF77zy2AH1= vJz Q1fOU8lYFpZXTXIHb+559UqvIB8AdgR3SAJGHHt4RKA0F7f5ipYBBrC6cyXJyyoprT10EMvU8= VGi wXvTyJz3fjoYsdFzpWPlJEBRMedCot60g5dmbdrZ5DWClAr0yau47zpWj3enf1tLWaqcsuylW= svi uGjKGw7KHQd3bxALOknAp4dN3QwBYCKuZ7AddY9yjynVaD5X7nF9nO5BjR/i1DG86lem3iBDX= zXs ZDn8R38=3D =3D2wuH -----END PGP PUBLIC KEY BLOCK----- --------------2D82B1FDA2C0BF04A0178389-- --IlXSuJXAwFX31QSGBlKtSGJwPbIgwtFQl-- --7p42MbmcR2R1URc5b0nLq1zIkTD8u7F9m Content-Type: application/pgp-signature; name="OpenPGP_signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="OpenPGP_signature" -----BEGIN PGP SIGNATURE----- wsB5BAABCAAjFiEEhRJncuj2BJSl0Jf3sN6d1ii/Ey8FAmFMBkIFAwAAAAAACgkQsN6d1ii/Ey/C QAf+MW8NU9ZWXXfs6ZXLLjQIV2BF+hUkXZKRQdnZdeNvIr2UQrI40xq5SihwSro9Tnr9vLldkD/y 2Krat7LKnzMF/MfK5XXm2v9iuTK3Rc/1AYCnovaiDbRJCd+h+3cWWccEyhNEtsjV7m70m9+E9oYV zx0iarlETkSzZfilELCEFvgn037PJveprAhaODuxL8h7JV0zFwkGyUOowQz5TiY/iQ3Nmzv2GzF8 3WS/lzTV8NhJgMqwSVecAUBJkdRG/hCzxBuoTuPuaSp8YBSWwfgCtfWL3Cz1f3aLsBtGH4wi18L5 Wifa075NKRESCVJDxHEM2tbFJVfYiXXe4Wgxg9LwFw== =c79E -----END PGP SIGNATURE----- --7p42MbmcR2R1URc5b0nLq1zIkTD8u7F9m--