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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Fri, 6 Dec 2019 09:30:09 -0000 Received: from d06av25.portsmouth.uk.ibm.com (d06av25.portsmouth.uk.ibm.com [9.149.105.61]) by b06cxnps4076.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id xB69U8N923068704 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 6 Dec 2019 09:30:08 GMT Received: from d06av25.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 4CC4711C052; Fri, 6 Dec 2019 09:30:07 +0000 (GMT) Received: from d06av25.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id BD56711C04A; Fri, 6 Dec 2019 09:30:06 +0000 (GMT) Received: from localhost.localdomain (unknown [9.145.185.65]) by d06av25.portsmouth.uk.ibm.com (Postfix) with ESMTP; Fri, 6 Dec 2019 09:30:06 +0000 (GMT) Subject: Re: [PATCH v2 06/13] s390x: protvirt: KVM intercept changes To: Cornelia Huck References: <20191129094809.26684-1-frankja@linux.ibm.com> <20191129094809.26684-7-frankja@linux.ibm.com> <20191205181532.46bee55c.cohuck@redhat.com> <3cdbba69-c465-f2ce-d3e4-15e0b8d1218e@linux.ibm.com> <20191205184637.4e6f4d23.cohuck@redhat.com> <20191206092913.3af251dd.cohuck@redhat.com> <20191206100821.06b933e8.cohuck@redhat.com> From: Janosch Frank Autocrypt: addr=frankja@linux.ibm.com; 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Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.1.1 MIME-Version: 1.0 In-Reply-To: <20191206100821.06b933e8.cohuck@redhat.com> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="XCkOthSP7zicKPp88Dmd9lBAZuwLoSdLY" X-TM-AS-GCONF: 00 x-cbid: 19120609-0028-0000-0000-000003C5CCCB X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19120609-0029-0000-0000-00002488F1B3 Message-Id: <89bdb9af-d499-588b-9d05-09d83a66a9b4@linux.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.95,18.0.572 definitions=2019-12-06_02:2019-12-04,2019-12-06 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 malwarescore=0 priorityscore=1501 clxscore=1015 mlxscore=0 impostorscore=0 bulkscore=0 mlxlogscore=999 suspectscore=0 adultscore=0 phishscore=0 spamscore=0 lowpriorityscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-1910280000 definitions=main-1912060081 X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x [generic] [fuzzy] X-Received-From: 148.163.156.1 X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.23 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: thuth@redhat.com, pmorel@linux.ibm.com, david@redhat.com, qemu-devel@nongnu.org, borntraeger@de.ibm.com, qemu-s390x@nongnu.org, mihajlov@linux.ibm.com Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --XCkOthSP7zicKPp88Dmd9lBAZuwLoSdLY Content-Type: multipart/mixed; boundary="PQfNkW1ifFEebNM37lR9T2QykSFn917m8" --PQfNkW1ifFEebNM37lR9T2QykSFn917m8 Content-Type: text/plain; charset=windows-1252 Content-Language: en-US Content-Transfer-Encoding: quoted-printable On 12/6/19 10:08 AM, Cornelia Huck wrote: > On Fri, 6 Dec 2019 09:45:41 +0100 > Janosch Frank wrote: >=20 >> On 12/6/19 9:29 AM, Cornelia Huck wrote: >>> On Fri, 6 Dec 2019 08:44:52 +0100 >>> Janosch Frank wrote: >>> =20 >>>> On 12/5/19 6:46 PM, Cornelia Huck wrote: =20 >>>>> On Thu, 5 Dec 2019 18:34:32 +0100 >>>>> Janosch Frank wrote: >>>>> =20 >>>>>> On 12/5/19 6:15 PM, Cornelia Huck wrote: =20 >>>>>>> On Fri, 29 Nov 2019 04:48:02 -0500 >>>>>>> Janosch Frank wrote: >>>>>>> =20 >>>>>>>> Secure guests no longer intercept with code 4 for an instruction= >>>>>>>> interception. Instead they have codes 104 and 108 for secure >>>>>>>> instruction interception and secure instruction notification >>>>>>>> respectively. >>>>>>>> >>>>>>>> The 104 mirrors the 4 interception. >>>>>>>> >>>>>>>> The 108 is a notification interception to let KVM and QEMU know = that >>>>>>>> something changed and we need to update tracking information or >>>>>>>> perform specific tasks. It's currently taken for the following >>>>>>>> instructions: >>>>>>>> >>>>>>>> * stpx (To inform about the changed prefix location) >>>>>>>> * sclp (On incorrect SCCB values, so we can inject a IRQ) >>>>>>>> * sigp (All but "stop and store status") >>>>>>>> * diag308 (Subcodes 0/1) >>>>>>>> >>>>>>>> Signed-off-by: Janosch Frank >>>>>>>> --- >>>>>>>> target/s390x/kvm.c | 6 ++++++ >>>>>>>> 1 file changed, 6 insertions(+) >>>>>>>> =20 >>>>> =20 >>>>>>>> @@ -1664,6 +1668,8 @@ static int handle_intercept(S390CPU *cpu) >>>>>>>> (long)cs->kvm_run->psw_addr); >>>>>>>> switch (icpt_code) { >>>>>>>> case ICPT_INSTRUCTION: >>>>>>>> + case ICPT_PV_INSTR: >>>>>>>> + case ICPT_PV_INSTR_NOTIFICATION: >>>>>>>> r =3D handle_instruction(cpu, run); =20 >>>>>>> >>>>>>> I'm still a bit uneasy about going through the same path for both= 104 >>>>>>> and 108. How does the handler figure out whether it should emulat= e an >>>>>>> instruction, or just process a notification? Is it guaranteed tha= t a >>>>>>> given instruction is always showing up as either a 104 or a 108, = so >>>>>>> that the handler can check the pv state? =20 >>>>>> >>>>>> diag 308 subcode 0/1 are 108, but all other subcodes are defined a= s a >>>>>> 104 (if they are an exit at all)... =20 >>>>> >>>>> I think that's a reason to really split 108 from 4/104, or at least= add >>>>> an parameter... =20 >>>> >>>> And still call the diag 308 handler or have separate handlers? =20 >>> >>> I'd probably split it into a "normal" one and one for pv special >>> handling... does that make sense? >>> =20 >> IMHO: not really >> We still need to do ipa/ipb parsing for both paths, which will result = in >> code duplication. Looking at diag308 subcode 4, we would have a code 4= >> one which just does the device resets and reboots and one which does a= ll >> that, plus the teardown of the protected guest. >> >> I tried to inline as much as possible to have as little changes as >> possible. Notable exception is sclp, which has more checks than >> emulation code... >=20 > Fair enough. >=20 > But taking a step back: What's the purpose of the new exits, then? > IIUC, we have the following cases: >=20 > - code 4: normal guest, nothing special > - code 104: protected guest, emulate the instruction > - code 108: protected guest, notification for the instruction >=20 > The backend code can figure out what to do simply by checking whether > the guest is protected or not (as whatever needs to be done is simply > determined by that anyway). >=20 > Are we overlooking something? Or is the information contained in the > different exits simply redundant? The difference is in the entry after the exit: On a 104 we have a "continuation", i.e. the data that's a result of the emulation by KVM/QEMU is used to complete the instruction. Copying the sccb from the satellite block into guest2 memory, etc. For a 108 we don't have any special handling (except for maybe state checking) and just continue with the next instruction. --PQfNkW1ifFEebNM37lR9T2QykSFn917m8-- --XCkOthSP7zicKPp88Dmd9lBAZuwLoSdLY Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- iQIzBAEBCAAdFiEEwGNS88vfc9+v45Yq41TmuOI4ufgFAl3qH54ACgkQ41TmuOI4 ufiakA//fa17EkBF6WvCeJ9sNDGn40QtY3SaHxNREYZgQf/YU1aP2aJMQRyBu5qO j4vq/i37URivORKRfHF8oJ/0GNXxsAhkalNG//kWUZqfzkAJy0TSGVCOa9TRD7/P CkE7YE04kxeWeoq+pSByOTbg+kzSV8WX5CY61GjdHVWBDAnV1dW66xRmThc1k79m F8a6e18UVWS4CR4Mp+nl55VCtYG51uJhfIpEIVZUD1aP0DvpIUlhwVDlGyr2Y8B0 vPVJ34o0We1iGbom/PxPwTL6ZKSUlxoamjdU9wqtB/DCdkoZwm3CqXX1PWBW06eV Z1YpA+c22il1+aGqVgbm/0S4zsco5PMUPPyZmQKVd4+7Y1DZ1Fj94f6FQ/nCWn+2 WTN8NLg6sGnsRC5aV2+HsamtxhIuLaNXIQZh8eM40WxM7NtPkBXh5khUCKJziFo7 AfrwSt2xidb8/N2YFqRJH6cvBa2GnIAyLeiioHupyvFr8oKIQt3qZFiKzDzGMPFJ f/mBttrY0GSf0/sexJVkFZMQfpiRsfQGcx0y59YtBnVtCDsQ8wA3PNOnxN0/fPsP vJonwn59dmCBVxsOUO/pJFKgyaFAGL4frB/SZWMdtOU3/7cWUq1jpn0NvG/vUrXM kV4HI1AK1xKc4YrOOtbOwWbsS8jCVuMYPJLRf/OJ3dms7vv72PY= =vw3B -----END PGP SIGNATURE----- --XCkOthSP7zicKPp88Dmd9lBAZuwLoSdLY--