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Fri, 3 Nov 2023 14:14:14 +0000 (GMT) Date: Fri, 3 Nov 2023 14:44:24 +0100 From: Claudio Imbrenda To: Nico Boehr Cc: frankja@linux.ibm.com, thuth@redhat.com, kvm@vger.kernel.org, linux-s390@vger.kernel.org Subject: Re: [kvm-unit-tests PATCH v7 3/8] s390x: sie: switch to home space mode before entering SIE Message-ID: <20231103144424.139994a5@p-imbrenda> In-Reply-To: <20231103092954.238491-4-nrb@linux.ibm.com> References: <20231103092954.238491-1-nrb@linux.ibm.com> <20231103092954.238491-4-nrb@linux.ibm.com> Organization: IBM X-Mailer: Claws Mail 4.1.1 (GTK 3.24.38; x86_64-redhat-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-GUID: 0DMuTPgGRj27A6CowotpCSlZOh-Iv5fe X-Proofpoint-ORIG-GUID: 11EG2Oz-Y-aSLDMLMH2u4t1UxLZNr5vy X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.272,Aquarius:18.0.987,Hydra:6.0.619,FMLib:17.11.176.26 definitions=2023-11-03_13,2023-11-02_03,2023-05-22_02 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 bulkscore=0 adultscore=0 suspectscore=0 mlxlogscore=999 spamscore=0 lowpriorityscore=0 clxscore=1015 mlxscore=0 phishscore=0 priorityscore=1501 malwarescore=0 impostorscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2310240000 definitions=main-2311030120 Precedence: bulk List-ID: X-Mailing-List: linux-s390@vger.kernel.org On Fri, 3 Nov 2023 10:29:32 +0100 Nico Boehr wrote: > This is to prepare for running guests without MSO/MSL, which is > currently not possible. > > We already have code in sie64a to setup a guest primary ASCE before > entering SIE, so we can in theory switch to the page tables which > translate gpa to hpa. > > But the host is running in primary space mode already, so changing the > primary ASCE before entering SIE will also affect the host's code and > data. > > To make this switch useful, the host should run in a different address > space mode. Hence, set up and change to home address space mode before > installing the guest ASCE. > > The home space ASCE is just copied over from the primary space ASCE, so > no functional change is intended, also for tests that want to use > MSO/MSL. If a test intends to use a different primary space ASCE, it can > now just set the guest.asce in the save_area. > > Signed-off-by: Nico Boehr > Reviewed-by: Thomas Huth Reviewed-by: Claudio Imbrenda > --- > lib/s390x/asm/arch_def.h | 1 + > lib/s390x/sie.c | 26 ++++++++++++++++++++++++++ > 2 files changed, 27 insertions(+) > > diff --git a/lib/s390x/asm/arch_def.h b/lib/s390x/asm/arch_def.h > index 5beaf15b57e7..745a33878de5 100644 > --- a/lib/s390x/asm/arch_def.h > +++ b/lib/s390x/asm/arch_def.h > @@ -92,6 +92,7 @@ enum address_space { > }; > > #define PSW_MASK_DAT 0x0400000000000000UL > +#define PSW_MASK_HOME 0x0000C00000000000UL > #define PSW_MASK_IO 0x0200000000000000UL > #define PSW_MASK_EXT 0x0100000000000000UL > #define PSW_MASK_KEY 0x00F0000000000000UL > diff --git a/lib/s390x/sie.c b/lib/s390x/sie.c > index b44febdeaaac..7f4474555ff7 100644 > --- a/lib/s390x/sie.c > +++ b/lib/s390x/sie.c > @@ -52,6 +52,8 @@ void sie_handle_validity(struct vm *vm) > > void sie(struct vm *vm) > { > + uint64_t old_cr13; > + > if (vm->sblk->sdf == 2) > memcpy(vm->sblk->pv_grregs, vm->save_area.guest.grs, > sizeof(vm->save_area.guest.grs)); > @@ -59,6 +61,24 @@ void sie(struct vm *vm) > /* Reset icptcode so we don't trip over it below */ > vm->sblk->icptcode = 0; > > + /* > + * Set up home address space to match primary space. Instead of running > + * in home space all the time, we switch every time in sie() because: > + * - tests that depend on running in primary space mode don't need to be > + * touched > + * - it avoids regressions in tests > + * - switching every time makes it easier to extend this in the future, > + * for example to allow tests to run in whatever space they want > + */ > + old_cr13 = stctg(13); > + lctlg(13, stctg(1)); > + > + /* switch to home space so guest tables can be different from host */ > + psw_mask_set_bits(PSW_MASK_HOME); > + > + /* also handle all interruptions in home space while in SIE */ > + irq_set_dat_mode(true, AS_HOME); > + > while (vm->sblk->icptcode == 0) { > sie64a(vm->sblk, &vm->save_area); > sie_handle_validity(vm); > @@ -66,6 +86,12 @@ void sie(struct vm *vm) > vm->save_area.guest.grs[14] = vm->sblk->gg14; > vm->save_area.guest.grs[15] = vm->sblk->gg15; > > + irq_set_dat_mode(true, AS_PRIM); > + psw_mask_clear_bits(PSW_MASK_HOME); > + > + /* restore the old CR 13 */ > + lctlg(13, old_cr13); > + > if (vm->sblk->sdf == 2) > memcpy(vm->save_area.guest.grs, vm->sblk->pv_grregs, > sizeof(vm->save_area.guest.grs));