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Tue, 16 May 2023 17:30:33 +0000 (GMT) Date: Tue, 16 May 2023 19:30:18 +0200 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 v2 5/6] s390x: lib: sie: don't reenter SIE on pgm int Message-ID: <20230516193018.2e6cab64@p-imbrenda> In-Reply-To: <20230516130456.256205-6-nrb@linux.ibm.com> References: <20230516130456.256205-1-nrb@linux.ibm.com> <20230516130456.256205-6-nrb@linux.ibm.com> Organization: IBM X-Mailer: Claws Mail 4.1.1 (GTK 3.24.37; 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-ORIG-GUID: 3d70aQGzdrSMKYvO5BQwBmw-JcnG6oqj X-Proofpoint-GUID: P8i_mVAuNP93zFYn5K2Jmrwwj8f1-Xi_ X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.254,Aquarius:18.0.957,Hydra:6.0.573,FMLib:17.11.170.22 definitions=2023-05-16_09,2023-05-16_01,2023-02-09_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 impostorscore=0 bulkscore=0 mlxlogscore=514 malwarescore=0 phishscore=0 clxscore=1015 lowpriorityscore=0 suspectscore=0 spamscore=0 adultscore=0 mlxscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2304280000 definitions=main-2305160145 Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Tue, 16 May 2023 15:04:55 +0200 Nico Boehr wrote: > At the moment, when a PGM int occurs while in SIE, we will just reenter > SIE after the interrupt handler was called. > > This is because sie() has a loop which checks icptcode and re-enters SIE > if it is zero. > > However, this behaviour is quite undesirable for SIE tests, since it > doesn't give the host the chance to assert on the PGM int. Instead, we > will just re-enter SIE, on nullifing conditions even causing the > exception again. > > In sie(), check whether a pgm int code is set in lowcore. If it has, > exit the loop so the test can react to the interrupt. Add a new function > read_pgm_int_code() to obtain the interrupt code. > > Note that this introduces a slight oddity with sie and pgm int in > certain cases: If a PGM int occurs between a expect_pgm_int() and sie(), > we will now never enter SIE until the pgm_int_code is cleared by e.g. > clear_pgm_int(). > > Signed-off-by: Nico Boehr > --- > lib/s390x/asm/interrupt.h | 1 + > lib/s390x/interrupt.c | 15 +++++++++++++++ > lib/s390x/sie.c | 4 +++- > lib/s390x/sie.h | 1 - > 4 files changed, 19 insertions(+), 2 deletions(-) > > diff --git a/lib/s390x/asm/interrupt.h b/lib/s390x/asm/interrupt.h > index 55759002dce2..2d7eb1907458 100644 > --- a/lib/s390x/asm/interrupt.h > +++ b/lib/s390x/asm/interrupt.h > @@ -81,6 +81,7 @@ void handle_svc_int(void); > void expect_pgm_int(void); > void expect_ext_int(void); > uint16_t clear_pgm_int(void); > +uint16_t read_pgm_int_code(void); > void check_pgm_int_code(uint16_t code); > > #define IRQ_DAT_ON true > diff --git a/lib/s390x/interrupt.c b/lib/s390x/interrupt.c > index 2e5309cee40f..82b4259d433c 100644 > --- a/lib/s390x/interrupt.c > +++ b/lib/s390x/interrupt.c > @@ -60,6 +60,21 @@ uint16_t clear_pgm_int(void) > return code; > } > > +/** > + * read_pgm_int_code - Get the program interruption code of the last pgm int > + * on the current CPU. > + * > + * This is similar to clear_pgm_int(), except that it doesn't clear the > + * interruption information from lowcore. > + * > + * Returns 0 when none occured. > + */ > +uint16_t read_pgm_int_code(void) could this whole function go in the header as static inline? > +{ > + mb(); is the mb really needed? > + return lowcore.pgm_int_code; > +} > + > /** > * check_pgm_int_code - Check the program interrupt code on the current CPU. > * @code the expected program interrupt code on the current CPU > diff --git a/lib/s390x/sie.c b/lib/s390x/sie.c > index ffa8ec91a423..632740edd431 100644 > --- a/lib/s390x/sie.c > +++ b/lib/s390x/sie.c > @@ -13,6 +13,7 @@ > #include > #include > #include > +#include > #include > #include > > @@ -65,7 +66,8 @@ void sie(struct vm *vm) > /* also handle all interruptions in home space while in SIE */ > irq_set_dat_mode(IRQ_DAT_ON, AS_HOME); > > - while (vm->sblk->icptcode == 0) { > + /* leave SIE when we have an intercept or an interrupt so the test can react to it */ > + while (vm->sblk->icptcode == 0 && !read_pgm_int_code()) { > sie64a(vm->sblk, &vm->save_area); > sie_handle_validity(vm); > } > diff --git a/lib/s390x/sie.h b/lib/s390x/sie.h > index 0b00fb709776..147cb0f2a556 100644 > --- a/lib/s390x/sie.h > +++ b/lib/s390x/sie.h > @@ -284,6 +284,5 @@ void sie_handle_validity(struct vm *vm); > void sie_guest_sca_create(struct vm *vm); > void sie_guest_create(struct vm *vm, uint64_t guest_mem, uint64_t guest_mem_len); > void sie_guest_destroy(struct vm *vm); > -bool sie_had_pgm_int(struct vm *vm); ... ? > > #endif /* _S390X_SIE_H_ */