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Shenoy" , Nadav Amit Subject: [PATCH 1/1] powerpc/rtas: Implement reentrant rtas call Date: Wed, 8 Apr 2020 19:39:02 -0300 Message-Id: <20200408223901.760733-1-leonardo@linux.ibm.com> X-Mailer: git-send-email 2.25.2 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-TM-AS-GCONF: 00 X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.138, 18.0.676 definitions=2020-04-08_09:2020-04-07, 2020-04-08 signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 mlxlogscore=999 phishscore=0 spamscore=0 suspectscore=0 mlxscore=0 adultscore=0 clxscore=1011 priorityscore=1501 bulkscore=0 malwarescore=0 impostorscore=0 lowpriorityscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2003020000 definitions=main-2004080156 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" Implement rtas_call_reentrant() for reentrant rtas-calls: "ibm,int-on", "ibm,int-off",ibm,get-xive" and "ibm,set-xive". On LoPAPR Version 1.1 (March 24, 2016), from 7.3.10.1 to 7.3.10.4, items 2 and 3 say: 2 - For the PowerPC External Interrupt option: The * call must be reentrant to the number of processors on the platform. 3 - For the PowerPC External Interrupt option: The * argument call buffer for each simultaneous call must be physically unique. So, these rtas-calls can be called in a lockless way, if using a different buffer for each call. This can be useful to avoid deadlocks in crashing, where rtas-calls are needed, but some other thread crashed holding the rtas.lock. Signed-off-by: Leonardo Bras --- arch/powerpc/include/asm/rtas.h | 1 + arch/powerpc/kernel/rtas.c | 21 +++++++++++++++++++++ arch/powerpc/sysdev/xics/ics-rtas.c | 22 +++++++++++----------- 3 files changed, 33 insertions(+), 11 deletions(-) diff --git a/arch/powerpc/include/asm/rtas.h b/arch/powerpc/include/asm/rtas.h index 3c1887351c71..1ad1c85dab5e 100644 --- a/arch/powerpc/include/asm/rtas.h +++ b/arch/powerpc/include/asm/rtas.h @@ -352,6 +352,7 @@ extern struct rtas_t rtas; extern int rtas_token(const char *service); extern int rtas_service_present(const char *service); extern int rtas_call(int token, int, int, int *, ...); +int rtas_call_reentrant(int token, int nargs, int nret, int *outputs, ...); void rtas_call_unlocked(struct rtas_args *args, int token, int nargs, int nret, ...); extern void __noreturn rtas_restart(char *cmd); diff --git a/arch/powerpc/kernel/rtas.c b/arch/powerpc/kernel/rtas.c index c5fa251b8950..85e7511afe25 100644 --- a/arch/powerpc/kernel/rtas.c +++ b/arch/powerpc/kernel/rtas.c @@ -483,6 +483,27 @@ int rtas_call(int token, int nargs, int nret, int *outputs, ...) } EXPORT_SYMBOL(rtas_call); +/* + * Used for reentrant rtas calls. + * According to LoPAR documentation, only "ibm,int-on", "ibm,int-off", + * "ibm,get-xive" and "ibm,set-xive" are currently reentrant. + * Reentrant calls need their own rtas_args buffer, so not using rtas.args. + */ +int rtas_call_reentrant(int token, int nargs, int nret, int *outputs, ...) +{ + va_list list; + struct rtas_args rtas_args; + + if (!rtas.entry || token == RTAS_UNKNOWN_SERVICE) + return -1; + + va_start(list, outputs); + va_rtas_call_unlocked(&rtas_args, token, nargs, nret, list); + va_end(list); + + return be32_to_cpu(rtas_args.rets[0]); +} + /* For RTAS_BUSY (-2), delay for 1 millisecond. For an extended busy status * code of 990n, perform the hinted delay of 10^n (last digit) milliseconds. */ diff --git a/arch/powerpc/sysdev/xics/ics-rtas.c b/arch/powerpc/sysdev/xics/ics-rtas.c index 6aabc74688a6..4cf18000f07c 100644 --- a/arch/powerpc/sysdev/xics/ics-rtas.c +++ b/arch/powerpc/sysdev/xics/ics-rtas.c @@ -50,8 +50,8 @@ static void ics_rtas_unmask_irq(struct irq_data *d) server = xics_get_irq_server(d->irq, irq_data_get_affinity_mask(d), 0); - call_status = rtas_call(ibm_set_xive, 3, 1, NULL, hw_irq, server, - DEFAULT_PRIORITY); + call_status = rtas_call_reentrant(ibm_set_xive, 3, 1, NULL, hw_irq, + server, DEFAULT_PRIORITY); if (call_status != 0) { printk(KERN_ERR "%s: ibm_set_xive irq %u server %x returned %d\n", @@ -60,7 +60,7 @@ static void ics_rtas_unmask_irq(struct irq_data *d) } /* Now unmask the interrupt (often a no-op) */ - call_status = rtas_call(ibm_int_on, 1, 1, NULL, hw_irq); + call_status = rtas_call_reentrant(ibm_int_on, 1, 1, NULL, hw_irq); if (call_status != 0) { printk(KERN_ERR "%s: ibm_int_on irq=%u returned %d\n", __func__, hw_irq, call_status); @@ -91,7 +91,7 @@ static void ics_rtas_mask_real_irq(unsigned int hw_irq) if (hw_irq == XICS_IPI) return; - call_status = rtas_call(ibm_int_off, 1, 1, NULL, hw_irq); + call_status = rtas_call_reentrant(ibm_int_off, 1, 1, NULL, hw_irq); if (call_status != 0) { printk(KERN_ERR "%s: ibm_int_off irq=%u returned %d\n", __func__, hw_irq, call_status); @@ -99,8 +99,8 @@ static void ics_rtas_mask_real_irq(unsigned int hw_irq) } /* Have to set XIVE to 0xff to be able to remove a slot */ - call_status = rtas_call(ibm_set_xive, 3, 1, NULL, hw_irq, - xics_default_server, 0xff); + call_status = rtas_call_reentrant(ibm_set_xive, 3, 1, NULL, hw_irq, + xics_default_server, 0xff); if (call_status != 0) { printk(KERN_ERR "%s: ibm_set_xive(0xff) irq=%u returned %d\n", __func__, hw_irq, call_status); @@ -131,7 +131,7 @@ static int ics_rtas_set_affinity(struct irq_data *d, if (hw_irq == XICS_IPI || hw_irq == XICS_IRQ_SPURIOUS) return -1; - status = rtas_call(ibm_get_xive, 1, 3, xics_status, hw_irq); + status = rtas_call_reentrant(ibm_get_xive, 1, 3, xics_status, hw_irq); if (status) { printk(KERN_ERR "%s: ibm,get-xive irq=%u returns %d\n", @@ -146,8 +146,8 @@ static int ics_rtas_set_affinity(struct irq_data *d, return -1; } - status = rtas_call(ibm_set_xive, 3, 1, NULL, - hw_irq, irq_server, xics_status[1]); + status = rtas_call_reentrant(ibm_set_xive, 3, 1, NULL, + hw_irq, irq_server, xics_status[1]); if (status) { printk(KERN_ERR "%s: ibm,set-xive irq=%u returns %d\n", @@ -179,7 +179,7 @@ static int ics_rtas_map(struct ics *ics, unsigned int virq) return -EINVAL; /* Check if RTAS knows about this interrupt */ - rc = rtas_call(ibm_get_xive, 1, 3, status, hw_irq); + rc = rtas_call_reentrant(ibm_get_xive, 1, 3, status, hw_irq); if (rc) return -ENXIO; @@ -198,7 +198,7 @@ static long ics_rtas_get_server(struct ics *ics, unsigned long vec) { int rc, status[2]; - rc = rtas_call(ibm_get_xive, 1, 3, status, vec); + rc = rtas_call_reentrant(ibm_get_xive, 1, 3, status, vec); if (rc) return -1; return status[0]; -- 2.25.2