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Violators will be prosecuted; (version=TLSv1/SSLv3 cipher=AES256-GCM-SHA384 bits=256/256) Fri, 21 Jun 2019 01:22:32 +0100 Received: from d06av21.portsmouth.uk.ibm.com (d06av21.portsmouth.uk.ibm.com [9.149.105.232]) by b06cxnps4074.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id x5L0MVOF48169088 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 21 Jun 2019 00:22:31 GMT Received: from d06av21.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 452AC5204F; Fri, 21 Jun 2019 00:22:31 +0000 (GMT) Received: from ozlabs.au.ibm.com (unknown [9.192.253.14]) by d06av21.portsmouth.uk.ibm.com (Postfix) with ESMTP id 9F0195204E; Fri, 21 Jun 2019 00:22:30 +0000 (GMT) Received: from [9.81.215.199] (unknown [9.81.215.199]) (using TLSv1.2 with cipher AES128-SHA (128/128 bits)) (No client certificate requested) by ozlabs.au.ibm.com (Postfix) with ESMTPSA id A89F5A004E; Fri, 21 Jun 2019 10:22:26 +1000 (AEST) Subject: Re: [PATCH v2] ocxl: Allow contexts to be attached with a NULL mm To: "Alastair D'Silva" , alastair@d-silva.org References: <20190620041203.12274-1-alastair@au1.ibm.com> From: Andrew Donnellan Date: Fri, 21 Jun 2019 10:22:26 +1000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.0 MIME-Version: 1.0 In-Reply-To: <20190620041203.12274-1-alastair@au1.ibm.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-AU Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 x-cbid: 19062100-4275-0000-0000-00000344378D X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 19062100-4276-0000-0000-0000385468AA Message-Id: X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:, , definitions=2019-06-20_15:, , signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=0 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 mlxscore=0 impostorscore=0 mlxlogscore=827 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1810050000 definitions=main-1906210000 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: Arnd Bergmann , linux-kernel@vger.kernel.org, Nicholas Piggin , Masahiro Yamada , Paul Mackerras , Suraj Jitindar Singh , Greg Kroah-Hartman , Frederic Barrat , Andrew Morton , linuxppc-dev@lists.ozlabs.org, Thomas Gleixner Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" On 20/6/19 2:12 pm, Alastair D'Silva wrote: > From: Alastair D'Silva > > If an OpenCAPI context is to be used directly by a kernel driver, there > may not be a suitable mm to use. > > The patch makes the mm parameter to ocxl_context_attach optional. > > Signed-off-by: Alastair D'Silva Acked-by: Andrew Donnellan > --- > arch/powerpc/mm/book3s64/radix_tlb.c | 5 +++++ > drivers/misc/ocxl/context.c | 9 ++++++--- > drivers/misc/ocxl/link.c | 28 ++++++++++++++++++++++++---- > 3 files changed, 35 insertions(+), 7 deletions(-) > > diff --git a/arch/powerpc/mm/book3s64/radix_tlb.c b/arch/powerpc/mm/book3s64/radix_tlb.c > index bb9835681315..ce8a77fae6a7 100644 > --- a/arch/powerpc/mm/book3s64/radix_tlb.c > +++ b/arch/powerpc/mm/book3s64/radix_tlb.c > @@ -666,6 +666,11 @@ EXPORT_SYMBOL(radix__flush_tlb_page); > #define radix__flush_all_mm radix__local_flush_all_mm > #endif /* CONFIG_SMP */ > > +/* > + * If kernel TLBIs ever become local rather than global, then > + * drivers/misc/ocxl/link.c:ocxl_link_add_pe will need some work, as it > + * assumes kernel TLBIs are global. > + */ > void radix__flush_tlb_kernel_range(unsigned long start, unsigned long end) > { > _tlbie_pid(0, RIC_FLUSH_ALL); > diff --git a/drivers/misc/ocxl/context.c b/drivers/misc/ocxl/context.c > index bab9c9364184..994563a078eb 100644 > --- a/drivers/misc/ocxl/context.c > +++ b/drivers/misc/ocxl/context.c > @@ -69,6 +69,7 @@ static void xsl_fault_error(void *data, u64 addr, u64 dsisr) > int ocxl_context_attach(struct ocxl_context *ctx, u64 amr, struct mm_struct *mm) > { > int rc; > + unsigned long pidr = 0; > > // Locks both status & tidr > mutex_lock(&ctx->status_mutex); > @@ -77,9 +78,11 @@ int ocxl_context_attach(struct ocxl_context *ctx, u64 amr, struct mm_struct *mm) > goto out; > } > > - rc = ocxl_link_add_pe(ctx->afu->fn->link, ctx->pasid, > - mm->context.id, ctx->tidr, amr, mm, > - xsl_fault_error, ctx); > + if (mm) > + pidr = mm->context.id; > + > + rc = ocxl_link_add_pe(ctx->afu->fn->link, ctx->pasid, pidr, ctx->tidr, > + amr, mm, xsl_fault_error, ctx); > if (rc) > goto out; > > diff --git a/drivers/misc/ocxl/link.c b/drivers/misc/ocxl/link.c > index cce5b0d64505..58d111afd9f6 100644 > --- a/drivers/misc/ocxl/link.c > +++ b/drivers/misc/ocxl/link.c > @@ -224,6 +224,17 @@ static irqreturn_t xsl_fault_handler(int irq, void *data) > ack_irq(spa, ADDRESS_ERROR); > return IRQ_HANDLED; > } > + > + if (!pe_data->mm) { > + /* > + * translation fault from a kernel context - an OpenCAPI > + * device tried to access a bad kernel address > + */ > + rcu_read_unlock(); > + pr_warn("Unresolved OpenCAPI xsl fault in kernel context\n"); > + ack_irq(spa, ADDRESS_ERROR); > + return IRQ_HANDLED; > + } > WARN_ON(pe_data->mm->context.id != pid); > > if (mmget_not_zero(pe_data->mm)) { > @@ -523,7 +534,13 @@ int ocxl_link_add_pe(void *link_handle, int pasid, u32 pidr, u32 tidr, > pe->amr = cpu_to_be64(amr); > pe->software_state = cpu_to_be32(SPA_PE_VALID); > > - mm_context_add_copro(mm); > + /* > + * For user contexts, register a copro so that TLBIs are seen > + * by the nest MMU. If we have a kernel context, TLBIs are > + * already global. > + */ > + if (mm) > + mm_context_add_copro(mm); > /* > * Barrier is to make sure PE is visible in the SPA before it > * is used by the device. It also helps with the global TLBI > @@ -546,7 +563,8 @@ int ocxl_link_add_pe(void *link_handle, int pasid, u32 pidr, u32 tidr, > * have a reference on mm_users. Incrementing mm_count solves > * the problem. > */ > - mmgrab(mm); > + if (mm) > + mmgrab(mm); > trace_ocxl_context_add(current->pid, spa->spa_mem, pasid, pidr, tidr); > unlock: > mutex_unlock(&spa->spa_lock); > @@ -652,8 +670,10 @@ int ocxl_link_remove_pe(void *link_handle, int pasid) > if (!pe_data) { > WARN(1, "Couldn't find pe data when removing PE\n"); > } else { > - mm_context_remove_copro(pe_data->mm); > - mmdrop(pe_data->mm); > + if (pe_data->mm) { > + mm_context_remove_copro(pe_data->mm); > + mmdrop(pe_data->mm); > + } > kfree_rcu(pe_data, rcu); > } > unlock: > -- Andrew Donnellan OzLabs, ADL Canberra ajd@linux.ibm.com IBM Australia Limited