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Tue, 1 Mar 2022 01:12:44 GMT Received: from b01ledav004.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id ED268112063; Tue, 1 Mar 2022 01:12:43 +0000 (GMT) Received: from b01ledav004.gho.pok.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 3BC60112062; Tue, 1 Mar 2022 01:12:43 +0000 (GMT) Received: from localhost.localdomain (unknown [9.160.161.44]) by b01ledav004.gho.pok.ibm.com (Postfix) with ESMTP; Tue, 1 Mar 2022 01:12:43 +0000 (GMT) Message-ID: <3956e1c1fdfde69127055ff1c0256c7d71104030.camel@linux.ibm.com> Subject: [PATCH v6 3/9] powerpc/vas: Add paste address mmap fault handler From: Haren Myneni To: mpe@ellerman.id.au, linuxppc-dev@lists.ozlabs.org, npiggin@gmail.com, nathanl@linux.ibm.com Date: Mon, 28 Feb 2022 17:12:41 -0800 In-Reply-To: <3968502921a0ce3c332d7fe8da8545ae85fc09d0.camel@linux.ibm.com> References: <3968502921a0ce3c332d7fe8da8545ae85fc09d0.camel@linux.ibm.com> Content-Type: text/plain; charset="UTF-8" User-Agent: Evolution 3.36.5 (3.36.5-2.fc32) MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-TM-AS-GCONF: 00 X-Proofpoint-GUID: N_Mo1eToyPMYb5qPh7RQrVc2x8hmhCzT X-Proofpoint-ORIG-GUID: jSlSp2_bgHfAmJ4MTh4O42ittxJNhDFR X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.816,Hydra:6.0.425,FMLib:17.11.64.514 definitions=2022-02-28_10,2022-02-26_01,2022-02-23_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 lowpriorityscore=0 phishscore=0 bulkscore=0 mlxscore=0 suspectscore=0 impostorscore=0 malwarescore=0 priorityscore=1501 mlxlogscore=999 adultscore=0 clxscore=1015 spamscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2201110000 definitions=main-2203010004 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: , Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" The user space opens VAS windows and issues NX requests by pasting CRB on the corresponding paste address mmap. When the system lost credits due to core removal, the kernel has to close the window in the hypervisor and make the window inactive by unmapping this paste address. Also the OS has to handle NX request page faults if the user space issue NX requests. This handler maps the new paste address with the same VMA when the window is active again (due to core add with DLPAR). Otherwise returns paste failure. Signed-off-by: Haren Myneni Reviewed-by: Nicholas Piggin --- arch/powerpc/include/asm/vas.h | 10 ++++ arch/powerpc/platforms/book3s/vas-api.c | 68 +++++++++++++++++++++++++ 2 files changed, 78 insertions(+) diff --git a/arch/powerpc/include/asm/vas.h b/arch/powerpc/include/asm/vas.h index 57573d9c1e09..27251af18c65 100644 --- a/arch/powerpc/include/asm/vas.h +++ b/arch/powerpc/include/asm/vas.h @@ -29,6 +29,12 @@ #define VAS_THRESH_FIFO_GT_QTR_FULL 2 #define VAS_THRESH_FIFO_GT_EIGHTH_FULL 3 +/* + * VAS window Linux status bits + */ +#define VAS_WIN_ACTIVE 0x0 /* Used in platform independent */ + /* vas mmap() */ + /* * Get/Set bit fields */ @@ -59,6 +65,9 @@ struct vas_user_win_ref { struct pid *pid; /* PID of owner */ struct pid *tgid; /* Thread group ID of owner */ struct mm_struct *mm; /* Linux process mm_struct */ + struct mutex mmap_mutex; /* protects paste address mmap() */ + /* with DLPAR close/open windows */ + struct vm_area_struct *vma; /* Save VMA and used in DLPAR ops */ }; /* @@ -67,6 +76,7 @@ struct vas_user_win_ref { struct vas_window { u32 winid; u32 wcreds_max; /* Window credits */ + u32 status; /* Window status used in OS */ enum vas_cop_type cop; struct vas_user_win_ref task_ref; char *dbgname; diff --git a/arch/powerpc/platforms/book3s/vas-api.c b/arch/powerpc/platforms/book3s/vas-api.c index 4d82c92ddd52..217b4a624d09 100644 --- a/arch/powerpc/platforms/book3s/vas-api.c +++ b/arch/powerpc/platforms/book3s/vas-api.c @@ -316,6 +316,7 @@ static int coproc_ioc_tx_win_open(struct file *fp, unsigned long arg) return PTR_ERR(txwin); } + mutex_init(&txwin->task_ref.mmap_mutex); cp_inst->txwin = txwin; return 0; @@ -350,6 +351,70 @@ static int coproc_release(struct inode *inode, struct file *fp) return 0; } +/* + * This fault handler is invoked when the core generates page fault on + * the paste address. Happens if the kernel closes window in hypervisor + * (on pseries) due to lost credit or the paste address is not mapped. + */ +static vm_fault_t vas_mmap_fault(struct vm_fault *vmf) +{ + struct vm_area_struct *vma = vmf->vma; + struct file *fp = vma->vm_file; + struct coproc_instance *cp_inst = fp->private_data; + struct vas_window *txwin; + vm_fault_t fault; + u64 paste_addr; + + /* + * window is not opened. Shouldn't expect this error. + */ + if (!cp_inst || !cp_inst->txwin) { + pr_err("%s(): Unexpected fault on paste address with TX window closed\n", + __func__); + return VM_FAULT_SIGBUS; + } + + txwin = cp_inst->txwin; + /* + * When the LPAR lost credits due to core removal or during + * migration, invalidate the existing mapping for the current + * paste addresses and set windows in-active (zap_page_range in + * reconfig_close_windows()). + * New mapping will be done later after migration or new credits + * available. So continue to receive faults if the user space + * issue NX request. + */ + if (txwin->task_ref.vma != vmf->vma) { + pr_err("%s(): No previous mapping with paste address\n", + __func__); + return VM_FAULT_SIGBUS; + } + + mutex_lock(&txwin->task_ref.mmap_mutex); + /* + * The window may be inactive due to lost credit (Ex: core + * removal with DLPAR). If the window is active again when + * the credit is available, map the new paste address at the + * the window virtual address. + */ + if (txwin->status == VAS_WIN_ACTIVE) { + paste_addr = cp_inst->coproc->vops->paste_addr(txwin); + if (paste_addr) { + fault = vmf_insert_pfn(vma, vma->vm_start, + (paste_addr >> PAGE_SHIFT)); + mutex_unlock(&txwin->task_ref.mmap_mutex); + return fault; + } + } + mutex_unlock(&txwin->task_ref.mmap_mutex); + + return VM_FAULT_SIGBUS; +} + +static const struct vm_operations_struct vas_vm_ops = { + .fault = vas_mmap_fault, +}; + static int coproc_mmap(struct file *fp, struct vm_area_struct *vma) { struct coproc_instance *cp_inst = fp->private_data; @@ -398,6 +463,9 @@ static int coproc_mmap(struct file *fp, struct vm_area_struct *vma) pr_devel("%s(): paste addr %llx at %lx, rc %d\n", __func__, paste_addr, vma->vm_start, rc); + txwin->task_ref.vma = vma; + vma->vm_ops = &vas_vm_ops; + return rc; } -- 2.27.0