2 files changed, 78 insertions, 0 deletions

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
@@ -30,6 +30,12 @@
 #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
  */
 #define GET_FIELD(m, v)                (((v) & (m)) >> MASK_LSH(m))
@@ -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;
 }