[PATCH 04/10] powerpc/pseries/vas: Reopen windows with DLPAR core add

@@ -29,6 +29,18 @@
 #define VAS_THRESH_FIFO_GT_QTR_FULL	2
 #define VAS_THRESH_FIFO_GT_EIGHTH_FULL	3
 
+/*
+ * VAS window status
+ */
+#define VAS_WIN_ACTIVE		0x0	/* Used in platform independent */
+					/* vas mmap() */
+#define VAS_WIN_CLOSED		0x1
+#define VAS_WIN_INACTIVE	0x2	/* Inactive due to HW failure */
+#define VAS_WIN_MOD_IN_PROCESS	0x3	/* Process of being modified, */
+					/* deallocated, or quiesced */
+#define VAS_WIN_NO_CRED_CLOSE	0x4	/* Linux specific status when */
+					/* window is closed due to lost */
+					/* credit */
 /*
  * Get/Set bit fields
  */

@@ -59,6 +71,8 @@ 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 */
 };
 
 /*

@@ -67,6 +81,7 @@ struct vas_user_win_ref {
 struct vas_window {
 	u32 winid;
 	u32 wcreds_max;	/* Window credits */
+	u32 status;
 	enum vas_cop_type cop;
 	struct vas_user_win_ref task_ref;
 	char *dbgname;

@@ -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;

@@ -493,6 +493,7 @@ static int get_vas_capabilities(u8 feat, enum vas_cop_feat_type type,
 	memset(vcaps, 0, sizeof(*vcaps));
 	INIT_LIST_HEAD(&vcaps->list);
 
+	vcaps->feat = feat;
 	caps = &vcaps->caps;
 
 	rc = h_query_vas_capabilities(H_QUERY_VAS_CAPABILITIES, feat,

@@ -531,6 +532,149 @@ static int get_vas_capabilities(u8 feat, enum vas_cop_feat_type type,
 	return 0;
 }
 
+/*
+ * VAS windows can be closed due to lost credits when the core is
+ * removed. So reopen them if credits are available due to DLPAR
+ * core add and set the window active status. When NX sees the page
+ * fault on the unmapped paste address, the kernel handles the fault
+ * by setting the remapping to new paste address if the window is
+ * active.
+ */
+static int reconfig_open_windows(struct vas_caps *vcaps, int creds)
+{
+	long domain[PLPAR_HCALL9_BUFSIZE] = {VAS_DEFAULT_DOMAIN_ID};
+	struct vas_cop_feat_caps *caps = &vcaps->caps;
+	struct pseries_vas_window *win = NULL;
+	int rc, mv_ents = 0;
+
+	/*
+	 * Nothing to do if there are no closed windows.
+	 */
+	if (!vcaps->close_wins)
+		return 0;
+
+	/*
+	 * For the core removal, the hypervisor reduces the credits
+	 * assigned to the LPAR and the kernel closes VAS windows
+	 * in the hypervisor depends on reduced credits. The kernel
+	 * uses LIFO (the last windows that are opened will be closed
+	 * first) and expects to open in the same order when credits
+	 * are available.
+	 * For example, 40 windows are closed when the LPAR lost 2 cores
+	 * (dedicated). If 1 core is added, this LPAR can have 20 more
+	 * credits. It means the kernel can reopen 20 windows. So move
+	 * 20 entries in the VAS windows lost and reopen next 20 windows.
+	 */
+	if (vcaps->close_wins > creds)
+		mv_ents = vcaps->close_wins - creds;
+
+	list_for_each_entry(win, &vcaps->list, win_list) {
+		if (!mv_ents)
+			break;
+
+		mv_ents--;
+	}
+
+	while (vcaps->close_wins && win) {
+		/*
+		 * Nothing to do on this window if it is active.
+		 */
+		if (win->vas_win.status != VAS_WIN_NO_CRED_CLOSE) {
+			win = list_next_entry(win, win_list);
+			continue;
+		}
+
+		rc = allocate_setup_window(win, (u64 *)&domain[0],
+					   caps->win_type);
+		if (rc)
+			return rc;
+
+		rc = h_modify_vas_window(win);
+		if (rc)
+			goto out;
+
+		mutex_lock(&win->vas_win.task_ref.mmap_mutex);
+
+		/*
+		 * Set window status to active
+		 */
+		win->vas_win.status = VAS_WIN_ACTIVE;
+		win->win_type = caps->win_type;
+		mutex_unlock(&win->vas_win.task_ref.mmap_mutex);
+		atomic_inc(&caps->used_creds);
+		win = list_next_entry(win, win_list);
+		vcaps->close_wins--;
+	}
+
+	return 0;
+out:
+	/*
+	 * Window modify HCALL failed. So close the window to the
+	 * hypervisor and return.
+	 */
+	free_irq_setup(win);
+	h_deallocate_vas_window(win->vas_win.winid);
+	return rc;
+}
+
+/*
+ * Get new VAS capabilities when the core add/removal configuration
+ * changes. Reconfig window configurations based on the credits
+ * availability from this new capabilities.
+ */
+static int vas_reconfig_capabilties(u8 type)
+{
+	int lpar_creds, avail_creds;
+	struct hv_vas_cop_feat_caps *hv_caps;
+	struct vas_cop_feat_caps *caps;
+	struct vas_caps *vcaps;
+	int rc = 0;
+
+	if (type >= VAS_MAX_FEAT_TYPE) {
+		pr_err("Invalid credit type %d\n", type);
+		return -EINVAL;
+	}
+
+	vcaps = &vascaps[type];
+	caps = &vcaps->caps;
+
+	hv_caps = kmalloc(sizeof(*hv_caps), GFP_KERNEL);
+	if (!hv_caps)
+		return -ENOMEM;
+
+	mutex_lock(&vas_pseries_mutex);
+	rc = h_query_vas_capabilities(H_QUERY_VAS_CAPABILITIES, vcaps->feat,
+				      (u64)virt_to_phys(hv_caps));
+	if (rc)
+		goto out;
+
+	lpar_creds = be16_to_cpu(hv_caps->target_lpar_creds);
+
+	atomic_set(&caps->target_creds, lpar_creds);
+
+	/*
+	 * The total number of available credits are decreased due to
+	 * DLPAR core removal. Means some windows have to be closed.
+	 * Hold the vas_pseries_mutex before closing the required windows
+	 * so that the user space can not open new windows.
+	 */
+	if (atomic_read(&caps->used_creds) < lpar_creds) {
+		/*
+		 * If the existing used credits is less than the new
+		 * available credits, reopen windows if they are
+		 * closed due to the previous DLPAR (core removal).
+		 */
+		avail_creds = lpar_creds -
+				atomic_read(&caps->used_creds);
+		rc = reconfig_open_windows(vcaps, avail_creds);
+	}
+
+out:
+	mutex_unlock(&vas_pseries_mutex);
+	kfree(hv_caps);
+	return rc;
+}
+
 /*
  * Total number of default credits available (target_credits)
  * in LPAR depends on number of cores configured. It varies based on

@@ -554,6 +698,10 @@ static int pseries_vas_notifier(struct notifier_block *nb,
 	if (!intserv)
 		return NOTIFY_OK;
 
+	rc = vas_reconfig_capabilties(VAS_GZIP_DEF_FEAT_TYPE);
+	if (rc)
+		pr_err("Failed reconfig VAS capabilities with DLPAR\n");
+
 	return rc;
 }
 

@@ -84,6 +84,8 @@ struct vas_cop_feat_caps {
 struct vas_caps {
 	struct vas_cop_feat_caps caps;
 	struct list_head list;	/* List of open windows */
+	int close_wins;		/* closed windows in the hypervisor for DLPAR */
+	u8 feat;		/* Feature type */
 };
 
 /*