powerpc/vas: Add support for user receive window

Add support for user space receive window (for the Fast thread-wakeup
coprocessor type)

Signed-off-by: Sukadev Bhattiprolu <sukadev@linux.vnet.ibm.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

diff --git a/arch/powerpc/platforms/powernv/vas-window.c b/arch/powerpc/platforms/powernv/vas-window.c
index 82754924c2bc0f992237c330e7fc682487293282..2b3eb01ab1107145395b0c697da4743bd2e97c8c 100644 (file)
--- a/arch/powerpc/platforms/powernv/vas-window.c
+++ b/arch/powerpc/platforms/powernv/vas-window.c
@@ -16,7 +16,8 @@
 #include <linux/log2.h>
 #include <linux/rcupdate.h>
 #include <linux/cred.h>
-
+#include <asm/switch_to.h>
+#include <asm/ppc-opcode.h>
 #include "vas.h"
 #include "copy-paste.h"
 
@@ -597,6 +598,32 @@ static void put_rx_win(struct vas_window *rxwin)
        atomic_dec(&rxwin->num_txwins);
 }
 
+/*
+ * Find the user space receive window given the @pswid.
+ *      - We must have a valid vasid and it must belong to this instance.
+ *        (so both send and receive windows are on the same VAS instance)
+ *      - The window must refer to an OPEN, FTW, RECEIVE window.
+ *
+ * NOTE: We access ->windows[] table and assume that vinst->mutex is held.
+ */
+static struct vas_window *get_user_rxwin(struct vas_instance *vinst, u32 pswid)
+{
+       int vasid, winid;
+       struct vas_window *rxwin;
+
+       decode_pswid(pswid, &vasid, &winid);
+
+       if (vinst->vas_id != vasid)
+               return ERR_PTR(-EINVAL);
+
+       rxwin = vinst->windows[winid];
+
+       if (!rxwin || rxwin->tx_win || rxwin->cop != VAS_COP_TYPE_FTW)
+               return ERR_PTR(-EINVAL);
+
+       return rxwin;
+}
+
 /*
  * Get the VAS receive window associated with NX engine identified
  * by @cop and if applicable, @pswid.
@@ -610,10 +637,10 @@ static struct vas_window *get_vinst_rxwin(struct vas_instance *vinst,
 
        mutex_lock(&vinst->mutex);
 
-       if (cop == VAS_COP_TYPE_842 || cop == VAS_COP_TYPE_842_HIPRI)
-               rxwin = vinst->rxwin[cop] ?: ERR_PTR(-EINVAL);
+       if (cop == VAS_COP_TYPE_FTW)
+               rxwin = get_user_rxwin(vinst, pswid);
        else
-               rxwin = ERR_PTR(-EINVAL);
+               rxwin = vinst->rxwin[cop] ?: ERR_PTR(-EINVAL);
 
        if (!IS_ERR(rxwin))
                atomic_inc(&rxwin->num_txwins);
@@ -937,10 +964,9 @@ static void init_winctx_for_txwin(struct vas_window *txwin,
        winctx->tx_word_mode = txattr->tx_win_ord_mode;
        winctx->rsvd_txbuf_count = txattr->rsvd_txbuf_count;
 
-       if (winctx->nx_win) {
+       winctx->intr_disable = true;
+       if (winctx->nx_win)
                winctx->data_stamp = true;
-               winctx->intr_disable = true;
-       }
 
        winctx->lpid = txattr->lpid;
        winctx->pidr = txattr->pidr;
@@ -985,6 +1011,14 @@ struct vas_window *vas_tx_win_open(int vasid, enum vas_cop_type cop,
        if (!tx_win_args_valid(cop, attr))
                return ERR_PTR(-EINVAL);
 
+       /*
+        * If caller did not specify a vasid but specified the PSWID of a
+        * receive window (applicable only to FTW windows), use the vasid
+        * from that receive window.
+        */
+       if (vasid == -1 && attr->pswid)
+               decode_pswid(attr->pswid, &vasid, NULL);
+
        vinst = find_vas_instance(vasid);
        if (!vinst) {
                pr_devel("vasid %d not found!\n", vasid);
@@ -1031,6 +1065,14 @@ struct vas_window *vas_tx_win_open(int vasid, enum vas_cop_type cop,
                }
        }
 
+       /*
+        * Now that we have a send window, ensure context switch issues
+        * CP_ABORT for this thread.
+        */
+       rc = -EINVAL;
+       if (set_thread_uses_vas() < 0)
+               goto free_window;
+
        set_vinst_win(vinst, txwin);
 
        return txwin;