Define the vas_rx_win_open() interface. This interface is intended to be
used by the Nest Accelerator (NX) driver(s) to setup receive windows for
one or more NX engines (which implement compression/encryption algorithms
in the hardware).
Follow-on patches will provide an interface to close the window and to open
a send window that kenrel subsystems can use to access the NX engines.
The interface to open a receive window is expected to be invoked for each
instance of VAS in the system.
Signed-off-by: Sukadev Bhattiprolu <suka...@linux.vnet.ibm.com>
---
Changelog[v6]:
- Add support for FTW windows
Changelog[v4]:
- Export the symbols
Changelog[v3]:
- Fault receive windows must enable interrupts and disable
notifications. NX Windows are opposite.
- Use macros rather than enum for threshold-control mode
- Ignore irq_ports for in-kernel windows. They are needed for
user space windows and will be added later
---
arch/powerpc/include/asm/vas.h | 47 ++++
arch/powerpc/platforms/powernv/vas-window.c | 357 +++++++++++++++++++++++++++-
arch/powerpc/platforms/powernv/vas.h | 14 ++
3 files changed, 417 insertions(+), 1 deletion(-)
diff --git a/arch/powerpc/include/asm/vas.h b/arch/powerpc/include/asm/vas.h
index 30667db..a3778d7 100644
--- a/arch/powerpc/include/asm/vas.h
+++ b/arch/powerpc/include/asm/vas.h
@@ -35,6 +35,36 @@ enum vas_cop_type {
};
/*
+ * Receive window attributes specified by the (in-kernel) owner of window.
+ */
+struct vas_rx_win_attr {
+ void *rx_fifo;
+ int rx_fifo_size;
+ int wcreds_max;
+
+ bool pin_win;
+ bool rej_no_credit;
+ bool tx_wcred_mode;
+ bool rx_wcred_mode;
+ bool tx_win_ord_mode;
+ bool rx_win_ord_mode;
+ bool data_stamp;
+ bool nx_win;
+ bool fault_win;
+ bool user_win;
+ bool notify_disable;
+ bool intr_disable;
+ bool notify_early;
+
+ int lnotify_lpid;
+ int lnotify_pid;
+ int lnotify_tid;
+ uint32_t pswid;
+
+ int tc_mode;
+};
+
+/*
* Return a system-wide unique id for the VAS window @win.
*/
extern uint32_t vas_win_id(struct vas_window *win);
@@ -44,4 +74,21 @@ extern uint32_t vas_win_id(struct vas_window *win);
* can map that address into their address space.
*/
extern uint64_t vas_win_paste_addr(struct vas_window *win);
+
+/*
+ * Helper to initialize receive window attributes to defaults for an
+ * NX window.
+ */
+extern void vas_init_rx_win_attr(struct vas_rx_win_attr *rxattr,
+ enum vas_cop_type cop);
+
+/*
+ * Open a VAS receive window for the instance of VAS identified by @vasid
+ * Use @attr to initialize the attributes of the window.
+ *
+ * Return a handle to the window or ERR_PTR() on error.
+ */
+extern struct vas_window *vas_rx_win_open(int vasid, enum vas_cop_type cop,
+ struct vas_rx_win_attr *attr);
+
#endif /* _MISC_VAS_H */
diff --git a/arch/powerpc/platforms/powernv/vas-window.c
b/arch/powerpc/platforms/powernv/vas-window.c
index 42c1d4f..ff64022 100644
--- a/arch/powerpc/platforms/powernv/vas-window.c
+++ b/arch/powerpc/platforms/powernv/vas-window.c
@@ -12,6 +12,8 @@
#include <linux/slab.h>
#include <linux/io.h>
#include <linux/log2.h>
+#include <linux/rcupdate.h>
+#include <linux/cred.h>
#include "vas.h"
@@ -544,7 +546,7 @@ void vas_window_free(struct vas_window *window)
vas_release_window_id(&vinst->ida, winid);
}
-struct vas_window *vas_window_alloc(struct vas_instance *vinst)
+static struct vas_window *vas_window_alloc(struct vas_instance *vinst)
{
int winid;
struct vas_window *window;
@@ -570,6 +572,359 @@ struct vas_window *vas_window_alloc(struct vas_instance
*vinst)
return ERR_PTR(-ENOMEM);
}
+/*
+ * Check if current task has permissions to pair with the process that
+ * opened the receive window @rxwin. For now the check is based on
+ * kill_ok_by_cred() - i.e equivalent to current task being able to
+ * send a signal to owner of @rxwin.
+ */
+static bool valid_permissions(struct vas_window *rxwin)
+{
+ bool rc;
+ struct task_struct *wtask;
+ const struct cred *txcred, *rxcred;
+
+ rcu_read_lock();
+ wtask = find_task_by_vpid(rxwin->pid);
+
+ /*
+ * CHECK: Don't need to get_task_struct(wtask) since we hold
+ * RCU till we complete the uid checks? Since rxwin is
+ * open, the task has not exited.
+ */
+
+ txcred = current_cred();
+ rxcred = __task_cred(wtask);
+
+ rc = false;
+ if (uid_eq(txcred->euid, rxcred->suid) ||
+ uid_eq(txcred->euid, rxcred->uid) ||
+ uid_eq(txcred->uid, rxcred->suid) ||
+ uid_eq(txcred->uid, rxcred->uid) ||
+ capable(CAP_KILL))
+ rc = true;
+
+ rcu_read_unlock();
+
+ return rc;
+}
+
+/*
+ * Find the user space receive window given the @pswid.
+ *
+ * The pswid, aka rx_win_handle, comes from user space so we should
+ * validate it carefully.
+ * - We must have a valid vasid and it must belong to this instance.
+ * - The window must refer to an OPEN, FTW, RECEIVE window.
+ * - Calling process must have "kill" capabilities to the process
+ * that opened/owns the receive window.
+ * - Anything else?
+ *
+ * NOTE: We access ->windows[] table and assume that vinst->mutex is held.
+ */
+struct vas_window *get_user_rxwin(struct vas_instance *vinst, uint32_t 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);
+
+ if (!valid_permissions(rxwin))
+ return ERR_PTR(-EACCES);
+
+ return rxwin;
+}
+
+/*
+ * Get the VAS receive window associated with NX engine identified
+ * by @cop and if applicable, @pswid.
+ *
+ * See also function header of set_vinst_win().
+ */
+struct vas_window *get_vinst_rxwin(struct vas_instance *vinst,
+ enum vas_cop_type cop, uint32_t pswid)
+{
+ struct vas_window *rxwin;
+
+ mutex_lock(&vinst->mutex);
+
+ if (cop == VAS_COP_TYPE_FTW)
+ rxwin = get_user_rxwin(vinst, pswid);
+ else
+ rxwin = vinst->rxwin[cop] ?: ERR_PTR(-EINVAL);
+
+ if (!IS_ERR(rxwin))
+ atomic_inc(&rxwin->num_txwins);
+
+ mutex_unlock(&vinst->mutex);
+
+ return rxwin;
+}
+
+/*
+ * We have two tables of windows in a VAS instance. The first one,
+ * ->windows[], contains all the windows in the instance and allows
+ * looking up a window by its id. It is used to look up send windows
+ * during fault handling and receive windows when pairing user space
+ * send/receive windows.
+ *
+ * The second table, ->rxwin[], contains receive windows that are
+ * associated with NX engines. This table has VAS_COP_TYPE_MAX
+ * entries and is used to look up a receive window by its
+ * coprocessor type.
+ *
+ * Here, we save @window in the ->windows[] table. If it is a receive
+ * window, we also save the window in the ->rxwin[] table.
+ */
+static void set_vinst_win(struct vas_instance *vinst,
+ struct vas_window *window)
+{
+ int id = window->winid;
+
+ mutex_lock(&vinst->mutex);
+
+ /*
+ * There should only be one receive window for a coprocessor type
+ * unless its a user (FTW) window.
+ */
+ if (!window->user_win && !window->tx_win) {
+ WARN_ON_ONCE(vinst->rxwin[window->cop]);
+ vinst->rxwin[window->cop] = window;
+ }
+
+ WARN_ON_ONCE(vinst->windows[id] != NULL);
+ vinst->windows[id] = window;
+
+ mutex_unlock(&vinst->mutex);
+}
+
+/*
+ * Clear this window from the table(s) of windows for this VAS instance.
+ * See also function header of set_vinst_win().
+ */
+void clear_vinst_win(struct vas_window *window)
+{
+ int id = window->winid;
+ struct vas_instance *vinst = window->vinst;
+
+ mutex_lock(&vinst->mutex);
+
+ if (!window->tx_win) {
+ WARN_ON_ONCE(!vinst->rxwin[window->cop]);
+ vinst->rxwin[window->cop] = NULL;
+ }
+
+ WARN_ON_ONCE(vinst->windows[id] != window);
+ vinst->windows[id] = NULL;
+
+ mutex_unlock(&vinst->mutex);
+}
+
+static void init_winctx_for_rxwin(struct vas_window *rxwin,
+ struct vas_rx_win_attr *rxattr,
+ struct vas_winctx *winctx)
+{
+ /*
+ * We first zero (memset()) all fields and only set non-zero fields.
+ * Following fields are 0/false but maybe deserve a comment:
+ *
+ * ->notify_os_intr_reg In powerNV, send intrs to HV
+ * ->notify_disable False for NX windows
+ * ->intr_disable False for Fault Windows
+ * ->xtra_write False for NX windows
+ * ->notify_early NA for NX windows
+ * ->rsvd_txbuf_count NA for Rx windows
+ * ->lpid, ->pid, ->tid NA for Rx windows
+ */
+
+ memset(winctx, 0, sizeof(struct vas_winctx));
+
+ winctx->rx_fifo = rxattr->rx_fifo;
+ winctx->rx_fifo_size = rxattr->rx_fifo_size;
+ winctx->wcreds_max = rxattr->wcreds_max ?: VAS_WCREDS_DEFAULT;
+ winctx->pin_win = rxattr->pin_win;
+
+ winctx->nx_win = rxattr->nx_win;
+ winctx->fault_win = rxattr->fault_win;
+ winctx->rx_word_mode = rxattr->rx_win_ord_mode;
+ winctx->tx_word_mode = rxattr->tx_win_ord_mode;
+ winctx->rx_wcred_mode = rxattr->rx_wcred_mode;
+ winctx->tx_wcred_mode = rxattr->tx_wcred_mode;
+
+ if (winctx->nx_win) {
+ winctx->data_stamp = true;
+ winctx->intr_disable = true;
+ winctx->pin_win = true;
+
+ WARN_ON_ONCE(winctx->fault_win);
+ WARN_ON_ONCE(!winctx->rx_word_mode);
+ WARN_ON_ONCE(!winctx->tx_word_mode);
+ WARN_ON_ONCE(winctx->notify_after_count);
+ } else if (winctx->fault_win) {
+ winctx->notify_disable = true;
+ } else if (winctx->user_win) {
+ /*
+ * Section 1.8.1 Low Latency Core-Core Wake up of
+ * the VAS workbook:
+ *
+ * - disable credit checks ([tr]x_wcred_mode = false)
+ * - disable FIFO writes
+ * - enable ASB_Notify, disable interrupt
+ */
+ winctx->fifo_disable = true;
+ winctx->intr_disable = true;
+ winctx->rx_fifo = NULL;
+ }
+
+ winctx->lnotify_lpid = rxattr->lnotify_lpid;
+ winctx->lnotify_pid = rxattr->lnotify_pid;
+ winctx->lnotify_tid = rxattr->lnotify_tid;
+ winctx->pswid = rxattr->pswid;
+ winctx->dma_type = VAS_DMA_TYPE_INJECT;
+ winctx->tc_mode = rxattr->tc_mode;
+
+ winctx->min_scope = VAS_SCOPE_LOCAL;
+ winctx->max_scope = VAS_SCOPE_VECTORED_GROUP;
+}
+
+static bool rx_win_args_valid(enum vas_cop_type cop,
+ struct vas_rx_win_attr *attr)
+{
+ dump_rx_win_attr(attr);
+
+ if (cop >= VAS_COP_TYPE_MAX)
+ return false;
+
+ if (cop != VAS_COP_TYPE_FTW &&
+ attr->rx_fifo_size < VAS_RX_FIFO_SIZE_MIN)
+ return false;
+
+ if (attr->rx_fifo_size > VAS_RX_FIFO_SIZE_MAX)
+ return false;
+
+ if (attr->nx_win) {
+ /* cannot be fault or user window if it is nx */
+ if (attr->fault_win || attr->user_win)
+ return false;
+ /*
+ * Section 3.1.4.32: NX Windows must not disable notification,
+ * and must not enable interrupts or early notification.
+ */
+ if (attr->notify_disable || !attr->intr_disable ||
+ attr->notify_early)
+ return false;
+ } else if (attr->fault_win) {
+ /* cannot be both fault and user window */
+ if (attr->user_win)
+ return false;
+
+ /*
+ * Section 3.1.4.32: Fault windows must disable notification
+ * but not interrupts.
+ */
+ if (!attr->notify_disable || attr->intr_disable)
+ return false;
+
+ } else if (attr->user_win) {
+ /*
+ * User receive windows are only for fast-thread-wakeup
+ * (FTW). They don't need a FIFO and must disable interrupts
+ */
+ if (attr->rx_fifo || attr->rx_fifo_size || !attr->intr_disable)
+ return false;
+ } else {
+ /* Rx window must be one of NX or Fault or User window. */
+ return false;
+ }
+
+ return true;
+}
+
+void vas_init_rx_win_attr(struct vas_rx_win_attr *rxattr, enum vas_cop_type
cop)
+{
+ memset(rxattr, 0, sizeof(*rxattr));
+
+ if (cop == VAS_COP_TYPE_842 || cop == VAS_COP_TYPE_842_HIPRI) {
+ rxattr->pin_win = true;
+ rxattr->nx_win = true;
+ rxattr->fault_win = false;
+ rxattr->intr_disable = true;
+ rxattr->rx_wcred_mode = true;
+ rxattr->tx_wcred_mode = true;
+ rxattr->rx_win_ord_mode = true;
+ rxattr->tx_win_ord_mode = true;
+ } else if (cop == VAS_COP_TYPE_FAULT) {
+ rxattr->pin_win = true;
+ rxattr->fault_win = true;
+ rxattr->notify_disable = true;
+ rxattr->rx_wcred_mode = true;
+ rxattr->tx_wcred_mode = true;
+ rxattr->rx_win_ord_mode = true;
+ rxattr->tx_win_ord_mode = true;
+ } else if (cop == VAS_COP_TYPE_FTW) {
+ rxattr->user_win = true;
+ rxattr->intr_disable = true;
+
+ /*
+ * As noted in the VAS Workbook we disable credit checks.
+ * If we enable credit checks in the future, we must also
+ * implement a mechanism to return the user credits or new
+ * paste operations will fail.
+ */
+ }
+}
+EXPORT_SYMBOL_GPL(vas_init_rx_win_attr);
+
+struct vas_window *vas_rx_win_open(int vasid, enum vas_cop_type cop,
+ struct vas_rx_win_attr *rxattr)
+{
+ struct vas_instance *vinst;
+ struct vas_window *rxwin;
+ struct vas_winctx winctx;
+
+ if (!vas_initialized())
+ return ERR_PTR(-EAGAIN);
+
+ if (!rx_win_args_valid(cop, rxattr))
+ return ERR_PTR(-EINVAL);
+
+ vinst = find_vas_instance(vasid);
+ if (!vinst) {
+ pr_devel("VAS: vasid %d not found!\n", vasid);
+ return ERR_PTR(-EINVAL);
+ }
+ pr_devel("VAS: Found instance %d\n", vasid);
+
+ rxwin = vas_window_alloc(vinst);
+ if (IS_ERR(rxwin)) {
+ pr_devel("VAS: Unable to allocate memory for Rx window\n");
+ return rxwin;
+ }
+
+ rxwin->tx_win = false;
+ rxwin->nx_win = rxattr->nx_win;
+ rxwin->user_win = rxattr->user_win;
+ rxwin->cop = cop;
+ if (rxattr->user_win)
+ rxwin->pid = task_pid_vnr(current);
+
+ init_winctx_for_rxwin(rxwin, rxattr, &winctx);
+ init_winctx_regs(rxwin, &winctx);
+
+ set_vinst_win(vinst, rxwin);
+
+ return rxwin;
+}
+EXPORT_SYMBOL_GPL(vas_rx_win_open);
+
/* stub for now */
int vas_win_close(struct vas_window *window)
{
diff --git a/arch/powerpc/platforms/powernv/vas.h
b/arch/powerpc/platforms/powernv/vas.h
index 3eadf90..61fd80f 100644
--- a/arch/powerpc/platforms/powernv/vas.h
+++ b/arch/powerpc/platforms/powernv/vas.h
@@ -289,6 +289,9 @@ enum vas_notify_after_count {
/*
* One per instance of VAS. Each instance will have a separate set of
* receive windows, one per coprocessor type.
+ *
+ * See also function header of set_vinst_win() for details on ->windows[]
+ * and ->rxwin[] tables.
*/
struct vas_instance {
int vas_id;
@@ -397,6 +400,16 @@ extern struct vas_instance *find_vas_instance(int vasid);
#define VREG(r) VREG_SFX(r, _OFFSET)
#ifdef vas_debug
+static inline void dump_rx_win_attr(struct vas_rx_win_attr *attr)
+{
+ pr_err("VAS: fault %d, notify %d, intr %d early %d\n",
+ attr->fault_win, attr->notify_disable,
+ attr->intr_disable, attr->notify_early);
+
+ pr_err("VAS: rx_fifo_size %d, max value %d\n",
+ attr->rx_fifo_size, VAS_RX_FIFO_SIZE_MAX);
+}
+
static inline void vas_log_write(struct vas_window *win, char *name,
void *regptr, uint64_t val)
{
@@ -409,6 +422,7 @@ static inline void vas_log_write(struct vas_window *win,
char *name,
#else /* vas_debug */
#define vas_log_write(win, name, reg, val)
+#define dump_rx_win_attr(attr)
#endif /* vas_debug */
--
2.7.4
