KVM: Don't pre-reserve xarray entries when storing empty/NULL attributesgrafted

Skip the xarray reservation loop when clearing all memory attributes, as
storing NULL only erases the entry and never needs to allocate, so no
reservation (and no cleanup of a failed one) is required in that case.

Suggested-by: Sean Christopherson <seanjc@google.com>
Cc: David Ballesteros <davimaba.v@proton.me>
Signed-off-by: Zeng Chi <zengchi@kylinos.cn>
Link: https://patch.msgid.link/20260921102442.1232375-1-zeng_chi911@163.com
[sean: split to separate patch]
Signed-off-by: Sean Christopherson <seanjc@google.com>

1 files changed, 394 insertions, 0 deletions

diff --git a/drivers/net/arcnet/com20020.c b/drivers/net/arcnet/com20020.c
new file mode 100644
index 000000000..21f962357
--- /dev/null
+++ b/drivers/net/arcnet/com20020.c
@@ -0,0 +1,394 @@
+/*
+ * Linux ARCnet driver - COM20020 chipset support
+ *
+ * Written 1997 by David Woodhouse.
+ * Written 1994-1999 by Avery Pennarun.
+ * Written 1999 by Martin Mares <mj@ucw.cz>.
+ * Derived from skeleton.c by Donald Becker.
+ *
+ * Special thanks to Contemporary Controls, Inc. (www.ccontrols.com)
+ *  for sponsoring the further development of this driver.
+ *
+ * **********************
+ *
+ * The original copyright of skeleton.c was as follows:
+ *
+ * skeleton.c Written 1993 by Donald Becker.
+ * Copyright 1993 United States Government as represented by the
+ * Director, National Security Agency.  This software may only be used
+ * and distributed according to the terms of the GNU General Public License as
+ * modified by SRC, incorporated herein by reference.
+ *
+ * **********************
+ *
+ * For more details, see drivers/net/arcnet.c
+ *
+ * **********************
+ */
+
+#define pr_fmt(fmt) "arcnet:" KBUILD_MODNAME ": " fmt
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/types.h>
+#include <linux/ioport.h>
+#include <linux/errno.h>
+#include <linux/delay.h>
+#include <linux/netdevice.h>
+#include <linux/init.h>
+#include <linux/interrupt.h>
+#include <linux/io.h>
+
+#include "arcdevice.h"
+#include "com20020.h"
+
+static const char * const clockrates[] = {
+	"XXXXXXX", "XXXXXXXX", "XXXXXX", "2.5 Mb/s",
+	"1.25Mb/s", "625 Kb/s", "312.5 Kb/s", "156.25 Kb/s",
+	"Reserved", "Reserved", "Reserved"
+};
+
+static void com20020_command(struct net_device *dev, int command);
+static int com20020_status(struct net_device *dev);
+static void com20020_setmask(struct net_device *dev, int mask);
+static int com20020_reset(struct net_device *dev, int really_reset);
+static void com20020_copy_to_card(struct net_device *dev, int bufnum,
+				  int offset, void *buf, int count);
+static void com20020_copy_from_card(struct net_device *dev, int bufnum,
+				    int offset, void *buf, int count);
+static void com20020_set_rx_mode(struct net_device *dev);
+static void com20020_close(struct net_device *);
+
+static void com20020_copy_from_card(struct net_device *dev, int bufnum,
+				    int offset, void *buf, int count)
+{
+	int ioaddr = dev->base_addr, ofs = 512 * bufnum + offset;
+
+	/* set up the address register */
+	outb((ofs >> 8) | RDDATAflag | AUTOINCflag,
+	     ioaddr + COM20020_REG_W_ADDR_HI);
+	outb(ofs & 0xff, ioaddr + COM20020_REG_W_ADDR_LO);
+
+	/* copy the data */
+	TIME(dev, "insb", count,
+	     insb(ioaddr + COM20020_REG_RW_MEMDATA, buf, count));
+}
+
+static void com20020_copy_to_card(struct net_device *dev, int bufnum,
+				  int offset, void *buf, int count)
+{
+	int ioaddr = dev->base_addr, ofs = 512 * bufnum + offset;
+
+	/* set up the address register */
+	outb((ofs >> 8) | AUTOINCflag, ioaddr + COM20020_REG_W_ADDR_HI);
+	outb(ofs & 0xff, ioaddr + COM20020_REG_W_ADDR_LO);
+
+	/* copy the data */
+	TIME(dev, "outsb", count,
+	     outsb(ioaddr + COM20020_REG_RW_MEMDATA, buf, count));
+}
+
+/* Reset the card and check some basic stuff during the detection stage. */
+int com20020_check(struct net_device *dev)
+{
+	int ioaddr = dev->base_addr, status;
+	struct arcnet_local *lp = netdev_priv(dev);
+
+	outb(XTOcfg(3) | RESETcfg, ioaddr + COM20020_REG_W_CONFIG);
+	udelay(5);
+	outb(XTOcfg(3), ioaddr + COM20020_REG_W_CONFIG);
+	mdelay(RESETtime);
+
+	lp->setup = lp->clockm ? 0 : (lp->clockp << 1);
+	lp->setup2 = (lp->clockm << 4) | 8;
+
+	/* CHECK: should we do this for SOHARD cards ? */
+	/* Enable P1Mode for backplane mode */
+	lp->setup = lp->setup | P1MODE;
+
+	com20020_set_subaddress(lp, ioaddr, SUB_SETUP1);
+	outb(lp->setup, ioaddr + COM20020_REG_W_XREG);
+
+	if (lp->clockm != 0) {
+		com20020_set_subaddress(lp, ioaddr, SUB_SETUP2);
+		outb(lp->setup2, ioaddr + COM20020_REG_W_XREG);
+
+		/* must now write the magic "restart operation" command */
+		mdelay(1);
+		outb(STARTIOcmd, ioaddr + COM20020_REG_W_COMMAND);
+	}
+
+	lp->config = (lp->timeout << 3) | (lp->backplane << 2) | SUB_NODE;
+	/* set node ID to 0x42 (but transmitter is disabled, so it's okay) */
+	outb(lp->config, ioaddr + COM20020_REG_W_CONFIG);
+	outb(0x42, ioaddr + COM20020_REG_W_XREG);
+
+	status = inb(ioaddr + COM20020_REG_R_STATUS);
+
+	if ((status & 0x99) != (NORXflag | TXFREEflag | RESETflag)) {
+		arc_printk(D_NORMAL, dev, "status invalid (%Xh).\n", status);
+		return -ENODEV;
+	}
+	arc_printk(D_INIT_REASONS, dev, "status after reset: %X\n", status);
+
+	outb(CFLAGScmd | RESETclear | CONFIGclear,
+	     ioaddr + COM20020_REG_W_COMMAND);
+	status = inb(ioaddr + COM20020_REG_R_STATUS);
+	arc_printk(D_INIT_REASONS, dev, "status after reset acknowledged: %X\n",
+		   status);
+
+	/* Read first location of memory */
+	outb(0 | RDDATAflag | AUTOINCflag, ioaddr + COM20020_REG_W_ADDR_HI);
+	outb(0, ioaddr + COM20020_REG_W_ADDR_LO);
+
+	status = inb(ioaddr + COM20020_REG_RW_MEMDATA);
+	if (status != TESTvalue) {
+		arc_printk(D_NORMAL, dev, "Signature byte not found (%02Xh != D1h).\n",
+			   status);
+		return -ENODEV;
+	}
+	return 0;
+}
+
+static int com20020_set_hwaddr(struct net_device *dev, void *addr)
+{
+	int ioaddr = dev->base_addr;
+	struct arcnet_local *lp = netdev_priv(dev);
+	struct sockaddr *hwaddr = addr;
+
+	dev_addr_set(dev, hwaddr->sa_data);
+	com20020_set_subaddress(lp, ioaddr, SUB_NODE);
+	outb(dev->dev_addr[0], ioaddr + COM20020_REG_W_XREG);
+
+	return 0;
+}
+
+static int com20020_netdev_open(struct net_device *dev)
+{
+	int ioaddr = dev->base_addr;
+	struct arcnet_local *lp = netdev_priv(dev);
+
+	lp->config |= TXENcfg;
+	outb(lp->config, ioaddr + COM20020_REG_W_CONFIG);
+
+	return arcnet_open(dev);
+}
+
+static int com20020_netdev_close(struct net_device *dev)
+{
+	int ioaddr = dev->base_addr;
+	struct arcnet_local *lp = netdev_priv(dev);
+
+	arcnet_close(dev);
+
+	/* disable transmitter */
+	lp->config &= ~TXENcfg;
+	outb(lp->config, ioaddr + COM20020_REG_W_CONFIG);
+	return 0;
+}
+
+const struct net_device_ops com20020_netdev_ops = {
+	.ndo_open	= com20020_netdev_open,
+	.ndo_stop	= com20020_netdev_close,
+	.ndo_start_xmit = arcnet_send_packet,
+	.ndo_tx_timeout = arcnet_timeout,
+	.ndo_set_mac_address = com20020_set_hwaddr,
+	.ndo_set_rx_mode = com20020_set_rx_mode,
+};
+
+/* Set up the struct net_device associated with this card.  Called after
+ * probing succeeds.
+ */
+int com20020_found(struct net_device *dev, int shared)
+{
+	struct arcnet_local *lp;
+	int ioaddr = dev->base_addr;
+
+	/* Initialize the rest of the device structure. */
+
+	lp = netdev_priv(dev);
+
+	lp->hw.owner = THIS_MODULE;
+	lp->hw.command = com20020_command;
+	lp->hw.status = com20020_status;
+	lp->hw.intmask = com20020_setmask;
+	lp->hw.reset = com20020_reset;
+	lp->hw.copy_to_card = com20020_copy_to_card;
+	lp->hw.copy_from_card = com20020_copy_from_card;
+	lp->hw.close = com20020_close;
+
+	/* FIXME: do this some other way! */
+	if (!dev->dev_addr[0])
+		arcnet_set_addr(dev, inb(ioaddr + 8));
+
+	com20020_set_subaddress(lp, ioaddr, SUB_SETUP1);
+	outb(lp->setup, ioaddr + COM20020_REG_W_XREG);
+
+	if (lp->card_flags & ARC_CAN_10MBIT) {
+		com20020_set_subaddress(lp, ioaddr, SUB_SETUP2);
+		outb(lp->setup2, ioaddr + COM20020_REG_W_XREG);
+
+		/* must now write the magic "restart operation" command */
+		mdelay(1);
+		outb(STARTIOcmd, ioaddr + COM20020_REG_W_COMMAND);
+	}
+
+	lp->config = (lp->timeout << 3) | (lp->backplane << 2) | SUB_NODE;
+	/* Default 0x38 + register: Node ID */
+	outb(lp->config, ioaddr + COM20020_REG_W_CONFIG);
+	outb(dev->dev_addr[0], ioaddr + COM20020_REG_W_XREG);
+
+	/* reserve the irq */
+	if (request_irq(dev->irq, arcnet_interrupt, shared,
+			"arcnet (COM20020)", dev)) {
+		arc_printk(D_NORMAL, dev, "Can't get IRQ %d!\n", dev->irq);
+		return -ENODEV;
+	}
+
+	arc_printk(D_NORMAL, dev, "%s: station %02Xh found at %03lXh, IRQ %d.\n",
+		   lp->card_name, dev->dev_addr[0], dev->base_addr, dev->irq);
+
+	if (lp->backplane)
+		arc_printk(D_NORMAL, dev, "Using backplane mode.\n");
+
+	if (lp->timeout != 3)
+		arc_printk(D_NORMAL, dev, "Using extended timeout value of %d\n",
+			   lp->timeout);
+
+	arc_printk(D_NORMAL, dev, "Using CKP %d - data rate %s\n",
+		   lp->setup >> 1,
+		   clockrates[3 -
+			      ((lp->setup2 & 0xF0) >> 4) +
+			      ((lp->setup & 0x0F) >> 1)]);
+			/* The clockrates array index looks very fragile.
+			 * It seems like it could have negative indexing.
+			 */
+
+	if (register_netdev(dev)) {
+		free_irq(dev->irq, dev);
+		return -EIO;
+	}
+	return 0;
+}
+
+/* Do a hardware reset on the card, and set up necessary registers.
+ *
+ * This should be called as little as possible, because it disrupts the
+ * token on the network (causes a RECON) and requires a significant delay.
+ *
+ * However, it does make sure the card is in a defined state.
+ */
+static int com20020_reset(struct net_device *dev, int really_reset)
+{
+	struct arcnet_local *lp = netdev_priv(dev);
+	u_int ioaddr = dev->base_addr;
+	u_char inbyte;
+
+	arc_printk(D_DEBUG, dev, "%s: %d: %s: dev: %p, lp: %p, dev->name: %s\n",
+		   __FILE__, __LINE__, __func__, dev, lp, dev->name);
+	arc_printk(D_INIT, dev, "Resetting %s (status=%02Xh)\n",
+		   dev->name, inb(ioaddr + COM20020_REG_R_STATUS));
+
+	arc_printk(D_DEBUG, dev, "%s: %d: %s\n", __FILE__, __LINE__, __func__);
+	lp->config |= (lp->timeout << 3) | (lp->backplane << 2);
+	/* power-up defaults */
+	outb(lp->config, ioaddr + COM20020_REG_W_CONFIG);
+	arc_printk(D_DEBUG, dev, "%s: %d: %s\n", __FILE__, __LINE__, __func__);
+
+	if (really_reset) {
+		/* reset the card */
+		outb(lp->config | RESETcfg, ioaddr + COM20020_REG_W_CONFIG);
+		udelay(5);
+		outb(lp->config, ioaddr + COM20020_REG_W_CONFIG);
+		mdelay(RESETtime * 2);
+				/* COM20020 seems to be slower sometimes */
+	}
+	/* clear flags & end reset */
+	arc_printk(D_DEBUG, dev, "%s: %d: %s\n", __FILE__, __LINE__, __func__);
+	outb(CFLAGScmd | RESETclear | CONFIGclear,
+	     ioaddr + COM20020_REG_W_COMMAND);
+
+	/* verify that the ARCnet signature byte is present */
+	arc_printk(D_DEBUG, dev, "%s: %d: %s\n", __FILE__, __LINE__, __func__);
+
+	com20020_copy_from_card(dev, 0, 0, &inbyte, 1);
+	arc_printk(D_DEBUG, dev, "%s: %d: %s\n", __FILE__, __LINE__, __func__);
+	if (inbyte != TESTvalue) {
+		arc_printk(D_DEBUG, dev, "%s: %d: %s\n",
+			   __FILE__, __LINE__, __func__);
+		arc_printk(D_NORMAL, dev, "reset failed: TESTvalue not present.\n");
+		return 1;
+	}
+	/* enable extended (512-byte) packets */
+	outb(CONFIGcmd | EXTconf, ioaddr + COM20020_REG_W_COMMAND);
+
+	arc_printk(D_DEBUG, dev, "%s: %d: %s\n", __FILE__, __LINE__, __func__);
+
+	/* done!  return success. */
+	return 0;
+}
+
+static void com20020_setmask(struct net_device *dev, int mask)
+{
+	u_int ioaddr = dev->base_addr;
+
+	arc_printk(D_DURING, dev, "Setting mask to %x at %x\n", mask, ioaddr);
+	outb(mask, ioaddr + COM20020_REG_W_INTMASK);
+}
+
+static void com20020_command(struct net_device *dev, int cmd)
+{
+	u_int ioaddr = dev->base_addr;
+
+	outb(cmd, ioaddr + COM20020_REG_W_COMMAND);
+}
+
+static int com20020_status(struct net_device *dev)
+{
+	u_int ioaddr = dev->base_addr;
+
+	return inb(ioaddr + COM20020_REG_R_STATUS) +
+		(inb(ioaddr + COM20020_REG_R_DIAGSTAT) << 8);
+}
+
+static void com20020_close(struct net_device *dev)
+{
+	struct arcnet_local *lp = netdev_priv(dev);
+	int ioaddr = dev->base_addr;
+
+	/* disable transmitter */
+	lp->config &= ~TXENcfg;
+	outb(lp->config, ioaddr + COM20020_REG_W_CONFIG);
+}
+
+/* ARCnet does not support multicast, only unicast and broadcast */
+static void com20020_set_rx_mode(struct net_device *dev)
+{
+	struct arcnet_local *lp = netdev_priv(dev);
+	int ioaddr = dev->base_addr;
+
+	if ((dev->flags & IFF_PROMISC) && (dev->flags & IFF_UP)) {
+		/* Enable promiscuous mode */
+		if (!(lp->setup & PROMISCset))
+			arc_printk(D_NORMAL, dev, "Setting promiscuous flag...\n");
+		com20020_set_subaddress(lp, ioaddr, SUB_SETUP1);
+		lp->setup |= PROMISCset;
+		outb(lp->setup, ioaddr + COM20020_REG_W_XREG);
+	} else {
+		/* Disable promiscuous mode, use normal mode */
+		if ((lp->setup & PROMISCset))
+			arc_printk(D_NORMAL, dev, "Resetting promiscuous flag...\n");
+		com20020_set_subaddress(lp, ioaddr, SUB_SETUP1);
+		lp->setup &= ~PROMISCset;
+		outb(lp->setup, ioaddr + COM20020_REG_W_XREG);
+	}
+}
+
+#ifdef CONFIG_ARCNET_COM20020_PCI_MODULE
+EXPORT_SYMBOL(com20020_check);
+EXPORT_SYMBOL(com20020_found);
+EXPORT_SYMBOL(com20020_netdev_ops);
+#endif
+
+MODULE_DESCRIPTION("ARCnet COM20020 chipset core driver");
+MODULE_LICENSE("GPL");