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, 177 insertions, 0 deletions

diff --git a/drivers/usb/host/ehci-grlib.c b/drivers/usb/host/ehci-grlib.c
new file mode 100644
index 000000000..bd9762eaa
--- /dev/null
+++ b/drivers/usb/host/ehci-grlib.c
@@ -0,0 +1,177 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * Driver for Aeroflex Gaisler GRLIB GRUSBHC EHCI host controller
+ *
+ * GRUSBHC is typically found on LEON/GRLIB SoCs
+ *
+ * (c) Jan Andersson <jan@gaisler.com>
+ *
+ * Based on ehci-ppc-of.c which is:
+ * (c) Valentine Barshak <vbarshak@ru.mvista.com>
+ * and in turn based on "ehci-ppc-soc.c" by Stefan Roese <sr@denx.de>
+ * and "ohci-ppc-of.c" by Sylvain Munaut <tnt@246tNt.com>
+ */
+
+#include <linux/err.h>
+#include <linux/signal.h>
+
+#include <linux/of_irq.h>
+#include <linux/of_address.h>
+#include <linux/of_platform.h>
+
+#define GRUSBHC_HCIVERSION 0x0100 /* Known value of cap. reg. HCIVERSION */
+
+static const struct hc_driver ehci_grlib_hc_driver = {
+	.description		= hcd_name,
+	.product_desc		= "GRLIB GRUSBHC EHCI",
+	.hcd_priv_size		= sizeof(struct ehci_hcd),
+
+	/*
+	 * generic hardware linkage
+	 */
+	.irq			= ehci_irq,
+	.flags			= HCD_MEMORY | HCD_DMA | HCD_USB2 | HCD_BH,
+
+	/*
+	 * basic lifecycle operations
+	 */
+	.reset			= ehci_setup,
+	.start			= ehci_run,
+	.stop			= ehci_stop,
+	.shutdown		= ehci_shutdown,
+
+	/*
+	 * managing i/o requests and associated device resources
+	 */
+	.urb_enqueue		= ehci_urb_enqueue,
+	.urb_dequeue		= ehci_urb_dequeue,
+	.endpoint_disable	= ehci_endpoint_disable,
+	.endpoint_reset		= ehci_endpoint_reset,
+
+	/*
+	 * scheduling support
+	 */
+	.get_frame_number	= ehci_get_frame,
+
+	/*
+	 * root hub support
+	 */
+	.hub_status_data	= ehci_hub_status_data,
+	.hub_control		= ehci_hub_control,
+#ifdef	CONFIG_PM
+	.bus_suspend		= ehci_bus_suspend,
+	.bus_resume		= ehci_bus_resume,
+#endif
+	.relinquish_port	= ehci_relinquish_port,
+	.port_handed_over	= ehci_port_handed_over,
+
+	.clear_tt_buffer_complete	= ehci_clear_tt_buffer_complete,
+};
+
+
+static int ehci_hcd_grlib_probe(struct platform_device *op)
+{
+	struct device_node *dn = op->dev.of_node;
+	struct usb_hcd *hcd;
+	struct ehci_hcd	*ehci = NULL;
+	struct resource res;
+	u32 hc_capbase;
+	int irq;
+	int rv;
+
+	if (usb_disabled())
+		return -ENODEV;
+
+	dev_dbg(&op->dev, "initializing GRUSBHC EHCI USB Controller\n");
+
+	rv = of_address_to_resource(dn, 0, &res);
+	if (rv)
+		return rv;
+
+	/* usb_create_hcd requires dma_mask != NULL */
+	op->dev.dma_mask = &op->dev.coherent_dma_mask;
+	hcd = usb_create_hcd(&ehci_grlib_hc_driver, &op->dev,
+			"GRUSBHC EHCI USB");
+	if (!hcd)
+		return -ENOMEM;
+
+	hcd->rsrc_start = res.start;
+	hcd->rsrc_len = resource_size(&res);
+
+	irq = irq_of_parse_and_map(dn, 0);
+	if (!irq) {
+		dev_err(&op->dev, "%s: irq_of_parse_and_map failed\n",
+			__FILE__);
+		rv = -EBUSY;
+		goto err_irq;
+	}
+
+	hcd->regs = devm_ioremap_resource(&op->dev, &res);
+	if (IS_ERR(hcd->regs)) {
+		rv = PTR_ERR(hcd->regs);
+		goto err_ioremap;
+	}
+
+	ehci = hcd_to_ehci(hcd);
+
+	ehci->caps = hcd->regs;
+
+	/* determine endianness of this implementation */
+	hc_capbase = ehci_readl(ehci, &ehci->caps->hc_capbase);
+	if (HC_VERSION(ehci, hc_capbase) != GRUSBHC_HCIVERSION) {
+		ehci->big_endian_mmio = 1;
+		ehci->big_endian_desc = 1;
+		ehci->big_endian_capbase = 1;
+	}
+
+	rv = usb_add_hcd(hcd, irq, 0);
+	if (rv)
+		goto err_ioremap;
+
+	device_wakeup_enable(hcd->self.controller);
+	return 0;
+
+err_ioremap:
+	irq_dispose_mapping(irq);
+err_irq:
+	usb_put_hcd(hcd);
+
+	return rv;
+}
+
+
+static void ehci_hcd_grlib_remove(struct platform_device *op)
+{
+	struct usb_hcd *hcd = platform_get_drvdata(op);
+
+	dev_dbg(&op->dev, "stopping GRLIB GRUSBHC EHCI USB Controller\n");
+
+	usb_remove_hcd(hcd);
+
+	irq_dispose_mapping(hcd->irq);
+
+	usb_put_hcd(hcd);
+}
+
+
+static const struct of_device_id ehci_hcd_grlib_of_match[] = {
+	{
+		.name = "GAISLER_EHCI",
+	 },
+	{
+		.name = "01_026",
+	 },
+	{},
+};
+MODULE_DEVICE_TABLE(of, ehci_hcd_grlib_of_match);
+
+
+static struct platform_driver ehci_grlib_driver = {
+	.probe		= ehci_hcd_grlib_probe,
+	.remove		= ehci_hcd_grlib_remove,
+	.shutdown	= usb_hcd_platform_shutdown,
+	.driver = {
+		.name = "grlib-ehci",
+		.of_match_table = ehci_hcd_grlib_of_match,
+	},
+};