KVM: SEV: Do cache maintenance on the source VM during intra-host migrationgrafted

Manually perform cache maintenance on the source VM during intra-host
migration to ensure no stale data is left in CPU caches after the VM is
destroyed.  Because the source VM is "converted" to a non-SEV VM, KVM's
memory reclaim flows won't trigger cache maintenance, e.g. when all guest
memory is reclaimed in response to detaching from the mmu_notifier.

Note, relying on the destination VM to do cache maintenance isn't an option
as KVM doesn't require identical guest memory configurations, i.e. the
source VM may have access to memory that the destination VM does not.
Enforcing equivalent memory configurations is infeasible, as it would
require a *deep* comparison of memslots, e.g. to verify that not only are
the memslot identical, but what the memslots point at is also identical.

Fixes: b56639318bb2 ("KVM: SEV: Add support for SEV intra host migration")
Cc: stable@vger.kernel.org
Reported-by: Stefan Teodorescu <fane@google.com>
Signed-off-by: Sean Christopherson <seanjc@google.com>
Message-ID: <20260923163721.1584779-3-seanjc@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

1 files changed, 383 insertions, 0 deletions

diff --git a/drivers/usb/musb/mpfs.c b/drivers/usb/musb/mpfs.c
new file mode 100644
index 000000000..587127abd
--- /dev/null
+++ b/drivers/usb/musb/mpfs.c
@@ -0,0 +1,383 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * PolarFire SoC (MPFS) MUSB Glue Layer
+ *
+ * Copyright (c) 2020-2022 Microchip Corporation. All rights reserved.
+ * Based on {omap2430,tusb6010,ux500}.c
+ *
+ */
+
+#include <linux/clk.h>
+#include <linux/dma-mapping.h>
+#include <linux/err.h>
+#include <linux/io.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/usb/usb_phy_generic.h>
+#include "musb_core.h"
+#include "musb_dma.h"
+
+#define MPFS_MUSB_MAX_EP_NUM	8
+#define MPFS_MUSB_RAM_BITS	12
+
+struct mpfs_glue {
+	struct device *dev;
+	struct platform_device *musb;
+	struct platform_device *phy;
+	struct clk *clk;
+};
+
+static const struct musb_fifo_cfg mpfs_musb_mode_cfg[] = {
+	{ .hw_ep_num = 1, .style = FIFO_TX, .maxpacket = 512, },
+	{ .hw_ep_num = 1, .style = FIFO_RX, .maxpacket = 512, },
+	{ .hw_ep_num = 2, .style = FIFO_TX, .maxpacket = 512, },
+	{ .hw_ep_num = 2, .style = FIFO_RX, .maxpacket = 512, },
+	{ .hw_ep_num = 3, .style = FIFO_TX, .maxpacket = 512, },
+	{ .hw_ep_num = 3, .style = FIFO_RX, .maxpacket = 512, },
+	{ .hw_ep_num = 4, .style = FIFO_TX, .maxpacket = 1024, },
+	{ .hw_ep_num = 4, .style = FIFO_RX, .maxpacket = 4096, },
+};
+
+static const struct musb_hdrc_config mpfs_musb_hdrc_config = {
+	.fifo_cfg = mpfs_musb_mode_cfg,
+	.fifo_cfg_size = ARRAY_SIZE(mpfs_musb_mode_cfg),
+	.multipoint = true,
+	.dyn_fifo = true,
+	.num_eps = MPFS_MUSB_MAX_EP_NUM,
+	.ram_bits = MPFS_MUSB_RAM_BITS,
+};
+
+static void mpfs_musb_set_vbus(struct musb *musb, int is_on)
+{
+	u8 devctl;
+
+	/*
+	 * HDRC controls CPEN, but beware current surges during device
+	 * connect.  They can trigger transient overcurrent conditions
+	 * that must be ignored.
+	 */
+	devctl = musb_readb(musb->mregs, MUSB_DEVCTL);
+
+	if (is_on) {
+		musb->is_active = 1;
+		musb->xceiv->otg->default_a = 1;
+		musb->xceiv->otg->state = OTG_STATE_A_WAIT_VRISE;
+		devctl |= MUSB_DEVCTL_SESSION;
+		MUSB_HST_MODE(musb);
+	} else {
+		musb->is_active = 0;
+
+		/*
+		 * NOTE:  skipping A_WAIT_VFALL -> A_IDLE and
+		 * jumping right to B_IDLE...
+		 */
+		musb->xceiv->otg->default_a = 0;
+		musb->xceiv->otg->state = OTG_STATE_B_IDLE;
+		devctl &= ~MUSB_DEVCTL_SESSION;
+
+		MUSB_DEV_MODE(musb);
+	}
+
+	musb_writeb(musb->mregs, MUSB_DEVCTL, devctl);
+
+	dev_dbg(musb->controller, "VBUS %s, devctl %02x\n",
+		usb_otg_state_string(musb->xceiv->otg->state),
+		musb_readb(musb->mregs, MUSB_DEVCTL));
+}
+
+#define	POLL_SECONDS	2
+
+static void otg_timer(struct timer_list *t)
+{
+	struct musb		*musb = timer_container_of(musb, t,
+							      dev_timer);
+	void __iomem		*mregs = musb->mregs;
+	u8			devctl;
+	unsigned long		flags;
+
+	/*
+	 * We poll because PolarFire SoC won't expose several OTG-critical
+	 * status change events (from the transceiver) otherwise.
+	 */
+	devctl = musb_readb(mregs, MUSB_DEVCTL);
+	dev_dbg(musb->controller, "Poll devctl %02x (%s)\n", devctl,
+		usb_otg_state_string(musb->xceiv->otg->state));
+
+	spin_lock_irqsave(&musb->lock, flags);
+	switch (musb->xceiv->otg->state) {
+	case OTG_STATE_A_WAIT_BCON:
+		devctl &= ~MUSB_DEVCTL_SESSION;
+		musb_writeb(musb->mregs, MUSB_DEVCTL, devctl);
+
+		devctl = musb_readb(musb->mregs, MUSB_DEVCTL);
+		if (devctl & MUSB_DEVCTL_BDEVICE) {
+			musb->xceiv->otg->state = OTG_STATE_B_IDLE;
+			MUSB_DEV_MODE(musb);
+			mod_timer(&musb->dev_timer, jiffies + POLL_SECONDS * HZ);
+		} else {
+			musb->xceiv->otg->state = OTG_STATE_A_IDLE;
+			MUSB_HST_MODE(musb);
+		}
+		break;
+	case OTG_STATE_A_WAIT_VFALL:
+		if (devctl & MUSB_DEVCTL_VBUS) {
+			mod_timer(&musb->dev_timer, jiffies + POLL_SECONDS * HZ);
+			break;
+		}
+		musb->xceiv->otg->state = OTG_STATE_A_WAIT_VRISE;
+		break;
+	case OTG_STATE_B_IDLE:
+		/*
+		 * There's no ID-changed IRQ, so we have no good way to tell
+		 * when to switch to the A-Default state machine (by setting
+		 * the DEVCTL.Session bit).
+		 *
+		 * Workaround:  whenever we're in B_IDLE, try setting the
+		 * session flag every few seconds.  If it works, ID was
+		 * grounded and we're now in the A-Default state machine.
+		 *
+		 * NOTE: setting the session flag is _supposed_ to trigger
+		 * SRP but clearly it doesn't.
+		 */
+		musb_writeb(mregs, MUSB_DEVCTL, devctl | MUSB_DEVCTL_SESSION);
+		devctl = musb_readb(mregs, MUSB_DEVCTL);
+		if (devctl & MUSB_DEVCTL_BDEVICE)
+			mod_timer(&musb->dev_timer, jiffies + POLL_SECONDS * HZ);
+		else
+			musb->xceiv->otg->state = OTG_STATE_A_IDLE;
+		break;
+	default:
+		break;
+	}
+	spin_unlock_irqrestore(&musb->lock, flags);
+}
+
+static void __maybe_unused mpfs_musb_try_idle(struct musb *musb, unsigned long timeout)
+{
+	static unsigned long last_timer;
+
+	if (timeout == 0)
+		timeout = jiffies + msecs_to_jiffies(3);
+
+	/* Never idle if active, or when VBUS timeout is not set as host */
+	if (musb->is_active || (musb->a_wait_bcon == 0 &&
+				musb->xceiv->otg->state == OTG_STATE_A_WAIT_BCON)) {
+		dev_dbg(musb->controller, "%s active, deleting timer\n",
+			usb_otg_state_string(musb->xceiv->otg->state));
+		timer_delete(&musb->dev_timer);
+		last_timer = jiffies;
+		return;
+	}
+
+	if (time_after(last_timer, timeout) && timer_pending(&musb->dev_timer)) {
+		dev_dbg(musb->controller, "Longer idle timer already pending, ignoring...\n");
+		return;
+	}
+	last_timer = timeout;
+
+	dev_dbg(musb->controller, "%s inactive, starting idle timer for %u ms\n",
+		usb_otg_state_string(musb->xceiv->otg->state),
+		jiffies_to_msecs(timeout - jiffies));
+	mod_timer(&musb->dev_timer, timeout);
+}
+
+static irqreturn_t mpfs_musb_interrupt(int irq, void *__hci)
+{
+	unsigned long flags;
+	irqreturn_t ret = IRQ_NONE;
+	struct musb *musb = __hci;
+
+	spin_lock_irqsave(&musb->lock, flags);
+
+	musb->int_usb = musb_readb(musb->mregs, MUSB_INTRUSB);
+	musb->int_tx = musb_readw(musb->mregs, MUSB_INTRTX);
+	musb->int_rx = musb_readw(musb->mregs, MUSB_INTRRX);
+
+	if (musb->int_usb || musb->int_tx || musb->int_rx) {
+		musb_writeb(musb->mregs, MUSB_INTRUSB, musb->int_usb);
+		musb_writew(musb->mregs, MUSB_INTRTX, musb->int_tx);
+		musb_writew(musb->mregs, MUSB_INTRRX, musb->int_rx);
+		ret = musb_interrupt(musb);
+	}
+
+	/* Poll for ID change */
+	if (musb->xceiv->otg->state == OTG_STATE_B_IDLE)
+		mod_timer(&musb->dev_timer, jiffies + POLL_SECONDS * HZ);
+
+	spin_unlock_irqrestore(&musb->lock, flags);
+
+	return ret;
+}
+
+static int mpfs_musb_init(struct musb *musb)
+{
+	struct device *dev = musb->controller;
+
+	musb->xceiv = devm_usb_get_phy(dev, USB_PHY_TYPE_USB2);
+	if (IS_ERR(musb->xceiv)) {
+		dev_err(dev, "HS UDC: no transceiver configured\n");
+		return PTR_ERR(musb->xceiv);
+	}
+
+	timer_setup(&musb->dev_timer, otg_timer, 0);
+
+	musb->dyn_fifo = true;
+	musb->isr = mpfs_musb_interrupt;
+
+	musb_platform_set_vbus(musb, 1);
+
+	return 0;
+}
+
+static int mpfs_musb_exit(struct musb *musb)
+{
+	timer_delete_sync(&musb->dev_timer);
+
+	return 0;
+}
+
+static const struct musb_platform_ops mpfs_ops = {
+	.quirks		= MUSB_DMA_INVENTRA,
+	.init		= mpfs_musb_init,
+	.exit		= mpfs_musb_exit,
+	.fifo_mode	= 2,
+#ifdef CONFIG_USB_INVENTRA_DMA
+	.dma_init	= musbhs_dma_controller_create,
+	.dma_exit	= musbhs_dma_controller_destroy,
+#endif
+#ifndef CONFIG_USB_MUSB_HOST
+	.try_idle	= mpfs_musb_try_idle,
+#endif
+	.set_vbus	= mpfs_musb_set_vbus
+};
+
+static int mpfs_probe(struct platform_device *pdev)
+{
+	struct musb_hdrc_platform_data *pdata = dev_get_platdata(&pdev->dev);
+	struct mpfs_glue *glue;
+	struct platform_device *musb_pdev;
+	struct device *dev = &pdev->dev;
+	struct clk *clk;
+	int ret;
+
+	glue = devm_kzalloc(dev, sizeof(*glue), GFP_KERNEL);
+	if (!glue)
+		return -ENOMEM;
+
+	musb_pdev = platform_device_alloc("musb-hdrc", PLATFORM_DEVID_AUTO);
+	if (!musb_pdev) {
+		dev_err(dev, "failed to allocate musb device\n");
+		return -ENOMEM;
+	}
+
+	clk = devm_clk_get(&pdev->dev, NULL);
+	if (IS_ERR(clk)) {
+		dev_err(&pdev->dev, "failed to get clock\n");
+		ret = PTR_ERR(clk);
+		goto err_phy_release;
+	}
+
+	ret = clk_prepare_enable(clk);
+	if (ret) {
+		dev_err(&pdev->dev, "failed to enable clock\n");
+		goto err_phy_release;
+	}
+
+	musb_pdev->dev.parent = dev;
+	musb_pdev->dev.coherent_dma_mask = DMA_BIT_MASK(39);
+	musb_pdev->dev.dma_mask = &musb_pdev->dev.coherent_dma_mask;
+	device_set_of_node_from_dev(&musb_pdev->dev, dev);
+
+	glue->dev = dev;
+	glue->musb = musb_pdev;
+	glue->clk = clk;
+
+	pdata = devm_kzalloc(dev, sizeof(*pdata), GFP_KERNEL);
+	if (!pdata) {
+		ret = -ENOMEM;
+		goto err_clk_disable;
+	}
+
+	pdata->config = &mpfs_musb_hdrc_config;
+	pdata->platform_ops = &mpfs_ops;
+
+	pdata->extvbus = device_property_read_bool(dev, "microchip,ext-vbus-drv");
+
+	pdata->mode = usb_get_dr_mode(dev);
+	if (pdata->mode == USB_DR_MODE_UNKNOWN) {
+		dev_info(dev, "No dr_mode property found, defaulting to otg\n");
+		pdata->mode = USB_DR_MODE_OTG;
+	}
+
+	glue->phy = usb_phy_generic_register();
+	if (IS_ERR(glue->phy)) {
+		dev_err(dev, "failed to register usb-phy %ld\n",
+			PTR_ERR(glue->phy));
+		ret = PTR_ERR(glue->phy);
+		goto err_clk_disable;
+	}
+
+	platform_set_drvdata(pdev, glue);
+
+	ret = platform_device_add_resources(musb_pdev, pdev->resource, pdev->num_resources);
+	if (ret) {
+		dev_err(dev, "failed to add resources\n");
+		goto err_clk_disable;
+	}
+
+	ret = platform_device_add_data(musb_pdev, pdata, sizeof(*pdata));
+	if (ret) {
+		dev_err(dev, "failed to add platform_data\n");
+		goto err_clk_disable;
+	}
+
+	ret = platform_device_add(musb_pdev);
+	if (ret) {
+		dev_err(dev, "failed to register musb device\n");
+		goto err_clk_disable;
+	}
+
+	dev_info(&pdev->dev, "Registered MPFS MUSB driver\n");
+	return 0;
+
+err_clk_disable:
+	clk_disable_unprepare(clk);
+
+err_phy_release:
+	usb_phy_generic_unregister(glue->phy);
+	platform_device_put(musb_pdev);
+	return ret;
+}
+
+static void mpfs_remove(struct platform_device *pdev)
+{
+	struct mpfs_glue *glue = platform_get_drvdata(pdev);
+
+	clk_disable_unprepare(glue->clk);
+	platform_device_unregister(glue->musb);
+	usb_phy_generic_unregister(pdev);
+}
+
+#ifdef CONFIG_OF
+static const struct of_device_id mpfs_id_table[] = {
+	{ .compatible = "microchip,mpfs-musb" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, mpfs_id_table);
+#endif
+
+static struct platform_driver mpfs_musb_driver = {
+	.probe = mpfs_probe,
+	.remove = mpfs_remove,
+	.driver = {
+		.name = "mpfs-musb",
+		.of_match_table = of_match_ptr(mpfs_id_table)
+	},
+};
+
+module_platform_driver(mpfs_musb_driver);
+
+MODULE_DESCRIPTION("PolarFire SoC MUSB Glue Layer");
+MODULE_LICENSE("GPL");