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, 274 insertions, 0 deletions

diff --git a/drivers/usb/host/ssb-hcd.c b/drivers/usb/host/ssb-hcd.c
new file mode 100644
index 000000000..016987764
--- /dev/null
+++ b/drivers/usb/host/ssb-hcd.c
@@ -0,0 +1,274 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Sonics Silicon Backplane
+ * Broadcom USB-core driver  (SSB bus glue)
+ *
+ * Copyright 2011-2012 Hauke Mehrtens <hauke@hauke-m.de>
+ *
+ * Based on ssb-ohci driver
+ * Copyright 2007 Michael Buesch <m@bues.ch>
+ *
+ * Derived from the OHCI-PCI driver
+ * Copyright 1999 Roman Weissgaerber
+ * Copyright 2000-2002 David Brownell
+ * Copyright 1999 Linus Torvalds
+ * Copyright 1999 Gregory P. Smith
+ *
+ * Derived from the USBcore related parts of Broadcom-SB
+ * Copyright 2005-2011 Broadcom Corporation
+ */
+#include <linux/ssb/ssb.h>
+#include <linux/delay.h>
+#include <linux/platform_device.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/usb/ehci_pdriver.h>
+#include <linux/usb/ohci_pdriver.h>
+
+MODULE_AUTHOR("Hauke Mehrtens");
+MODULE_DESCRIPTION("Common USB driver for SSB Bus");
+MODULE_LICENSE("GPL");
+
+#define SSB_HCD_TMSLOW_HOSTMODE	(1 << 29)
+
+struct ssb_hcd_device {
+	struct platform_device *ehci_dev;
+	struct platform_device *ohci_dev;
+
+	u32 enable_flags;
+};
+
+static void ssb_hcd_5354wa(struct ssb_device *dev)
+{
+#ifdef CONFIG_SSB_DRIVER_MIPS
+	/* Work around for 5354 failures */
+	if (dev->id.revision == 2 && dev->bus->chip_id == 0x5354) {
+		/* Change syn01 reg */
+		ssb_write32(dev, 0x894, 0x00fe00fe);
+
+		/* Change syn03 reg */
+		ssb_write32(dev, 0x89c, ssb_read32(dev, 0x89c) | 0x1);
+	}
+#endif
+}
+
+static void ssb_hcd_usb20wa(struct ssb_device *dev)
+{
+	if (dev->id.coreid == SSB_DEV_USB20_HOST) {
+		/*
+		 * USB 2.0 special considerations:
+		 *
+		 * In addition to the standard SSB reset sequence, the Host
+		 * Control Register must be programmed to bring the USB core
+		 * and various phy components out of reset.
+		 */
+		ssb_write32(dev, 0x200, 0x7ff);
+
+		/* Change Flush control reg */
+		ssb_write32(dev, 0x400, ssb_read32(dev, 0x400) & ~8);
+		ssb_read32(dev, 0x400);
+
+		/* Change Shim control reg */
+		ssb_write32(dev, 0x304, ssb_read32(dev, 0x304) & ~0x100);
+		ssb_read32(dev, 0x304);
+
+		udelay(1);
+
+		ssb_hcd_5354wa(dev);
+	}
+}
+
+/* based on arch/mips/brcm-boards/bcm947xx/pcibios.c */
+static u32 ssb_hcd_init_chip(struct ssb_device *dev)
+{
+	u32 flags = 0;
+
+	if (dev->id.coreid == SSB_DEV_USB11_HOSTDEV)
+		/* Put the device into host-mode. */
+		flags |= SSB_HCD_TMSLOW_HOSTMODE;
+
+	ssb_device_enable(dev, flags);
+
+	ssb_hcd_usb20wa(dev);
+
+	return flags;
+}
+
+static const struct usb_ehci_pdata ehci_pdata = {
+};
+
+static const struct usb_ohci_pdata ohci_pdata = {
+};
+
+static struct platform_device *ssb_hcd_create_pdev(struct ssb_device *dev, bool ohci, u32 addr, u32 len)
+{
+	struct platform_device *hci_dev;
+	struct resource hci_res[2];
+	int ret;
+
+	memset(hci_res, 0, sizeof(hci_res));
+
+	hci_res[0].start = addr;
+	hci_res[0].end = hci_res[0].start + len - 1;
+	hci_res[0].flags = IORESOURCE_MEM;
+
+	hci_res[1].start = dev->irq;
+	hci_res[1].flags = IORESOURCE_IRQ;
+
+	hci_dev = platform_device_alloc(ohci ? "ohci-platform" :
+					"ehci-platform" , 0);
+	if (!hci_dev)
+		return ERR_PTR(-ENOMEM);
+
+	hci_dev->dev.parent = dev->dev;
+	hci_dev->dev.dma_mask = &hci_dev->dev.coherent_dma_mask;
+
+	ret = platform_device_add_resources(hci_dev, hci_res,
+					    ARRAY_SIZE(hci_res));
+	if (ret)
+		goto err_alloc;
+	if (ohci)
+		ret = platform_device_add_data(hci_dev, &ohci_pdata,
+					       sizeof(ohci_pdata));
+	else
+		ret = platform_device_add_data(hci_dev, &ehci_pdata,
+					       sizeof(ehci_pdata));
+	if (ret)
+		goto err_alloc;
+	ret = platform_device_add(hci_dev);
+	if (ret)
+		goto err_alloc;
+
+	return hci_dev;
+
+err_alloc:
+	platform_device_put(hci_dev);
+	return ERR_PTR(ret);
+}
+
+static int ssb_hcd_probe(struct ssb_device *dev,
+				   const struct ssb_device_id *id)
+{
+	int err, tmp;
+	int start, len;
+	u16 chipid_top;
+	u16 coreid = dev->id.coreid;
+	struct ssb_hcd_device *usb_dev;
+
+	/* USBcores are only connected on embedded devices. */
+	chipid_top = (dev->bus->chip_id & 0xFF00);
+	if (chipid_top != 0x4700 && chipid_top != 0x5300)
+		return -ENODEV;
+
+	/* TODO: Probably need checks here; is the core connected? */
+
+	if (dma_set_mask_and_coherent(dev->dma_dev, DMA_BIT_MASK(32)))
+		return -EOPNOTSUPP;
+
+	usb_dev = devm_kzalloc(dev->dev, sizeof(struct ssb_hcd_device),
+			       GFP_KERNEL);
+	if (!usb_dev)
+		return -ENOMEM;
+
+	/* We currently always attach SSB_DEV_USB11_HOSTDEV
+	 * as HOST OHCI. If we want to attach it as Client device,
+	 * we must branch here and call into the (yet to
+	 * be written) Client mode driver. Same for remove(). */
+	usb_dev->enable_flags = ssb_hcd_init_chip(dev);
+
+	tmp = ssb_read32(dev, SSB_ADMATCH0);
+
+	start = ssb_admatch_base(tmp);
+	len = (coreid == SSB_DEV_USB20_HOST) ? 0x800 : ssb_admatch_size(tmp);
+	usb_dev->ohci_dev = ssb_hcd_create_pdev(dev, true, start, len);
+	if (IS_ERR(usb_dev->ohci_dev))
+		return PTR_ERR(usb_dev->ohci_dev);
+
+	if (coreid == SSB_DEV_USB20_HOST) {
+		start = ssb_admatch_base(tmp) + 0x800; /* ehci core offset */
+		usb_dev->ehci_dev = ssb_hcd_create_pdev(dev, false, start, len);
+		if (IS_ERR(usb_dev->ehci_dev)) {
+			err = PTR_ERR(usb_dev->ehci_dev);
+			goto err_unregister_ohci_dev;
+		}
+	}
+
+	ssb_set_drvdata(dev, usb_dev);
+	return 0;
+
+err_unregister_ohci_dev:
+	platform_device_unregister(usb_dev->ohci_dev);
+	return err;
+}
+
+static void ssb_hcd_remove(struct ssb_device *dev)
+{
+	struct ssb_hcd_device *usb_dev = ssb_get_drvdata(dev);
+	struct platform_device *ohci_dev = usb_dev->ohci_dev;
+	struct platform_device *ehci_dev = usb_dev->ehci_dev;
+
+	if (ohci_dev)
+		platform_device_unregister(ohci_dev);
+	if (ehci_dev)
+		platform_device_unregister(ehci_dev);
+
+	ssb_device_disable(dev, 0);
+}
+
+static void ssb_hcd_shutdown(struct ssb_device *dev)
+{
+	ssb_device_disable(dev, 0);
+}
+
+#ifdef CONFIG_PM
+
+static int ssb_hcd_suspend(struct ssb_device *dev, pm_message_t state)
+{
+	ssb_device_disable(dev, 0);
+
+	return 0;
+}
+
+static int ssb_hcd_resume(struct ssb_device *dev)
+{
+	struct ssb_hcd_device *usb_dev = ssb_get_drvdata(dev);
+
+	ssb_device_enable(dev, usb_dev->enable_flags);
+
+	return 0;
+}
+
+#else /* !CONFIG_PM */
+#define ssb_hcd_suspend	NULL
+#define ssb_hcd_resume	NULL
+#endif /* CONFIG_PM */
+
+static const struct ssb_device_id ssb_hcd_table[] = {
+	SSB_DEVICE(SSB_VENDOR_BROADCOM, SSB_DEV_USB11_HOSTDEV, SSB_ANY_REV),
+	SSB_DEVICE(SSB_VENDOR_BROADCOM, SSB_DEV_USB11_HOST, SSB_ANY_REV),
+	SSB_DEVICE(SSB_VENDOR_BROADCOM, SSB_DEV_USB20_HOST, SSB_ANY_REV),
+	{},
+};
+MODULE_DEVICE_TABLE(ssb, ssb_hcd_table);
+
+static struct ssb_driver ssb_hcd_driver = {
+	.name		= KBUILD_MODNAME,
+	.id_table	= ssb_hcd_table,
+	.probe		= ssb_hcd_probe,
+	.remove		= ssb_hcd_remove,
+	.shutdown	= ssb_hcd_shutdown,
+	.suspend	= ssb_hcd_suspend,
+	.resume		= ssb_hcd_resume,
+};
+
+static int __init ssb_hcd_init(void)
+{
+	return ssb_driver_register(&ssb_hcd_driver);
+}
+module_init(ssb_hcd_init);
+
+static void __exit ssb_hcd_exit(void)
+{
+	ssb_driver_unregister(&ssb_hcd_driver);
+}
+module_exit(ssb_hcd_exit);