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, 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,
+	},
+};