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, 168 insertions, 0 deletions

diff --git a/drivers/usb/cdns3/host.c b/drivers/usb/cdns3/host.c
new file mode 100644
index 000000000..f0df114c2
--- /dev/null
+++ b/drivers/usb/cdns3/host.c
@@ -0,0 +1,168 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Cadence USBSS and USBSSP DRD Driver - host side
+ *
+ * Copyright (C) 2018-2019 Cadence Design Systems.
+ * Copyright (C) 2017-2018 NXP
+ *
+ * Authors: Peter Chen <peter.chen@nxp.com>
+ *          Pawel Laszczak <pawell@cadence.com>
+ */
+
+#include <linux/platform_device.h>
+#include <linux/slab.h>
+#include "core.h"
+#include "drd.h"
+#include "host-export.h"
+#include <linux/usb/hcd.h>
+#include "../host/xhci.h"
+#include "../host/xhci-plat.h"
+
+/*
+ * The XECP_PORT_CAP_REG and XECP_AUX_CTRL_REG1 exist only
+ * in Cadence USB3 dual-role controller, so it can't be used
+ * with Cadence CDNSP dual-role controller.
+ */
+#define XECP_PORT_CAP_REG	0x8000
+#define XECP_AUX_CTRL_REG1	0x8120
+
+#define CFG_RXDET_P3_EN		BIT(15)
+#define LPM_2_STB_SWITCH_EN	BIT(25)
+
+static void xhci_cdns3_plat_start(struct usb_hcd *hcd)
+{
+	struct xhci_hcd *xhci = hcd_to_xhci(hcd);
+	u32 value;
+
+	/* set usbcmd.EU3S */
+	value = readl(&xhci->op_regs->command);
+	value |= CMD_PM_INDEX;
+	writel(value, &xhci->op_regs->command);
+
+	if (hcd->regs) {
+		value = readl(hcd->regs + XECP_AUX_CTRL_REG1);
+		value |= CFG_RXDET_P3_EN;
+		writel(value, hcd->regs + XECP_AUX_CTRL_REG1);
+
+		value = readl(hcd->regs + XECP_PORT_CAP_REG);
+		value |= LPM_2_STB_SWITCH_EN;
+		writel(value, hcd->regs + XECP_PORT_CAP_REG);
+	}
+}
+
+static int xhci_cdns3_resume_quirk(struct usb_hcd *hcd)
+{
+	xhci_cdns3_plat_start(hcd);
+	return 0;
+}
+
+static const struct xhci_plat_priv xhci_plat_cdns3_xhci = {
+	.quirks = XHCI_SKIP_PHY_INIT | XHCI_AVOID_BEI,
+	.plat_start = xhci_cdns3_plat_start,
+	.resume_quirk = xhci_cdns3_resume_quirk,
+};
+
+static const struct xhci_plat_priv xhci_plat_cdnsp_xhci = {
+	.quirks = XHCI_CDNS_SCTX_QUIRK,
+};
+
+static int __cdns_host_init(struct cdns *cdns)
+{
+	struct platform_device *xhci;
+	int ret;
+	struct usb_hcd *hcd;
+
+	cdns_drd_host_on(cdns);
+
+	xhci = platform_device_alloc("xhci-hcd", PLATFORM_DEVID_AUTO);
+	if (!xhci) {
+		dev_err(cdns->dev, "couldn't allocate xHCI device\n");
+		return -ENOMEM;
+	}
+
+	xhci->dev.parent = cdns->dev;
+	cdns->host_dev = xhci;
+
+	ret = platform_device_add_resources(xhci, cdns->xhci_res,
+					    CDNS_XHCI_RESOURCES_NUM);
+	if (ret) {
+		dev_err(cdns->dev, "couldn't add resources to xHCI device\n");
+		goto err1;
+	}
+
+	if (cdns->version < CDNSP_CONTROLLER_V2)
+		cdns->xhci_plat_data = kmemdup(&xhci_plat_cdns3_xhci,
+				sizeof(struct xhci_plat_priv), GFP_KERNEL);
+	else
+		cdns->xhci_plat_data = kmemdup(&xhci_plat_cdnsp_xhci,
+				sizeof(struct xhci_plat_priv), GFP_KERNEL);
+
+	if (!cdns->xhci_plat_data) {
+		ret = -ENOMEM;
+		goto err1;
+	}
+
+	if (cdns->pdata && (cdns->pdata->quirks & CDNS3_DEFAULT_PM_RUNTIME_ALLOW))
+		cdns->xhci_plat_data->quirks |= XHCI_DEFAULT_PM_RUNTIME_ALLOW;
+
+	ret = platform_device_add_data(xhci, cdns->xhci_plat_data,
+			sizeof(struct xhci_plat_priv));
+	if (ret)
+		goto free_memory;
+
+	ret = platform_device_add(xhci);
+	if (ret) {
+		dev_err(cdns->dev, "failed to register xHCI device\n");
+		goto free_memory;
+	}
+
+	/* Glue needs to access xHCI region register for Power management */
+	hcd = platform_get_drvdata(xhci);
+	if (hcd)
+		cdns->xhci_regs = hcd->regs;
+
+	return 0;
+
+free_memory:
+	kfree(cdns->xhci_plat_data);
+err1:
+	platform_device_put(xhci);
+	return ret;
+}
+
+static void cdns_host_exit(struct cdns *cdns)
+{
+	kfree(cdns->xhci_plat_data);
+	platform_device_unregister(cdns->host_dev);
+	cdns->host_dev = NULL;
+	cdns_drd_host_off(cdns);
+}
+
+static int cdns_host_resume(struct cdns *cdns, bool power_lost)
+{
+	struct usb_hcd *hcd = platform_get_drvdata(cdns->host_dev);
+	struct xhci_plat_priv *priv = hcd_to_xhci_priv(hcd);
+
+	priv->power_lost = power_lost;
+
+	return 0;
+}
+
+int cdns_host_init(struct cdns *cdns)
+{
+	struct cdns_role_driver *rdrv;
+
+	rdrv = devm_kzalloc(cdns->dev, sizeof(*rdrv), GFP_KERNEL);
+	if (!rdrv)
+		return -ENOMEM;
+
+	rdrv->start	= __cdns_host_init;
+	rdrv->stop	= cdns_host_exit;
+	rdrv->resume	= cdns_host_resume;
+	rdrv->state	= CDNS_ROLE_STATE_INACTIVE;
+	rdrv->name	= "host";
+
+	cdns->roles[USB_ROLE_HOST] = rdrv;
+
+	return 0;
+}