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, 129 insertions, 0 deletions

diff --git a/drivers/usb/dwc3/ulpi.c b/drivers/usb/dwc3/ulpi.c
new file mode 100644
index 000000000..a256b7f5d
--- /dev/null
+++ b/drivers/usb/dwc3/ulpi.c
@@ -0,0 +1,129 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * ulpi.c - DesignWare USB3 Controller's ULPI PHY interface
+ *
+ * Copyright (C) 2015 Intel Corporation
+ *
+ * Author: Heikki Krogerus <heikki.krogerus@linux.intel.com>
+ */
+
+#include <linux/delay.h>
+#include <linux/time64.h>
+#include <linux/ulpi/regs.h>
+#include <linux/ulpi/driver.h>
+
+#include "core.h"
+#include "io.h"
+
+#define USB_VENDOR_MICROCHIP 0x0424
+
+#define DWC3_ULPI_ADDR(a) \
+		((a >= ULPI_EXT_VENDOR_SPECIFIC) ? \
+		DWC3_GUSB2PHYACC_ADDR(ULPI_ACCESS_EXTENDED) | \
+		DWC3_GUSB2PHYACC_EXTEND_ADDR(a) : DWC3_GUSB2PHYACC_ADDR(a))
+
+#define DWC3_ULPI_BASE_DELAY	DIV_ROUND_UP(NSEC_PER_SEC, 60000000L)
+
+static int dwc3_ulpi_busyloop(struct dwc3 *dwc, u8 addr, bool read)
+{
+	unsigned long ns = 5L * DWC3_ULPI_BASE_DELAY;
+	unsigned int count = 10000;
+	u32 reg;
+
+	if (addr >= ULPI_EXT_VENDOR_SPECIFIC)
+		ns += DWC3_ULPI_BASE_DELAY;
+
+	if (read)
+		ns += DWC3_ULPI_BASE_DELAY;
+
+	reg = dwc3_readl(dwc, DWC3_GUSB2PHYCFG(0));
+	if (reg & DWC3_GUSB2PHYCFG_SUSPHY)
+		usleep_range(1000, 1200);
+
+	while (count--) {
+		ndelay(ns);
+		reg = dwc3_readl(dwc, DWC3_GUSB2PHYACC(0));
+		if (reg & DWC3_GUSB2PHYACC_DONE)
+			return 0;
+		cpu_relax();
+	}
+
+	return -ETIMEDOUT;
+}
+
+static int dwc3_ulpi_read(struct device *dev, u8 addr)
+{
+	struct dwc3 *dwc = dev_get_drvdata(dev);
+	u32 reg;
+	int ret;
+
+	reg = DWC3_GUSB2PHYACC_NEWREGREQ | DWC3_ULPI_ADDR(addr);
+	dwc3_writel(dwc, DWC3_GUSB2PHYACC(0), reg);
+
+	ret = dwc3_ulpi_busyloop(dwc, addr, true);
+	if (ret)
+		return ret;
+
+	reg = dwc3_readl(dwc, DWC3_GUSB2PHYACC(0));
+
+	return DWC3_GUSB2PHYACC_DATA(reg);
+}
+
+static int dwc3_ulpi_write(struct device *dev, u8 addr, u8 val)
+{
+	struct dwc3 *dwc = dev_get_drvdata(dev);
+	u32 reg;
+
+	reg = DWC3_GUSB2PHYACC_NEWREGREQ | DWC3_ULPI_ADDR(addr);
+	reg |= DWC3_GUSB2PHYACC_WRITE | val;
+	dwc3_writel(dwc, DWC3_GUSB2PHYACC(0), reg);
+
+	return dwc3_ulpi_busyloop(dwc, addr, false);
+}
+
+static const struct ulpi_ops dwc3_ulpi_ops = {
+	.read = dwc3_ulpi_read,
+	.write = dwc3_ulpi_write,
+};
+
+static void dwc3_ulpi_detect_config(struct dwc3 *dwc)
+{
+	struct ulpi *ulpi = dwc->ulpi;
+
+	switch (ulpi->id.vendor) {
+	case USB_VENDOR_MICROCHIP:
+		switch (ulpi->id.product) {
+		case 0x0009:
+			/* Microchip USB3340 ULPI PHY */
+			dwc->enable_usb2_transceiver_delay = true;
+			break;
+		default:
+			break;
+		}
+		break;
+	default:
+		break;
+	}
+}
+
+int dwc3_ulpi_init(struct dwc3 *dwc)
+{
+	/* Register the interface */
+	dwc->ulpi = ulpi_register_interface(dwc->dev, &dwc3_ulpi_ops);
+	if (IS_ERR(dwc->ulpi)) {
+		dev_err(dwc->dev, "failed to register ULPI interface");
+		return PTR_ERR(dwc->ulpi);
+	}
+
+	dwc3_ulpi_detect_config(dwc);
+
+	return 0;
+}
+
+void dwc3_ulpi_exit(struct dwc3 *dwc)
+{
+	if (dwc->ulpi) {
+		ulpi_unregister_interface(dwc->ulpi);
+		dwc->ulpi = NULL;
+	}
+}