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, 220 insertions, 0 deletions

diff --git a/drivers/net/phy/davicom.c b/drivers/net/phy/davicom.c
new file mode 100644
index 000000000..fa3692508
--- /dev/null
+++ b/drivers/net/phy/davicom.c
@@ -0,0 +1,220 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * drivers/net/phy/davicom.c
+ *
+ * Driver for Davicom PHYs
+ *
+ * Author: Andy Fleming
+ *
+ * Copyright (c) 2004 Freescale Semiconductor, Inc.
+ */
+#include <linux/kernel.h>
+#include <linux/string.h>
+#include <linux/errno.h>
+#include <linux/unistd.h>
+#include <linux/interrupt.h>
+#include <linux/init.h>
+#include <linux/delay.h>
+#include <linux/netdevice.h>
+#include <linux/etherdevice.h>
+#include <linux/skbuff.h>
+#include <linux/spinlock.h>
+#include <linux/mm.h>
+#include <linux/module.h>
+#include <linux/mii.h>
+#include <linux/ethtool.h>
+#include <linux/phy.h>
+
+#include <asm/io.h>
+#include <asm/irq.h>
+#include <linux/uaccess.h>
+
+#define MII_DM9161_SCR		0x10
+#define MII_DM9161_SCR_INIT	0x0610
+#define MII_DM9161_SCR_RMII	0x0100
+
+/* DM9161 Interrupt Register */
+#define MII_DM9161_INTR	0x15
+#define MII_DM9161_INTR_PEND		0x8000
+#define MII_DM9161_INTR_DPLX_MASK	0x0800
+#define MII_DM9161_INTR_SPD_MASK	0x0400
+#define MII_DM9161_INTR_LINK_MASK	0x0200
+#define MII_DM9161_INTR_MASK		0x0100
+#define MII_DM9161_INTR_DPLX_CHANGE	0x0010
+#define MII_DM9161_INTR_SPD_CHANGE	0x0008
+#define MII_DM9161_INTR_LINK_CHANGE	0x0004
+#define MII_DM9161_INTR_INIT		0x0000
+#define MII_DM9161_INTR_STOP	\
+	(MII_DM9161_INTR_DPLX_MASK | MII_DM9161_INTR_SPD_MASK |	\
+	 MII_DM9161_INTR_LINK_MASK | MII_DM9161_INTR_MASK)
+#define MII_DM9161_INTR_CHANGE	\
+	(MII_DM9161_INTR_DPLX_CHANGE | \
+	 MII_DM9161_INTR_SPD_CHANGE | \
+	 MII_DM9161_INTR_LINK_CHANGE)
+
+/* DM9161 10BT Configuration/Status */
+#define MII_DM9161_10BTCSR	0x12
+#define MII_DM9161_10BTCSR_INIT	0x7800
+
+MODULE_DESCRIPTION("Davicom PHY driver");
+MODULE_AUTHOR("Andy Fleming");
+MODULE_LICENSE("GPL");
+
+
+static int dm9161_ack_interrupt(struct phy_device *phydev)
+{
+	int err = phy_read(phydev, MII_DM9161_INTR);
+
+	return (err < 0) ? err : 0;
+}
+
+#define DM9161_DELAY 1
+static int dm9161_config_intr(struct phy_device *phydev)
+{
+	int temp, err;
+
+	temp = phy_read(phydev, MII_DM9161_INTR);
+
+	if (temp < 0)
+		return temp;
+
+	if (phydev->interrupts == PHY_INTERRUPT_ENABLED) {
+		err = dm9161_ack_interrupt(phydev);
+		if (err)
+			return err;
+
+		temp &= ~(MII_DM9161_INTR_STOP);
+		err = phy_write(phydev, MII_DM9161_INTR, temp);
+	} else {
+		temp |= MII_DM9161_INTR_STOP;
+		err = phy_write(phydev, MII_DM9161_INTR, temp);
+		if (err)
+			return err;
+
+		err = dm9161_ack_interrupt(phydev);
+	}
+
+	return err;
+}
+
+static irqreturn_t dm9161_handle_interrupt(struct phy_device *phydev)
+{
+	int irq_status;
+
+	irq_status = phy_read(phydev, MII_DM9161_INTR);
+	if (irq_status < 0) {
+		phy_error(phydev);
+		return IRQ_NONE;
+	}
+
+	if (!(irq_status & MII_DM9161_INTR_CHANGE))
+		return IRQ_NONE;
+
+	phy_trigger_machine(phydev);
+
+	return IRQ_HANDLED;
+}
+
+static int dm9161_config_aneg(struct phy_device *phydev)
+{
+	int err;
+
+	/* Isolate the PHY */
+	err = phy_write(phydev, MII_BMCR, BMCR_ISOLATE);
+
+	if (err < 0)
+		return err;
+
+	/* Configure the new settings */
+	err = genphy_config_aneg(phydev);
+
+	if (err < 0)
+		return err;
+
+	return 0;
+}
+
+static int dm9161_config_init(struct phy_device *phydev)
+{
+	int err, temp;
+
+	/* Isolate the PHY */
+	err = phy_write(phydev, MII_BMCR, BMCR_ISOLATE);
+
+	if (err < 0)
+		return err;
+
+	switch (phydev->interface) {
+	case PHY_INTERFACE_MODE_MII:
+		temp = MII_DM9161_SCR_INIT;
+		break;
+	case PHY_INTERFACE_MODE_RMII:
+		temp =  MII_DM9161_SCR_INIT | MII_DM9161_SCR_RMII;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	/* Do not bypass the scrambler/descrambler */
+	err = phy_write(phydev, MII_DM9161_SCR, temp);
+	if (err < 0)
+		return err;
+
+	/* Clear 10BTCSR to default */
+	err = phy_write(phydev, MII_DM9161_10BTCSR, MII_DM9161_10BTCSR_INIT);
+
+	if (err < 0)
+		return err;
+
+	/* Reconnect the PHY, and enable Autonegotiation */
+	return phy_write(phydev, MII_BMCR, BMCR_ANENABLE);
+}
+
+static struct phy_driver dm91xx_driver[] = {
+{
+	.phy_id		= 0x0181b880,
+	.name		= "Davicom DM9161E",
+	.phy_id_mask	= 0x0ffffff0,
+	/* PHY_BASIC_FEATURES */
+	.config_init	= dm9161_config_init,
+	.config_aneg	= dm9161_config_aneg,
+	.config_intr	= dm9161_config_intr,
+	.handle_interrupt = dm9161_handle_interrupt,
+}, {
+	.phy_id		= 0x0181b8b0,
+	.name		= "Davicom DM9161B/C",
+	.phy_id_mask	= 0x0ffffff0,
+	/* PHY_BASIC_FEATURES */
+	.config_init	= dm9161_config_init,
+	.config_aneg	= dm9161_config_aneg,
+	.config_intr	= dm9161_config_intr,
+	.handle_interrupt = dm9161_handle_interrupt,
+}, {
+	.phy_id		= 0x0181b8a0,
+	.name		= "Davicom DM9161A",
+	.phy_id_mask	= 0x0ffffff0,
+	/* PHY_BASIC_FEATURES */
+	.config_init	= dm9161_config_init,
+	.config_aneg	= dm9161_config_aneg,
+	.config_intr	= dm9161_config_intr,
+	.handle_interrupt = dm9161_handle_interrupt,
+}, {
+	.phy_id		= 0x00181b80,
+	.name		= "Davicom DM9131",
+	.phy_id_mask	= 0x0ffffff0,
+	/* PHY_BASIC_FEATURES */
+	.config_intr	= dm9161_config_intr,
+	.handle_interrupt = dm9161_handle_interrupt,
+} };
+
+module_phy_driver(dm91xx_driver);
+
+static const struct mdio_device_id __maybe_unused davicom_tbl[] = {
+	{ 0x0181b880, 0x0ffffff0 },
+	{ 0x0181b8b0, 0x0ffffff0 },
+	{ 0x0181b8a0, 0x0ffffff0 },
+	{ 0x00181b80, 0x0ffffff0 },
+	{ }
+};
+
+MODULE_DEVICE_TABLE(mdio, davicom_tbl);