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, 102 insertions, 0 deletions

diff --git a/drivers/net/phy/et1011c.c b/drivers/net/phy/et1011c.c
new file mode 100644
index 000000000..6cd8d7758
--- /dev/null
+++ b/drivers/net/phy/et1011c.c
@@ -0,0 +1,102 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * drivers/net/phy/et1011c.c
+ *
+ * Driver for LSI ET1011C PHYs
+ *
+ * Author: Chaithrika U S
+ *
+ * Copyright (c) 2008 Texas Instruments
+ */
+#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 <linux/io.h>
+#include <linux/uaccess.h>
+#include <asm/irq.h>
+
+#define ET1011C_STATUS_REG	(0x1A)
+#define ET1011C_CONFIG_REG	(0x16)
+#define ET1011C_SPEED_MASK		(0x0300)
+#define ET1011C_GIGABIT_SPEED		(0x0200)
+#define ET1011C_TX_FIFO_MASK		(0x3000)
+#define ET1011C_TX_FIFO_DEPTH_8		(0x0000)
+#define ET1011C_TX_FIFO_DEPTH_16	(0x1000)
+#define ET1011C_INTERFACE_MASK		(0x0007)
+#define ET1011C_GMII_INTERFACE		(0x0002)
+#define ET1011C_SYS_CLK_EN		(0x01 << 4)
+
+
+MODULE_DESCRIPTION("LSI ET1011C PHY driver");
+MODULE_AUTHOR("Chaithrika U S");
+MODULE_LICENSE("GPL");
+
+static int et1011c_config_aneg(struct phy_device *phydev)
+{
+	int ctl = phy_read(phydev, MII_BMCR);
+
+	if (ctl < 0)
+		return ctl;
+	ctl &= ~(BMCR_FULLDPLX | BMCR_SPEED100 | BMCR_SPEED1000 |
+		 BMCR_ANENABLE);
+	/* First clear the PHY */
+	phy_write(phydev, MII_BMCR, ctl | BMCR_RESET);
+
+	return genphy_config_aneg(phydev);
+}
+
+static int et1011c_read_status(struct phy_device *phydev)
+{
+	static int speed;
+	int ret;
+	u32 val;
+
+	ret = genphy_read_status(phydev);
+
+	if (speed != phydev->speed) {
+		speed = phydev->speed;
+		val = phy_read(phydev, ET1011C_STATUS_REG);
+		if ((val & ET1011C_SPEED_MASK) ==
+					ET1011C_GIGABIT_SPEED) {
+			val = phy_read(phydev, ET1011C_CONFIG_REG);
+			val &= ~ET1011C_TX_FIFO_MASK;
+			phy_write(phydev, ET1011C_CONFIG_REG, val |
+					  ET1011C_GMII_INTERFACE |
+					  ET1011C_SYS_CLK_EN |
+					  ET1011C_TX_FIFO_DEPTH_16);
+
+		}
+	}
+	return ret;
+}
+
+static struct phy_driver et1011c_driver[] = { {
+	.phy_id		= 0x0282f014,
+	.name		= "ET1011C",
+	.phy_id_mask	= 0xfffffff0,
+	/* PHY_GBIT_FEATURES */
+	.config_aneg	= et1011c_config_aneg,
+	.read_status	= et1011c_read_status,
+} };
+
+module_phy_driver(et1011c_driver);
+
+static const struct mdio_device_id __maybe_unused et1011c_tbl[] = {
+	{ 0x0282f014, 0xfffffff0 },
+	{ }
+};
+
+MODULE_DEVICE_TABLE(mdio, et1011c_tbl);