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, 96 insertions, 0 deletions

diff --git a/drivers/net/phy/teranetics.c b/drivers/net/phy/teranetics.c
new file mode 100644
index 000000000..46c5ff7d7
--- /dev/null
+++ b/drivers/net/phy/teranetics.c
@@ -0,0 +1,96 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Driver for Teranetics PHY
+ *
+ * Author: Shaohui Xie <Shaohui.Xie@freescale.com>
+ *
+ * Copyright 2015 Freescale Semiconductor, Inc.
+ */
+
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/mii.h>
+#include <linux/ethtool.h>
+#include <linux/mdio.h>
+#include <linux/phy.h>
+
+MODULE_DESCRIPTION("Teranetics PHY driver");
+MODULE_AUTHOR("Shaohui Xie <Shaohui.Xie@freescale.com>");
+MODULE_LICENSE("GPL v2");
+
+#define PHY_ID_TN2020	0x00a19410
+#define MDIO_PHYXS_LNSTAT_SYNC0	0x0001
+#define MDIO_PHYXS_LNSTAT_SYNC1	0x0002
+#define MDIO_PHYXS_LNSTAT_SYNC2	0x0004
+#define MDIO_PHYXS_LNSTAT_SYNC3	0x0008
+#define MDIO_PHYXS_LNSTAT_ALIGN 0x1000
+
+#define MDIO_PHYXS_LANE_READY	(MDIO_PHYXS_LNSTAT_SYNC0 | \
+				MDIO_PHYXS_LNSTAT_SYNC1 | \
+				MDIO_PHYXS_LNSTAT_SYNC2 | \
+				MDIO_PHYXS_LNSTAT_SYNC3 | \
+				MDIO_PHYXS_LNSTAT_ALIGN)
+
+static int teranetics_aneg_done(struct phy_device *phydev)
+{
+	/* auto negotiation state can only be checked when using copper
+	 * port, if using fiber port, just lie it's done.
+	 */
+	if (!phy_read_mmd(phydev, MDIO_MMD_VEND1, 93))
+		return genphy_c45_aneg_done(phydev);
+
+	return 1;
+}
+
+static int teranetics_read_status(struct phy_device *phydev)
+{
+	int reg;
+
+	phydev->link = 1;
+
+	phydev->speed = SPEED_10000;
+	phydev->duplex = DUPLEX_FULL;
+
+	if (!phy_read_mmd(phydev, MDIO_MMD_VEND1, 93)) {
+		reg = phy_read_mmd(phydev, MDIO_MMD_PHYXS, MDIO_PHYXS_LNSTAT);
+		if (reg < 0 ||
+		    !((reg & MDIO_PHYXS_LANE_READY) == MDIO_PHYXS_LANE_READY)) {
+			phydev->link = 0;
+			return 0;
+		}
+
+		reg = phy_read_mmd(phydev, MDIO_MMD_AN, MDIO_STAT1);
+		if (reg < 0 || !(reg & MDIO_STAT1_LSTATUS))
+			phydev->link = 0;
+	}
+
+	return 0;
+}
+
+static int teranetics_match_phy_device(struct phy_device *phydev,
+				       const struct phy_driver *phydrv)
+{
+	return phydev->c45_ids.device_ids[3] == PHY_ID_TN2020;
+}
+
+static struct phy_driver teranetics_driver[] = {
+{
+	.phy_id		= PHY_ID_TN2020,
+	.phy_id_mask	= 0xffffffff,
+	.name		= "Teranetics TN2020",
+	.features       = PHY_10GBIT_FEATURES,
+	.aneg_done	= teranetics_aneg_done,
+	.config_aneg    = gen10g_config_aneg,
+	.read_status	= teranetics_read_status,
+	.match_phy_device = teranetics_match_phy_device,
+},
+};
+
+module_phy_driver(teranetics_driver);
+
+static const struct mdio_device_id __maybe_unused teranetics_tbl[] = {
+	{ PHY_ID_TN2020, 0xffffffff },
+	{ }
+};
+
+MODULE_DEVICE_TABLE(mdio, teranetics_tbl);