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, 222 insertions, 0 deletions

diff --git a/drivers/net/phy/bcm87xx.c b/drivers/net/phy/bcm87xx.c
new file mode 100644
index 000000000..299f9a8f3
--- /dev/null
+++ b/drivers/net/phy/bcm87xx.c
@@ -0,0 +1,222 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (C) 2011 - 2012 Cavium, Inc.
+ */
+
+#include <linux/module.h>
+#include <linux/phy.h>
+#include <linux/of.h>
+
+#define PHY_ID_BCM8706	0x0143bdc1
+#define PHY_ID_BCM8727	0x0143bff0
+
+#define BCM87XX_PMD_RX_SIGNAL_DETECT	0x000a
+#define BCM87XX_10GBASER_PCS_STATUS	0x0020
+#define BCM87XX_XGXS_LANE_STATUS	0x0018
+
+#define BCM87XX_LASI_CONTROL		0x9002
+#define BCM87XX_LASI_STATUS		0x9005
+
+#if IS_ENABLED(CONFIG_OF_MDIO)
+/* Set and/or override some configuration registers based on the
+ * broadcom,c45-reg-init property stored in the of_node for the phydev.
+ *
+ * broadcom,c45-reg-init = <devid reg mask value>,...;
+ *
+ * There may be one or more sets of <devid reg mask value>:
+ *
+ * devid: which sub-device to use.
+ * reg: the register.
+ * mask: if non-zero, ANDed with existing register value.
+ * value: ORed with the masked value and written to the regiser.
+ *
+ */
+static int bcm87xx_of_reg_init(struct phy_device *phydev)
+{
+	const __be32 *paddr;
+	const __be32 *paddr_end;
+	int len, ret;
+
+	if (!phydev->mdio.dev.of_node)
+		return 0;
+
+	paddr = of_get_property(phydev->mdio.dev.of_node,
+				"broadcom,c45-reg-init", &len);
+	if (!paddr)
+		return 0;
+
+	paddr_end = paddr + (len /= sizeof(*paddr));
+
+	ret = 0;
+
+	while (paddr + 3 < paddr_end) {
+		u16 devid	= be32_to_cpup(paddr++);
+		u16 reg		= be32_to_cpup(paddr++);
+		u16 mask	= be32_to_cpup(paddr++);
+		u16 val_bits	= be32_to_cpup(paddr++);
+		int val = 0;
+
+		if (mask) {
+			val = phy_read_mmd(phydev, devid, reg);
+			if (val < 0) {
+				ret = val;
+				goto err;
+			}
+			val &= mask;
+		}
+		val |= val_bits;
+
+		ret = phy_write_mmd(phydev, devid, reg, val);
+		if (ret < 0)
+			goto err;
+	}
+err:
+	return ret;
+}
+#else
+static int bcm87xx_of_reg_init(struct phy_device *phydev)
+{
+	return 0;
+}
+#endif /* CONFIG_OF_MDIO */
+
+static int bcm87xx_get_features(struct phy_device *phydev)
+{
+	linkmode_set_bit(ETHTOOL_LINK_MODE_10000baseR_FEC_BIT,
+			 phydev->supported);
+	return 0;
+}
+
+static int bcm87xx_config_init(struct phy_device *phydev)
+{
+	return bcm87xx_of_reg_init(phydev);
+}
+
+static int bcm87xx_config_aneg(struct phy_device *phydev)
+{
+	return -EINVAL;
+}
+
+static int bcm87xx_read_status(struct phy_device *phydev)
+{
+	int rx_signal_detect;
+	int pcs_status;
+	int xgxs_lane_status;
+
+	rx_signal_detect = phy_read_mmd(phydev, MDIO_MMD_PMAPMD,
+					BCM87XX_PMD_RX_SIGNAL_DETECT);
+	if (rx_signal_detect < 0)
+		return rx_signal_detect;
+
+	if ((rx_signal_detect & 1) == 0)
+		goto no_link;
+
+	pcs_status = phy_read_mmd(phydev, MDIO_MMD_PCS,
+				  BCM87XX_10GBASER_PCS_STATUS);
+	if (pcs_status < 0)
+		return pcs_status;
+
+	if ((pcs_status & 1) == 0)
+		goto no_link;
+
+	xgxs_lane_status = phy_read_mmd(phydev, MDIO_MMD_PHYXS,
+					BCM87XX_XGXS_LANE_STATUS);
+	if (xgxs_lane_status < 0)
+		return xgxs_lane_status;
+
+	if ((xgxs_lane_status & 0x1000) == 0)
+		goto no_link;
+
+	phydev->speed = 10000;
+	phydev->link = 1;
+	phydev->duplex = 1;
+	return 0;
+
+no_link:
+	phydev->link = 0;
+	return 0;
+}
+
+static int bcm87xx_config_intr(struct phy_device *phydev)
+{
+	int reg, err;
+
+	reg = phy_read_mmd(phydev, MDIO_MMD_PCS, BCM87XX_LASI_CONTROL);
+
+	if (reg < 0)
+		return reg;
+
+	if (phydev->interrupts == PHY_INTERRUPT_ENABLED) {
+		err = phy_read_mmd(phydev, MDIO_MMD_PCS, BCM87XX_LASI_STATUS);
+		if (err)
+			return err;
+
+		reg |= 1;
+		err = phy_write_mmd(phydev, MDIO_MMD_PCS,
+				    BCM87XX_LASI_CONTROL, reg);
+	} else {
+		reg &= ~1;
+		err = phy_write_mmd(phydev, MDIO_MMD_PCS,
+				    BCM87XX_LASI_CONTROL, reg);
+		if (err)
+			return err;
+
+		err = phy_read_mmd(phydev, MDIO_MMD_PCS, BCM87XX_LASI_STATUS);
+	}
+
+	return err;
+}
+
+static irqreturn_t bcm87xx_handle_interrupt(struct phy_device *phydev)
+{
+	int irq_status;
+
+	irq_status = phy_read(phydev, BCM87XX_LASI_STATUS);
+	if (irq_status < 0) {
+		phy_error(phydev);
+		return IRQ_NONE;
+	}
+
+	if (irq_status == 0)
+		return IRQ_NONE;
+
+	phy_trigger_machine(phydev);
+
+	return IRQ_HANDLED;
+}
+
+static int bcm87xx_match_phy_device(struct phy_device *phydev,
+				    const struct phy_driver *phydrv)
+{
+	return phydev->c45_ids.device_ids[4] == phydrv->phy_id;
+}
+
+static struct phy_driver bcm87xx_driver[] = {
+{
+	.phy_id		= PHY_ID_BCM8706,
+	.phy_id_mask	= 0xffffffff,
+	.name		= "Broadcom BCM8706",
+	.get_features	= bcm87xx_get_features,
+	.config_init	= bcm87xx_config_init,
+	.config_aneg	= bcm87xx_config_aneg,
+	.read_status	= bcm87xx_read_status,
+	.config_intr	= bcm87xx_config_intr,
+	.handle_interrupt = bcm87xx_handle_interrupt,
+	.match_phy_device = bcm87xx_match_phy_device,
+}, {
+	.phy_id		= PHY_ID_BCM8727,
+	.phy_id_mask	= 0xffffffff,
+	.name		= "Broadcom BCM8727",
+	.get_features	= bcm87xx_get_features,
+	.config_init	= bcm87xx_config_init,
+	.config_aneg	= bcm87xx_config_aneg,
+	.read_status	= bcm87xx_read_status,
+	.config_intr	= bcm87xx_config_intr,
+	.handle_interrupt = bcm87xx_handle_interrupt,
+	.match_phy_device = bcm87xx_match_phy_device,
+} };
+
+module_phy_driver(bcm87xx_driver);
+
+MODULE_LICENSE("GPL v2");
+MODULE_DESCRIPTION("Broadcom BCM87xx PHY driver");