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, 428 insertions, 0 deletions

diff --git a/drivers/thunderbolt/clx.c b/drivers/thunderbolt/clx.c
new file mode 100644
index 000000000..1637e79d9
--- /dev/null
+++ b/drivers/thunderbolt/clx.c
@@ -0,0 +1,428 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * CLx support
+ *
+ * Copyright (C) 2020 - 2023, Intel Corporation
+ * Authors: Gil Fine <gil.fine@intel.com>
+ *	    Mika Westerberg <mika.westerberg@linux.intel.com>
+ */
+
+#include <linux/module.h>
+
+#include "tb.h"
+
+static bool clx_enabled = true;
+module_param_named(clx, clx_enabled, bool, 0444);
+MODULE_PARM_DESC(clx, "allow low power states on the high-speed lanes (default: true)");
+
+static const char *clx_name(unsigned int clx)
+{
+	switch (clx) {
+	case TB_CL0S | TB_CL1 | TB_CL2:
+		return "CL0s/CL1/CL2";
+	case TB_CL1 | TB_CL2:
+		return "CL1/CL2";
+	case TB_CL0S | TB_CL2:
+		return "CL0s/CL2";
+	case TB_CL0S | TB_CL1:
+		return "CL0s/CL1";
+	case TB_CL0S:
+		return "CL0s";
+	case 0:
+		return "disabled";
+	default:
+		return "unknown";
+	}
+}
+
+static int tb_port_pm_secondary_set(struct tb_port *port, bool secondary)
+{
+	u32 phy;
+	int ret;
+
+	ret = tb_port_read(port, &phy, TB_CFG_PORT,
+			   port->cap_phy + LANE_ADP_CS_1, 1);
+	if (ret)
+		return ret;
+
+	if (secondary)
+		phy |= LANE_ADP_CS_1_PMS;
+	else
+		phy &= ~LANE_ADP_CS_1_PMS;
+
+	return tb_port_write(port, &phy, TB_CFG_PORT,
+			     port->cap_phy + LANE_ADP_CS_1, 1);
+}
+
+static int tb_port_pm_secondary_enable(struct tb_port *port)
+{
+	return tb_port_pm_secondary_set(port, true);
+}
+
+static int tb_port_pm_secondary_disable(struct tb_port *port)
+{
+	return tb_port_pm_secondary_set(port, false);
+}
+
+/* Called for USB4 or Titan Ridge routers only */
+static bool tb_port_clx_supported(struct tb_port *port, unsigned int clx)
+{
+	u32 val, mask = 0;
+	bool ret;
+
+	/* Don't enable CLx in case of two single-lane links */
+	if (!port->bonded && port->dual_link_port)
+		return false;
+
+	/* Don't enable CLx in case of inter-domain link */
+	if (port->xdomain)
+		return false;
+
+	if (tb_switch_is_usb4(port->sw)) {
+		if (!usb4_port_clx_supported(port))
+			return false;
+	} else if (!tb_lc_is_clx_supported(port)) {
+		return false;
+	}
+
+	if (clx & TB_CL0S)
+		mask |= LANE_ADP_CS_0_CL0S_SUPPORT;
+	if (clx & TB_CL1)
+		mask |= LANE_ADP_CS_0_CL1_SUPPORT;
+	if (clx & TB_CL2)
+		mask |= LANE_ADP_CS_0_CL2_SUPPORT;
+
+	ret = tb_port_read(port, &val, TB_CFG_PORT,
+			   port->cap_phy + LANE_ADP_CS_0, 1);
+	if (ret)
+		return false;
+
+	return !!(val & mask);
+}
+
+static int tb_port_clx_set(struct tb_port *port, unsigned int clx, bool enable)
+{
+	u32 phy, mask = 0;
+	int ret;
+
+	if (clx & TB_CL0S)
+		mask |= LANE_ADP_CS_1_CL0S_ENABLE;
+	if (clx & TB_CL1)
+		mask |= LANE_ADP_CS_1_CL1_ENABLE;
+	if (clx & TB_CL2)
+		mask |= LANE_ADP_CS_1_CL2_ENABLE;
+
+	if (!mask)
+		return -EOPNOTSUPP;
+
+	ret = tb_port_read(port, &phy, TB_CFG_PORT,
+			   port->cap_phy + LANE_ADP_CS_1, 1);
+	if (ret)
+		return ret;
+
+	if (enable)
+		phy |= mask;
+	else
+		phy &= ~mask;
+
+	return tb_port_write(port, &phy, TB_CFG_PORT,
+			     port->cap_phy + LANE_ADP_CS_1, 1);
+}
+
+static int tb_port_clx_disable(struct tb_port *port, unsigned int clx)
+{
+	return tb_port_clx_set(port, clx, false);
+}
+
+static int tb_port_clx_enable(struct tb_port *port, unsigned int clx)
+{
+	return tb_port_clx_set(port, clx, true);
+}
+
+static int tb_port_clx(struct tb_port *port)
+{
+	u32 val;
+	int ret;
+
+	if (!tb_port_clx_supported(port, TB_CL0S | TB_CL1 | TB_CL2))
+		return 0;
+
+	ret = tb_port_read(port, &val, TB_CFG_PORT,
+			   port->cap_phy + LANE_ADP_CS_1, 1);
+	if (ret)
+		return ret;
+
+	if (val & LANE_ADP_CS_1_CL0S_ENABLE)
+		ret |= TB_CL0S;
+	if (val & LANE_ADP_CS_1_CL1_ENABLE)
+		ret |= TB_CL1;
+	if (val & LANE_ADP_CS_1_CL2_ENABLE)
+		ret |= TB_CL2;
+
+	return ret;
+}
+
+/**
+ * tb_port_clx_is_enabled() - Is given CL state enabled
+ * @port: USB4 port to check
+ * @clx: Mask of CL states to check
+ *
+ * Return: %true if any of the given CL states is enabled for @port,
+ * %false otherwise.
+ */
+bool tb_port_clx_is_enabled(struct tb_port *port, unsigned int clx)
+{
+	return !!(tb_port_clx(port) & clx);
+}
+
+/**
+ * tb_switch_clx_is_supported() - Is CLx supported on this type of router
+ * @sw: The router to check CLx support for
+ *
+ * Return: %true if CLx is supported, %false otherwise.
+ */
+static bool tb_switch_clx_is_supported(const struct tb_switch *sw)
+{
+	if (!clx_enabled)
+		return false;
+
+	if (sw->quirks & QUIRK_NO_CLX)
+		return false;
+
+	/*
+	 * CLx is not enabled and validated on Intel USB4 platforms
+	 * before Alder Lake.
+	 */
+	if (tb_switch_is_tiger_lake(sw))
+		return false;
+
+	return tb_switch_is_usb4(sw) || tb_switch_is_titan_ridge(sw);
+}
+
+/**
+ * tb_switch_clx_init() - Initialize router CL states
+ * @sw: Router
+ *
+ * Can be called for any router. Initializes the current CL state by
+ * reading it from the hardware.
+ *
+ * Return: %0 on success, negative errno otherwise.
+ */
+int tb_switch_clx_init(struct tb_switch *sw)
+{
+	struct tb_port *up, *down;
+	unsigned int clx, tmp;
+
+	if (tb_switch_is_icm(sw))
+		return 0;
+
+	if (!tb_route(sw))
+		return 0;
+
+	if (!tb_switch_clx_is_supported(sw))
+		return 0;
+
+	up = tb_upstream_port(sw);
+	down = tb_switch_downstream_port(sw);
+
+	clx = tb_port_clx(up);
+	tmp = tb_port_clx(down);
+	if (clx != tmp)
+		tb_sw_warn(sw, "CLx: inconsistent configuration %#x != %#x\n",
+			   clx, tmp);
+
+	tb_sw_dbg(sw, "CLx: current mode: %s\n", clx_name(clx));
+
+	sw->clx = clx;
+	return 0;
+}
+
+static int tb_switch_pm_secondary_resolve(struct tb_switch *sw)
+{
+	struct tb_port *up, *down;
+	int ret;
+
+	if (!tb_route(sw))
+		return 0;
+
+	up = tb_upstream_port(sw);
+	down = tb_switch_downstream_port(sw);
+	ret = tb_port_pm_secondary_enable(up);
+	if (ret)
+		return ret;
+
+	return tb_port_pm_secondary_disable(down);
+}
+
+static int tb_switch_mask_clx_objections(struct tb_switch *sw)
+{
+	int up_port = sw->config.upstream_port_number;
+	u32 offset, val[2], mask_obj, unmask_obj;
+	int ret, i;
+
+	/* Only Titan Ridge of pre-USB4 devices support CLx states */
+	if (!tb_switch_is_titan_ridge(sw))
+		return 0;
+
+	if (!tb_route(sw))
+		return 0;
+
+	/*
+	 * In Titan Ridge there are only 2 dual-lane Thunderbolt ports:
+	 * Port A consists of lane adapters 1,2 and
+	 * Port B consists of lane adapters 3,4
+	 * If upstream port is A, (lanes are 1,2), we mask objections from
+	 * port B (lanes 3,4) and unmask objections from Port A and vice-versa.
+	 */
+	if (up_port == 1) {
+		mask_obj = TB_LOW_PWR_C0_PORT_B_MASK;
+		unmask_obj = TB_LOW_PWR_C1_PORT_A_MASK;
+		offset = TB_LOW_PWR_C1_CL1;
+	} else {
+		mask_obj = TB_LOW_PWR_C1_PORT_A_MASK;
+		unmask_obj = TB_LOW_PWR_C0_PORT_B_MASK;
+		offset = TB_LOW_PWR_C3_CL1;
+	}
+
+	ret = tb_sw_read(sw, &val, TB_CFG_SWITCH,
+			 sw->cap_lp + offset, ARRAY_SIZE(val));
+	if (ret)
+		return ret;
+
+	for (i = 0; i < ARRAY_SIZE(val); i++) {
+		val[i] |= mask_obj;
+		val[i] &= ~unmask_obj;
+	}
+
+	return tb_sw_write(sw, &val, TB_CFG_SWITCH,
+			   sw->cap_lp + offset, ARRAY_SIZE(val));
+}
+
+static bool validate_mask(unsigned int clx)
+{
+	/* Previous states need to be enabled */
+	if (clx & TB_CL1)
+		return (clx & TB_CL0S) == TB_CL0S;
+	return true;
+}
+
+/**
+ * tb_switch_clx_enable() - Enable CLx on upstream port of specified router
+ * @sw: Router to enable CLx for
+ * @clx: The CLx state to enable
+ *
+ * CLx is enabled only if both sides of the link support CLx, and if both sides
+ * of the link are not configured as two single lane links and only if the link
+ * is not inter-domain link. The complete set of conditions is described in CM
+ * Guide 1.0 section 8.1.
+ *
+ * Return: %0 on success, negative errno otherwise.
+ */
+int tb_switch_clx_enable(struct tb_switch *sw, unsigned int clx)
+{
+	bool up_clx_support, down_clx_support;
+	struct tb_switch *parent_sw;
+	struct tb_port *up, *down;
+	int ret;
+
+	if (!clx || sw->clx == clx)
+		return 0;
+
+	if (!validate_mask(clx))
+		return -EINVAL;
+
+	parent_sw = tb_switch_parent(sw);
+	if (!parent_sw)
+		return 0;
+
+	if (!tb_switch_clx_is_supported(parent_sw) ||
+	    !tb_switch_clx_is_supported(sw))
+		return 0;
+
+	/* Only support CL2 for v2 routers */
+	if ((clx & TB_CL2) &&
+	    (usb4_switch_version(parent_sw) < 2 ||
+	     usb4_switch_version(sw) < 2))
+		return -EOPNOTSUPP;
+
+	ret = tb_switch_pm_secondary_resolve(sw);
+	if (ret)
+		return ret;
+
+	up = tb_upstream_port(sw);
+	down = tb_switch_downstream_port(sw);
+
+	up_clx_support = tb_port_clx_supported(up, clx);
+	down_clx_support = tb_port_clx_supported(down, clx);
+
+	tb_port_dbg(up, "CLx: %s %ssupported\n", clx_name(clx),
+		    up_clx_support ? "" : "not ");
+	tb_port_dbg(down, "CLx: %s %ssupported\n", clx_name(clx),
+		    down_clx_support ? "" : "not ");
+
+	if (!up_clx_support || !down_clx_support)
+		return -EOPNOTSUPP;
+
+	ret = tb_port_clx_enable(up, clx);
+	if (ret)
+		return ret;
+
+	ret = tb_port_clx_enable(down, clx);
+	if (ret) {
+		tb_port_clx_disable(up, clx);
+		return ret;
+	}
+
+	ret = tb_switch_mask_clx_objections(sw);
+	if (ret) {
+		tb_port_clx_disable(up, clx);
+		tb_port_clx_disable(down, clx);
+		return ret;
+	}
+
+	sw->clx |= clx;
+
+	tb_sw_dbg(sw, "CLx: %s enabled\n", clx_name(clx));
+	return 0;
+}
+
+/**
+ * tb_switch_clx_disable() - Disable CLx on upstream port of specified router
+ * @sw: Router to disable CLx for
+ *
+ * Disables all CL states of the given router. Can be called on any
+ * router and if the states were not enabled already does nothing.
+ *
+ * Return: CL states that were disabled or negative errno otherwise.
+ */
+int tb_switch_clx_disable(struct tb_switch *sw)
+{
+	unsigned int clx = sw->clx;
+	struct tb_port *up, *down;
+	int ret;
+
+	if (!tb_switch_clx_is_supported(sw))
+		return 0;
+
+	if (!clx)
+		return 0;
+
+	if (sw->is_unplugged)
+		return clx;
+
+	up = tb_upstream_port(sw);
+	down = tb_switch_downstream_port(sw);
+
+	ret = tb_port_clx_disable(up, clx);
+	if (ret)
+		return ret;
+
+	ret = tb_port_clx_disable(down, clx);
+	if (ret)
+		return ret;
+
+	sw->clx = 0;
+
+	tb_sw_dbg(sw, "CLx: %s disabled\n", clx_name(clx));
+	return clx;
+}