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, 269 insertions, 0 deletions

diff --git a/drivers/bcma/driver_gpio.c b/drivers/bcma/driver_gpio.c
new file mode 100644
index 000000000..ea45222f2
--- /dev/null
+++ b/drivers/bcma/driver_gpio.c
@@ -0,0 +1,269 @@
+/*
+ * Broadcom specific AMBA
+ * GPIO driver
+ *
+ * Copyright 2011, Broadcom Corporation
+ * Copyright 2012, Hauke Mehrtens <hauke@hauke-m.de>
+ *
+ * Licensed under the GNU/GPL. See COPYING for details.
+ */
+
+#include <linux/gpio/driver.h>
+#include <linux/interrupt.h>
+#include <linux/export.h>
+#include <linux/property.h>
+
+#include <linux/bcma/bcma.h>
+
+#include "bcma_private.h"
+
+#define BCMA_GPIO_MAX_PINS	32
+
+const struct software_node bcma_gpio_swnode = {
+	.name = "bcma-gpio",
+};
+EXPORT_SYMBOL_GPL(bcma_gpio_swnode);
+
+static int bcma_gpio_get_value(struct gpio_chip *chip, unsigned gpio)
+{
+	struct bcma_drv_cc *cc = gpiochip_get_data(chip);
+
+	return !!bcma_chipco_gpio_in(cc, 1 << gpio);
+}
+
+static int bcma_gpio_set_value(struct gpio_chip *chip, unsigned int gpio,
+			       int value)
+{
+	struct bcma_drv_cc *cc = gpiochip_get_data(chip);
+
+	bcma_chipco_gpio_out(cc, 1 << gpio, value ? 1 << gpio : 0);
+
+	return 0;
+}
+
+static int bcma_gpio_direction_input(struct gpio_chip *chip, unsigned gpio)
+{
+	struct bcma_drv_cc *cc = gpiochip_get_data(chip);
+
+	bcma_chipco_gpio_outen(cc, 1 << gpio, 0);
+	return 0;
+}
+
+static int bcma_gpio_direction_output(struct gpio_chip *chip, unsigned gpio,
+				      int value)
+{
+	struct bcma_drv_cc *cc = gpiochip_get_data(chip);
+
+	bcma_chipco_gpio_outen(cc, 1 << gpio, 1 << gpio);
+	bcma_chipco_gpio_out(cc, 1 << gpio, value ? 1 << gpio : 0);
+	return 0;
+}
+
+static int bcma_gpio_request(struct gpio_chip *chip, unsigned gpio)
+{
+	struct bcma_drv_cc *cc = gpiochip_get_data(chip);
+
+	bcma_chipco_gpio_control(cc, 1 << gpio, 0);
+	/* clear pulldown */
+	bcma_chipco_gpio_pulldown(cc, 1 << gpio, 0);
+	/* Set pullup */
+	bcma_chipco_gpio_pullup(cc, 1 << gpio, 1 << gpio);
+
+	return 0;
+}
+
+static void bcma_gpio_free(struct gpio_chip *chip, unsigned gpio)
+{
+	struct bcma_drv_cc *cc = gpiochip_get_data(chip);
+
+	/* clear pullup */
+	bcma_chipco_gpio_pullup(cc, 1 << gpio, 0);
+}
+
+#if IS_BUILTIN(CONFIG_BCM47XX) || IS_BUILTIN(CONFIG_ARCH_BCM_5301X)
+
+static void bcma_gpio_irq_unmask(struct irq_data *d)
+{
+	struct gpio_chip *gc = irq_data_get_irq_chip_data(d);
+	struct bcma_drv_cc *cc = gpiochip_get_data(gc);
+	int gpio = irqd_to_hwirq(d);
+	u32 val = bcma_chipco_gpio_in(cc, BIT(gpio));
+
+	gpiochip_enable_irq(gc, gpio);
+	bcma_chipco_gpio_polarity(cc, BIT(gpio), val);
+	bcma_chipco_gpio_intmask(cc, BIT(gpio), BIT(gpio));
+}
+
+static void bcma_gpio_irq_mask(struct irq_data *d)
+{
+	struct gpio_chip *gc = irq_data_get_irq_chip_data(d);
+	struct bcma_drv_cc *cc = gpiochip_get_data(gc);
+	int gpio = irqd_to_hwirq(d);
+
+	bcma_chipco_gpio_intmask(cc, BIT(gpio), 0);
+	gpiochip_disable_irq(gc, gpio);
+}
+
+static const struct irq_chip bcma_gpio_irq_chip = {
+	.name		= "BCMA-GPIO",
+	.irq_mask	= bcma_gpio_irq_mask,
+	.irq_unmask	= bcma_gpio_irq_unmask,
+	.flags		= IRQCHIP_IMMUTABLE,
+	GPIOCHIP_IRQ_RESOURCE_HELPERS,
+};
+
+static irqreturn_t bcma_gpio_irq_handler(int irq, void *dev_id)
+{
+	struct bcma_drv_cc *cc = dev_id;
+	struct gpio_chip *gc = &cc->gpio;
+	u32 val = bcma_cc_read32(cc, BCMA_CC_GPIOIN);
+	u32 mask = bcma_cc_read32(cc, BCMA_CC_GPIOIRQ);
+	u32 pol = bcma_cc_read32(cc, BCMA_CC_GPIOPOL);
+	unsigned long irqs = (val ^ pol) & mask;
+	int gpio;
+
+	if (!irqs)
+		return IRQ_NONE;
+
+	for_each_set_bit(gpio, &irqs, gc->ngpio)
+		generic_handle_domain_irq_safe(gc->irq.domain, gpio);
+	bcma_chipco_gpio_polarity(cc, irqs, val & irqs);
+
+	return IRQ_HANDLED;
+}
+
+static int bcma_gpio_irq_init(struct bcma_drv_cc *cc)
+{
+	struct gpio_chip *chip = &cc->gpio;
+	struct gpio_irq_chip *girq = &chip->irq;
+	int hwirq, err;
+
+	if (cc->core->bus->hosttype != BCMA_HOSTTYPE_SOC)
+		return 0;
+
+	hwirq = bcma_core_irq(cc->core, 0);
+	err = request_irq(hwirq, bcma_gpio_irq_handler, IRQF_SHARED, "gpio",
+			  cc);
+	if (err)
+		return err;
+
+	bcma_chipco_gpio_intmask(cc, ~0, 0);
+	bcma_cc_set32(cc, BCMA_CC_IRQMASK, BCMA_CC_IRQ_GPIO);
+
+	gpio_irq_chip_set_chip(girq, &bcma_gpio_irq_chip);
+	/* This will let us handle the parent IRQ in the driver */
+	girq->parent_handler = NULL;
+	girq->num_parents = 0;
+	girq->parents = NULL;
+	girq->default_type = IRQ_TYPE_NONE;
+	girq->handler = handle_simple_irq;
+
+	return 0;
+}
+
+static void bcma_gpio_irq_exit(struct bcma_drv_cc *cc)
+{
+	if (cc->core->bus->hosttype != BCMA_HOSTTYPE_SOC)
+		return;
+
+	bcma_cc_mask32(cc, BCMA_CC_IRQMASK, ~BCMA_CC_IRQ_GPIO);
+	free_irq(bcma_core_irq(cc->core, 0), cc);
+}
+#else
+static int bcma_gpio_irq_init(struct bcma_drv_cc *cc)
+{
+	return 0;
+}
+
+static void bcma_gpio_irq_exit(struct bcma_drv_cc *cc)
+{
+}
+#endif
+
+int bcma_gpio_init(struct bcma_drv_cc *cc)
+{
+	struct bcma_bus *bus = cc->core->bus;
+	struct gpio_chip *chip = &cc->gpio;
+	int err;
+
+	chip->label		= "bcma_gpio";
+	chip->owner		= THIS_MODULE;
+	chip->request		= bcma_gpio_request;
+	chip->free		= bcma_gpio_free;
+	chip->get		= bcma_gpio_get_value;
+	chip->set		= bcma_gpio_set_value;
+	chip->direction_input	= bcma_gpio_direction_input;
+	chip->direction_output	= bcma_gpio_direction_output;
+	chip->parent		= bus->dev;
+
+	/*
+	 * Register software node only for the host SoC bus, unless there is
+	 * already a firmware node assigned. There is only one SoC instance
+	 * in the system, so there are no concerns with registration conflicts.
+	 */
+	if (bus->hosttype == BCMA_HOSTTYPE_SOC && !dev_fwnode(&cc->core->dev)) {
+		err = software_node_register(&bcma_gpio_swnode);
+		if (err)
+			return err;
+		chip->fwnode = software_node_fwnode(&bcma_gpio_swnode);
+	} else {
+		chip->fwnode = dev_fwnode(&cc->core->dev);
+	}
+
+	switch (bus->chipinfo.id) {
+	case BCMA_CHIP_ID_BCM4707:
+	case BCMA_CHIP_ID_BCM5357:
+	case BCMA_CHIP_ID_BCM53572:
+	case BCMA_CHIP_ID_BCM53573:
+	case BCMA_CHIP_ID_BCM47094:
+		chip->ngpio	= 32;
+		break;
+	default:
+		chip->ngpio	= 16;
+	}
+
+	/*
+	 * Register SoC GPIO devices with absolute GPIO pin base.
+	 * On MIPS, we don't have Device Tree and we can't use relative (per chip)
+	 * GPIO numbers.
+	 * On some ARM devices, user space may want to access some system GPIO
+	 * pins directly, which is easier to do with a predictable GPIO base.
+	 */
+	if (IS_BUILTIN(CONFIG_BCM47XX) ||
+	    cc->core->bus->hosttype == BCMA_HOSTTYPE_SOC)
+		chip->base		= bus->num * BCMA_GPIO_MAX_PINS;
+	else
+		chip->base		= -1;
+
+	err = bcma_gpio_irq_init(cc);
+	if (err)
+		goto err_unregister_swnode;
+
+	err = gpiochip_add_data(chip, cc);
+	if (err)
+		goto err_irq_exit;
+
+	return 0;
+
+err_irq_exit:
+	bcma_gpio_irq_exit(cc);
+err_unregister_swnode:
+	if (bus->hosttype == BCMA_HOSTTYPE_SOC &&
+	    chip->fwnode && is_software_node(chip->fwnode)) {
+		software_node_unregister(&bcma_gpio_swnode);
+		chip->fwnode = NULL;
+	}
+	return err;
+}
+
+int bcma_gpio_unregister(struct bcma_drv_cc *cc)
+{
+	bcma_gpio_irq_exit(cc);
+	gpiochip_remove(&cc->gpio);
+	if (cc->core->bus->hosttype == BCMA_HOSTTYPE_SOC &&
+	    cc->gpio.fwnode && is_software_node(cc->gpio.fwnode)) {
+		software_node_unregister(&bcma_gpio_swnode);
+		cc->gpio.fwnode = NULL;
+	}
+	return 0;
+}