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>

3 files changed, 325 insertions, 0 deletions

diff --git a/drivers/misc/rp1/Kconfig b/drivers/misc/rp1/Kconfig
new file mode 100644
index 000000000..2c13b3968
--- /dev/null
+++ b/drivers/misc/rp1/Kconfig
@@ -0,0 +1,16 @@
+# SPDX-License-Identifier: GPL-2.0-only
+#
+# RaspberryPi RP1 misc device
+#
+
+config MISC_RP1
+	tristate "RaspberryPi RP1 misc device"
+	depends on OF_IRQ && PCI_MSI
+	help
+	  Support the RP1 peripheral chip found on Raspberry Pi 5 board.
+
+	  This device supports several sub-devices including e.g. Ethernet
+	  controller, USB controller, I2C, SPI and UART.
+
+	  The driver is responsible for enabling the DT node once the PCIe
+	  endpoint has been configured, and handling interrupts.
diff --git a/drivers/misc/rp1/Makefile b/drivers/misc/rp1/Makefile
new file mode 100644
index 000000000..ab32b433d
--- /dev/null
+++ b/drivers/misc/rp1/Makefile
@@ -0,0 +1,2 @@
+# SPDX-License-Identifier: GPL-2.0-only
+obj-$(CONFIG_MISC_RP1)		+= rp1_pci.o
diff --git a/drivers/misc/rp1/rp1_pci.c b/drivers/misc/rp1/rp1_pci.c
new file mode 100644
index 000000000..207a67691
--- /dev/null
+++ b/drivers/misc/rp1/rp1_pci.c
@@ -0,0 +1,307 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright (c) 2018-2025 Raspberry Pi Ltd.
+ *
+ * All rights reserved.
+ */
+
+#include <linux/err.h>
+#include <linux/interrupt.h>
+#include <linux/irq.h>
+#include <linux/irqchip/chained_irq.h>
+#include <linux/irqdomain.h>
+#include <linux/module.h>
+#include <linux/msi.h>
+#include <linux/of_platform.h>
+#include <linux/pci.h>
+#include <linux/platform_device.h>
+
+#define RP1_HW_IRQ_MASK		GENMASK(5, 0)
+
+#define REG_SET			0x800
+#define REG_CLR			0xc00
+
+/* MSI-X CFG registers start at 0x8 */
+#define MSIX_CFG(x) (0x8 + (4 * (x)))
+
+#define MSIX_CFG_IACK_EN        BIT(3)
+#define MSIX_CFG_IACK           BIT(2)
+#define MSIX_CFG_ENABLE         BIT(0)
+
+/* Address map */
+#define RP1_PCIE_APBS_BASE	0x108000
+
+/* Interrupts */
+#define RP1_INT_END		61
+
+struct rp1_dev {
+	struct pci_dev *pdev;
+	struct irq_domain *domain;
+	struct irq_data *pcie_irqds[64];
+	void __iomem *bar1;
+	bool level_triggered_irq[RP1_INT_END];
+};
+
+static void msix_cfg_set(struct rp1_dev *rp1, unsigned int hwirq, u32 value)
+{
+	iowrite32(value, rp1->bar1 + RP1_PCIE_APBS_BASE + REG_SET + MSIX_CFG(hwirq));
+}
+
+static void msix_cfg_clr(struct rp1_dev *rp1, unsigned int hwirq, u32 value)
+{
+	iowrite32(value, rp1->bar1 + RP1_PCIE_APBS_BASE + REG_CLR + MSIX_CFG(hwirq));
+}
+
+static void rp1_mask_irq(struct irq_data *irqd)
+{
+	struct rp1_dev *rp1 = irqd->domain->host_data;
+	struct irq_data *pcie_irqd = rp1->pcie_irqds[irqd->hwirq];
+
+	pci_msi_mask_irq(pcie_irqd);
+}
+
+static void rp1_unmask_irq(struct irq_data *irqd)
+{
+	struct rp1_dev *rp1 = irqd->domain->host_data;
+	struct irq_data *pcie_irqd = rp1->pcie_irqds[irqd->hwirq];
+
+	pci_msi_unmask_irq(pcie_irqd);
+}
+
+static int rp1_irq_set_type(struct irq_data *irqd, unsigned int type)
+{
+	struct rp1_dev *rp1 = irqd->domain->host_data;
+	unsigned int hwirq = (unsigned int)irqd->hwirq;
+
+	switch (type) {
+	case IRQ_TYPE_LEVEL_HIGH:
+		dev_dbg(&rp1->pdev->dev, "MSIX IACK EN for IRQ %u\n", hwirq);
+		msix_cfg_set(rp1, hwirq, MSIX_CFG_IACK_EN);
+		rp1->level_triggered_irq[hwirq] = true;
+	break;
+	case IRQ_TYPE_EDGE_RISING:
+		msix_cfg_clr(rp1, hwirq, MSIX_CFG_IACK_EN);
+		rp1->level_triggered_irq[hwirq] = false;
+		break;
+	default:
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
+static struct irq_chip rp1_irq_chip = {
+	.name		= "rp1_irq_chip",
+	.irq_mask	= rp1_mask_irq,
+	.irq_unmask	= rp1_unmask_irq,
+	.irq_set_type	= rp1_irq_set_type,
+};
+
+static void rp1_chained_handle_irq(struct irq_desc *desc)
+{
+	unsigned int hwirq = desc->irq_data.hwirq & RP1_HW_IRQ_MASK;
+	struct rp1_dev *rp1 = irq_desc_get_handler_data(desc);
+	struct irq_chip *chip = irq_desc_get_chip(desc);
+	unsigned int virq;
+
+	chained_irq_enter(chip, desc);
+
+	virq = irq_find_mapping(rp1->domain, hwirq);
+	generic_handle_irq(virq);
+	if (rp1->level_triggered_irq[hwirq])
+		msix_cfg_set(rp1, hwirq, MSIX_CFG_IACK);
+
+	chained_irq_exit(chip, desc);
+}
+
+static int rp1_irq_xlate(struct irq_domain *d, struct device_node *node,
+			 const u32 *intspec, unsigned int intsize,
+			 unsigned long *out_hwirq, unsigned int *out_type)
+{
+	struct rp1_dev *rp1 = d->host_data;
+	struct irq_data *pcie_irqd;
+	unsigned long hwirq;
+	int pcie_irq;
+	int ret;
+
+	ret = irq_domain_xlate_twocell(d, node, intspec, intsize,
+				       &hwirq, out_type);
+	if (ret)
+		return ret;
+
+	pcie_irq = pci_irq_vector(rp1->pdev, hwirq);
+	pcie_irqd = irq_get_irq_data(pcie_irq);
+	rp1->pcie_irqds[hwirq] = pcie_irqd;
+	*out_hwirq = hwirq;
+
+	return 0;
+}
+
+static int rp1_irq_activate(struct irq_domain *d, struct irq_data *irqd,
+			    bool reserve)
+{
+	struct rp1_dev *rp1 = d->host_data;
+
+	msix_cfg_set(rp1, (unsigned int)irqd->hwirq, MSIX_CFG_ENABLE);
+	msix_cfg_set(rp1, (unsigned int)irqd->hwirq, MSIX_CFG_IACK);
+
+	return 0;
+}
+
+static void rp1_irq_deactivate(struct irq_domain *d, struct irq_data *irqd)
+{
+	struct rp1_dev *rp1 = d->host_data;
+
+	msix_cfg_clr(rp1, (unsigned int)irqd->hwirq, MSIX_CFG_ENABLE);
+}
+
+static const struct irq_domain_ops rp1_domain_ops = {
+	.xlate      = rp1_irq_xlate,
+	.activate   = rp1_irq_activate,
+	.deactivate = rp1_irq_deactivate,
+};
+
+static void rp1_unregister_interrupts(struct pci_dev *pdev)
+{
+	struct rp1_dev *rp1 = pci_get_drvdata(pdev);
+	int irq, i;
+
+	for (i = 0; i < RP1_INT_END; i++)
+		irq_set_chained_handler_and_data(pci_irq_vector(pdev, i), NULL, NULL);
+
+	if (rp1->domain) {
+		for (i = 0; i < RP1_INT_END; i++) {
+			irq = irq_find_mapping(rp1->domain, i);
+			irq_dispose_mapping(irq);
+		}
+
+		irq_domain_remove(rp1->domain);
+	}
+
+	pci_free_irq_vectors(pdev);
+}
+
+static int rp1_probe(struct pci_dev *pdev, const struct pci_device_id *id)
+{
+	struct device *dev = &pdev->dev;
+	struct device_node *rp1_node;
+	struct rp1_dev *rp1;
+	int err = 0;
+	int i;
+
+	rp1_node = dev_of_node(dev);
+
+	if (!rp1_node) {
+		dev_err(dev, "Missing of_node for device\n");
+		err = -EINVAL;
+		goto err_out;
+	}
+
+	rp1 = devm_kzalloc(&pdev->dev, sizeof(*rp1), GFP_KERNEL);
+	if (!rp1) {
+		err = -ENOMEM;
+		goto err_out;
+	}
+
+	rp1->pdev = pdev;
+
+	if (pci_resource_len(pdev, 1) <= 0x10000) {
+		dev_err(&pdev->dev,
+			"Not initialized - is the firmware running?\n");
+		err = -EINVAL;
+		goto err_out;
+	}
+
+	err = pcim_enable_device(pdev);
+	if (err < 0) {
+		err = dev_err_probe(&pdev->dev, err,
+				    "Enabling PCI device has failed");
+		goto err_out;
+	}
+
+	rp1->bar1 = pcim_iomap(pdev, 1, 0);
+	if (!rp1->bar1) {
+		dev_err(&pdev->dev, "Cannot map PCI BAR\n");
+		err = -EIO;
+		goto err_out;
+	}
+
+	pci_set_master(pdev);
+
+	err = pci_alloc_irq_vectors(pdev, RP1_INT_END, RP1_INT_END,
+				    PCI_IRQ_MSIX);
+	if (err < 0) {
+		err = dev_err_probe(&pdev->dev, err,
+				    "Failed to allocate MSI-X vectors\n");
+		goto err_out;
+	} else if (err != RP1_INT_END) {
+		dev_err(&pdev->dev, "Cannot allocate enough interrupts\n");
+		err = -EINVAL;
+		goto err_out;
+	}
+
+	pci_set_drvdata(pdev, rp1);
+	rp1->domain = irq_domain_create_linear(of_fwnode_handle(rp1_node), RP1_INT_END,
+					       &rp1_domain_ops, rp1);
+	if (!rp1->domain) {
+		dev_err(&pdev->dev, "Error creating IRQ domain\n");
+		err = -ENOMEM;
+		goto err_unregister_interrupts;
+	}
+
+	for (i = 0; i < RP1_INT_END; i++) {
+		unsigned int irq = irq_create_mapping(rp1->domain, i);
+
+		if (!irq) {
+			dev_err(&pdev->dev, "Failed to create IRQ mapping\n");
+			err = -EINVAL;
+			goto err_unregister_interrupts;
+		}
+
+		irq_set_chip_and_handler(irq, &rp1_irq_chip, handle_level_irq);
+		irq_set_probe(irq);
+		irq_set_chained_handler_and_data(pci_irq_vector(pdev, i),
+						 rp1_chained_handle_irq, rp1);
+	}
+
+	err = of_platform_default_populate(rp1_node, NULL, dev);
+	if (err) {
+		dev_err_probe(&pdev->dev, err, "Error populating devicetree\n");
+		goto err_unregister_interrupts;
+	}
+
+	return 0;
+
+err_unregister_interrupts:
+	rp1_unregister_interrupts(pdev);
+err_out:
+	return err;
+}
+
+static void rp1_remove(struct pci_dev *pdev)
+{
+	struct device *dev = &pdev->dev;
+
+	of_platform_depopulate(dev);
+	rp1_unregister_interrupts(pdev);
+}
+
+static const struct pci_device_id dev_id_table[] = {
+	{ PCI_DEVICE(PCI_VENDOR_ID_RPI, PCI_DEVICE_ID_RPI_RP1_C0) },
+	{ }
+};
+MODULE_DEVICE_TABLE(pci, dev_id_table);
+
+static struct pci_driver rp1_driver = {
+	.name		= KBUILD_MODNAME,
+	.id_table	= dev_id_table,
+	.probe		= rp1_probe,
+	.remove		= rp1_remove,
+};
+
+module_pci_driver(rp1_driver);
+
+MODULE_AUTHOR("Phil Elwell <phil@raspberrypi.com>");
+MODULE_AUTHOR("Andrea della Porta <andrea.porta@suse.com>");
+MODULE_DESCRIPTION("RaspberryPi RP1 misc device");
+MODULE_LICENSE("GPL");