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, 185 insertions, 0 deletions

diff --git a/arch/arm/mach-versatile/versatile.c b/arch/arm/mach-versatile/versatile.c
new file mode 100644
index 000000000..581c97dc4
--- /dev/null
+++ b/arch/arm/mach-versatile/versatile.c
@@ -0,0 +1,185 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Versatile board support using the device tree
+ *
+ *  Copyright (C) 2010 Secret Lab Technologies Ltd.
+ *  Copyright (C) 2009 Jeremy Kerr <jeremy.kerr@canonical.com>
+ *  Copyright (C) 2004 ARM Limited
+ *  Copyright (C) 2000 Deep Blue Solutions Ltd
+ */
+
+#include <linux/init.h>
+#include <linux/io.h>
+#include <linux/of.h>
+#include <linux/of_address.h>
+#include <linux/of_irq.h>
+#include <linux/of_platform.h>
+#include <linux/slab.h>
+#include <linux/amba/bus.h>
+#include <linux/amba/mmci.h>
+#include <asm/mach-types.h>
+#include <asm/mach/arch.h>
+#include <asm/mach/map.h>
+
+/* macro to get at MMIO space when running virtually */
+#define IO_ADDRESS(x)		(((x) & 0x0fffffff) + (((x) >> 4) & 0x0f000000) + 0xf0000000)
+#define __io_address(n)		((void __iomem __force *)IO_ADDRESS(n))
+
+/*
+ * ------------------------------------------------------------------------
+ *  Versatile Registers
+ * ------------------------------------------------------------------------
+ */
+#define VERSATILE_SYS_PCICTL_OFFSET           0x44
+#define VERSATILE_SYS_MCI_OFFSET              0x48
+
+/*
+ * VERSATILE peripheral addresses
+ */
+#define VERSATILE_MMCI0_BASE           0x10005000	/* MMC interface */
+#define VERSATILE_MMCI1_BASE           0x1000B000	/* MMC Interface */
+#define VERSATILE_SCTL_BASE            0x101E0000	/* System controller */
+
+/*
+ * System controller bit assignment
+ */
+#define VERSATILE_REFCLK	0
+#define VERSATILE_TIMCLK	1
+
+#define VERSATILE_TIMER1_EnSel	15
+#define VERSATILE_TIMER2_EnSel	17
+#define VERSATILE_TIMER3_EnSel	19
+#define VERSATILE_TIMER4_EnSel	21
+
+static void __iomem *versatile_sys_base;
+
+static unsigned int mmc_status(struct device *dev)
+{
+	struct amba_device *adev = container_of(dev, struct amba_device, dev);
+	u32 mask;
+
+	if (adev->res.start == VERSATILE_MMCI0_BASE)
+		mask = 1;
+	else
+		mask = 2;
+
+	return readl(versatile_sys_base + VERSATILE_SYS_MCI_OFFSET) & mask;
+}
+
+static struct mmci_platform_data mmc0_plat_data = {
+	.ocr_mask	= MMC_VDD_32_33|MMC_VDD_33_34,
+	.status		= mmc_status,
+};
+
+static struct mmci_platform_data mmc1_plat_data = {
+	.ocr_mask	= MMC_VDD_32_33|MMC_VDD_33_34,
+	.status		= mmc_status,
+};
+
+/*
+ * Lookup table for attaching a specific name and platform_data pointer to
+ * devices as they get created by of_platform_populate().  Ideally this table
+ * would not exist, but the current clock implementation depends on some devices
+ * having a specific name.
+ */
+struct of_dev_auxdata versatile_auxdata_lookup[] __initdata = {
+	OF_DEV_AUXDATA("arm,primecell", VERSATILE_MMCI0_BASE, "fpga:05", &mmc0_plat_data),
+	OF_DEV_AUXDATA("arm,primecell", VERSATILE_MMCI1_BASE, "fpga:0b", &mmc1_plat_data),
+	{}
+};
+
+static struct map_desc versatile_io_desc[] __initdata __maybe_unused = {
+	{
+		.virtual	=  IO_ADDRESS(VERSATILE_SCTL_BASE),
+		.pfn		= __phys_to_pfn(VERSATILE_SCTL_BASE),
+		.length		= SZ_4K * 9,
+		.type		= MT_DEVICE
+	}
+};
+
+static void __init versatile_map_io(void)
+{
+	debug_ll_io_init();
+	iotable_init(versatile_io_desc, ARRAY_SIZE(versatile_io_desc));
+}
+
+static void __init versatile_init_early(void)
+{
+	u32 val;
+
+	/*
+	 * set clock frequency:
+	 *	VERSATILE_REFCLK is 32KHz
+	 *	VERSATILE_TIMCLK is 1MHz
+	 */
+	val = readl(__io_address(VERSATILE_SCTL_BASE));
+	writel((VERSATILE_TIMCLK << VERSATILE_TIMER1_EnSel) |
+	       (VERSATILE_TIMCLK << VERSATILE_TIMER2_EnSel) |
+	       (VERSATILE_TIMCLK << VERSATILE_TIMER3_EnSel) |
+	       (VERSATILE_TIMCLK << VERSATILE_TIMER4_EnSel) | val,
+	       __io_address(VERSATILE_SCTL_BASE));
+}
+
+static void __init versatile_dt_pci_init(void)
+{
+	u32 val;
+	struct device_node *np;
+	struct property *newprop;
+
+	np = of_find_compatible_node(NULL, NULL, "arm,versatile-pci");
+	if (!np)
+		return;
+
+	/* Check if PCI backplane is detected */
+	val = readl(versatile_sys_base + VERSATILE_SYS_PCICTL_OFFSET);
+	if (val & 1) {
+		/*
+		 * Enable PCI accesses. Note that the documentation is
+		 * inconsistent whether or not this is needed, but the old
+		 * driver had it so we will keep it.
+		 */
+		writel(1, versatile_sys_base + VERSATILE_SYS_PCICTL_OFFSET);
+		goto out_put_node;
+	}
+
+	newprop = kzalloc_obj(*newprop);
+	if (!newprop)
+		goto out_put_node;
+
+	newprop->name = kstrdup("status", GFP_KERNEL);
+	newprop->value = kstrdup("disabled", GFP_KERNEL);
+	newprop->length = sizeof("disabled");
+	of_update_property(np, newprop);
+
+	pr_info("Not plugged into PCI backplane!\n");
+
+out_put_node:
+	of_node_put(np);
+}
+
+static void __init versatile_dt_init(void)
+{
+	struct device_node *np;
+
+	np = of_find_compatible_node(NULL, NULL, "arm,core-module-versatile");
+	if (np)
+		versatile_sys_base = of_iomap(np, 0);
+	WARN_ON(!versatile_sys_base);
+
+	versatile_dt_pci_init();
+
+	of_platform_default_populate(NULL, versatile_auxdata_lookup, NULL);
+}
+
+static const char *const versatile_dt_match[] __initconst = {
+	"arm,versatile-ab",
+	"arm,versatile-pb",
+	NULL,
+};
+
+DT_MACHINE_START(VERSATILE_PB, "ARM-Versatile (Device Tree Support)")
+	.map_io		= versatile_map_io,
+	.init_early	= versatile_init_early,
+	.init_machine	= versatile_dt_init,
+	.dt_compat	= versatile_dt_match,
+MACHINE_END