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, 239 insertions, 0 deletions

diff --git a/drivers/hid/hid-icade.c b/drivers/hid/hid-icade.c
new file mode 100644
index 000000000..f3716cfac
--- /dev/null
+++ b/drivers/hid/hid-icade.c
@@ -0,0 +1,239 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ *  ION iCade input driver
+ *
+ *  Copyright (c) 2012 Bastien Nocera <hadess@hadess.net>
+ *  Copyright (c) 2012 Benjamin Tissoires <benjamin.tissoires@gmail.com>
+ */
+
+/*
+ */
+
+#include <linux/device.h>
+#include <linux/hid.h>
+#include <linux/module.h>
+
+#include "hid-ids.h"
+
+/*
+ *   ↑      A C Y L
+ *  ← →
+ *   ↓      B X Z R
+ *
+ *
+ *  UP ON,OFF  = w,e
+ *  RT ON,OFF  = d,c
+ *  DN ON,OFF  = x,z
+ *  LT ON,OFF  = a,q
+ *  A  ON,OFF  = y,t
+ *  B  ON,OFF  = h,r
+ *  C  ON,OFF  = u,f
+ *  X  ON,OFF  = j,n
+ *  Y  ON,OFF  = i,m
+ *  Z  ON,OFF  = k,p
+ *  L  ON,OFF  = o,g
+ *  R  ON,OFF  = l,v
+ */
+
+/* The translation code uses HID usage instead of input layer
+ * keys. This code generates a lookup table that makes
+ * translation quick.
+ *
+ * #include <linux/input.h>
+ * #include <stdio.h>
+ * #include <assert.h>
+ *
+ * #define unk     KEY_UNKNOWN
+ *
+ * < copy of hid_keyboard[] from hid-input.c >
+ *
+ * struct icade_key_translation {
+ *     int         from;
+ *     const char *to;
+ *     int         press;
+ * };
+ *
+ * static const struct icade_key_translation icade_keys[] = {
+ *    { KEY_W,        "KEY_UP",         1 },
+ *    { KEY_E,        "KEY_UP",         0 },
+ *    { KEY_D,        "KEY_RIGHT",      1 },
+ *    { KEY_C,        "KEY_RIGHT",      0 },
+ *    { KEY_X,        "KEY_DOWN",       1 },
+ *    { KEY_Z,        "KEY_DOWN",       0 },
+ *    { KEY_A,        "KEY_LEFT",       1 },
+ *    { KEY_Q,        "KEY_LEFT",       0 },
+ *    { KEY_Y,        "BTN_A",          1 },
+ *    { KEY_T,        "BTN_A",          0 },
+ *    { KEY_H,        "BTN_B",          1 },
+ *    { KEY_R,        "BTN_B",          0 },
+ *    { KEY_U,        "BTN_C",          1 },
+ *    { KEY_F,        "BTN_C",          0 },
+ *    { KEY_J,        "BTN_X",          1 },
+ *    { KEY_N,        "BTN_X",          0 },
+ *    { KEY_I,        "BTN_Y",          1 },
+ *    { KEY_M,        "BTN_Y",          0 },
+ *    { KEY_K,        "BTN_Z",          1 },
+ *    { KEY_P,        "BTN_Z",          0 },
+ *    { KEY_O,        "BTN_THUMBL",     1 },
+ *    { KEY_G,        "BTN_THUMBL",     0 },
+ *    { KEY_L,        "BTN_THUMBR",     1 },
+ *    { KEY_V,        "BTN_THUMBR",     0 },
+ *
+ *    { }
+ * };
+ *
+ * static int
+ * usage_for_key (int key)
+ * {
+ *     int i;
+ *     for (i = 0; i < 256; i++) {
+ *     if (hid_keyboard[i] == key)
+ *         return i;
+ *     }
+ *     assert(0);
+ * }
+ *
+ * int main (int argc, char **argv)
+ * {
+ *     const struct icade_key_translation *trans;
+ *     int max_usage = 0;
+ *
+ *     for (trans = icade_keys; trans->from; trans++) {
+ *         int usage = usage_for_key (trans->from);
+ *         max_usage = usage > max_usage ? usage : max_usage;
+ *     }
+ *
+ *     printf ("#define ICADE_MAX_USAGE %d\n\n", max_usage);
+ *     printf ("struct icade_key {\n");
+ *     printf ("\tu16 to;\n");
+ *     printf ("\tu8 press:1;\n");
+ *     printf ("};\n\n");
+ *     printf ("static const struct icade_key "
+ *             "icade_usage_table[%d] = {\n", max_usage + 1);
+ *     for (trans = icade_keys; trans->from; trans++) {
+ *         printf ("\t[%d] = { %s, %d },\n",
+ *                 usage_for_key (trans->from), trans->to, trans->press);
+ *     }
+ *     printf ("};\n");
+ *
+ *     return 0;
+ * }
+ */
+
+#define ICADE_MAX_USAGE 29
+
+struct icade_key {
+	u16 to;
+	u8 press:1;
+};
+
+static const struct icade_key icade_usage_table[30] = {
+	[26] = { KEY_UP, 1 },
+	[8] = { KEY_UP, 0 },
+	[7] = { KEY_RIGHT, 1 },
+	[6] = { KEY_RIGHT, 0 },
+	[27] = { KEY_DOWN, 1 },
+	[29] = { KEY_DOWN, 0 },
+	[4] = { KEY_LEFT, 1 },
+	[20] = { KEY_LEFT, 0 },
+	[28] = { BTN_A, 1 },
+	[23] = { BTN_A, 0 },
+	[11] = { BTN_B, 1 },
+	[21] = { BTN_B, 0 },
+	[24] = { BTN_C, 1 },
+	[9] = { BTN_C, 0 },
+	[13] = { BTN_X, 1 },
+	[17] = { BTN_X, 0 },
+	[12] = { BTN_Y, 1 },
+	[16] = { BTN_Y, 0 },
+	[14] = { BTN_Z, 1 },
+	[19] = { BTN_Z, 0 },
+	[18] = { BTN_THUMBL, 1 },
+	[10] = { BTN_THUMBL, 0 },
+	[15] = { BTN_THUMBR, 1 },
+	[25] = { BTN_THUMBR, 0 },
+};
+
+static const struct icade_key *icade_find_translation(u16 from)
+{
+	if (from > ICADE_MAX_USAGE)
+		return NULL;
+	return &icade_usage_table[from];
+}
+
+static int icade_event(struct hid_device *hdev, struct hid_field *field,
+		struct hid_usage *usage, __s32 value)
+{
+	const struct icade_key *trans;
+
+	if (!(hdev->claimed & HID_CLAIMED_INPUT) || !field->hidinput ||
+			!usage->type)
+		return 0;
+
+	/* We ignore the fake key up, and act only on key down */
+	if (!value)
+		return 1;
+
+	trans = icade_find_translation(usage->hid & HID_USAGE);
+
+	if (!trans)
+		return 1;
+
+	input_event(field->hidinput->input, usage->type,
+			trans->to, trans->press);
+
+	return 1;
+}
+
+static int icade_input_mapping(struct hid_device *hdev, struct hid_input *hi,
+		struct hid_field *field, struct hid_usage *usage,
+		unsigned long **bit, int *max)
+{
+	const struct icade_key *trans;
+
+	if ((usage->hid & HID_USAGE_PAGE) == HID_UP_KEYBOARD) {
+		trans = icade_find_translation(usage->hid & HID_USAGE);
+
+		if (!trans)
+			return -1;
+
+		hid_map_usage(hi, usage, bit, max, EV_KEY, trans->to);
+		set_bit(trans->to, hi->input->keybit);
+
+		return 1;
+	}
+
+	/* ignore others */
+	return -1;
+
+}
+
+static int icade_input_mapped(struct hid_device *hdev, struct hid_input *hi,
+		struct hid_field *field, struct hid_usage *usage,
+		unsigned long **bit, int *max)
+{
+	if (usage->type == EV_KEY)
+		set_bit(usage->type, hi->input->evbit);
+
+	return -1;
+}
+
+static const struct hid_device_id icade_devices[] = {
+	{ HID_BLUETOOTH_DEVICE(USB_VENDOR_ID_ION, USB_DEVICE_ID_ICADE) },
+
+	{ }
+};
+MODULE_DEVICE_TABLE(hid, icade_devices);
+
+static struct hid_driver icade_driver = {
+	.name = "icade",
+	.id_table = icade_devices,
+	.event = icade_event,
+	.input_mapped = icade_input_mapped,
+	.input_mapping = icade_input_mapping,
+};
+module_hid_driver(icade_driver);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Bastien Nocera <hadess@hadess.net>");
+MODULE_DESCRIPTION("ION iCade input driver");