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, 159 insertions, 0 deletions

diff --git a/drivers/media/common/ttpci-eeprom.c b/drivers/media/common/ttpci-eeprom.c
new file mode 100644
index 000000000..ef8746684
--- /dev/null
+++ b/drivers/media/common/ttpci-eeprom.c
@@ -0,0 +1,159 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+    Retrieve encoded MAC address from 24C16 serial 2-wire EEPROM,
+    decode it and store it in the associated adapter struct for
+    use by dvb_net.c
+
+    This card appear to have the 24C16 write protect held to ground,
+    thus permitting normal read/write operation. Theoretically it
+    would be possible to write routines to burn a different (encoded)
+    MAC address into the EEPROM.
+
+    Robert Schlabbach	GMX
+    Michael Glaum	KVH Industries
+    Holger Waechtler	Convergence
+
+    Copyright (C) 2002-2003 Ralph Metzler <rjkm@metzlerbros.de>
+			    Metzler Brothers Systementwicklung GbR
+
+
+*/
+
+#include <asm/errno.h>
+#include <linux/init.h>
+#include <linux/module.h>
+#include <linux/string.h>
+#include <linux/i2c.h>
+#include <linux/etherdevice.h>
+
+#include "ttpci-eeprom.h"
+
+#if 1
+#define dprintk(x...) do { printk(x); } while (0)
+#else
+#define dprintk(x...) do { } while (0)
+#endif
+
+
+static int check_mac_tt(u8 *buf)
+{
+	int i;
+	u16 tmp = 0xffff;
+
+	for (i = 0; i < 8; i++) {
+		tmp  = (tmp << 8) | ((tmp >> 8) ^ buf[i]);
+		tmp ^= (tmp >> 4) & 0x0f;
+		tmp ^= (tmp << 12) ^ ((tmp & 0xff) << 5);
+	}
+	tmp ^= 0xffff;
+	return (((tmp >> 8) ^ buf[8]) | ((tmp & 0xff) ^ buf[9]));
+}
+
+static int getmac_tt(u8 * decodedMAC, u8 * encodedMAC)
+{
+	u8 xor[20] = { 0x72, 0x23, 0x68, 0x19, 0x5c, 0xa8, 0x71, 0x2c,
+		       0x54, 0xd3, 0x7b, 0xf1, 0x9E, 0x23, 0x16, 0xf6,
+		       0x1d, 0x36, 0x64, 0x78};
+	u8 data[20];
+	int i;
+
+	/* In case there is a sig check failure have the orig contents available */
+	memcpy(data, encodedMAC, 20);
+
+	for (i = 0; i < 20; i++)
+		data[i] ^= xor[i];
+	for (i = 0; i < 10; i++)
+		data[i] = ((data[2 * i + 1] << 8) | data[2 * i])
+			>> ((data[2 * i + 1] >> 6) & 3);
+
+	if (check_mac_tt(data))
+		return -ENODEV;
+
+	decodedMAC[0] = data[2]; decodedMAC[1] = data[1]; decodedMAC[2] = data[0];
+	decodedMAC[3] = data[6]; decodedMAC[4] = data[5]; decodedMAC[5] = data[4];
+	return 0;
+}
+
+int ttpci_eeprom_decode_mac(u8 *decodedMAC, u8 *encodedMAC)
+{
+	u8 xor[20] = { 0x72, 0x23, 0x68, 0x19, 0x5c, 0xa8, 0x71, 0x2c,
+		       0x54, 0xd3, 0x7b, 0xf1, 0x9E, 0x23, 0x16, 0xf6,
+		       0x1d, 0x36, 0x64, 0x78};
+	u8 data[20];
+	int i;
+
+	memcpy(data, encodedMAC, 20);
+
+	for (i = 0; i < 20; i++)
+		data[i] ^= xor[i];
+	for (i = 0; i < 10; i++)
+		data[i] = ((data[2 * i + 1] << 8) | data[2 * i])
+			>> ((data[2 * i + 1] >> 6) & 3);
+
+	if (check_mac_tt(data))
+		return -ENODEV;
+
+	decodedMAC[0] = data[2];
+	decodedMAC[1] = data[1];
+	decodedMAC[2] = data[0];
+	decodedMAC[3] = data[6];
+	decodedMAC[4] = data[5];
+	decodedMAC[5] = data[4];
+	return 0;
+}
+EXPORT_SYMBOL(ttpci_eeprom_decode_mac);
+
+static int ttpci_eeprom_read_encodedMAC(struct i2c_adapter *adapter, u8 * encodedMAC)
+{
+	int ret;
+	u8 b0[] = { 0xcc };
+
+	struct i2c_msg msg[] = {
+		{ .addr = 0x50, .flags = 0, .buf = b0, .len = 1 },
+		{ .addr = 0x50, .flags = I2C_M_RD, .buf = encodedMAC, .len = 20 }
+	};
+
+	/* dprintk("%s\n", __func__); */
+
+	ret = i2c_transfer(adapter, msg, 2);
+
+	if (ret != 2)		/* Assume EEPROM isn't there */
+		return (-ENODEV);
+
+	return 0;
+}
+
+
+int ttpci_eeprom_parse_mac(struct i2c_adapter *adapter, u8 *proposed_mac)
+{
+	int ret;
+	u8 encodedMAC[20];
+	u8 decodedMAC[6];
+
+	ret = ttpci_eeprom_read_encodedMAC(adapter, encodedMAC);
+
+	if (ret != 0) {		/* Will only be -ENODEV */
+		dprintk("Couldn't read from EEPROM: not there?\n");
+		eth_zero_addr(proposed_mac);
+		return ret;
+	}
+
+	ret = getmac_tt(decodedMAC, encodedMAC);
+	if( ret != 0 ) {
+		dprintk("adapter failed MAC signature check\n");
+		dprintk("encoded MAC from EEPROM was %*phC",
+			(int)sizeof(encodedMAC), &encodedMAC);
+		eth_zero_addr(proposed_mac);
+		return ret;
+	}
+
+	memcpy(proposed_mac, decodedMAC, 6);
+	dprintk("adapter has MAC addr = %pM\n", decodedMAC);
+	return 0;
+}
+
+EXPORT_SYMBOL(ttpci_eeprom_parse_mac);
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Ralph Metzler, Marcus Metzler, others");
+MODULE_DESCRIPTION("Decode dvb_net MAC address from EEPROM of PCI DVB cards made by Siemens, Technotrend, Hauppauge");