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, 535 insertions, 0 deletions

diff --git a/drivers/char/dsp56k.c b/drivers/char/dsp56k.c
new file mode 100644
index 000000000..1c2c84397
--- /dev/null
+++ b/drivers/char/dsp56k.c
@@ -0,0 +1,535 @@
+/*
+ * The DSP56001 Device Driver, saviour of the Free World(tm)
+ *
+ * Authors: Fredrik Noring   <noring@nocrew.org>
+ *          lars brinkhoff   <lars@nocrew.org>
+ *          Tomas Berndtsson <tomas@nocrew.org>
+ *
+ * First version May 1996
+ *
+ * History:
+ *  97-01-29   Tomas Berndtsson,
+ *               Integrated with Linux 2.1.21 kernel sources.
+ *  97-02-15   Tomas Berndtsson,
+ *               Fixed for kernel 2.1.26
+ *
+ * BUGS:
+ *  Hmm... there must be something here :)
+ *
+ * Copyright (C) 1996,1997 Fredrik Noring, lars brinkhoff & Tomas Berndtsson
+ *
+ * This file is subject to the terms and conditions of the GNU General Public
+ * License.  See the file COPYING in the main directory of this archive
+ * for more details.
+ */
+
+#include <linux/module.h>
+#include <linux/major.h>
+#include <linux/types.h>
+#include <linux/errno.h>
+#include <linux/delay.h>	/* guess what */
+#include <linux/fs.h>
+#include <linux/mm.h>
+#include <linux/init.h>
+#include <linux/device.h>
+#include <linux/mutex.h>
+#include <linux/firmware.h>
+#include <linux/platform_device.h>
+#include <linux/uaccess.h>	/* For put_user and get_user */
+
+#include <asm/atarihw.h>
+#include <asm/traps.h>
+
+#include <asm/dsp56k.h>
+
+/* minor devices */
+#define DSP56K_DEV_56001        0    /* The only device so far */
+
+#define TIMEOUT    10   /* Host port timeout in number of tries */
+#define MAXIO    2048   /* Maximum number of words before sleep */
+#define DSP56K_MAX_BINARY_LENGTH (3*64*1024)
+
+#define DSP56K_TX_INT_ON	dsp56k_host_interface.icr |=  DSP56K_ICR_TREQ
+#define DSP56K_RX_INT_ON	dsp56k_host_interface.icr |=  DSP56K_ICR_RREQ
+#define DSP56K_TX_INT_OFF	dsp56k_host_interface.icr &= ~DSP56K_ICR_TREQ
+#define DSP56K_RX_INT_OFF	dsp56k_host_interface.icr &= ~DSP56K_ICR_RREQ
+
+#define DSP56K_TRANSMIT		(dsp56k_host_interface.isr & DSP56K_ISR_TXDE)
+#define DSP56K_RECEIVE		(dsp56k_host_interface.isr & DSP56K_ISR_RXDF)
+
+#define handshake(count, maxio, timeout, ENABLE, f) \
+{ \
+	long i, t, m; \
+	while (count > 0) { \
+		m = min_t(unsigned long, count, maxio); \
+		for (i = 0; i < m; i++) { \
+			for (t = 0; t < timeout && !ENABLE; t++) \
+				msleep(20); \
+			if(!ENABLE) \
+				return -EIO; \
+			f; \
+		} \
+		count -= m; \
+		if (m == maxio) msleep(20); \
+	} \
+}
+
+#define tx_wait(n) \
+{ \
+	int t; \
+	for(t = 0; t < n && !DSP56K_TRANSMIT; t++) \
+		msleep(10); \
+	if(!DSP56K_TRANSMIT) { \
+		return -EIO; \
+	} \
+}
+
+#define rx_wait(n) \
+{ \
+	int t; \
+	for(t = 0; t < n && !DSP56K_RECEIVE; t++) \
+		msleep(10); \
+	if(!DSP56K_RECEIVE) { \
+		return -EIO; \
+	} \
+}
+
+static DEFINE_MUTEX(dsp56k_mutex);
+static struct dsp56k_device {
+	unsigned long in_use;
+	long maxio, timeout;
+	int tx_wsize, rx_wsize;
+} dsp56k;
+
+static const struct class dsp56k_class = {
+	.name = "dsp56k",
+};
+
+static int dsp56k_reset(void)
+{
+	u_char status;
+	
+	/* Power down the DSP */
+	sound_ym.rd_data_reg_sel = 14;
+	status = sound_ym.rd_data_reg_sel & 0xef;
+	sound_ym.wd_data = status;
+	sound_ym.wd_data = status | 0x10;
+  
+	udelay(10);
+  
+	/* Power up the DSP */
+	sound_ym.rd_data_reg_sel = 14;
+	sound_ym.wd_data = sound_ym.rd_data_reg_sel & 0xef;
+
+	return 0;
+}
+
+static int dsp56k_upload(u_char __user *bin, int len)
+{
+	struct platform_device *pdev;
+	const struct firmware *fw;
+	const char fw_name[] = "dsp56k/bootstrap.bin";
+	int err;
+	int i;
+
+	dsp56k_reset();
+
+	pdev = platform_device_register_simple("dsp56k", 0, NULL, 0);
+	if (IS_ERR(pdev)) {
+		printk(KERN_ERR "Failed to register device for \"%s\"\n",
+		       fw_name);
+		return -EINVAL;
+	}
+	err = request_firmware(&fw, fw_name, &pdev->dev);
+	platform_device_unregister(pdev);
+	if (err) {
+		printk(KERN_ERR "Failed to load image \"%s\" err %d\n",
+		       fw_name, err);
+		return err;
+	}
+	if (fw->size % 3) {
+		printk(KERN_ERR "Bogus length %d in image \"%s\"\n",
+		       fw->size, fw_name);
+		release_firmware(fw);
+		return -EINVAL;
+	}
+	for (i = 0; i < fw->size; i = i + 3) {
+		/* tx_wait(10); */
+		dsp56k_host_interface.data.b[1] = fw->data[i];
+		dsp56k_host_interface.data.b[2] = fw->data[i + 1];
+		dsp56k_host_interface.data.b[3] = fw->data[i + 2];
+	}
+	release_firmware(fw);
+	for (; i < 512; i++) {
+		/* tx_wait(10); */
+		dsp56k_host_interface.data.b[1] = 0;
+		dsp56k_host_interface.data.b[2] = 0;
+		dsp56k_host_interface.data.b[3] = 0;
+	}
+  
+	for (i = 0; i < len; i++) {
+		tx_wait(10);
+		get_user(dsp56k_host_interface.data.b[1], bin++);
+		get_user(dsp56k_host_interface.data.b[2], bin++);
+		get_user(dsp56k_host_interface.data.b[3], bin++);
+	}
+
+	tx_wait(10);
+	dsp56k_host_interface.data.l = 3;    /* Magic execute */
+
+	return 0;
+}
+
+static ssize_t dsp56k_read(struct file *file, char __user *buf, size_t count,
+			   loff_t *ppos)
+{
+	struct inode *inode = file_inode(file);
+	int dev = iminor(inode) & 0x0f;
+
+	switch(dev)
+	{
+	case DSP56K_DEV_56001:
+	{
+
+		long n;
+
+		/* Don't do anything if nothing is to be done */
+		if (!count) return 0;
+
+		n = 0;
+		switch (dsp56k.rx_wsize) {
+		case 1:  /* 8 bit */
+		{
+			handshake(count, dsp56k.maxio, dsp56k.timeout, DSP56K_RECEIVE,
+				  put_user(dsp56k_host_interface.data.b[3], buf+n++));
+			return n;
+		}
+		case 2:  /* 16 bit */
+		{
+			short __user *data;
+
+			count /= 2;
+			data = (short __user *) buf;
+			handshake(count, dsp56k.maxio, dsp56k.timeout, DSP56K_RECEIVE,
+				  put_user(dsp56k_host_interface.data.w[1], data+n++));
+			return 2*n;
+		}
+		case 3:  /* 24 bit */
+		{
+			count /= 3;
+			handshake(count, dsp56k.maxio, dsp56k.timeout, DSP56K_RECEIVE,
+				  put_user(dsp56k_host_interface.data.b[1], buf+n++);
+				  put_user(dsp56k_host_interface.data.b[2], buf+n++);
+				  put_user(dsp56k_host_interface.data.b[3], buf+n++));
+			return 3*n;
+		}
+		case 4:  /* 32 bit */
+		{
+			long __user *data;
+
+			count /= 4;
+			data = (long __user *) buf;
+			handshake(count, dsp56k.maxio, dsp56k.timeout, DSP56K_RECEIVE,
+				  put_user(dsp56k_host_interface.data.l, data+n++));
+			return 4*n;
+		}
+		}
+		return -EFAULT;
+	}
+
+	default:
+		printk(KERN_ERR "DSP56k driver: Unknown minor device: %d\n", dev);
+		return -ENXIO;
+	}
+}
+
+static ssize_t dsp56k_write(struct file *file, const char __user *buf, size_t count,
+			    loff_t *ppos)
+{
+	struct inode *inode = file_inode(file);
+	int dev = iminor(inode) & 0x0f;
+
+	switch(dev)
+	{
+	case DSP56K_DEV_56001:
+	{
+		long n;
+
+		/* Don't do anything if nothing is to be done */
+		if (!count) return 0;
+
+		n = 0;
+		switch (dsp56k.tx_wsize) {
+		case 1:  /* 8 bit */
+		{
+			handshake(count, dsp56k.maxio, dsp56k.timeout, DSP56K_TRANSMIT,
+				  get_user(dsp56k_host_interface.data.b[3], buf+n++));
+			return n;
+		}
+		case 2:  /* 16 bit */
+		{
+			const short __user *data;
+
+			count /= 2;
+			data = (const short __user *)buf;
+			handshake(count, dsp56k.maxio, dsp56k.timeout, DSP56K_TRANSMIT,
+				  get_user(dsp56k_host_interface.data.w[1], data+n++));
+			return 2*n;
+		}
+		case 3:  /* 24 bit */
+		{
+			count /= 3;
+			handshake(count, dsp56k.maxio, dsp56k.timeout, DSP56K_TRANSMIT,
+				  get_user(dsp56k_host_interface.data.b[1], buf+n++);
+				  get_user(dsp56k_host_interface.data.b[2], buf+n++);
+				  get_user(dsp56k_host_interface.data.b[3], buf+n++));
+			return 3*n;
+		}
+		case 4:  /* 32 bit */
+		{
+			const long __user *data;
+
+			count /= 4;
+			data = (const long __user *)buf;
+			handshake(count, dsp56k.maxio, dsp56k.timeout, DSP56K_TRANSMIT,
+				  get_user(dsp56k_host_interface.data.l, data+n++));
+			return 4*n;
+		}
+		}
+
+		return -EFAULT;
+	}
+	default:
+		printk(KERN_ERR "DSP56k driver: Unknown minor device: %d\n", dev);
+		return -ENXIO;
+	}
+}
+
+static long dsp56k_ioctl(struct file *file, unsigned int cmd,
+			 unsigned long arg)
+{
+	int dev = iminor(file_inode(file)) & 0x0f;
+	void __user *argp = (void __user *)arg;
+
+	switch(dev)
+	{
+	case DSP56K_DEV_56001:
+
+		switch(cmd) {
+		case DSP56K_UPLOAD:
+		{
+			char __user *bin;
+			int r, len;
+			struct dsp56k_upload __user *binary = argp;
+    
+			if(get_user(len, &binary->len) < 0)
+				return -EFAULT;
+			if(get_user(bin, &binary->bin) < 0)
+				return -EFAULT;
+		
+			if (len <= 0) {
+				return -EINVAL;      /* nothing to upload?!? */
+			}
+			if (len > DSP56K_MAX_BINARY_LENGTH) {
+				return -EINVAL;
+			}
+			mutex_lock(&dsp56k_mutex);
+			r = dsp56k_upload(bin, len);
+			mutex_unlock(&dsp56k_mutex);
+			if (r < 0) {
+				return r;
+			}
+    
+			break;
+		}
+		case DSP56K_SET_TX_WSIZE:
+			if (arg > 4 || arg < 1)
+				return -EINVAL;
+			mutex_lock(&dsp56k_mutex);
+			dsp56k.tx_wsize = (int) arg;
+			mutex_unlock(&dsp56k_mutex);
+			break;
+		case DSP56K_SET_RX_WSIZE:
+			if (arg > 4 || arg < 1)
+				return -EINVAL;
+			mutex_lock(&dsp56k_mutex);
+			dsp56k.rx_wsize = (int) arg;
+			mutex_unlock(&dsp56k_mutex);
+			break;
+		case DSP56K_HOST_FLAGS:
+		{
+			int dir, out, status;
+			struct dsp56k_host_flags __user *hf = argp;
+    
+			if(get_user(dir, &hf->dir) < 0)
+				return -EFAULT;
+			if(get_user(out, &hf->out) < 0)
+				return -EFAULT;
+
+			mutex_lock(&dsp56k_mutex);
+			if ((dir & 0x1) && (out & 0x1))
+				dsp56k_host_interface.icr |= DSP56K_ICR_HF0;
+			else if (dir & 0x1)
+				dsp56k_host_interface.icr &= ~DSP56K_ICR_HF0;
+			if ((dir & 0x2) && (out & 0x2))
+				dsp56k_host_interface.icr |= DSP56K_ICR_HF1;
+			else if (dir & 0x2)
+				dsp56k_host_interface.icr &= ~DSP56K_ICR_HF1;
+
+			status = 0;
+			if (dsp56k_host_interface.icr & DSP56K_ICR_HF0) status |= 0x1;
+			if (dsp56k_host_interface.icr & DSP56K_ICR_HF1) status |= 0x2;
+			if (dsp56k_host_interface.isr & DSP56K_ISR_HF2) status |= 0x4;
+			if (dsp56k_host_interface.isr & DSP56K_ISR_HF3) status |= 0x8;
+			mutex_unlock(&dsp56k_mutex);
+			return put_user(status, &hf->status);
+		}
+		case DSP56K_HOST_CMD:
+			if (arg > 31)
+				return -EINVAL;
+			mutex_lock(&dsp56k_mutex);
+			dsp56k_host_interface.cvr = (u_char)((arg & DSP56K_CVR_HV_MASK) |
+							     DSP56K_CVR_HC);
+			mutex_unlock(&dsp56k_mutex);
+			break;
+		default:
+			return -EINVAL;
+		}
+		return 0;
+
+	default:
+		printk(KERN_ERR "DSP56k driver: Unknown minor device: %d\n", dev);
+		return -ENXIO;
+	}
+}
+
+/* As of 2.1.26 this should be dsp56k_poll,
+ * but how do I then check device minor number?
+ * Do I need this function at all???
+ */
+#if 0
+static __poll_t dsp56k_poll(struct file *file, poll_table *wait)
+{
+	int dev = iminor(file_inode(file)) & 0x0f;
+
+	switch(dev)
+	{
+	case DSP56K_DEV_56001:
+		/* poll_wait(file, ???, wait); */
+		return EPOLLIN | EPOLLRDNORM | EPOLLOUT;
+
+	default:
+		printk("DSP56k driver: Unknown minor device: %d\n", dev);
+		return 0;
+	}
+}
+#endif
+
+static int dsp56k_open(struct inode *inode, struct file *file)
+{
+	int dev = iminor(inode) & 0x0f;
+	int ret = 0;
+
+	mutex_lock(&dsp56k_mutex);
+	switch(dev)
+	{
+	case DSP56K_DEV_56001:
+
+		if (test_and_set_bit(0, &dsp56k.in_use)) {
+			ret = -EBUSY;
+			goto out;
+		}
+
+		dsp56k.timeout = TIMEOUT;
+		dsp56k.maxio = MAXIO;
+		dsp56k.rx_wsize = dsp56k.tx_wsize = 4; 
+
+		DSP56K_TX_INT_OFF;
+		DSP56K_RX_INT_OFF;
+
+		/* Zero host flags */
+		dsp56k_host_interface.icr &= ~DSP56K_ICR_HF0;
+		dsp56k_host_interface.icr &= ~DSP56K_ICR_HF1;
+
+		break;
+
+	default:
+		ret = -ENODEV;
+	}
+out:
+	mutex_unlock(&dsp56k_mutex);
+	return ret;
+}
+
+static int dsp56k_release(struct inode *inode, struct file *file)
+{
+	int dev = iminor(inode) & 0x0f;
+
+	switch(dev)
+	{
+	case DSP56K_DEV_56001:
+		clear_bit(0, &dsp56k.in_use);
+		break;
+	default:
+		printk(KERN_ERR "DSP56k driver: Unknown minor device: %d\n", dev);
+		return -ENXIO;
+	}
+
+	return 0;
+}
+
+static const struct file_operations dsp56k_fops = {
+	.owner		= THIS_MODULE,
+	.read		= dsp56k_read,
+	.write		= dsp56k_write,
+	.unlocked_ioctl	= dsp56k_ioctl,
+	.open		= dsp56k_open,
+	.release	= dsp56k_release,
+	.llseek		= noop_llseek,
+};
+
+
+/****** Init and module functions ******/
+
+static const char banner[] __initconst = KERN_INFO "DSP56k driver installed\n";
+
+static int __init dsp56k_init_driver(void)
+{
+	int err;
+
+	if(!MACH_IS_ATARI || !ATARIHW_PRESENT(DSP56K)) {
+		printk("DSP56k driver: Hardware not present\n");
+		return -ENODEV;
+	}
+
+	if(register_chrdev(DSP56K_MAJOR, "dsp56k", &dsp56k_fops)) {
+		printk("DSP56k driver: Unable to register driver\n");
+		return -ENODEV;
+	}
+	err = class_register(&dsp56k_class);
+	if (err)
+		goto out_chrdev;
+	device_create(&dsp56k_class, NULL, MKDEV(DSP56K_MAJOR, 0), NULL,
+		      "dsp56k");
+
+	printk(banner);
+	goto out;
+
+out_chrdev:
+	unregister_chrdev(DSP56K_MAJOR, "dsp56k");
+out:
+	return err;
+}
+module_init(dsp56k_init_driver);
+
+static void __exit dsp56k_cleanup_driver(void)
+{
+	device_destroy(&dsp56k_class, MKDEV(DSP56K_MAJOR, 0));
+	class_unregister(&dsp56k_class);
+	unregister_chrdev(DSP56K_MAJOR, "dsp56k");
+}
+module_exit(dsp56k_cleanup_driver);
+
+MODULE_DESCRIPTION("Atari DSP56001 Device Driver");
+MODULE_LICENSE("GPL");
+MODULE_FIRMWARE("dsp56k/bootstrap.bin");