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, 309 insertions, 0 deletions

diff --git a/net/sunrpc/debugfs.c b/net/sunrpc/debugfs.c
new file mode 100644
index 000000000..32417db34
--- /dev/null
+++ b/net/sunrpc/debugfs.c
@@ -0,0 +1,309 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * debugfs interface for sunrpc
+ *
+ * (c) 2014 Jeff Layton <jlayton@primarydata.com>
+ */
+
+#include <linux/debugfs.h>
+#include <linux/sunrpc/sched.h>
+#include <linux/sunrpc/clnt.h>
+
+#include "netns.h"
+#include "fail.h"
+
+static struct dentry *topdir;
+static struct dentry *rpc_clnt_dir;
+static struct dentry *rpc_xprt_dir;
+
+static int
+tasks_show(struct seq_file *f, void *v)
+{
+	u32 xid = 0;
+	struct rpc_task *task = v;
+	struct rpc_clnt *clnt = task->tk_client;
+	const char *rpc_waitq = "none";
+
+	if (RPC_IS_QUEUED(task))
+		rpc_waitq = rpc_qname(task->tk_waitqueue);
+
+	if (task->tk_rqstp)
+		xid = be32_to_cpu(task->tk_rqstp->rq_xid);
+
+	seq_printf(f, "%5u %04x %6d 0x%x 0x%x %8ld %ps %sv%u %s a:%ps q:%s\n",
+		task->tk_pid, task->tk_flags, task->tk_status,
+		clnt->cl_clid, xid, rpc_task_timeout(task), task->tk_ops,
+		clnt->cl_program->name, clnt->cl_vers, rpc_proc_name(task),
+		task->tk_action, rpc_waitq);
+	return 0;
+}
+
+static void *
+tasks_start(struct seq_file *f, loff_t *ppos)
+	__acquires(&clnt->cl_lock)
+{
+	struct rpc_clnt *clnt = f->private;
+	loff_t pos = *ppos;
+	struct rpc_task *task;
+
+	spin_lock(&clnt->cl_lock);
+	list_for_each_entry(task, &clnt->cl_tasks, tk_task)
+		if (pos-- == 0)
+			return task;
+	return NULL;
+}
+
+static void *
+tasks_next(struct seq_file *f, void *v, loff_t *pos)
+{
+	struct rpc_clnt *clnt = f->private;
+	struct rpc_task *task = v;
+	struct list_head *next = task->tk_task.next;
+
+	++*pos;
+
+	/* If there's another task on list, return it */
+	if (next == &clnt->cl_tasks)
+		return NULL;
+	return list_entry(next, struct rpc_task, tk_task);
+}
+
+static void
+tasks_stop(struct seq_file *f, void *v)
+	__releases(&clnt->cl_lock)
+{
+	struct rpc_clnt *clnt = f->private;
+	spin_unlock(&clnt->cl_lock);
+	seq_printf(f, "clnt[%pISpc] RPC tasks[%d]\n",
+		   (struct sockaddr *)&clnt->cl_xprt->addr,
+		   atomic_read(&clnt->cl_task_count));
+}
+
+static const struct seq_operations tasks_seq_operations = {
+	.start	= tasks_start,
+	.next	= tasks_next,
+	.stop	= tasks_stop,
+	.show	= tasks_show,
+};
+
+static int tasks_open(struct inode *inode, struct file *filp)
+{
+	int ret = seq_open(filp, &tasks_seq_operations);
+	if (!ret) {
+		struct seq_file *seq = filp->private_data;
+		struct rpc_clnt *clnt = seq->private = inode->i_private;
+
+		if (!refcount_inc_not_zero(&clnt->cl_count)) {
+			seq_release(inode, filp);
+			ret = -EINVAL;
+		}
+	}
+
+	return ret;
+}
+
+static int
+tasks_release(struct inode *inode, struct file *filp)
+{
+	struct seq_file *seq = filp->private_data;
+	struct rpc_clnt *clnt = seq->private;
+
+	rpc_release_client(clnt);
+	return seq_release(inode, filp);
+}
+
+static const struct file_operations tasks_fops = {
+	.owner		= THIS_MODULE,
+	.open		= tasks_open,
+	.read		= seq_read,
+	.llseek		= seq_lseek,
+	.release	= tasks_release,
+};
+
+static int do_xprt_debugfs(struct rpc_clnt *clnt, struct rpc_xprt *xprt, void *numv)
+{
+	int len;
+	char name[24]; /* enough for "../../rpc_xprt/ + 8 hex digits + NULL */
+	char link[9]; /* enough for 8 hex digits + NULL */
+	int *nump = numv;
+
+	if (IS_ERR_OR_NULL(xprt->debugfs))
+		return 0;
+	len = snprintf(name, sizeof(name), "../../rpc_xprt/%s",
+		       xprt->debugfs->d_name.name);
+	if (len >= sizeof(name))
+		return -1;
+	if (*nump == 0)
+		strcpy(link, "xprt");
+	else {
+		len = snprintf(link, sizeof(link), "xprt%d", *nump);
+		if (len >= sizeof(link))
+			return -1;
+	}
+	debugfs_create_symlink(link, clnt->cl_debugfs, name);
+	(*nump)++;
+	return 0;
+}
+
+void
+rpc_clnt_debugfs_register(struct rpc_clnt *clnt)
+{
+	int len;
+	char name[9]; /* enough for 8 hex digits + NULL */
+	int xprtnum = 0;
+
+	len = snprintf(name, sizeof(name), "%x", clnt->cl_clid);
+	if (len >= sizeof(name))
+		return;
+
+	/* make the per-client dir */
+	clnt->cl_debugfs = debugfs_create_dir(name, rpc_clnt_dir);
+
+	/* make tasks file */
+	debugfs_create_file("tasks", S_IFREG | 0400, clnt->cl_debugfs, clnt,
+			    &tasks_fops);
+
+	rpc_clnt_iterate_for_each_xprt(clnt, do_xprt_debugfs, &xprtnum);
+}
+
+void
+rpc_clnt_debugfs_unregister(struct rpc_clnt *clnt)
+{
+	debugfs_remove_recursive(clnt->cl_debugfs);
+	clnt->cl_debugfs = NULL;
+}
+
+static int
+xprt_info_show(struct seq_file *f, void *v)
+{
+	struct rpc_xprt *xprt = f->private;
+
+	seq_printf(f, "netid: %s\n", xprt->address_strings[RPC_DISPLAY_NETID]);
+	seq_printf(f, "addr:  %s\n", xprt->address_strings[RPC_DISPLAY_ADDR]);
+	seq_printf(f, "port:  %s\n", xprt->address_strings[RPC_DISPLAY_PORT]);
+	seq_printf(f, "state: 0x%lx\n", xprt->state);
+	seq_printf(f, "netns: %u\n", xprt->xprt_net->ns.inum);
+
+	if (xprt->ops->get_srcaddr) {
+		int ret, buflen;
+		char buf[INET6_ADDRSTRLEN];
+
+		buflen = ARRAY_SIZE(buf);
+		ret = xprt->ops->get_srcaddr(xprt, buf, buflen);
+		if (ret < 0)
+			ret = sprintf(buf, "<closed>");
+		seq_printf(f, "saddr: %.*s\n", ret, buf);
+	}
+	return 0;
+}
+
+static int
+xprt_info_open(struct inode *inode, struct file *filp)
+{
+	int ret;
+	struct rpc_xprt *xprt = inode->i_private;
+
+	ret = single_open(filp, xprt_info_show, xprt);
+
+	if (!ret) {
+		if (!xprt_get(xprt)) {
+			single_release(inode, filp);
+			ret = -EINVAL;
+		}
+	}
+	return ret;
+}
+
+static int
+xprt_info_release(struct inode *inode, struct file *filp)
+{
+	struct rpc_xprt *xprt = inode->i_private;
+
+	xprt_put(xprt);
+	return single_release(inode, filp);
+}
+
+static const struct file_operations xprt_info_fops = {
+	.owner		= THIS_MODULE,
+	.open		= xprt_info_open,
+	.read		= seq_read,
+	.llseek		= seq_lseek,
+	.release	= xprt_info_release,
+};
+
+void
+rpc_xprt_debugfs_register(struct rpc_xprt *xprt)
+{
+	int len, id;
+	static atomic_t	cur_id;
+	char		name[9]; /* 8 hex digits + NULL term */
+
+	id = (unsigned int)atomic_inc_return(&cur_id);
+
+	len = snprintf(name, sizeof(name), "%x", id);
+	if (len >= sizeof(name))
+		return;
+
+	/* make the per-client dir */
+	xprt->debugfs = debugfs_create_dir(name, rpc_xprt_dir);
+
+	/* make tasks file */
+	debugfs_create_file("info", S_IFREG | 0400, xprt->debugfs, xprt,
+			    &xprt_info_fops);
+}
+
+void
+rpc_xprt_debugfs_unregister(struct rpc_xprt *xprt)
+{
+	debugfs_remove_recursive(xprt->debugfs);
+	xprt->debugfs = NULL;
+}
+
+#if IS_ENABLED(CONFIG_FAIL_SUNRPC)
+struct fail_sunrpc_attr fail_sunrpc = {
+	.attr			= FAULT_ATTR_INITIALIZER,
+};
+EXPORT_SYMBOL_GPL(fail_sunrpc);
+
+static void fail_sunrpc_init(void)
+{
+	struct dentry *dir;
+
+	dir = fault_create_debugfs_attr("fail_sunrpc", NULL,
+					&fail_sunrpc.attr);
+
+	debugfs_create_bool("ignore-client-disconnect", S_IFREG | 0600, dir,
+			    &fail_sunrpc.ignore_client_disconnect);
+
+	debugfs_create_bool("ignore-server-disconnect", S_IFREG | 0600, dir,
+			    &fail_sunrpc.ignore_server_disconnect);
+
+	debugfs_create_bool("ignore-cache-wait", S_IFREG | 0600, dir,
+			    &fail_sunrpc.ignore_cache_wait);
+}
+#else
+static void fail_sunrpc_init(void)
+{
+}
+#endif
+
+void __exit
+sunrpc_debugfs_exit(void)
+{
+	debugfs_remove_recursive(topdir);
+	topdir = NULL;
+	rpc_clnt_dir = NULL;
+	rpc_xprt_dir = NULL;
+}
+
+void __init
+sunrpc_debugfs_init(void)
+{
+	topdir = debugfs_create_dir("sunrpc", NULL);
+
+	rpc_clnt_dir = debugfs_create_dir("rpc_clnt", topdir);
+
+	rpc_xprt_dir = debugfs_create_dir("rpc_xprt", topdir);
+
+	fail_sunrpc_init();
+}