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, 385 insertions, 0 deletions

diff --git a/scripts/dtc/dtc.c b/scripts/dtc/dtc.c
new file mode 100644
index 000000000..6dae60de0
--- /dev/null
+++ b/scripts/dtc/dtc.c
@@ -0,0 +1,385 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * (C) Copyright David Gibson <dwg@au1.ibm.com>, IBM Corporation.  2005.
+ */
+
+#include <sys/stat.h>
+
+#include "dtc.h"
+#include "srcpos.h"
+
+/*
+ * Command line options
+ */
+int quiet;		/* Level of quietness */
+unsigned int reservenum;/* Number of memory reservation slots */
+int minsize;		/* Minimum blob size */
+int padsize;		/* Additional padding to blob */
+int alignsize;		/* Additional padding to blob according to the alignsize */
+int phandle_format = PHANDLE_EPAPR;	/* Use linux,phandle or phandle properties */
+int generate_symbols;	/* enable symbols & fixup support */
+int generate_fixups;		/* suppress generation of fixups on symbol support */
+int auto_label_aliases;		/* auto generate labels -> aliases */
+int annotate;		/* Level of annotation: 1 for input source location
+			   >1 for full input source location. */
+
+static int is_power_of_2(int x)
+{
+	return (x > 0) && ((x & (x - 1)) == 0);
+}
+
+static void fill_fullpaths(struct node *tree, const char *prefix)
+{
+	struct node *child;
+	const char *unit;
+
+	tree->fullpath = join_path(prefix, tree->name);
+
+	unit = strchr(tree->name, '@');
+	if (unit)
+		tree->basenamelen = unit - tree->name;
+	else
+		tree->basenamelen = strlen(tree->name);
+
+	for_each_child(tree, child)
+		fill_fullpaths(child, tree->fullpath);
+}
+
+/* Usage related data. */
+static const char usage_synopsis[] = "dtc [options] <input file>";
+static const char usage_short_opts[] = "qI:O:o:V:d:R:S:p:a:fb:i:H:sW:E:@LAThv";
+static struct option const usage_long_opts[] = {
+	{"quiet",            no_argument, NULL, 'q'},
+	{"in-format",         a_argument, NULL, 'I'},
+	{"out",               a_argument, NULL, 'o'},
+	{"out-format",        a_argument, NULL, 'O'},
+	{"out-version",       a_argument, NULL, 'V'},
+	{"out-dependency",    a_argument, NULL, 'd'},
+	{"reserve",           a_argument, NULL, 'R'},
+	{"space",             a_argument, NULL, 'S'},
+	{"pad",               a_argument, NULL, 'p'},
+	{"align",             a_argument, NULL, 'a'},
+	{"boot-cpu",          a_argument, NULL, 'b'},
+	{"force",            no_argument, NULL, 'f'},
+	{"include",           a_argument, NULL, 'i'},
+	{"sort",             no_argument, NULL, 's'},
+	{"phandle",           a_argument, NULL, 'H'},
+	{"warning",           a_argument, NULL, 'W'},
+	{"error",             a_argument, NULL, 'E'},
+	{"symbols",	     no_argument, NULL, '@'},
+	{"local-fixups",     no_argument, NULL, 'L'},
+	{"auto-alias",       no_argument, NULL, 'A'},
+	{"annotate",         no_argument, NULL, 'T'},
+	{"help",             no_argument, NULL, 'h'},
+	{"version",          no_argument, NULL, 'v'},
+	{NULL,               no_argument, NULL, 0x0},
+};
+static const char * const usage_opts_help[] = {
+	"\n\tQuiet: -q suppress warnings, -qq errors, -qqq all",
+	"\n\tInput formats are:\n"
+	 "\t\tdts - device tree source text\n"
+	 "\t\tdtb - device tree blob\n"
+	 "\t\tfs  - /proc/device-tree style directory",
+	"\n\tOutput file",
+	"\n\tOutput formats are:\n"
+	 "\t\tdts - device tree source text\n"
+	 "\t\tdtb - device tree blob\n"
+#ifndef NO_YAML
+	 "\t\tyaml - device tree encoded as YAML\n"
+#endif
+	 "\t\tasm - assembler source",
+	"\n\tBlob version to produce, defaults to "stringify(DEFAULT_FDT_VERSION)" (for dtb and asm output)",
+	"\n\tOutput dependency file",
+	"\n\tMake space for <number> reserve map entries (for dtb and asm output)",
+	"\n\tMake the blob at least <bytes> long (extra space)",
+	"\n\tAdd padding to the blob of <bytes> long (extra space)",
+	"\n\tMake the blob align to the <bytes> (extra space)",
+	"\n\tSet the physical boot cpu",
+	"\n\tTry to produce output even if the input tree has errors",
+	"\n\tAdd a path to search for include files",
+	"\n\tSort nodes and properties before outputting (useful for comparing trees)",
+	"\n\tValid phandle formats are:\n"
+	 "\t\tlegacy - \"linux,phandle\" properties only\n"
+	 "\t\tepapr  - \"phandle\" properties only\n"
+	 "\t\tboth   - Both \"linux,phandle\" and \"phandle\" properties",
+	"\n\tEnable/disable warnings (prefix with \"no-\")",
+	"\n\tEnable/disable errors (prefix with \"no-\")",
+	"\n\tEnable generation of symbols",
+	"\n\tPossibly generates a __local_fixups__ and a __fixups__ node at the root node",
+	"\n\tEnable auto-alias of labels",
+	"\n\tAnnotate output .dts with input source file and line (-T -T for more details)",
+	"\n\tPrint this help and exit",
+	"\n\tPrint version and exit",
+	NULL,
+};
+
+static const char *guess_type_by_name(const char *fname, const char *fallback)
+{
+	const char *s;
+
+	s = strrchr(fname, '.');
+	if (s == NULL)
+		return fallback;
+	if (!strcasecmp(s, ".dts"))
+		return "dts";
+	if (!strcasecmp(s, ".yaml"))
+		return "yaml";
+	if (!strcasecmp(s, ".dtbo"))
+		return "dtb";
+	if (!strcasecmp(s, ".dtb"))
+		return "dtb";
+	return fallback;
+}
+
+static const char *guess_input_format(const char *fname, const char *fallback)
+{
+	struct stat statbuf;
+	fdt32_t magic;
+	FILE *f;
+
+	if (stat(fname, &statbuf) != 0)
+		return fallback;
+
+	if (S_ISDIR(statbuf.st_mode))
+		return "fs";
+
+	if (!S_ISREG(statbuf.st_mode))
+		return fallback;
+
+	f = fopen(fname, "r");
+	if (f == NULL)
+		return fallback;
+	if (fread(&magic, 4, 1, f) != 1) {
+		fclose(f);
+		return fallback;
+	}
+	fclose(f);
+
+	if (fdt32_to_cpu(magic) == FDT_MAGIC)
+		return "dtb";
+
+	return guess_type_by_name(fname, fallback);
+}
+
+int main(int argc, char *argv[])
+{
+	struct dt_info *dti;
+	const char *inform = NULL;
+	const char *outform = NULL;
+	const char *outname = "-";
+	const char *depname = NULL;
+	bool force = false, sort = false;
+	const char *arg;
+	int opt;
+	FILE *outf = NULL;
+	int outversion = DEFAULT_FDT_VERSION;
+	long long cmdline_boot_cpuid = -1;
+
+	quiet      = 0;
+	reservenum = 0;
+	minsize    = 0;
+	padsize    = 0;
+	alignsize  = 0;
+
+	while ((opt = util_getopt_long()) != EOF) {
+		switch (opt) {
+		case 'I':
+			inform = optarg;
+			break;
+		case 'O':
+			outform = optarg;
+			break;
+		case 'o':
+			outname = optarg;
+			break;
+		case 'V':
+			outversion = strtol(optarg, NULL, 0);
+			break;
+		case 'd':
+			depname = optarg;
+			break;
+		case 'R':
+			reservenum = strtoul(optarg, NULL, 0);
+			break;
+		case 'S':
+			minsize = strtol(optarg, NULL, 0);
+			break;
+		case 'p':
+			padsize = strtol(optarg, NULL, 0);
+			break;
+		case 'a':
+			alignsize = strtol(optarg, NULL, 0);
+			if (!is_power_of_2(alignsize))
+				die("Invalid argument \"%d\" to -a option\n",
+				    alignsize);
+			break;
+		case 'f':
+			force = true;
+			break;
+		case 'q':
+			quiet++;
+			break;
+		case 'b':
+			cmdline_boot_cpuid = strtoll(optarg, NULL, 0);
+			break;
+		case 'i':
+			srcfile_add_search_path(optarg);
+			break;
+		case 'v':
+			util_version();
+		case 'H':
+			if (streq(optarg, "legacy"))
+				phandle_format = PHANDLE_LEGACY;
+			else if (streq(optarg, "epapr"))
+				phandle_format = PHANDLE_EPAPR;
+			else if (streq(optarg, "both"))
+				phandle_format = PHANDLE_BOTH;
+			else
+				die("Invalid argument \"%s\" to -H option\n",
+				    optarg);
+			break;
+
+		case 's':
+			sort = true;
+			break;
+
+		case 'W':
+			parse_checks_option(true, false, optarg);
+			break;
+
+		case 'E':
+			parse_checks_option(false, true, optarg);
+			break;
+
+		case '@':
+			generate_symbols = 1;
+			break;
+
+		case 'L':
+			generate_fixups = 1;
+			break;
+
+		case 'A':
+			auto_label_aliases = 1;
+			break;
+		case 'T':
+			annotate++;
+			break;
+
+		case 'h':
+			usage(NULL);
+		default:
+			usage("unknown option");
+		}
+	}
+
+	if (argc > (optind+1))
+		usage("missing files");
+	else if (argc < (optind+1))
+		arg = "-";
+	else
+		arg = argv[optind];
+
+	/* minsize and padsize are mutually exclusive */
+	if (minsize && padsize)
+		die("Can't set both -p and -S\n");
+
+	if (depname) {
+		depfile = fopen(depname, "w");
+		if (!depfile)
+			die("Couldn't open dependency file %s: %s\n", depname,
+			    strerror(errno));
+
+		fprint_path_escaped(depfile, outname);
+		fputc(':', depfile);
+	}
+
+	if (inform == NULL)
+		inform = guess_input_format(arg, "dts");
+	if (outform == NULL) {
+		outform = guess_type_by_name(outname, NULL);
+		if (outform == NULL) {
+			if (streq(inform, "dts"))
+				outform = "dtb";
+			else
+				outform = "dts";
+		}
+	}
+	if (annotate && (!streq(inform, "dts") || !streq(outform, "dts")))
+		die("--annotate requires -I dts -O dts\n");
+	if (streq(inform, "dts"))
+		dti = dt_from_source(arg);
+	else if (streq(inform, "fs"))
+		dti = dt_from_fs(arg);
+	else if(streq(inform, "dtb"))
+		dti = dt_from_blob(arg);
+	else
+		die("Unknown input format \"%s\"\n", inform);
+
+	dti->outname = outname;
+
+	if (depfile) {
+		fputc('\n', depfile);
+		fclose(depfile);
+	}
+
+	if (cmdline_boot_cpuid != -1)
+		dti->boot_cpuid_phys = cmdline_boot_cpuid;
+
+	fill_fullpaths(dti->dt, "");
+
+	/* on a plugin, generate by default */
+	if (dti->dtsflags & DTSF_PLUGIN) {
+		generate_fixups = 1;
+	}
+
+	process_checks(force, dti);
+
+	if (auto_label_aliases)
+		generate_label_tree(dti, "aliases", false);
+
+	generate_labels_from_tree(dti, "__symbols__");
+
+	if (generate_symbols)
+		generate_label_tree(dti, "__symbols__", true);
+
+	fixup_phandles(dti, "__fixups__");
+	local_fixup_phandles(dti, "__local_fixups__");
+
+	if (generate_fixups) {
+		generate_fixups_tree(dti, "__fixups__");
+		generate_local_fixups_tree(dti, "__local_fixups__");
+	}
+
+	if (sort)
+		sort_tree(dti);
+
+	if (streq(outname, "-")) {
+		outf = stdout;
+	} else {
+		outf = fopen(outname, "wb");
+		if (! outf)
+			die("Couldn't open output file %s: %s\n",
+			    outname, strerror(errno));
+	}
+
+	if (streq(outform, "dts")) {
+		dt_to_source(outf, dti);
+#ifndef NO_YAML
+	} else if (streq(outform, "yaml")) {
+		if (!streq(inform, "dts"))
+			die("YAML output format requires dts input format\n");
+		dt_to_yaml(outf, dti);
+#endif
+	} else if (streq(outform, "dtb")) {
+		dt_to_blob(outf, dti, outversion);
+	} else if (streq(outform, "asm")) {
+		dt_to_asm(outf, dti, outversion);
+	} else if (streq(outform, "null")) {
+		/* do nothing */
+	} else {
+		die("Unknown output format \"%s\"\n", outform);
+	}
+
+	exit(0);
+}