From 93de2a6a4b91b72607136dd656edf03fb399d27f Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Wed, 23 Sep 2026 09:37:21 -0700 Subject: KVM: SEV: Do cache maintenance on the source VM during intra-host migration 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 Signed-off-by: Sean Christopherson Message-ID: <20260923163721.1584779-3-seanjc@google.com> Signed-off-by: Paolo Bonzini --- scripts/insert-sys-cert.c | 410 ++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 410 insertions(+) create mode 100644 scripts/insert-sys-cert.c (limited to 'scripts/insert-sys-cert.c') diff --git a/scripts/insert-sys-cert.c b/scripts/insert-sys-cert.c new file mode 100644 index 000000000..8902836c2 --- /dev/null +++ b/scripts/insert-sys-cert.c @@ -0,0 +1,410 @@ +/* Write the contents of the into kernel symbol system_extra_cert + * + * Copyright (C) IBM Corporation, 2015 + * + * Author: Mehmet Kayaalp + * + * This software may be used and distributed according to the terms + * of the GNU General Public License, incorporated herein by reference. + * + * Usage: insert-sys-cert [-s -b -c + */ + +#define _GNU_SOURCE +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#define CERT_SYM "system_extra_cert" +#define USED_SYM "system_extra_cert_used" +#define LSIZE_SYM "system_certificate_list_size" + +#define info(format, args...) fprintf(stderr, "INFO: " format, ## args) +#define warn(format, args...) fprintf(stdout, "WARNING: " format, ## args) +#define err(format, args...) fprintf(stderr, "ERROR: " format, ## args) + +#if UINTPTR_MAX == 0xffffffff +#define CURRENT_ELFCLASS ELFCLASS32 +#define Elf_Ehdr Elf32_Ehdr +#define Elf_Shdr Elf32_Shdr +#define Elf_Sym Elf32_Sym +#else +#define CURRENT_ELFCLASS ELFCLASS64 +#define Elf_Ehdr Elf64_Ehdr +#define Elf_Shdr Elf64_Shdr +#define Elf_Sym Elf64_Sym +#endif + +static unsigned char endianness(void) +{ + uint16_t two_byte = 0x00FF; + uint8_t low_address = *((uint8_t *)&two_byte); + + if (low_address == 0) + return ELFDATA2MSB; + else + return ELFDATA2LSB; +} + +struct sym { + char *name; + unsigned long address; + unsigned long offset; + void *content; + int size; +}; + +static unsigned long get_offset_from_address(Elf_Ehdr *hdr, unsigned long addr) +{ + Elf_Shdr *x; + unsigned int i, num_sections; + + x = (void *)hdr + hdr->e_shoff; + if (hdr->e_shnum == SHN_UNDEF) + num_sections = x[0].sh_size; + else + num_sections = hdr->e_shnum; + + for (i = 1; i < num_sections; i++) { + unsigned long start = x[i].sh_addr; + unsigned long end = start + x[i].sh_size; + unsigned long offset = x[i].sh_offset; + + if (addr >= start && addr <= end) + return addr - start + offset; + } + return 0; +} + + +#define LINE_SIZE 100 + +static void get_symbol_from_map(Elf_Ehdr *hdr, FILE *f, char *name, + struct sym *s) +{ + char l[LINE_SIZE]; + char *w, *p, *n; + + s->size = 0; + s->address = 0; + s->offset = 0; + if (fseek(f, 0, SEEK_SET) != 0) { + perror("File seek failed"); + exit(EXIT_FAILURE); + } + while (fgets(l, LINE_SIZE, f)) { + p = strchr(l, '\n'); + if (!p) { + err("Missing line ending.\n"); + return; + } + n = strstr(l, name); + if (n) + break; + } + if (!n) { + err("Unable to find symbol: %s\n", name); + return; + } + w = strchr(l, ' '); + if (!w) + return; + + *w = '\0'; + s->address = strtoul(l, NULL, 16); + if (s->address == 0) + return; + s->offset = get_offset_from_address(hdr, s->address); + s->name = name; + s->content = (void *)hdr + s->offset; +} + +static Elf_Sym *find_elf_symbol(Elf_Ehdr *hdr, Elf_Shdr *symtab, char *name) +{ + Elf_Sym *sym, *symtab_start; + char *strtab, *symname; + unsigned int link; + Elf_Shdr *x; + int i, n; + + x = (void *)hdr + hdr->e_shoff; + link = symtab->sh_link; + symtab_start = (void *)hdr + symtab->sh_offset; + n = symtab->sh_size / symtab->sh_entsize; + strtab = (void *)hdr + x[link].sh_offset; + + for (i = 0; i < n; i++) { + sym = &symtab_start[i]; + symname = strtab + sym->st_name; + if (strcmp(symname, name) == 0) + return sym; + } + err("Unable to find symbol: %s\n", name); + return NULL; +} + +static void get_symbol_from_table(Elf_Ehdr *hdr, Elf_Shdr *symtab, + char *name, struct sym *s) +{ + Elf_Shdr *sec; + int secndx; + Elf_Sym *elf_sym; + Elf_Shdr *x; + + x = (void *)hdr + hdr->e_shoff; + s->size = 0; + s->address = 0; + s->offset = 0; + elf_sym = find_elf_symbol(hdr, symtab, name); + if (!elf_sym) + return; + secndx = elf_sym->st_shndx; + if (!secndx) + return; + sec = &x[secndx]; + s->size = elf_sym->st_size; + s->address = elf_sym->st_value; + s->offset = s->address - sec->sh_addr + + sec->sh_offset; + s->name = name; + s->content = (void *)hdr + s->offset; +} + +static Elf_Shdr *get_symbol_table(Elf_Ehdr *hdr) +{ + Elf_Shdr *x; + unsigned int i, num_sections; + + x = (void *)hdr + hdr->e_shoff; + if (hdr->e_shnum == SHN_UNDEF) + num_sections = x[0].sh_size; + else + num_sections = hdr->e_shnum; + + for (i = 1; i < num_sections; i++) + if (x[i].sh_type == SHT_SYMTAB) + return &x[i]; + return NULL; +} + +static void *map_file(char *file_name, int *size) +{ + struct stat st; + void *map; + int fd; + + fd = open(file_name, O_RDWR); + if (fd < 0) { + perror(file_name); + return NULL; + } + if (fstat(fd, &st)) { + perror("Could not determine file size"); + close(fd); + return NULL; + } + *size = st.st_size; + map = mmap(NULL, *size, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0); + if (map == MAP_FAILED) { + perror("Mapping to memory failed"); + close(fd); + return NULL; + } + close(fd); + return map; +} + +static char *read_file(char *file_name, int *size) +{ + struct stat st; + char *buf; + int fd; + + fd = open(file_name, O_RDONLY); + if (fd < 0) { + perror(file_name); + return NULL; + } + if (fstat(fd, &st)) { + perror("Could not determine file size"); + close(fd); + return NULL; + } + *size = st.st_size; + buf = malloc(*size); + if (!buf) { + perror("Allocating memory failed"); + close(fd); + return NULL; + } + if (read(fd, buf, *size) != *size) { + perror("File read failed"); + close(fd); + return NULL; + } + close(fd); + return buf; +} + +static void print_sym(Elf_Ehdr *hdr, struct sym *s) +{ + info("sym: %s\n", s->name); + info("addr: 0x%lx\n", s->address); + info("size: %d\n", s->size); + info("offset: 0x%lx\n", (unsigned long)s->offset); +} + +static void print_usage(char *e) +{ + printf("Usage %s [-s ] -b -c \n", e); +} + +int main(int argc, char **argv) +{ + char *system_map_file = NULL; + char *vmlinux_file = NULL; + char *cert_file = NULL; + int vmlinux_size; + int cert_size; + Elf_Ehdr *hdr; + char *cert; + FILE *system_map; + unsigned long *lsize; + int *used; + int opt; + Elf_Shdr *symtab = NULL; + struct sym cert_sym, lsize_sym, used_sym; + + while ((opt = getopt(argc, argv, "b:c:s:")) != -1) { + switch (opt) { + case 's': + system_map_file = optarg; + break; + case 'b': + vmlinux_file = optarg; + break; + case 'c': + cert_file = optarg; + break; + default: + break; + } + } + + if (!vmlinux_file || !cert_file) { + print_usage(argv[0]); + exit(EXIT_FAILURE); + } + + cert = read_file(cert_file, &cert_size); + if (!cert) + exit(EXIT_FAILURE); + + hdr = map_file(vmlinux_file, &vmlinux_size); + if (!hdr) + exit(EXIT_FAILURE); + + if (vmlinux_size < sizeof(*hdr)) { + err("Invalid ELF file.\n"); + exit(EXIT_FAILURE); + } + + if ((hdr->e_ident[EI_MAG0] != ELFMAG0) || + (hdr->e_ident[EI_MAG1] != ELFMAG1) || + (hdr->e_ident[EI_MAG2] != ELFMAG2) || + (hdr->e_ident[EI_MAG3] != ELFMAG3)) { + err("Invalid ELF magic.\n"); + exit(EXIT_FAILURE); + } + + if (hdr->e_ident[EI_CLASS] != CURRENT_ELFCLASS) { + err("ELF class mismatch.\n"); + exit(EXIT_FAILURE); + } + + if (hdr->e_ident[EI_DATA] != endianness()) { + err("ELF endian mismatch.\n"); + exit(EXIT_FAILURE); + } + + if (hdr->e_shoff > vmlinux_size) { + err("Could not find section header.\n"); + exit(EXIT_FAILURE); + } + + symtab = get_symbol_table(hdr); + if (!symtab) { + warn("Could not find the symbol table.\n"); + if (!system_map_file) { + err("Please provide a System.map file.\n"); + print_usage(argv[0]); + exit(EXIT_FAILURE); + } + + system_map = fopen(system_map_file, "r"); + if (!system_map) { + perror(system_map_file); + exit(EXIT_FAILURE); + } + get_symbol_from_map(hdr, system_map, CERT_SYM, &cert_sym); + get_symbol_from_map(hdr, system_map, USED_SYM, &used_sym); + get_symbol_from_map(hdr, system_map, LSIZE_SYM, &lsize_sym); + cert_sym.size = used_sym.address - cert_sym.address; + } else { + info("Symbol table found.\n"); + if (system_map_file) + warn("System.map is ignored.\n"); + get_symbol_from_table(hdr, symtab, CERT_SYM, &cert_sym); + get_symbol_from_table(hdr, symtab, USED_SYM, &used_sym); + get_symbol_from_table(hdr, symtab, LSIZE_SYM, &lsize_sym); + } + + if (!cert_sym.offset || !lsize_sym.offset || !used_sym.offset) + exit(EXIT_FAILURE); + + print_sym(hdr, &cert_sym); + print_sym(hdr, &used_sym); + print_sym(hdr, &lsize_sym); + + lsize = (unsigned long *)lsize_sym.content; + used = (int *)used_sym.content; + + if (cert_sym.size < cert_size) { + err("Certificate is larger than the reserved area!\n"); + exit(EXIT_FAILURE); + } + + /* If the existing cert is the same, don't overwrite */ + if (cert_size == *used && + strncmp(cert_sym.content, cert, cert_size) == 0) { + warn("Certificate was already inserted.\n"); + exit(EXIT_SUCCESS); + } + + if (*used > 0) + warn("Replacing previously inserted certificate.\n"); + + memcpy(cert_sym.content, cert, cert_size); + if (cert_size < cert_sym.size) + memset(cert_sym.content + cert_size, + 0, cert_sym.size - cert_size); + + *lsize = *lsize + cert_size - *used; + *used = cert_size; + info("Inserted the contents of %s into %lx.\n", cert_file, + cert_sym.address); + info("Used %d bytes out of %d bytes reserved.\n", *used, + cert_sym.size); + exit(EXIT_SUCCESS); +} -- cgit v1.3.1