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 --- tools/testing/selftests/ia64/.gitignore | 2 + tools/testing/selftests/ia64/Makefile | 9 + tools/testing/selftests/ia64/aliasing-test.c | 260 +++++++++++++++++++++++++++ 3 files changed, 271 insertions(+) create mode 100644 tools/testing/selftests/ia64/.gitignore create mode 100644 tools/testing/selftests/ia64/Makefile create mode 100644 tools/testing/selftests/ia64/aliasing-test.c (limited to 'tools/testing/selftests/ia64') diff --git a/tools/testing/selftests/ia64/.gitignore b/tools/testing/selftests/ia64/.gitignore new file mode 100644 index 000000000..e962fb2a0 --- /dev/null +++ b/tools/testing/selftests/ia64/.gitignore @@ -0,0 +1,2 @@ +# SPDX-License-Identifier: GPL-2.0-only +aliasing-test diff --git a/tools/testing/selftests/ia64/Makefile b/tools/testing/selftests/ia64/Makefile new file mode 100644 index 000000000..4bce1a84b --- /dev/null +++ b/tools/testing/selftests/ia64/Makefile @@ -0,0 +1,9 @@ +# SPDX-License-Identifier: GPL-2.0 +TEST_PROGS := aliasing-test + +all: $(TEST_PROGS) + +include ../lib.mk + +clean: + rm -fr $(TEST_PROGS) diff --git a/tools/testing/selftests/ia64/aliasing-test.c b/tools/testing/selftests/ia64/aliasing-test.c new file mode 100644 index 000000000..1ad6896f1 --- /dev/null +++ b/tools/testing/selftests/ia64/aliasing-test.c @@ -0,0 +1,260 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * Exercise /dev/mem mmap cases that have been troublesome in the past + * + * (c) Copyright 2007 Hewlett-Packard Development Company, L.P. + * Bjorn Helgaas + */ + +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +int sum; + +static int map_mem(char *path, off_t offset, size_t length, int touch) +{ + int fd, rc; + void *addr; + int *c; + + fd = open(path, O_RDWR); + if (fd == -1) { + perror(path); + return -1; + } + + if (fnmatch("/proc/bus/pci/*", path, 0) == 0) { + rc = ioctl(fd, PCIIOC_MMAP_IS_MEM); + if (rc == -1) + perror("PCIIOC_MMAP_IS_MEM ioctl"); + } + + addr = mmap(NULL, length, PROT_READ|PROT_WRITE, MAP_SHARED, fd, offset); + if (addr == MAP_FAILED) + return 1; + + if (touch) { + c = (int *) addr; + while (c < (int *) (addr + length)) + sum += *c++; + } + + rc = munmap(addr, length); + if (rc == -1) { + perror("munmap"); + return -1; + } + + close(fd); + return 0; +} + +static int scan_tree(char *path, char *file, off_t offset, size_t length, int touch) +{ + struct dirent **namelist; + char *name, *path2; + int i, n, r, rc = 0, result = 0; + struct stat buf; + + n = scandir(path, &namelist, 0, alphasort); + if (n < 0) { + perror("scandir"); + return -1; + } + + for (i = 0; i < n; i++) { + name = namelist[i]->d_name; + + if (fnmatch(".", name, 0) == 0) + goto skip; + if (fnmatch("..", name, 0) == 0) + goto skip; + + path2 = malloc(strlen(path) + strlen(name) + 3); + strcpy(path2, path); + strcat(path2, "/"); + strcat(path2, name); + + if (fnmatch(file, name, 0) == 0) { + rc = map_mem(path2, offset, length, touch); + if (rc == 0) + fprintf(stderr, "PASS: %s 0x%lx-0x%lx is %s\n", path2, offset, offset + length, touch ? "readable" : "mappable"); + else if (rc > 0) + fprintf(stderr, "PASS: %s 0x%lx-0x%lx not mappable\n", path2, offset, offset + length); + else { + fprintf(stderr, "FAIL: %s 0x%lx-0x%lx not accessible\n", path2, offset, offset + length); + return rc; + } + } else { + r = lstat(path2, &buf); + if (r == 0 && S_ISDIR(buf.st_mode)) { + rc = scan_tree(path2, file, offset, length, touch); + if (rc < 0) + return rc; + } + } + + result |= rc; + free(path2); + +skip: + free(namelist[i]); + } + free(namelist); + return result; +} + +char buf[1024]; + +static int read_rom(char *path) +{ + int fd, rc; + size_t size = 0; + + fd = open(path, O_RDWR); + if (fd == -1) { + perror(path); + return -1; + } + + rc = write(fd, "1", 2); + if (rc <= 0) { + close(fd); + perror("write"); + return -1; + } + + do { + rc = read(fd, buf, sizeof(buf)); + if (rc > 0) + size += rc; + } while (rc > 0); + + close(fd); + return size; +} + +static int scan_rom(char *path, char *file) +{ + struct dirent **namelist; + char *name, *path2; + int i, n, r, rc = 0, result = 0; + struct stat buf; + + n = scandir(path, &namelist, 0, alphasort); + if (n < 0) { + perror("scandir"); + return -1; + } + + for (i = 0; i < n; i++) { + name = namelist[i]->d_name; + + if (fnmatch(".", name, 0) == 0) + goto skip; + if (fnmatch("..", name, 0) == 0) + goto skip; + + path2 = malloc(strlen(path) + strlen(name) + 3); + strcpy(path2, path); + strcat(path2, "/"); + strcat(path2, name); + + if (fnmatch(file, name, 0) == 0) { + rc = read_rom(path2); + + /* + * It's OK if the ROM is unreadable. Maybe there + * is no ROM, or some other error occurred. The + * important thing is that no MCA happened. + */ + if (rc > 0) + fprintf(stderr, "PASS: %s read %d bytes\n", path2, rc); + else { + fprintf(stderr, "PASS: %s not readable\n", path2); + return rc; + } + } else { + r = lstat(path2, &buf); + if (r == 0 && S_ISDIR(buf.st_mode)) { + rc = scan_rom(path2, file); + if (rc < 0) + return rc; + } + } + + result |= rc; + free(path2); + +skip: + free(namelist[i]); + } + free(namelist); + return result; +} + +int main(void) +{ + int rc; + + if (map_mem("/dev/mem", 0, 0xA0000, 1) == 0) + fprintf(stderr, "PASS: /dev/mem 0x0-0xa0000 is readable\n"); + else + fprintf(stderr, "FAIL: /dev/mem 0x0-0xa0000 not accessible\n"); + + /* + * It's not safe to blindly read the VGA frame buffer. If you know + * how to poke the card the right way, it should respond, but it's + * not safe in general. Many machines, e.g., Intel chipsets, cover + * up a non-responding card by just returning -1, but others will + * report the failure as a machine check. + */ + if (map_mem("/dev/mem", 0xA0000, 0x20000, 0) == 0) + fprintf(stderr, "PASS: /dev/mem 0xa0000-0xc0000 is mappable\n"); + else + fprintf(stderr, "FAIL: /dev/mem 0xa0000-0xc0000 not accessible\n"); + + if (map_mem("/dev/mem", 0xC0000, 0x40000, 1) == 0) + fprintf(stderr, "PASS: /dev/mem 0xc0000-0x100000 is readable\n"); + else + fprintf(stderr, "FAIL: /dev/mem 0xc0000-0x100000 not accessible\n"); + + /* + * Often you can map all the individual pieces above (0-0xA0000, + * 0xA0000-0xC0000, and 0xC0000-0x100000), but can't map the whole + * thing at once. This is because the individual pieces use different + * attributes, and there's no single attribute supported over the + * whole region. + */ + rc = map_mem("/dev/mem", 0, 1024*1024, 0); + if (rc == 0) + fprintf(stderr, "PASS: /dev/mem 0x0-0x100000 is mappable\n"); + else if (rc > 0) + fprintf(stderr, "PASS: /dev/mem 0x0-0x100000 not mappable\n"); + else + fprintf(stderr, "FAIL: /dev/mem 0x0-0x100000 not accessible\n"); + + scan_tree("/sys/class/pci_bus", "legacy_mem", 0, 0xA0000, 1); + scan_tree("/sys/class/pci_bus", "legacy_mem", 0xA0000, 0x20000, 0); + scan_tree("/sys/class/pci_bus", "legacy_mem", 0xC0000, 0x40000, 1); + scan_tree("/sys/class/pci_bus", "legacy_mem", 0, 1024*1024, 0); + + scan_rom("/sys/devices", "rom"); + + scan_tree("/proc/bus/pci", "??.?", 0, 0xA0000, 1); + scan_tree("/proc/bus/pci", "??.?", 0xA0000, 0x20000, 0); + scan_tree("/proc/bus/pci", "??.?", 0xC0000, 0x40000, 1); + scan_tree("/proc/bus/pci", "??.?", 0, 1024*1024, 0); + + return rc; +} -- cgit v1.3.1