@@ -81,7 +81,7 @@ xen-hvmctx: xen-hvmctx.o
$(CC) $(LDFLAGS) -o $@ $< $(LDLIBS_libxenctrl) $(APPEND_LDFLAGS)
xen-hvmcrash: xen-hvmcrash.o
- $(CC) $(LDFLAGS) -o $@ $< $(LDLIBS_libxenctrl) $(APPEND_LDFLAGS)
+ $(CC) $(LDFLAGS) -o $@ $< $(LDLIBS_libxenctrl) $(LDLIBS_libxendevicemodel) $(APPEND_LDFLAGS)
xen-memshare: xen-memshare.o
$(CC) $(LDFLAGS) -o $@ $< $(LDLIBS_libxenctrl) $(APPEND_LDFLAGS)
@@ -1,7 +1,7 @@
/*
* xen-hvmcrash.c
*
- * Attempt to crash an HVM guest by overwriting RIP/EIP with a bogus value
+ * Attempt to crash an HVM guest by injecting #DF to every vcpu
*
* Copyright (c) 2010 Citrix Systems, Inc.
*
@@ -24,36 +24,25 @@
* DEALINGS IN THE SOFTWARE.
*/
-#include <inttypes.h>
#include <stdio.h>
#include <stdlib.h>
-#include <stddef.h>
-#include <stdint.h>
-#include <unistd.h>
#include <string.h>
#include <errno.h>
-#include <limits.h>
-
-#include <sys/types.h>
-#include <sys/stat.h>
-#include <arpa/inet.h>
#include <xenctrl.h>
-#include <xen/xen.h>
-#include <xen/domctl.h>
-#include <xen/hvm/save.h>
+#include <xendevicemodel.h>
+
+#include <xen/asm/x86-defns.h>
int
main(int argc, char **argv)
{
int domid;
xc_interface *xch;
+ xendevicemodel_handle *dmod;
xc_domaininfo_t dominfo;
- int ret;
- uint32_t len;
- uint8_t *buf;
- uint32_t off;
- struct hvm_save_descriptor *descriptor;
+ int vcpu_id, ret;
+ bool injected = false;
if (argc != 2 || !argv[1] || (domid = atoi(argv[1])) < 0) {
fprintf(stderr, "usage: %s <domid>\n", argv[0]);
@@ -83,59 +72,28 @@ main(int argc, char **argv)
exit(-1);
}
- /*
- * Calling with zero buffer length should return the buffer length
- * required.
- */
- ret = xc_domain_hvm_getcontext(xch, domid, 0, 0);
- if (ret < 0) {
- perror("xc_domain_hvm_getcontext");
- exit(1);
- }
-
- len = ret;
- buf = malloc(len);
- if (buf == NULL) {
- perror("malloc");
- exit(1);
- }
-
- ret = xc_domain_hvm_getcontext(xch, domid, buf, len);
- if (ret < 0) {
- perror("xc_domain_hvm_getcontext");
- exit(1);
- }
+ dmod = xc_interface_dmod_handle(xch);
- off = 0;
-
- while (off < len) {
- descriptor = (struct hvm_save_descriptor *)(buf + off);
-
- off += sizeof (struct hvm_save_descriptor);
-
- if (descriptor->typecode == HVM_SAVE_CODE(CPU)) {
- HVM_SAVE_TYPE(CPU) *cpu;
-
- /* Overwrite EIP/RIP with some recognisable but bogus value */
- cpu = (HVM_SAVE_TYPE(CPU) *)(buf + off);
- printf("CPU[%d]: RIP = %" PRIx64 "\n", descriptor->instance, cpu->rip);
- cpu->rip = 0xf001;
- } else if (descriptor->typecode == HVM_SAVE_CODE(END)) {
- break;
+ for (vcpu_id = 0; vcpu_id <= dominfo.max_vcpu_id; vcpu_id++) {
+ printf("Injecting #DF to vcpu ID #%d...\n", vcpu_id);
+ ret = xendevicemodel_inject_event(dmod, domid, vcpu_id,
+ X86_EXC_DF,
+ XEN_DMOP_EVENT_hw_exc, 0, 0, 0);
+ if (ret < 0) {
+ fprintf(stderr, "Could not inject #DF to vcpu ID #%d: %s\n", vcpu_id, strerror(errno));
+ continue;
}
-
- off += descriptor->length;
+ injected = true;
}
- ret = xc_domain_hvm_setcontext(xch, domid, buf, len);
+ ret = xc_domain_unpause(xch, domid);
if (ret < 0) {
- perror("xc_domain_hvm_setcontext");
+ perror("xc_domain_unpause");
exit(1);
}
- ret = xc_domain_unpause(xch, domid);
- if (ret < 0) {
- perror("xc_domain_unpause");
+ if (!injected) {
+ fprintf(stderr, "Could not inject #DF to any vcpu!\n");
exit(1);
}
xen-hvmcrash would previously save records, overwrite the instruction pointer with a bogus value, and then restore them to crash a domain just enough to cause the guest OS to memdump. This approach is found to be unreliable when tested on a guest running Windows 10 x64, with some executions doing nothing at all. Another approach would be to trigger NMIs. This approach is found to be unreliable when tested on Linux (Ubuntu 22.04), as Linux will ignore NMIs if it is not configured to handle such. Injecting a double fault abort to all vCPUs is found to be more reliable at crashing and invoking memdumps from Windows and Linux domains. This patch modifies the xen-hvmcrash tool to inject #DF to all vCPUs belonging to the specified domain, instead of overwriting RIP. Signed-off-by: Matthew Barnes <matthew.barnes@cloud.com> --- Changes in v3: - Keep xc_domain_{un,}pause() calls - Update xen-hvmcrash comment to reflect new behaviour Changes in v2: - Use xendevicemodel API instead of legacy devicemodel API - Return error status code if no vcpus could be injected - Use existing exception vector macro defined in `x86-defns.h` - Clean up unnecessary headers - Fix NULL build errors --- tools/misc/Makefile | 2 +- tools/misc/xen-hvmcrash.c | 84 ++++++++++----------------------------- 2 files changed, 22 insertions(+), 64 deletions(-)