When running with /sys/module/kvm_intel/parameters/unrestricted_guest=N,
test that a kernel warning does not occur informing us that
vcpu->mmio_needed=1. This can happen when KVM_RUN is called after a
triple fault.
This test was made to detect a bug that was reported by Syzkaller
(https://groups.google.com/forum/#!topic/syzkaller/lHfau8E3SOE) and
fixed with commit bbeac2830f4de ("KVM: X86: Fix residual mmio emulation
request to userspace").
Signed-off-by: Aaron Lewis <aaronlewis@xxxxxxxxxx>
Reviewed-by: Jim Mattson <jmattson@xxxxxxxxxx>
Reviewed-by: Peter Shier <pshier@xxxxxxxxxx>
---
tools/testing/selftests/kvm/.gitignore | 1 +
tools/testing/selftests/kvm/Makefile | 1 +
.../testing/selftests/kvm/include/kvm_util.h | 2 +
.../selftests/kvm/include/x86_64/processor.h | 2 +
tools/testing/selftests/kvm/lib/kvm_util.c | 36 +++++
.../selftests/kvm/lib/x86_64/processor.c | 16 +++
.../selftests/kvm/x86_64/mmio_warning_test.c | 126 ++++++++++++++++++
7 files changed, 184 insertions(+)
create mode 100644 tools/testing/selftests/kvm/x86_64/mmio_warning_test.c
diff --git a/tools/testing/selftests/kvm/.gitignore b/tools/testing/selftests/kvm/.gitignore
index df1bf9230a74..41266af0d3dc 100644
--- a/tools/testing/selftests/kvm/.gitignore
+++ b/tools/testing/selftests/kvm/.gitignore
@@ -2,6 +2,7 @@
/x86_64/evmcs_test
/x86_64/hyperv_cpuid
/x86_64/kvm_create_max_vcpus
+/x86_64/mmio_warning_test
/x86_64/platform_info_test
/x86_64/set_sregs_test
/x86_64/smm_test
diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile
index 79c524395ebe..670b938f1049 100644
--- a/tools/testing/selftests/kvm/Makefile
+++ b/tools/testing/selftests/kvm/Makefile
@@ -22,6 +22,7 @@ TEST_GEN_PROGS_x86_64 += x86_64/vmx_close_while_nested_test
TEST_GEN_PROGS_x86_64 += x86_64/smm_test
TEST_GEN_PROGS_x86_64 += x86_64/kvm_create_max_vcpus
TEST_GEN_PROGS_x86_64 += x86_64/vmx_set_nested_state_test
+TEST_GEN_PROGS_x86_64 += x86_64/mmio_warning_test
TEST_GEN_PROGS_x86_64 += dirty_log_test
TEST_GEN_PROGS_x86_64 += clear_dirty_log_test
diff --git a/tools/testing/selftests/kvm/include/kvm_util.h b/tools/testing/selftests/kvm/include/kvm_util.h
index 8c6b9619797d..c5c427c86598 100644
--- a/tools/testing/selftests/kvm/include/kvm_util.h
+++ b/tools/testing/selftests/kvm/include/kvm_util.h
@@ -137,6 +137,8 @@ struct kvm_vm *vm_create_default(uint32_t vcpuid, uint64_t extra_mem_size,
void *guest_code);
void vm_vcpu_add_default(struct kvm_vm *vm, uint32_t vcpuid, void *guest_code);
+bool vm_is_unrestricted_guest(struct kvm_vm *vm);
+
struct kvm_userspace_memory_region *
kvm_userspace_memory_region_find(struct kvm_vm *vm, uint64_t start,
uint64_t end);
diff --git a/tools/testing/selftests/kvm/include/x86_64/processor.h b/tools/testing/selftests/kvm/include/x86_64/processor.h
index 6063d5b2f356..af4d26de32d1 100644
--- a/tools/testing/selftests/kvm/include/x86_64/processor.h
+++ b/tools/testing/selftests/kvm/include/x86_64/processor.h
@@ -303,6 +303,8 @@ static inline unsigned long get_xmm(int n)
return 0;
}
+bool is_intel_cpu(void);
+
struct kvm_x86_state;
struct kvm_x86_state *vcpu_save_state(struct kvm_vm *vm, uint32_t vcpuid);
void vcpu_load_state(struct kvm_vm *vm, uint32_t vcpuid,
diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/selftests/kvm/lib/kvm_util.c
index e9113857f44e..b93b09ad9a11 100644
--- a/tools/testing/selftests/kvm/lib/kvm_util.c
+++ b/tools/testing/selftests/kvm/lib/kvm_util.c
@@ -1584,3 +1584,39 @@ void *addr_gva2hva(struct kvm_vm *vm, vm_vaddr_t gva)
{
return addr_gpa2hva(vm, addr_gva2gpa(vm, gva));
}
+
+/*
+ * Is Unrestricted Guest
+ *
+ * Input Args:
+ * vm - Virtual Machine
+ *
+ * Output Args: None
+ *
+ * Return: True if the unrestricted guest is set to 'Y', otherwise return false.
+ *
+ * Check if the unrestricted guest flag is enabled.
+ */
+bool vm_is_unrestricted_guest(struct kvm_vm *vm)
+{
+ char val = 'N';
+ size_t count;
+ FILE *f;
+
+ if (vm == NULL) {
+ /* Ensure that the KVM vendor-specific module is loaded. */
+ f = fopen(KVM_DEV_PATH, "r");
+ TEST_ASSERT(f != NULL, "Error in opening KVM dev file: %d",
+ errno);
+ fclose(f);
+ }
+
+ f = fopen("/sys/module/kvm_intel/parameters/unrestricted_guest", "r");
+ if (f) {
+ count = fread(&val, sizeof(char), 1, f);
+ TEST_ASSERT(count == 1, "Unable to read from param file.");
+ fclose(f);
+ }
+
+ return val == 'Y';
+}
diff --git a/tools/testing/selftests/kvm/lib/x86_64/processor.c b/tools/testing/selftests/kvm/lib/x86_64/processor.c
index dc7fae9fa424..bcc0e70e1856 100644
--- a/tools/testing/selftests/kvm/lib/x86_64/processor.c
+++ b/tools/testing/selftests/kvm/lib/x86_64/processor.c
@@ -1139,3 +1139,19 @@ void vcpu_load_state(struct kvm_vm *vm, uint32_t vcpuid, struct kvm_x86_state *s
r);
}
}
+
+bool is_intel_cpu(void)
+{
+ int eax, ebx, ecx, edx;
+ const uint32_t *chunk;
+ const int leaf = 0;
+
+ __asm__ __volatile__(
+ "cpuid"
+ : /* output */ "=a"(eax), "=b"(ebx),
+ "=c"(ecx), "=d"(edx)
+ : /* input */ "0"(leaf), "2"(0));
+
+ chunk = (const uint32_t *)("GenuineIntel");
+ return (ebx == chunk[0] && edx == chunk[1] && ecx == chunk[2]);
+}
diff --git a/tools/testing/selftests/kvm/x86_64/mmio_warning_test.c b/tools/testing/selftests/kvm/x86_64/mmio_warning_test.c
new file mode 100644
index 000000000000..00bb97d76000
--- /dev/null
+++ b/tools/testing/selftests/kvm/x86_64/mmio_warning_test.c
@@ -0,0 +1,126 @@
+/*
+ * mmio_warning_test
+ *
+ * Copyright (C) 2019, Google LLC.
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2.
+ *
+ * Test that we don't get a kernel warning when we call KVM_RUN after a
+ * triple fault occurs. To get the triple fault to occur we call KVM_RUN
+ * on a VCPU that hasn't been properly setup.
+ *
+ */
+
+#define _GNU_SOURCE
+#include <fcntl.h>
+#include <kvm_util.h>
+#include <linux/kvm.h>
+#include <processor.h>
+#include <pthread.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/ioctl.h>
+#include <sys/mman.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <test_util.h>
+#include <unistd.h>
+
+#define NTHREAD 4
+#define NPROCESS 5
+
+struct thread_context {
+ int kvmcpu;
+ struct kvm_run *run;
+};
+
+void *thr(void *arg)
+{
+ struct thread_context *tc = (struct thread_context *)arg;
+ int res;
+ int kvmcpu = tc->kvmcpu;
+ struct kvm_run *run = tc->run;
+
+ res = ioctl(kvmcpu, KVM_RUN, 0);
+ printf("ret1=%d exit_reason=%d suberror=%d\n",
+ res, run->exit_reason, run->internal.suberror);
+
+ return 0;
+}
+
+void test(void)
+{
+ int i, kvm, kvmvm, kvmcpu;
+ pthread_t th[NTHREAD];
+ struct kvm_run *run;
+ struct thread_context tc;
+
+ kvm = open("/dev/kvm", O_RDWR);
+ TEST_ASSERT(kvm != -1, "failed to open /dev/kvm");
+ kvmvm = ioctl(kvm, KVM_CREATE_VM, 0);
+ TEST_ASSERT(kvmvm != -1, "KVM_CREATE_VM failed");
+ kvmcpu = ioctl(kvmvm, KVM_CREATE_VCPU, 0);
+ TEST_ASSERT(kvmcpu != -1, "KVM_CREATE_VCPU failed");
+ run = (struct kvm_run *)mmap(0, 4096, PROT_READ|PROT_WRITE, MAP_SHARED,
+ kvmcpu, 0);
+ tc.kvmcpu = kvmcpu;
+ tc.run = run;
+ srand(getpid());
+ for (i = 0; i < NTHREAD; i++) {
+ pthread_create(&th[i], NULL, thr, (void *)(uintptr_t)&tc);
+ usleep(rand() % 10000);
+ }
+ for (i = 0; i < NTHREAD; i++)
+ pthread_join(th[i], NULL);
+}
+
+int get_warnings_count(void)
+{
+ int warnings;
+ FILE *f;
+
+ f = popen("dmesg | grep \"WARNING:\" | wc -l", "r");
+ fscanf(f, "%d", &warnings);
+ fclose(f);
+
+ return warnings;
+}
+
+int main(void)
+{
+ int warnings_before, warnings_after;
+
+ if (!is_intel_cpu()) {
+ printf("Must be run on an Intel CPU, skipping test\n");
+ exit(KSFT_SKIP);
+ }
+
+ if (vm_is_unrestricted_guest(NULL)) {
+ printf("Unrestricted guest must be disabled, skipping test\n");
+ exit(KSFT_SKIP);
+ }
+
+ warnings_before = get_warnings_count();
+
+ for (int i = 0; i < NPROCESS; ++i) {
+ int status;
+ int pid = fork();
+
+ if (pid < 0)
+ exit(1);
+ if (pid == 0) {
+ test();
+ exit(0);
+ }
+ while (waitpid(pid, &status, __WALL) != pid)
+ ;
+ }
+
+ warnings_after = get_warnings_count();
