From 8df98ae0ab2ead9a02228756eec26f8d7b17f499 Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Wed, 13 Mar 2019 13:19:26 -0700 Subject: KVM: selftests: assert on exit reason in CR4/cpuid sync test ...so that the test doesn't end up in an infinite loop if it fails for whatever reason, e.g. SHUTDOWN due to gcc inserting stack canary code into ucall() and attempting to derefence a null segment. Fixes: ca359066889f7 ("kvm: selftests: add cr4_cpuid_sync_test") Cc: Wei Huang Signed-off-by: Sean Christopherson Signed-off-by: Paolo Bonzini --- .../selftests/kvm/x86_64/cr4_cpuid_sync_test.c | 35 ++++++++++++---------- 1 file changed, 19 insertions(+), 16 deletions(-) (limited to 'tools') diff --git a/tools/testing/selftests/kvm/x86_64/cr4_cpuid_sync_test.c b/tools/testing/selftests/kvm/x86_64/cr4_cpuid_sync_test.c index d503a51fad30..7c2c4d4055a8 100644 --- a/tools/testing/selftests/kvm/x86_64/cr4_cpuid_sync_test.c +++ b/tools/testing/selftests/kvm/x86_64/cr4_cpuid_sync_test.c @@ -87,22 +87,25 @@ int main(int argc, char *argv[]) while (1) { rc = _vcpu_run(vm, VCPU_ID); - if (run->exit_reason == KVM_EXIT_IO) { - switch (get_ucall(vm, VCPU_ID, &uc)) { - case UCALL_SYNC: - /* emulate hypervisor clearing CR4.OSXSAVE */ - vcpu_sregs_get(vm, VCPU_ID, &sregs); - sregs.cr4 &= ~X86_CR4_OSXSAVE; - vcpu_sregs_set(vm, VCPU_ID, &sregs); - break; - case UCALL_ABORT: - TEST_ASSERT(false, "Guest CR4 bit (OSXSAVE) unsynchronized with CPUID bit."); - break; - case UCALL_DONE: - goto done; - default: - TEST_ASSERT(false, "Unknown ucall 0x%x.", uc.cmd); - } + TEST_ASSERT(run->exit_reason == KVM_EXIT_IO, + "Unexpected exit reason: %u (%s),\n", + run->exit_reason, + exit_reason_str(run->exit_reason)); + + switch (get_ucall(vm, VCPU_ID, &uc)) { + case UCALL_SYNC: + /* emulate hypervisor clearing CR4.OSXSAVE */ + vcpu_sregs_get(vm, VCPU_ID, &sregs); + sregs.cr4 &= ~X86_CR4_OSXSAVE; + vcpu_sregs_set(vm, VCPU_ID, &sregs); + break; + case UCALL_ABORT: + TEST_ASSERT(false, "Guest CR4 bit (OSXSAVE) unsynchronized with CPUID bit."); + break; + case UCALL_DONE: + goto done; + default: + TEST_ASSERT(false, "Unknown ucall 0x%x.", uc.cmd); } } -- cgit v1.2.3 From 0a3f29b5a77d6c27796d7a7adabafd199dc066d5 Mon Sep 17 00:00:00 2001 From: Sean Christopherson Date: Wed, 13 Mar 2019 16:19:30 -0700 Subject: KVM: selftests: explicitly disable PIE for tests KVM selftests embed the guest "image" as a function in the test itself and extract the guest code at runtime by manually parsing the elf headers. The parsing is very simple and doesn't supporting fancy things like position independent executables. Recent versions of gcc enable pie by default, which results in triple fault shutdowns in the guest due to the virtual address in the headers not matching up with the virtual address retrieved from the function pointer. Signed-off-by: Sean Christopherson Signed-off-by: Paolo Bonzini --- tools/testing/selftests/kvm/Makefile | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'tools') diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile index 3c1f4bdf9000..73d59c9d94a3 100644 --- a/tools/testing/selftests/kvm/Makefile +++ b/tools/testing/selftests/kvm/Makefile @@ -29,7 +29,7 @@ LIBKVM += $(LIBKVM_$(UNAME_M)) INSTALL_HDR_PATH = $(top_srcdir)/usr LINUX_HDR_PATH = $(INSTALL_HDR_PATH)/include/ LINUX_TOOL_INCLUDE = $(top_srcdir)/tools/include -CFLAGS += -O2 -g -std=gnu99 -I$(LINUX_TOOL_INCLUDE) -I$(LINUX_HDR_PATH) -Iinclude -I$( Date: Wed, 13 Mar 2019 12:43:14 -0700 Subject: KVM: selftests: disable stack protector for all KVM tests Since 4.8.3, gcc has enabled -fstack-protector by default. This is problematic for the KVM selftests as they do not configure fs or gs segments (the stack canary is pulled from fs:0x28). With the default behavior, gcc will insert a stack canary on any function that creates buffers of 8 bytes or more. As a result, ucall() will hit a triple fault shutdown due to reading a bad fs segment when inserting its stack canary, i.e. every test fails with an unexpected SHUTDOWN. Fixes: 14c47b7530e2d ("kvm: selftests: introduce ucall") Signed-off-by: Sean Christopherson Signed-off-by: Paolo Bonzini --- tools/testing/selftests/kvm/Makefile | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) (limited to 'tools') diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile index 73d59c9d94a3..7514fcea91a7 100644 --- a/tools/testing/selftests/kvm/Makefile +++ b/tools/testing/selftests/kvm/Makefile @@ -29,8 +29,8 @@ LIBKVM += $(LIBKVM_$(UNAME_M)) INSTALL_HDR_PATH = $(top_srcdir)/usr LINUX_HDR_PATH = $(INSTALL_HDR_PATH)/include/ LINUX_TOOL_INCLUDE = $(top_srcdir)/tools/include -CFLAGS += -O2 -g -std=gnu99 -no-pie -I$(LINUX_TOOL_INCLUDE) -I$(LINUX_HDR_PATH) -Iinclude -I$( Date: Wed, 13 Mar 2019 16:49:31 -0700 Subject: KVM: selftests: complete IO before migrating guest state Documentation/virtual/kvm/api.txt states: NOTE: For KVM_EXIT_IO, KVM_EXIT_MMIO, KVM_EXIT_OSI, KVM_EXIT_PAPR and KVM_EXIT_EPR the corresponding operations are complete (and guest state is consistent) only after userspace has re-entered the kernel with KVM_RUN. The kernel side will first finish incomplete operations and then check for pending signals. Userspace can re-enter the guest with an unmasked signal pending to complete pending operations. Because guest state may be inconsistent, starting state migration after an IO exit without first completing IO may result in test failures, e.g. a proposed change to KVM's handling of %rip in its fast PIO handling[1] will cause the new VM, i.e. the post-migration VM, to have its %rip set to the IN instruction that triggered KVM_EXIT_IO, leading to a test assertion due to a stage mismatch. For simplicitly, require KVM_CAP_IMMEDIATE_EXIT to complete IO and skip the test if it's not available. The addition of KVM_CAP_IMMEDIATE_EXIT predates the state selftest by more than a year. [1] https://patchwork.kernel.org/patch/10848545/ Fixes: fa3899add1056 ("kvm: selftests: add basic test for state save and restore") Reported-by: Jim Mattson Signed-off-by: Sean Christopherson Signed-off-by: Paolo Bonzini --- tools/testing/selftests/kvm/include/kvm_util.h | 1 + tools/testing/selftests/kvm/lib/kvm_util.c | 16 ++++++++++++++++ tools/testing/selftests/kvm/x86_64/state_test.c | 18 ++++++++++++++++-- 3 files changed, 33 insertions(+), 2 deletions(-) (limited to 'tools') diff --git a/tools/testing/selftests/kvm/include/kvm_util.h b/tools/testing/selftests/kvm/include/kvm_util.h index a84785b02557..07b71ad9734a 100644 --- a/tools/testing/selftests/kvm/include/kvm_util.h +++ b/tools/testing/selftests/kvm/include/kvm_util.h @@ -102,6 +102,7 @@ vm_paddr_t addr_gva2gpa(struct kvm_vm *vm, vm_vaddr_t gva); struct kvm_run *vcpu_state(struct kvm_vm *vm, uint32_t vcpuid); void vcpu_run(struct kvm_vm *vm, uint32_t vcpuid); int _vcpu_run(struct kvm_vm *vm, uint32_t vcpuid); +void vcpu_run_complete_io(struct kvm_vm *vm, uint32_t vcpuid); void vcpu_set_mp_state(struct kvm_vm *vm, uint32_t vcpuid, struct kvm_mp_state *mp_state); void vcpu_regs_get(struct kvm_vm *vm, uint32_t vcpuid, struct kvm_regs *regs); diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/selftests/kvm/lib/kvm_util.c index b52cfdefecbf..efa0aad8b3c6 100644 --- a/tools/testing/selftests/kvm/lib/kvm_util.c +++ b/tools/testing/selftests/kvm/lib/kvm_util.c @@ -1121,6 +1121,22 @@ int _vcpu_run(struct kvm_vm *vm, uint32_t vcpuid) return rc; } +void vcpu_run_complete_io(struct kvm_vm *vm, uint32_t vcpuid) +{ + struct vcpu *vcpu = vcpu_find(vm, vcpuid); + int ret; + + TEST_ASSERT(vcpu != NULL, "vcpu not found, vcpuid: %u", vcpuid); + + vcpu->state->immediate_exit = 1; + ret = ioctl(vcpu->fd, KVM_RUN, NULL); + vcpu->state->immediate_exit = 0; + + TEST_ASSERT(ret == -1 && errno == EINTR, + "KVM_RUN IOCTL didn't exit immediately, rc: %i, errno: %i", + ret, errno); +} + /* * VM VCPU Set MP State * diff --git a/tools/testing/selftests/kvm/x86_64/state_test.c b/tools/testing/selftests/kvm/x86_64/state_test.c index 4b3f556265f1..30f75856cf39 100644 --- a/tools/testing/selftests/kvm/x86_64/state_test.c +++ b/tools/testing/selftests/kvm/x86_64/state_test.c @@ -134,6 +134,11 @@ int main(int argc, char *argv[]) struct kvm_cpuid_entry2 *entry = kvm_get_supported_cpuid_entry(1); + if (!kvm_check_cap(KVM_CAP_IMMEDIATE_EXIT)) { + fprintf(stderr, "immediate_exit not available, skipping test\n"); + exit(KSFT_SKIP); + } + /* Create VM */ vm = vm_create_default(VCPU_ID, 0, guest_code); vcpu_set_cpuid(vm, VCPU_ID, kvm_get_supported_cpuid()); @@ -156,8 +161,6 @@ int main(int argc, char *argv[]) stage, run->exit_reason, exit_reason_str(run->exit_reason)); - memset(®s1, 0, sizeof(regs1)); - vcpu_regs_get(vm, VCPU_ID, ®s1); switch (get_ucall(vm, VCPU_ID, &uc)) { case UCALL_ABORT: TEST_ASSERT(false, "%s at %s:%d", (const char *)uc.args[0], @@ -176,6 +179,17 @@ int main(int argc, char *argv[]) uc.args[1] == stage, "Unexpected register values vmexit #%lx, got %lx", stage, (ulong)uc.args[1]); + /* + * When KVM exits to userspace with KVM_EXIT_IO, KVM guarantees + * guest state is consistent only after userspace re-enters the + * kernel with KVM_RUN. Complete IO prior to migrating state + * to a new VM. + */ + vcpu_run_complete_io(vm, VCPU_ID); + + memset(®s1, 0, sizeof(regs1)); + vcpu_regs_get(vm, VCPU_ID, ®s1); + state = vcpu_save_state(vm, VCPU_ID); kvm_vm_release(vm); -- cgit v1.2.3