On 5/18/20 1:16 PM, Makarand Sonare wrote:
When a nested VM with a VMX-preemption timer is migrated, verify that the
nested VM and its parent VM observe the VMX-preemption timer exit close to
the original expiration deadline.
Signed-off-by: Makarand Sonare <makarandsonare@xxxxxxxxxx>
Reviewed-by: Jim Mattson <jmattson@xxxxxxxxxx>
Change-Id: Ia79337c682ee161399525edc34201fad473fc190
---
tools/arch/x86/include/uapi/asm/kvm.h | 1 +
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 | 11 +-
.../selftests/kvm/include/x86_64/vmx.h | 27 ++
.../kvm/x86_64/vmx_preemption_timer_test.c | 256 ++++++++++++++++++
7 files changed, 295 insertions(+), 4 deletions(-)
create mode 100644 tools/testing/selftests/kvm/x86_64/vmx_preemption_timer_test.c
diff --git a/tools/arch/x86/include/uapi/asm/kvm.h b/tools/arch/x86/include/uapi/asm/kvm.h
index 60701178b9cc1..13dca545554dc 100644
--- a/tools/arch/x86/include/uapi/asm/kvm.h
+++ b/tools/arch/x86/include/uapi/asm/kvm.h
@@ -402,6 +402,7 @@ struct kvm_sync_regs {
struct kvm_vmx_nested_state_data {
__u8 vmcs12[KVM_STATE_NESTED_VMX_VMCS_SIZE];
__u8 shadow_vmcs12[KVM_STATE_NESTED_VMX_VMCS_SIZE];
+ __u64 preemption_timer_deadline;
};
struct kvm_vmx_nested_state_hdr {
diff --git a/tools/testing/selftests/kvm/.gitignore b/tools/testing/selftests/kvm/.gitignore
index 222e50104296a..f159718f90c0a 100644
--- a/tools/testing/selftests/kvm/.gitignore
+++ b/tools/testing/selftests/kvm/.gitignore
@@ -10,6 +10,7 @@
/x86_64/set_sregs_test
/x86_64/smm_test
/x86_64/state_test
+/x86_64/vmx_preemption_timer_test
/x86_64/svm_vmcall_test
/x86_64/sync_regs_test
/x86_64/vmx_close_while_nested_test
diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile
index c66f4eec34111..780f0c189a7bc 100644
--- a/tools/testing/selftests/kvm/Makefile
+++ b/tools/testing/selftests/kvm/Makefile
@@ -20,6 +20,7 @@ TEST_GEN_PROGS_x86_64 += x86_64/platform_info_test
TEST_GEN_PROGS_x86_64 += x86_64/set_sregs_test
TEST_GEN_PROGS_x86_64 += x86_64/smm_test
TEST_GEN_PROGS_x86_64 += x86_64/state_test
+TEST_GEN_PROGS_x86_64 += x86_64/vmx_preemption_timer_test
TEST_GEN_PROGS_x86_64 += x86_64/svm_vmcall_test
TEST_GEN_PROGS_x86_64 += x86_64/sync_regs_test
TEST_GEN_PROGS_x86_64 += x86_64/vmx_close_while_nested_test
diff --git a/tools/testing/selftests/kvm/include/kvm_util.h b/tools/testing/selftests/kvm/include/kvm_util.h
index e244c6ecfc1d5..919e161dd2893 100644
--- a/tools/testing/selftests/kvm/include/kvm_util.h
+++ b/tools/testing/selftests/kvm/include/kvm_util.h
@@ -314,6 +314,8 @@ void ucall_uninit(struct kvm_vm *vm);
void ucall(uint64_t cmd, int nargs, ...);
uint64_t get_ucall(struct kvm_vm *vm, uint32_t vcpu_id, struct ucall *uc);
+#define GUEST_SYNC_ARGS(stage, arg1, arg2, arg3, arg4) \
+ ucall(UCALL_SYNC, 6, "hello", stage, arg1, arg2, arg3, arg4)
#define GUEST_SYNC(stage) ucall(UCALL_SYNC, 2, "hello", stage)
#define GUEST_DONE() ucall(UCALL_DONE, 0)
#define __GUEST_ASSERT(_condition, _nargs, _args...) do { \
diff --git a/tools/testing/selftests/kvm/include/x86_64/processor.h b/tools/testing/selftests/kvm/include/x86_64/processor.h
index 7428513a4c687..7cb19eca6c72d 100644
--- a/tools/testing/selftests/kvm/include/x86_64/processor.h
+++ b/tools/testing/selftests/kvm/include/x86_64/processor.h
@@ -79,13 +79,16 @@ static inline uint64_t get_desc64_base(const struct desc64 *desc)
static inline uint64_t rdtsc(void)
{
uint32_t eax, edx;
-
+ uint32_t tsc_val;
/*
* The lfence is to wait (on Intel CPUs) until all previous
- * instructions have been executed.
+ * instructions have been executed. If software requires RDTSC to be
+ * executed prior to execution of any subsequent instruction, it can
+ * execute LFENCE immediately after RDTSC
*/
- __asm__ __volatile__("lfence; rdtsc" : "=a"(eax), "=d"(edx));
- return ((uint64_t)edx) << 32 | eax;
+ __asm__ __volatile__("lfence; rdtsc; lfence" : "=a"(eax), "=d"(edx));
+ tsc_val = ((uint64_t)edx) << 32 | eax;
+ return tsc_val;
}
static inline uint64_t rdtscp(uint32_t *aux)
diff --git a/tools/testing/selftests/kvm/include/x86_64/vmx.h b/tools/testing/selftests/kvm/include/x86_64/vmx.h
index 3d27069b9ed9c..ccff3e6e27048 100644
--- a/tools/testing/selftests/kvm/include/x86_64/vmx.h
+++ b/tools/testing/selftests/kvm/include/x86_64/vmx.h
@@ -575,6 +575,33 @@ struct vmx_pages {
void *eptp;
};
+union vmx_basic {
+ u64 val;
+ struct {
+ u32 revision;
+ u32 size:13,
+ reserved1:3,
+ width:1,
+ dual:1,
+ type:4,
+ insouts:1,
+ ctrl:1,
+ vm_entry_exception_ctrl:1,
+ reserved2:7;
+ };
+};
+
+union vmx_ctrl_msr {
+ u64 val;
+ struct {
+ u32 set, clr;
+ };
+};
+
+union vmx_basic basic;
+union vmx_ctrl_msr ctrl_pin_rev;
+union vmx_ctrl_msr ctrl_exit_rev;
+
struct vmx_pages *vcpu_alloc_vmx(struct kvm_vm *vm, vm_vaddr_t *p_vmx_gva);
bool prepare_for_vmx_operation(struct vmx_pages *vmx);
void prepare_vmcs(struct vmx_pages *vmx, void *guest_rip, void *guest_rsp);
diff --git a/tools/testing/selftests/kvm/x86_64/vmx_preemption_timer_test.c b/tools/testing/selftests/kvm/x86_64/vmx_preemption_timer_test.c
new file mode 100644
index 0000000000000..10893b11511be
--- /dev/null
+++ b/tools/testing/selftests/kvm/x86_64/vmx_preemption_timer_test.c
@@ -0,0 +1,256 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * VMX-preemption timer test
+ *
+ * Copyright (C) 2020, Google, LLC.
+ *
+ * Test to ensure the VM-Enter after migration doesn't
+ * incorrectly restarts the timer with the full timer
+ * value instead of partially decayed timer value
+ *
+ */
+#define _GNU_SOURCE /* for program_invocation_short_name */
+#include <fcntl.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/ioctl.h>
+
+#include "test_util.h"
+
+#include "kvm_util.h"
+#include "processor.h"
+#include "vmx.h"
+
+#define VCPU_ID 5
+#define PREEMPTION_TIMER_VALUE 100000000ull
+#define PREEMPTION_TIMER_VALUE_THRESHOLD1 80000000ull
+
+u32 vmx_pt_rate;
+bool l2_save_restore_done;
+static u64 l2_vmx_pt_start;
+volatile u64 l2_vmx_pt_finish;
+
+void l2_guest_code(void)
+{
+ u64 vmx_pt_delta;
+
+ vmcall();
+ l2_vmx_pt_start = (rdtsc() >> vmx_pt_rate) << vmx_pt_rate;
+
+ //
+ // Wait until the 1st threshold has passed
+ //
+ do {
+ l2_vmx_pt_finish = rdtsc();
+ vmx_pt_delta = (l2_vmx_pt_finish - l2_vmx_pt_start) >>
+ vmx_pt_rate;
+ } while (vmx_pt_delta < PREEMPTION_TIMER_VALUE_THRESHOLD1);
+
+ //
+ // Force L2 through Save and Restore cycle
+ //
+ GUEST_SYNC(1);
+
+ l2_save_restore_done = 1;
+
+ //
+ // Now wait for the preemption timer to fire and
+ // exit to L1
+ //
+ while ((l2_vmx_pt_finish = rdtsc()))
+ ;
+}
+
+void l1_guest_code(struct vmx_pages *vmx_pages)
+{
+#define L2_GUEST_STACK_SIZE 64
+ unsigned long l2_guest_stack[L2_GUEST_STACK_SIZE];
+ u64 l1_vmx_pt_start;
+ u64 l1_vmx_pt_finish;
+ u64 l1_tsc_deadline, l2_tsc_deadline;
+
+ GUEST_ASSERT(vmx_pages->vmcs_gpa);
+ GUEST_ASSERT(prepare_for_vmx_operation(vmx_pages));
+ GUEST_ASSERT(load_vmcs(vmx_pages));
+ GUEST_ASSERT(vmptrstz() == vmx_pages->vmcs_gpa);
+
+ prepare_vmcs(vmx_pages, l2_guest_code,
+ &l2_guest_stack[L2_GUEST_STACK_SIZE]);
+
+ GUEST_ASSERT(!vmlaunch());
+ GUEST_ASSERT(vmreadz(VM_EXIT_REASON) == EXIT_REASON_VMCALL);
+ vmwrite(GUEST_RIP, vmreadz(GUEST_RIP) + 3);
Please use vmcs_read(VM_EXIT_INSTRUCTION_LEN) instead of 3.
+
+ //
+ // Check for Preemption timer support and turn on PIN control
+ //
+ basic.val = rdmsr(MSR_IA32_VMX_BASIC);
+ ctrl_pin_rev.val = rdmsr(basic.ctrl ? MSR_IA32_VMX_TRUE_PINBASED_CTLS
+ : MSR_IA32_VMX_PINBASED_CTLS);
+ ctrl_exit_rev.val = rdmsr(basic.ctrl ? MSR_IA32_VMX_TRUE_EXIT_CTLS
+ : MSR_IA32_VMX_EXIT_CTLS);
+
+ if (!(ctrl_pin_rev.clr & PIN_BASED_VMX_PREEMPTION_TIMER) ||
+ !(ctrl_exit_rev.clr & VM_EXIT_SAVE_VMX_PREEMPTION_TIMER))
+ return;
+
Why not do this check in the beginning of L1, before VMLAUNCH of L2 ? If
these two controls are not supported, the test is just void.
+ GUEST_ASSERT(!vmwrite(PIN_BASED_VM_EXEC_CONTROL,
+ vmreadz(PIN_BASED_VM_EXEC_CONTROL) |
+ PIN_BASED_VMX_PREEMPTION_TIMER));
+
+ GUEST_ASSERT(!vmwrite(VMX_PREEMPTION_TIMER_VALUE,
+ PREEMPTION_TIMER_VALUE));
+
+ vmx_pt_rate = rdmsr(MSR_IA32_VMX_MISC) & 0x1F;
+
+ l2_save_restore_done = 0;
+
+ l1_vmx_pt_start = (rdtsc() >> vmx_pt_rate) << vmx_pt_rate;
+
+ GUEST_ASSERT(!vmresume());
+
+ l1_vmx_pt_finish = rdtsc();
+
+ //
+ // Ensure exit from L2 happens after L2 goes through
+ // save and restore
+ GUEST_ASSERT(l2_save_restore_done);
+
+ //
+ // Ensure the exit from L2 is due to preemption timer expiry
+ //
+ GUEST_ASSERT(vmreadz(VM_EXIT_REASON) == EXIT_REASON_PREEMPTION_TIMER);
I am wondering if checking just the EXIT reason is enough to determine
that L2 has gone through a successful migration.
+
+ l1_tsc_deadline = l1_vmx_pt_start +
+ (PREEMPTION_TIMER_VALUE << vmx_pt_rate);
+
+ l2_tsc_deadline = l2_vmx_pt_start +
+ (PREEMPTION_TIMER_VALUE << vmx_pt_rate);
+
+ //
+ // Sync with the host and pass the l1|l2 pt_expiry_finish times and
+ // tsc deadlines so that host can verify they are as expected
+ //
+ GUEST_SYNC_ARGS(2, l1_vmx_pt_finish, l1_tsc_deadline,
+ l2_vmx_pt_finish, l2_tsc_deadline);
+}
+
+void guest_code(struct vmx_pages *vmx_pages)
+{
+ if (vmx_pages)
+ l1_guest_code(vmx_pages);
+
+ GUEST_DONE();
+}
+
+int main(int argc, char *argv[])
+{
+ vm_vaddr_t vmx_pages_gva = 0;
+
+ struct kvm_regs regs1, regs2;
+ struct kvm_vm *vm;
+ struct kvm_run *run;
+ struct kvm_x86_state *state;
+ struct ucall uc;
+ int stage;
+
+ /*
+ * AMD currently does not implement any VMX features, so for now we
+ * just early out.
+ */
+ nested_vmx_check_supported();
+
+ /* Create VM */
+ vm = vm_create_default(VCPU_ID, 0, guest_code);
+ vcpu_set_cpuid(vm, VCPU_ID, kvm_get_supported_cpuid());
+ run = vcpu_state(vm, VCPU_ID);
+
+ vcpu_regs_get(vm, VCPU_ID, ®s1);
+
+ if (kvm_check_cap(KVM_CAP_NESTED_STATE)) {
+ vcpu_alloc_vmx(vm, &vmx_pages_gva);
+ vcpu_args_set(vm, VCPU_ID, 1, vmx_pages_gva);
+ } else {
+ pr_info("will skip nested state checks\n");
This error message looks odd. Shouldn't it say something like,
"nested state capability not available, skipping test"
+ goto done;
+ }
+
+ for (stage = 1;; stage++) {
+ _vcpu_run(vm, VCPU_ID);
+ TEST_ASSERT(run->exit_reason == KVM_EXIT_IO,
+ "Stage %d: unexpected exit reason: %u (%s),\n",
+ stage, run->exit_reason,
+ exit_reason_str(run->exit_reason));
+
+ switch (get_ucall(vm, VCPU_ID, &uc)) {
+ case UCALL_ABORT:
+ TEST_FAIL("%s at %s:%ld", (const char *)uc.args[0],
+ __FILE__, uc.args[1]);
+ /* NOT REACHED */
+ case UCALL_SYNC:
+ break;
+ case UCALL_DONE:
+ goto done;
+ default:
+ TEST_FAIL("Unknown ucall %lu", uc.cmd);
+ }
+
+ /* UCALL_SYNC is handled here. */
+ TEST_ASSERT(!strcmp((const char *)uc.args[0], "hello") &&
+ uc.args[1] == stage, "Stage %d: Unexpected register values vmexit, got %lx",
+ stage, (ulong)uc.args[1]);
+ //
+ // If this stage 2 then we should verify the vmx pt expiry
+ // is as expected
+ //
+ if (stage == 2) {
+
+ pr_info("Stage %d: L1 PT expiry TSC (%lu) , L1 TSC deadline (%lu)\n",
+ stage, uc.args[2], uc.args[3]);
+
+ pr_info("Stage %d: L2 PT expiry TSC (%lu) , L2 TSC deadline (%lu)\n",
+ stage, uc.args[4], uc.args[5]);
+
+ //
+ // From L1's perspective verify Preemption timer hasn't
+ // expired too early
+ //
+
+ TEST_ASSERT(uc.args[2] >= uc.args[3],
+ "Stage %d: L1 PT expiry TSC (%lu) < L1 TSC deadline (%lu)",
+ stage, uc.args[2], uc.args[3]);
+
+ //
+ // From L2's perspective verify Preemption timer hasn't
+ // expired too late
+ //
+ TEST_ASSERT(uc.args[4] < uc.args[5],
+ "Stage %d: L2 PT expiry TSC (%lu) > L2 TSC deadline (%lu)",
+ stage, uc.args[4], uc.args[5]);
+ }
+
For readability, it's better to put a block comment here for the entire
save/restore operation as a whole.
Also, this save/restore block should be placed before the above stage2
block.
+ state = vcpu_save_state(vm, VCPU_ID);
+ memset(®s1, 0, sizeof(regs1));
+ vcpu_regs_get(vm, VCPU_ID, ®s1);
+
+ kvm_vm_release(vm);
+
+ /* Restore state in a new VM. */
+ kvm_vm_restart(vm, O_RDWR);
+ vm_vcpu_add(vm, VCPU_ID);
+ vcpu_set_cpuid(vm, VCPU_ID, kvm_get_supported_cpuid());
+ vcpu_load_state(vm, VCPU_ID, state);
+ run = vcpu_state(vm, VCPU_ID);
+ free(state);
+
+ memset(®s2, 0, sizeof(regs2));
+ vcpu_regs_get(vm, VCPU_ID, ®s2);
+ TEST_ASSERT(!memcmp(®s1, ®s2, sizeof(regs2)),
+ "Unexpected register values after vcpu_load_state; rdi: %lx rsi: %lx",
+ (ulong) regs2.rdi, (ulong) regs2.rsi);
+ }
+
+done:
+ kvm_vm_free(vm);
+}
