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Subject[PATCH v3 11/12] KVM: selftests: nSVM: Add svm_nested_soft_inject_test
Date
From: "Maciej S. Szmigiero" <maciej.szmigiero@oracle.com>

Add a KVM self-test that checks whether a nSVM L1 is able to successfully
inject a software interrupt, a soft exception and a NMI into its L2 guest.

In practice, this tests both the next_rip field consistency and
L1-injected event with intervening L0 VMEXIT during its delivery:
the first nested VMRUN (that's also trying to inject a software interrupt)
will immediately trigger a L0 NPF.
This L0 NPF will have zero in its CPU-returned next_rip field, which if
incorrectly reused by KVM will trigger a #PF when trying to return to
such address 0 from the interrupt handler.

For NMI injection this tests whether the L1 NMI state isn't getting
incorrectly mixed with the L2 NMI state if a L1 -> L2 NMI needs to be
re-injected.

Reviewed-by: Maxim Levitsky <mlevitsk@redhat.com>
[sean: check exact L2 RIP on first soft interrupt]
Signed-off-by: Sean Christopherson <seanjc@google.com>
Signed-off-by: Maciej S. Szmigiero <maciej.szmigiero@oracle.com>
---
tools/testing/selftests/kvm/.gitignore | 3 +-
tools/testing/selftests/kvm/Makefile | 1 +
.../selftests/kvm/include/x86_64/processor.h | 17 ++
.../selftests/kvm/include/x86_64/svm_util.h | 12 +
.../kvm/x86_64/svm_nested_soft_inject_test.c | 217 ++++++++++++++++++
5 files changed, 249 insertions(+), 1 deletion(-)
create mode 100644 tools/testing/selftests/kvm/x86_64/svm_nested_soft_inject_test.c

diff --git a/tools/testing/selftests/kvm/.gitignore b/tools/testing/selftests/kvm/.gitignore
index 56140068b763..74f3099f0ad3 100644
--- a/tools/testing/selftests/kvm/.gitignore
+++ b/tools/testing/selftests/kvm/.gitignore
@@ -35,9 +35,10 @@
/x86_64/state_test
/x86_64/svm_vmcall_test
/x86_64/svm_int_ctl_test
-/x86_64/tsc_scaling_sync
+/x86_64/svm_nested_soft_inject_test
/x86_64/sync_regs_test
/x86_64/tsc_msrs_test
+/x86_64/tsc_scaling_sync
/x86_64/userspace_io_test
/x86_64/userspace_msr_exit_test
/x86_64/vmx_apic_access_test
diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile
index af582d168621..eedf6bf713d3 100644
--- a/tools/testing/selftests/kvm/Makefile
+++ b/tools/testing/selftests/kvm/Makefile
@@ -66,6 +66,7 @@ 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/svm_int_ctl_test
+TEST_GEN_PROGS_x86_64 += x86_64/svm_nested_soft_inject_test
TEST_GEN_PROGS_x86_64 += x86_64/tsc_scaling_sync
TEST_GEN_PROGS_x86_64 += x86_64/sync_regs_test
TEST_GEN_PROGS_x86_64 += x86_64/userspace_io_test
diff --git a/tools/testing/selftests/kvm/include/x86_64/processor.h b/tools/testing/selftests/kvm/include/x86_64/processor.h
index 37db341d4cc5..deff64605442 100644
--- a/tools/testing/selftests/kvm/include/x86_64/processor.h
+++ b/tools/testing/selftests/kvm/include/x86_64/processor.h
@@ -17,6 +17,8 @@

#include "../kvm_util.h"

+#define NMI_VECTOR 0x02
+
#define X86_EFLAGS_FIXED (1u << 1)

#define X86_CR4_VME (1ul << 0)
@@ -368,6 +370,21 @@ static inline void cpu_relax(void)
asm volatile("rep; nop" ::: "memory");
}

+#define vmmcall() \
+ __asm__ __volatile__( \
+ "vmmcall\n" \
+ )
+
+#define ud2() \
+ __asm__ __volatile__( \
+ "ud2\n" \
+ )
+
+#define hlt() \
+ __asm__ __volatile__( \
+ "hlt\n" \
+ )
+
bool is_intel_cpu(void);
bool is_amd_cpu(void);

diff --git a/tools/testing/selftests/kvm/include/x86_64/svm_util.h b/tools/testing/selftests/kvm/include/x86_64/svm_util.h
index a25aabd8f5e7..136ba6a5d027 100644
--- a/tools/testing/selftests/kvm/include/x86_64/svm_util.h
+++ b/tools/testing/selftests/kvm/include/x86_64/svm_util.h
@@ -16,6 +16,8 @@
#define CPUID_SVM_BIT 2
#define CPUID_SVM BIT_ULL(CPUID_SVM_BIT)

+#define SVM_EXIT_EXCP_BASE 0x040
+#define SVM_EXIT_HLT 0x078
#define SVM_EXIT_MSR 0x07c
#define SVM_EXIT_VMMCALL 0x081

@@ -36,6 +38,16 @@ struct svm_test_data {
uint64_t msr_gpa;
};

+#define stgi() \
+ __asm__ __volatile__( \
+ "stgi\n" \
+ )
+
+#define clgi() \
+ __asm__ __volatile__( \
+ "clgi\n" \
+ )
+
struct svm_test_data *vcpu_alloc_svm(struct kvm_vm *vm, vm_vaddr_t *p_svm_gva);
void generic_svm_setup(struct svm_test_data *svm, void *guest_rip, void *guest_rsp);
void run_guest(struct vmcb *vmcb, uint64_t vmcb_gpa);
diff --git a/tools/testing/selftests/kvm/x86_64/svm_nested_soft_inject_test.c b/tools/testing/selftests/kvm/x86_64/svm_nested_soft_inject_test.c
new file mode 100644
index 000000000000..f94f1b449aef
--- /dev/null
+++ b/tools/testing/selftests/kvm/x86_64/svm_nested_soft_inject_test.c
@@ -0,0 +1,217 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2022 Oracle and/or its affiliates.
+ *
+ * Based on:
+ * svm_int_ctl_test
+ *
+ * Copyright (C) 2021, Red Hat, Inc.
+ *
+ */
+
+#include <stdatomic.h>
+#include <stdio.h>
+#include <unistd.h>
+#include "apic.h"
+#include "kvm_util.h"
+#include "processor.h"
+#include "svm_util.h"
+#include "test_util.h"
+#include "../lib/kvm_util_internal.h"
+
+#define VCPU_ID 0
+#define INT_NR 0x20
+#define X86_FEATURE_NRIPS BIT(3)
+
+static_assert(ATOMIC_INT_LOCK_FREE == 2, "atomic int is not lockless");
+
+static unsigned int bp_fired;
+static void guest_bp_handler(struct ex_regs *regs)
+{
+ bp_fired++;
+}
+
+static unsigned int int_fired;
+static void l2_guest_code_int(void);
+
+static void guest_int_handler(struct ex_regs *regs)
+{
+ int_fired++;
+ GUEST_ASSERT_2(regs->rip == (unsigned long)l2_guest_code_int,
+ regs->rip, (unsigned long)l2_guest_code_int);
+}
+
+static void l2_guest_code_int(void)
+{
+ GUEST_ASSERT_1(int_fired == 1, int_fired);
+ vmmcall();
+ ud2();
+
+ GUEST_ASSERT_1(bp_fired == 1, bp_fired);
+ hlt();
+}
+
+static atomic_int nmi_stage;
+#define nmi_stage_get() atomic_load_explicit(&nmi_stage, memory_order_acquire)
+#define nmi_stage_inc() atomic_fetch_add_explicit(&nmi_stage, 1, memory_order_acq_rel)
+static void guest_nmi_handler(struct ex_regs *regs)
+{
+ nmi_stage_inc();
+
+ if (nmi_stage_get() == 1) {
+ vmmcall();
+ GUEST_ASSERT(false);
+ } else {
+ GUEST_ASSERT_1(nmi_stage_get() == 3, nmi_stage_get());
+ GUEST_DONE();
+ }
+}
+
+static void l2_guest_code_nmi(void)
+{
+ ud2();
+}
+
+static void l1_guest_code(struct svm_test_data *svm, uint64_t is_nmi, uint64_t idt_alt)
+{
+ #define L2_GUEST_STACK_SIZE 64
+ unsigned long l2_guest_stack[L2_GUEST_STACK_SIZE];
+ struct vmcb *vmcb = svm->vmcb;
+
+ if (is_nmi)
+ x2apic_enable();
+
+ /* Prepare for L2 execution. */
+ generic_svm_setup(svm,
+ is_nmi ? l2_guest_code_nmi : l2_guest_code_int,
+ &l2_guest_stack[L2_GUEST_STACK_SIZE]);
+
+ vmcb->control.intercept_exceptions |= BIT(PF_VECTOR) | BIT(UD_VECTOR);
+ vmcb->control.intercept |= BIT(INTERCEPT_NMI) | BIT(INTERCEPT_HLT);
+
+ if (is_nmi) {
+ vmcb->control.event_inj = SVM_EVTINJ_VALID | SVM_EVTINJ_TYPE_NMI;
+ } else {
+ vmcb->control.event_inj = INT_NR | SVM_EVTINJ_VALID | SVM_EVTINJ_TYPE_SOFT;
+ /* The return address pushed on stack */
+ vmcb->control.next_rip = vmcb->save.rip;
+ }
+
+ run_guest(vmcb, svm->vmcb_gpa);
+ GUEST_ASSERT_3(vmcb->control.exit_code == SVM_EXIT_VMMCALL,
+ vmcb->control.exit_code,
+ vmcb->control.exit_info_1, vmcb->control.exit_info_2);
+
+ if (is_nmi) {
+ clgi();
+ x2apic_write_reg(APIC_ICR, APIC_DEST_SELF | APIC_INT_ASSERT | APIC_DM_NMI);
+
+ GUEST_ASSERT_1(nmi_stage_get() == 1, nmi_stage_get());
+ nmi_stage_inc();
+
+ stgi();
+ /* self-NMI happens here */
+ while (true)
+ cpu_relax();
+ }
+
+ /* Skip over VMMCALL */
+ vmcb->save.rip += 3;
+
+ /* Switch to alternate IDT to cause intervening NPF again */
+ vmcb->save.idtr.base = idt_alt;
+ vmcb->control.clean = 0; /* &= ~BIT(VMCB_DT) would be enough */
+
+ vmcb->control.event_inj = BP_VECTOR | SVM_EVTINJ_VALID | SVM_EVTINJ_TYPE_EXEPT;
+ /* The return address pushed on stack, skip over UD2 */
+ vmcb->control.next_rip = vmcb->save.rip + 2;
+
+ run_guest(vmcb, svm->vmcb_gpa);
+ GUEST_ASSERT_3(vmcb->control.exit_code == SVM_EXIT_HLT,
+ vmcb->control.exit_code,
+ vmcb->control.exit_info_1, vmcb->control.exit_info_2);
+
+ GUEST_DONE();
+}
+
+static void run_test(bool is_nmi)
+{
+ struct kvm_vm *vm;
+ vm_vaddr_t svm_gva;
+ vm_vaddr_t idt_alt_vm;
+ struct kvm_guest_debug debug;
+
+ pr_info("Running %s test\n", is_nmi ? "NMI" : "soft int");
+
+ vm = vm_create_default(VCPU_ID, 0, (void *) l1_guest_code);
+
+ vm_init_descriptor_tables(vm);
+ vcpu_init_descriptor_tables(vm, VCPU_ID);
+
+ vm_install_exception_handler(vm, NMI_VECTOR, guest_nmi_handler);
+ vm_install_exception_handler(vm, BP_VECTOR, guest_bp_handler);
+ vm_install_exception_handler(vm, INT_NR, guest_int_handler);
+
+ vcpu_alloc_svm(vm, &svm_gva);
+
+ if (!is_nmi) {
+ void *idt, *idt_alt;
+
+ idt_alt_vm = vm_vaddr_alloc_page(vm);
+ idt_alt = addr_gva2hva(vm, idt_alt_vm);
+ idt = addr_gva2hva(vm, vm->idt);
+ memcpy(idt_alt, idt, getpagesize());
+ } else {
+ idt_alt_vm = 0;
+ }
+ vcpu_args_set(vm, VCPU_ID, 3, svm_gva, (uint64_t)is_nmi, (uint64_t)idt_alt_vm);
+
+ memset(&debug, 0, sizeof(debug));
+ vcpu_set_guest_debug(vm, VCPU_ID, &debug);
+
+ struct kvm_run *run = vcpu_state(vm, VCPU_ID);
+ struct ucall uc;
+
+ alarm(2);
+ vcpu_run(vm, VCPU_ID);
+ alarm(0);
+ TEST_ASSERT(run->exit_reason == KVM_EXIT_IO,
+ "Got exit_reason other than KVM_EXIT_IO: %u (%s)\n",
+ 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, vals = 0x%lx 0x%lx 0x%lx", (const char *)uc.args[0],
+ __FILE__, uc.args[1], uc.args[2], uc.args[3], uc.args[4]);
+ break;
+ /* NOT REACHED */
+ case UCALL_DONE:
+ goto done;
+ default:
+ TEST_FAIL("Unknown ucall 0x%lx.", uc.cmd);
+ }
+done:
+ kvm_vm_free(vm);
+}
+
+int main(int argc, char *argv[])
+{
+ struct kvm_cpuid_entry2 *cpuid;
+
+ /* Tell stdout not to buffer its content */
+ setbuf(stdout, NULL);
+
+ nested_svm_check_supported();
+
+ cpuid = kvm_get_supported_cpuid_entry(0x8000000a);
+ TEST_ASSERT(cpuid->edx & X86_FEATURE_NRIPS,
+ "KVM with nSVM is supposed to unconditionally advertise nRIP Save\n");
+
+ atomic_init(&nmi_stage, 0);
+
+ run_test(false);
+ run_test(true);
+
+ return 0;
+}
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