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KVM: selftest: Add a selftest for VMRUN/#VMEXIT with unmappable vmcb12

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Add a test that verifies that KVM correctly injects a #GP for nested
VMRUN and a shutdown for nested #VMEXIT, if the GPA of vmcb12 cannot be
mapped.

Signed-off-by: Yosry Ahmed <yosry@kernel.org>
Link: https://patch.msgid.link/20260303003421.2185681-27-yosry@kernel.org
Signed-off-by: Sean Christopherson <seanjc@google.com>
This commit is contained in:
Yosry Ahmed 2026-03-03 00:34:20 +00:00 committed by Sean Christopherson
parent b6dc21d896
commit 5e4c6da0bb
2 changed files with 99 additions and 0 deletions
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1
tools/testing/selftests/kvm/Makefile.kvm
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@ -110,6 +110,7 @@ TEST_GEN_PROGS_x86 += x86/state_test
TEST_GEN_PROGS_x86 += x86/vmx_preemption_timer_test
TEST_GEN_PROGS_x86 += x86/svm_vmcall_test
TEST_GEN_PROGS_x86 += x86/svm_int_ctl_test
TEST_GEN_PROGS_x86 += x86/svm_nested_invalid_vmcb12_gpa
TEST_GEN_PROGS_x86 += x86/svm_nested_shutdown_test
TEST_GEN_PROGS_x86 += x86/svm_nested_soft_inject_test
TEST_GEN_PROGS_x86 += x86/svm_lbr_nested_state

98
tools/testing/selftests/kvm/x86/svm_nested_invalid_vmcb12_gpa.c Normal file
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@ -0,0 +1,98 @@
// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright (C) 2026, Google LLC.
*/
#include "kvm_util.h"
#include "vmx.h"
#include "svm_util.h"
#include "kselftest.h"
#define L2_GUEST_STACK_SIZE 64
#define SYNC_GP 101
#define SYNC_L2_STARTED 102
u64 valid_vmcb12_gpa;
int gp_triggered;
static void guest_gp_handler(struct ex_regs *regs)
{
GUEST_ASSERT(!gp_triggered);
GUEST_SYNC(SYNC_GP);
gp_triggered = 1;
regs->rax = valid_vmcb12_gpa;
}
static void l2_guest_code(void)
{
GUEST_SYNC(SYNC_L2_STARTED);
vmcall();
}
static void l1_guest_code(struct svm_test_data *svm, u64 invalid_vmcb12_gpa)
{
unsigned long l2_guest_stack[L2_GUEST_STACK_SIZE];
generic_svm_setup(svm, l2_guest_code,
&l2_guest_stack[L2_GUEST_STACK_SIZE]);
valid_vmcb12_gpa = svm->vmcb_gpa;
run_guest(svm->vmcb, invalid_vmcb12_gpa); /* #GP */
/* GP handler should jump here */
GUEST_ASSERT(svm->vmcb->control.exit_code == SVM_EXIT_VMMCALL);
GUEST_DONE();
}
int main(int argc, char *argv[])
{
struct kvm_x86_state *state;
vm_vaddr_t nested_gva = 0;
struct kvm_vcpu *vcpu;
uint32_t maxphyaddr;
u64 max_legal_gpa;
struct kvm_vm *vm;
struct ucall uc;
TEST_REQUIRE(kvm_cpu_has(X86_FEATURE_SVM));
vm = vm_create_with_one_vcpu(&vcpu, l1_guest_code);
vm_install_exception_handler(vcpu->vm, GP_VECTOR, guest_gp_handler);
/*
* Find the max legal GPA that is not backed by a memslot (i.e. cannot
* be mapped by KVM).
*/
maxphyaddr = kvm_cpuid_property(vcpu->cpuid, X86_PROPERTY_MAX_PHY_ADDR);
max_legal_gpa = BIT_ULL(maxphyaddr) - PAGE_SIZE;
vcpu_alloc_svm(vm, &nested_gva);
vcpu_args_set(vcpu, 2, nested_gva, max_legal_gpa);
/* VMRUN with max_legal_gpa, KVM injects a #GP */
vcpu_run(vcpu);
TEST_ASSERT_KVM_EXIT_REASON(vcpu, KVM_EXIT_IO);
TEST_ASSERT_EQ(get_ucall(vcpu, &uc), UCALL_SYNC);
TEST_ASSERT_EQ(uc.args[1], SYNC_GP);
/*
* Enter L2 (with a legit vmcb12 GPA), then overwrite vmcb12 GPA with
* max_legal_gpa. KVM will fail to map vmcb12 on nested VM-Exit and
* cause a shutdown.
*/
vcpu_run(vcpu);
TEST_ASSERT_KVM_EXIT_REASON(vcpu, KVM_EXIT_IO);
TEST_ASSERT_EQ(get_ucall(vcpu, &uc), UCALL_SYNC);
TEST_ASSERT_EQ(uc.args[1], SYNC_L2_STARTED);
state = vcpu_save_state(vcpu);
state->nested.hdr.svm.vmcb_pa = max_legal_gpa;
vcpu_load_state(vcpu, state);
vcpu_run(vcpu);
TEST_ASSERT_KVM_EXIT_REASON(vcpu, KVM_EXIT_SHUTDOWN);
kvm_x86_state_cleanup(state);
kvm_vm_free(vm);
return 0;
}