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KVM: selftests: test behavior of unmapped L2 APIC-access address 

Add a regression test for commit 671ddc700f ("KVM: nVMX: Don't leak
L1 MMIO regions to L2").

First, check to see that an L2 guest can be launched with a valid
APIC-access address that is backed by a page of L1 physical memory.

Next, set the APIC-access address to a (valid) L1 physical address
that is not backed by memory. KVM can't handle this situation, so
resuming L2 should result in a KVM exit for internal error
(emulation).

Signed-off-by: Jim Mattson <jmattson@google.com>
Reviewed-by: Ricardo Koller <ricarkol@google.com>
Reviewed-by: Peter Shier <pshier@google.com>
Message-Id: <20201026180922.3120555-1-jmattson@google.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This commit is contained in:
Jim Mattson 2020-10-26 11:09:22 -07:00 committed by Paolo Bonzini
parent d383b3146d
commit 97a71a5455
5 changed files with 159 additions and 0 deletions
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1
tools/testing/selftests/kvm/.gitignore vendored
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@ -15,6 +15,7 @@
/x86_64/vmx_preemption_timer_test
/x86_64/svm_vmcall_test
/x86_64/sync_regs_test
/x86_64/vmx_apic_access_test
/x86_64/vmx_close_while_nested_test
/x86_64/vmx_dirty_log_test
/x86_64/vmx_set_nested_state_test

1
tools/testing/selftests/kvm/Makefile
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@ -49,6 +49,7 @@ 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/sync_regs_test
TEST_GEN_PROGS_x86_64 += x86_64/vmx_apic_access_test
TEST_GEN_PROGS_x86_64 += x86_64/vmx_close_while_nested_test
TEST_GEN_PROGS_x86_64 += x86_64/vmx_dirty_log_test
TEST_GEN_PROGS_x86_64 += x86_64/vmx_set_nested_state_test

6
tools/testing/selftests/kvm/include/x86_64/vmx.h
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@ -573,6 +573,10 @@ struct vmx_pages {
void *eptp_hva;
uint64_t eptp_gpa;
void *eptp;
void *apic_access_hva;
uint64_t apic_access_gpa;
void *apic_access;
};
union vmx_basic {
@ -615,5 +619,7 @@ void nested_map_memslot(struct vmx_pages *vmx, struct kvm_vm *vm,
uint32_t memslot, uint32_t eptp_memslot);
void prepare_eptp(struct vmx_pages *vmx, struct kvm_vm *vm,
uint32_t eptp_memslot);
void prepare_virtualize_apic_accesses(struct vmx_pages *vmx, struct kvm_vm *vm,
uint32_t eptp_memslot);
#endif /* SELFTEST_KVM_VMX_H */

9
tools/testing/selftests/kvm/lib/x86_64/vmx.c
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@ -542,3 +542,12 @@ void prepare_eptp(struct vmx_pages *vmx, struct kvm_vm *vm,
vmx->eptp_hva = addr_gva2hva(vm, (uintptr_t)vmx->eptp);
vmx->eptp_gpa = addr_gva2gpa(vm, (uintptr_t)vmx->eptp);
}
void prepare_virtualize_apic_accesses(struct vmx_pages *vmx, struct kvm_vm *vm,
uint32_t eptp_memslot)
{
vmx->apic_access = (void *)vm_vaddr_alloc(vm, getpagesize(),
0x10000, 0, 0);
vmx->apic_access_hva = addr_gva2hva(vm, (uintptr_t)vmx->apic_access);
vmx->apic_access_gpa = addr_gva2gpa(vm, (uintptr_t)vmx->apic_access);
}

142
tools/testing/selftests/kvm/x86_64/vmx_apic_access_test.c Normal file
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@ -0,0 +1,142 @@
// SPDX-License-Identifier: GPL-2.0-only
/*
* vmx_apic_access_test
*
* Copyright (C) 2020, Google LLC.
*
* This work is licensed under the terms of the GNU GPL, version 2.
*
* The first subtest simply checks to see that an L2 guest can be
* launched with a valid APIC-access address that is backed by a
* page of L1 physical memory.
*
* The second subtest sets the APIC-access address to a (valid) L1
* physical address that is not backed by memory. KVM can't handle
* this situation, so resuming L2 should result in a KVM exit for
* internal error (emulation). This is not an architectural
* requirement. It is just a shortcoming of KVM. The internal error
* is unfortunate, but it's better than what used to happen!
*/
#include "test_util.h"
#include "kvm_util.h"
#include "processor.h"
#include "vmx.h"
#include <string.h>
#include <sys/ioctl.h>
#include "kselftest.h"
#define VCPU_ID 0
/* The virtual machine object. */
static struct kvm_vm *vm;
static void l2_guest_code(void)
{
/* Exit to L1 */
__asm__ __volatile__("vmcall");
}
static void l1_guest_code(struct vmx_pages *vmx_pages, unsigned long high_gpa)
{
#define L2_GUEST_STACK_SIZE 64
unsigned long l2_guest_stack[L2_GUEST_STACK_SIZE];
uint32_t control;
GUEST_ASSERT(prepare_for_vmx_operation(vmx_pages));
GUEST_ASSERT(load_vmcs(vmx_pages));
/* Prepare the VMCS for L2 execution. */
prepare_vmcs(vmx_pages, l2_guest_code,
&l2_guest_stack[L2_GUEST_STACK_SIZE]);
control = vmreadz(CPU_BASED_VM_EXEC_CONTROL);
control |= CPU_BASED_ACTIVATE_SECONDARY_CONTROLS;
vmwrite(CPU_BASED_VM_EXEC_CONTROL, control);
control = vmreadz(SECONDARY_VM_EXEC_CONTROL);
control |= SECONDARY_EXEC_VIRTUALIZE_APIC_ACCESSES;
vmwrite(SECONDARY_VM_EXEC_CONTROL, control);
vmwrite(APIC_ACCESS_ADDR, vmx_pages->apic_access_gpa);
/* Try to launch L2 with the memory-backed APIC-access address. */
GUEST_SYNC(vmreadz(APIC_ACCESS_ADDR));
GUEST_ASSERT(!vmlaunch());
GUEST_ASSERT(vmreadz(VM_EXIT_REASON) == EXIT_REASON_VMCALL);
vmwrite(APIC_ACCESS_ADDR, high_gpa);
/* Try to resume L2 with the unbacked APIC-access address. */
GUEST_SYNC(vmreadz(APIC_ACCESS_ADDR));
GUEST_ASSERT(!vmresume());
GUEST_ASSERT(vmreadz(VM_EXIT_REASON) == EXIT_REASON_VMCALL);
GUEST_DONE();
}
int main(int argc, char *argv[])
{
unsigned long apic_access_addr = ~0ul;
unsigned int paddr_width;
unsigned int vaddr_width;
vm_vaddr_t vmx_pages_gva;
unsigned long high_gpa;
struct vmx_pages *vmx;
bool done = false;
nested_vmx_check_supported();
vm = vm_create_default(VCPU_ID, 0, (void *) l1_guest_code);
vcpu_set_cpuid(vm, VCPU_ID, kvm_get_supported_cpuid());
kvm_get_cpu_address_width(&paddr_width, &vaddr_width);
high_gpa = (1ul << paddr_width) - getpagesize();
if ((unsigned long)DEFAULT_GUEST_PHY_PAGES * getpagesize() > high_gpa) {
print_skip("No unbacked physical page available");
exit(KSFT_SKIP);
}
vmx = vcpu_alloc_vmx(vm, &vmx_pages_gva);
prepare_virtualize_apic_accesses(vmx, vm, 0);
vcpu_args_set(vm, VCPU_ID, 2, vmx_pages_gva, high_gpa);
while (!done) {
volatile struct kvm_run *run = vcpu_state(vm, VCPU_ID);
struct ucall uc;
vcpu_run(vm, VCPU_ID);
if (apic_access_addr == high_gpa) {
TEST_ASSERT(run->exit_reason ==
KVM_EXIT_INTERNAL_ERROR,
"Got exit reason other than KVM_EXIT_INTERNAL_ERROR: %u (%s)\n",
run->exit_reason,
exit_reason_str(run->exit_reason));
TEST_ASSERT(run->internal.suberror ==
KVM_INTERNAL_ERROR_EMULATION,
"Got internal suberror other than KVM_INTERNAL_ERROR_EMULATION: %u\n",
run->internal.suberror);
break;
}
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", (const char *)uc.args[0],
__FILE__, uc.args[1]);
/* NOT REACHED */
case UCALL_SYNC:
apic_access_addr = uc.args[1];
break;
case UCALL_DONE:
done = true;
break;
default:
TEST_ASSERT(false, "Unknown ucall %lu", uc.cmd);
}
}
kvm_vm_free(vm);
return 0;
}