[PATCH 7/7] KVM: selftests: Add "delete" testcase to set_memory_region_test

Sean Christopherson
2020-03-20T20:55:58Z

Add coverate for running a guest with no memslots, and for deleting
memslots while the guest is running. Enhance the test to use, and
expect, a unique value for MMIO reads, e.g. to verify each stage of
the test.

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
---
.../kvm/x86_64/set_memory_region_test.c | 122 ++++++++++++++++--
1 file changed, 108 insertions(+), 14 deletions(-)

diff --git a/tools/testing/selftests/kvm/x86_64/set_memory_region_test.c b/tools/testing/selftests/kvm/x86_64/set_memory_region_test.c
index c6691cff4e19..44aed8ac932b 100644
--- a/tools/testing/selftests/kvm/x86_64/set_memory_region_test.c
+++ b/tools/testing/selftests/kvm/x86_64/set_memory_region_test.c
@@ -26,42 +26,109 @@
#define MEM_REGION_SIZE 0x200000
#define MEM_REGION_SLOT 10

-static void guest_code(void)
+static const uint64_t MMIO_VAL = 0xbeefull;
+
+extern const uint64_t final_rip_start;
+extern const uint64_t final_rip_end;
+
+static inline uint64_t guest_spin_on_val(uint64_t spin_val)
{
uint64_t val;

do {
val = READ_ONCE(*((uint64_t *)MEM_REGION_GPA));
- } while (!val);
+ } while (val == spin_val);
+ return val;
+}

- if (val != 1)
- ucall(UCALL_ABORT, 1, val);
+static void guest_code(void)
+{
+ uint64_t val;

- GUEST_DONE();
+ /*
+ * Spin until the memory region is moved to a misaligned address. This
+ * may or may not trigger MMIO, as the window where the memslot is
+ * invalid is quite small.
+ */
+ val = guest_spin_on_val(0);
+ GUEST_ASSERT(val == 1 || val == MMIO_VAL);
+
+ /* Spin until the memory region is realigned. */
+ GUEST_ASSERT(guest_spin_on_val(MMIO_VAL) == 1);
+
+ /* Spin until the memory region is deleted. */
+ GUEST_ASSERT(guest_spin_on_val(1) == MMIO_VAL);
+
+ /* Spin until the memory region is recreated. */
+ GUEST_ASSERT(guest_spin_on_val(MMIO_VAL) == 0);
+
+ /* Spin until the memory region is deleted. */
+ GUEST_ASSERT(guest_spin_on_val(0) == MMIO_VAL);
+
+ asm("1:\n\t"
+ ".pushsection .rodata\n\t"
+ ".global final_rip_start\n\t"
+ "final_rip_start: .quad 1b\n\t"
+ ".popsection");
+
+ /* Spin indefinitely (until the code memslot is deleted). */
+ guest_spin_on_val(MMIO_VAL);
+
+ asm("1:\n\t"
+ ".pushsection .rodata\n\t"
+ ".global final_rip_end\n\t"
+ "final_rip_end: .quad 1b\n\t"
+ ".popsection");
+
+ GUEST_ASSERT(0);
}

static void *vcpu_worker(void *data)
{
struct kvm_vm *vm = data;
+ struct kvm_regs regs;
struct kvm_run *run;
struct ucall uc;
- uint64_t cmd;

/*
* Loop until the guest is done. Re-enter the guest on all MMIO exits,
- * which will occur if the guest attempts to access a memslot while it
- * is being moved.
+ * which will occur if the guest attempts to access a memslot after it
+ * has been deleted or while it is being moved .
*/
run = vcpu_state(vm, VCPU_ID);
- do {
+
+ memcpy(run->mmio.data, &MMIO_VAL, 8);
+ while (1) {
vcpu_run(vm, VCPU_ID);
- } while (run->exit_reason == KVM_EXIT_MMIO);
+ if (run->exit_reason != KVM_EXIT_MMIO)
+ break;

- TEST_ASSERT(run->exit_reason == KVM_EXIT_IO,
+ TEST_ASSERT(!run->mmio.is_write, "Unexpected exit mmio write");
+ TEST_ASSERT(run->mmio.len == 8,
+ "Unexpected exit mmio size = %u", run->mmio.len);
+
+ TEST_ASSERT(run->mmio.phys_addr == MEM_REGION_GPA,
+ "Unexpected exit mmio address = 0x%llx",
+ run->mmio.phys_addr);
+ }
+
+ if (run->exit_reason == KVM_EXIT_IO) {
+ (void)get_ucall(vm, VCPU_ID, &uc);
+ TEST_FAIL("%s at %s:%ld",
+ (const char *)uc.args[0], __FILE__, uc.args[1]);
+ }
+
+ TEST_ASSERT(run->exit_reason == KVM_EXIT_SHUTDOWN ||
+ run->exit_reason == KVM_INTERNAL_ERROR_EMULATION,
"Unexpected exit reason = %d", run->exit_reason);

- cmd = get_ucall(vm, VCPU_ID, &uc);
- TEST_ASSERT(cmd == UCALL_DONE, "Unexpected val in guest = %lu", uc.args[0]);
+ vcpu_regs_get(vm, VCPU_ID, &regs);
+
+ TEST_ASSERT(regs.rip >= final_rip_start &&
+ regs.rip < final_rip_end,
+ "Bad rip, expected 0x%lx - 0x%lx, got 0x%llx\n",
+ final_rip_start, final_rip_end, regs.rip);
+
return NULL;
}

@@ -72,6 +139,13 @@ static void test_move_memory_region(void)
uint64_t *hva;
uint64_t gpa;

+ vm = vm_create(VM_MODE_DEFAULT, 0, O_RDWR);
+ vm_vcpu_add(vm, VCPU_ID);
+ /* Fails with ENOSPC because the MMU can't create pages (no slots). */
+ TEST_ASSERT(_vcpu_run(vm, VCPU_ID) == -1 && errno == ENOSPC,
+ "Unexpected error code = %d", errno);
+ kvm_vm_free(vm);
+
vm = vm_create_default(VCPU_ID, 0, guest_code);

vcpu_set_cpuid(vm, VCPU_ID, kvm_get_supported_cpuid());
@@ -105,7 +179,6 @@ static void test_move_memory_region(void)
*/
vm_mem_region_move(vm, MEM_REGION_SLOT, MEM_REGION_GPA - 4096);
WRITE_ONCE(*hva, 2);
-
usleep(100000);

/*
@@ -116,6 +189,27 @@ static void test_move_memory_region(void)

/* Restore the original base, the guest should see "1". */
vm_mem_region_move(vm, MEM_REGION_SLOT, MEM_REGION_GPA);
+ usleep(100000);
+
+ /* Delete the memory region, the guest should not die. */
+ vm_mem_region_delete(vm, MEM_REGION_SLOT);
+ usleep(100000);
+
+ /* Recreate the memory region. The guest should see "0". */
+ vm_userspace_mem_region_add(vm, VM_MEM_SRC_ANONYMOUS_THP,
+ MEM_REGION_GPA, MEM_REGION_SLOT,
+ MEM_REGION_SIZE / getpagesize(), 0);
+ usleep(100000);
+
+ /* Delete the region again so that there's only one memslot left. */
+ vm_mem_region_delete(vm, MEM_REGION_SLOT);
+ usleep(100000);
+
+ /*
+ * Delete the primary memslot. This should cause an emulation error or
+ * shutdown due to the page tables getting nuked.
+ */
+ vm_mem_region_delete(vm, VM_PRIMARY_MEM_SLOT);

pthread_join(vcpu_thread, NULL);

--
2.24.1