[PATCH v4 19/19] KVM: selftests: Add test for KVM_SET_USER_MEMORY_REGION

[Sean Christopherson <sean.j.christopherson@intel.com>]

Add a KVM selftest to test moving the base gfn of a userspace memory
region.  The test is primarily targeted at x86 to verify its memslot
metadata is correctly updated, but also provides basic functionality
coverage on other architectures.

Signed-off-by: Sean Christopherson <sean.j.christopherson@intel.com>
---
 tools/testing/selftests/kvm/.gitignore        |   1 +
 tools/testing/selftests/kvm/Makefile          |   3 +
 .../testing/selftests/kvm/include/kvm_util.h  |   1 +
 tools/testing/selftests/kvm/lib/kvm_util.c    |  30 ++++
 .../selftests/kvm/set_memory_region_test.c    | 142 ++++++++++++++++++
 5 files changed, 177 insertions(+)
 create mode 100644 tools/testing/selftests/kvm/set_memory_region_test.c

diff --git a/tools/testing/selftests/kvm/.gitignore b/tools/testing/selftests/kvm/.gitignore
index 30072c3f52fb..6f60ceb81440 100644
--- a/tools/testing/selftests/kvm/.gitignore
+++ b/tools/testing/selftests/kvm/.gitignore
@@ -17,3 +17,4 @@
 /clear_dirty_log_test
 /dirty_log_test
 /kvm_create_max_vcpus
+/set_memory_region_test
diff --git a/tools/testing/selftests/kvm/Makefile b/tools/testing/selftests/kvm/Makefile
index 3138a916574a..01c79e02c5b7 100644
--- a/tools/testing/selftests/kvm/Makefile
+++ b/tools/testing/selftests/kvm/Makefile
@@ -29,15 +29,18 @@ TEST_GEN_PROGS_x86_64 += x86_64/xss_msr_test
 TEST_GEN_PROGS_x86_64 += clear_dirty_log_test
 TEST_GEN_PROGS_x86_64 += dirty_log_test
 TEST_GEN_PROGS_x86_64 += kvm_create_max_vcpus
+TEST_GEN_PROGS_x86_64 += set_memory_region_test
 
 TEST_GEN_PROGS_aarch64 += clear_dirty_log_test
 TEST_GEN_PROGS_aarch64 += dirty_log_test
 TEST_GEN_PROGS_aarch64 += kvm_create_max_vcpus
+TEST_GEN_PROGS_aarch64 += set_memory_region_test
 
 TEST_GEN_PROGS_s390x = s390x/memop
 TEST_GEN_PROGS_s390x += s390x/sync_regs_test
 TEST_GEN_PROGS_s390x += dirty_log_test
 TEST_GEN_PROGS_s390x += kvm_create_max_vcpus
+TEST_GEN_PROGS_s390x += set_memory_region_test
 
 TEST_GEN_PROGS += $(TEST_GEN_PROGS_$(UNAME_M))
 LIBKVM += $(LIBKVM_$(UNAME_M))
diff --git a/tools/testing/selftests/kvm/include/kvm_util.h b/tools/testing/selftests/kvm/include/kvm_util.h
index 29cccaf96baf..15d3b8690ffb 100644
--- a/tools/testing/selftests/kvm/include/kvm_util.h
+++ b/tools/testing/selftests/kvm/include/kvm_util.h
@@ -100,6 +100,7 @@ int _vcpu_ioctl(struct kvm_vm *vm, uint32_t vcpuid, unsigned long ioctl,
 		void *arg);
 void vm_ioctl(struct kvm_vm *vm, unsigned long ioctl, void *arg);
 void vm_mem_region_set_flags(struct kvm_vm *vm, uint32_t slot, uint32_t flags);
+void vm_mem_region_move(struct kvm_vm *vm, uint32_t slot, uint64_t new_gpa);
 void vm_vcpu_add(struct kvm_vm *vm, uint32_t vcpuid);
 vm_vaddr_t vm_vaddr_alloc(struct kvm_vm *vm, size_t sz, vm_vaddr_t vaddr_min,
 			  uint32_t data_memslot, uint32_t pgd_memslot);
diff --git a/tools/testing/selftests/kvm/lib/kvm_util.c b/tools/testing/selftests/kvm/lib/kvm_util.c
index 41cf45416060..464a75ce9843 100644
--- a/tools/testing/selftests/kvm/lib/kvm_util.c
+++ b/tools/testing/selftests/kvm/lib/kvm_util.c
@@ -756,6 +756,36 @@ void vm_mem_region_set_flags(struct kvm_vm *vm, uint32_t slot, uint32_t flags)
 		ret, errno, slot, flags);
 }
 
+/*
+ * VM Memory Region Move
+ *
+ * Input Args:
+ *   vm - Virtual Machine
+ *   slot - Slot of the memory region to move
+ *   flags - Starting guest physical address
+ *
+ * Output Args: None
+ *
+ * Return: None
+ *
+ * Change the gpa of a memory region.
+ */
+void vm_mem_region_move(struct kvm_vm *vm, uint32_t slot, uint64_t new_gpa)
+{
+	struct userspace_mem_region *region;
+	int ret;
+
+	region = memslot2region(vm, slot);
+
+	region->region.guest_phys_addr = new_gpa;
+
+	ret = ioctl(vm->fd, KVM_SET_USER_MEMORY_REGION, &region->region);
+
+	TEST_ASSERT(!ret, "KVM_SET_USER_MEMORY_REGION failed\n"
+		    "ret: %i errno: %i slot: %u flags: 0x%x",
+		    ret, errno, slot, new_gpa);
+}
+
 /*
  * VCPU mmap Size
  *
diff --git a/tools/testing/selftests/kvm/set_memory_region_test.c b/tools/testing/selftests/kvm/set_memory_region_test.c
new file mode 100644
index 000000000000..c9603b95ccf7
--- /dev/null
+++ b/tools/testing/selftests/kvm/set_memory_region_test.c
@@ -0,0 +1,142 @@
+// SPDX-License-Identifier: GPL-2.0
+#define _GNU_SOURCE /* for program_invocation_short_name */
+#include <fcntl.h>
+#include <pthread.h>
+#include <sched.h>
+#include <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/ioctl.h>
+
+#include <linux/compiler.h>
+
+#include <test_util.h>
+#include <kvm_util.h>
+#include <processor.h>
+
+#define VCPU_ID 0
+
+/*
+ * Somewhat arbitrary location and slot, intended to not overlap anything.  The
+ * location and size are specifically 2mb sized/aligned so that the initial
+ * region corresponds to exactly one large page (on x86 and arm64).
+ */
+#define MEM_REGION_GPA		0xc0000000
+#define MEM_REGION_SIZE		0x200000
+#define MEM_REGION_SLOT		10
+
+static void guest_code(void)
+{
+	uint64_t val;
+
+	do {
+		val = READ_ONCE(*((uint64_t *)MEM_REGION_GPA));
+	} while (!val);
+
+	if (val != 1)
+		ucall(UCALL_ABORT, 1, val);
+
+	GUEST_DONE();
+}
+
+static void *vcpu_worker(void *data)
+{
+	struct kvm_vm *vm = data;
+	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.
+	 */
+	run = vcpu_state(vm, VCPU_ID);
+	do {
+		vcpu_run(vm, VCPU_ID);
+	} while (run->exit_reason == KVM_EXIT_MMIO);
+
+	TEST_ASSERT(run->exit_reason == KVM_EXIT_IO,
+		    "Unexpected exit reason = %d", run->exit_reason);
+
+	cmd = get_ucall(vm, VCPU_ID, &uc);
+	TEST_ASSERT(cmd == UCALL_DONE, "Unexpected val in guest = %llu",
+		    uc.args[0]);
+	return NULL;
+}
+
+static void test_move_memory_region(void)
+{
+	pthread_t vcpu_thread;
+	struct kvm_vm *vm;
+	uint64_t *hva;
+	uint64_t gpa;
+
+	vm = vm_create_default(VCPU_ID, 0, guest_code);
+
+	vcpu_set_cpuid(vm, VCPU_ID, kvm_get_supported_cpuid());
+
+	vm_userspace_mem_region_add(vm, VM_MEM_SRC_ANONYMOUS_THP,
+				    MEM_REGION_GPA, MEM_REGION_SLOT,
+				    MEM_REGION_SIZE / getpagesize(), 0);
+
+	/*
+	 * Allocate and map two pages so that the GPA accessed by guest_code()
+	 * stays valid across the memslot move.
+	 */
+	gpa = vm_phy_pages_alloc(vm, 2, MEM_REGION_GPA, MEM_REGION_SLOT);
+	TEST_ASSERT(gpa == MEM_REGION_GPA, "Failed vm_phy_pages_alloc\n");
+
+	virt_map(vm, MEM_REGION_GPA, MEM_REGION_GPA, 2 * 4096, 0);
+
+	/* Ditto for the host mapping so that both pages can be zeroed. */
+	hva = addr_gpa2hva(vm, MEM_REGION_GPA);
+	memset(hva, 0, 2 * 4096);
+
+	pthread_create(&vcpu_thread, NULL, vcpu_worker, vm);
+
+	/* Ensure the guest thread is spun up. */
+	usleep(100000);
+
+	/*
+	 * Shift the region's base GPA.  The guest should not see "2" as the
+	 * hva->gpa translation is misaligned, i.e. the guest is accessing a
+	 * different host pfn.
+	 */
+	vm_mem_region_move(vm, MEM_REGION_SLOT, MEM_REGION_GPA - 4096);
+	WRITE_ONCE(*hva, 2);
+
+	usleep(100000);
+
+	/*
+	 * Note, value in memory needs to be changed *before* restoring the
+	 * memslot, else the guest could race the update and see "2".
+	 */
+	WRITE_ONCE(*hva, 1);
+
+	/* Restore the original base, the guest should see "1". */
+	vm_mem_region_move(vm, MEM_REGION_SLOT, MEM_REGION_GPA);
+
+	pthread_join(vcpu_thread, NULL);
+
+	kvm_vm_free(vm);
+}
+
+int main(int argc, char *argv[])
+{
+	int i, loops;
+
+	/* Tell stdout not to buffer its content */
+	setbuf(stdout, NULL);
+
+	if (argc > 1)
+		loops = atoi(argv[1]);
+	else
+		loops = 10;
+
+	for (i = 0; i < loops; i++)
+		test_move_memory_region();
+
+	return 0;
+}
-- 
2.24.1