[PATCH i-g-t v9 3/8] tests/intel/xe_madvise: Add purged-mmap-blocked subtest

[Arvind Yadav <arvind.yadav@intel.com>]

Add a new purged-mmap-blocked subtest that triggers an actual purge
via memory pressure and verifies that mmap() fails with -EINVAL once
the BO backing store has been permanently discarded.

The purgeable check moved from xe_gem_mmap_offset_ioctl()
into a new xe_gem_object_mmap() callback, so the blocking point is now
mmap() itself rather than the mmap offset ioctl:

  - DRM_IOCTL_XE_GEM_MMAP_OFFSET: always succeeds regardless of
    purgeable state (just returns the pre-allocated offset)
  - mmap() on DONTNEED BO: fails with -EBUSY (temporary state)
  - mmap() on purged BO: fails with -EINVAL (permanent, no backing store)

v5:
  - Add purged-mmap-blocked subtest to verify mmap is blocked after
    BO backing store is permanently purged.

v6:
  - DRM_IOCTL_XE_GEM_MMAP_OFFSET always succeeds; the purgeable check
    now happens in xe_gem_object_mmap() at mmap() time. For purged BOs,
    assert mmap() fails with -EINVAL.

v7:
  - Moved trigger_memory_pressure() and purgeable_mark_and_verify_purged()
    here. (Nishit)
  - Use xe_has_vram() instead of checking xe_visible_vram_size() > 0 for
    clearer dGPU/iGPU detection. (Nishit)
  - Fix purgeable_mark_and_verify_purged(): handle retained == 0 from
    DONTNEED (BO already purged) as success instead of incorrectly
    returning false. (Nishit)
  - Drop unused vm parameter from trigger_memory_pressure(). (Nishit)

Cc: Matthew Brost <matthew.brost@intel.com>
Cc: Thomas Hellström <thomas.hellstrom@linux.intel.com>
Cc: Himal Prasad Ghimiray <himal.prasad.ghimiray@intel.com>
Cc: Pravalika Gurram <pravalika.gurram@intel.com>
Reviewed-by: Nishit Sharma <nishit.sharma@intel.com>
Signed-off-by: Arvind Yadav <arvind.yadav@intel.com>
---
 tests/intel/xe_madvise.c | 136 +++++++++++++++++++++++++++++++++++++++
 1 file changed, 136 insertions(+)

diff --git a/tests/intel/xe_madvise.c b/tests/intel/xe_madvise.c
index 2c8c27fa9..619d64b46 100644
--- a/tests/intel/xe_madvise.c
+++ b/tests/intel/xe_madvise.c
@@ -59,6 +59,136 @@ static void purgeable_setup_simple_bo(int fd, uint32_t *vm, uint32_t *bo,
 	xe_wait_ufence(fd, &sync_val, 1, 0, NSEC_PER_SEC);
 }
 
+/**
+ * trigger_memory_pressure - Fill VRAM/RAM + 50% to force purgeable reclaim
+ * @fd: DRM file descriptor
+ *
+ * Allocates BOs in a temporary VM until memory is overcommitted by 50%,
+ * forcing the kernel to purge DONTNEED-marked BOs.
+ */
+static void trigger_memory_pressure(int fd)
+{
+	uint64_t mem_size, overpressure;
+	const uint64_t chunk = 8ull << 20; /* 8 MiB */
+	int max_objs, n = 0;
+	uint32_t *handles;
+	uint64_t total;
+	void *p;
+	uint32_t handle, vm;
+
+	/* Use a separate VM so pressure BOs don't affect the test VM */
+	vm = xe_vm_create(fd, 0, 0);
+
+	/* Purgeable BOs reside in VRAM (dGPU) or system memory (iGPU) */
+	mem_size = xe_has_vram(fd) ? xe_visible_vram_size(fd, 0) :
+		   igt_get_total_ram_mb() << 20;
+
+	/* Scale overpressure to 50% of memory, minimum 64MB */
+	overpressure = mem_size / 2;
+	if (overpressure < (64 << 20))
+		overpressure = 64 << 20;
+
+	max_objs = (mem_size + overpressure) / chunk + 1;
+	handles = malloc(max_objs * sizeof(*handles));
+	igt_assert(handles);
+
+	total = 0;
+	while (total < mem_size + overpressure && n < max_objs) {
+		uint32_t err;
+
+		err = __xe_bo_create(fd, vm, chunk,
+				     vram_if_possible(fd, 0),
+				     DRM_XE_GEM_CREATE_FLAG_NEEDS_VISIBLE_VRAM,
+				     NULL, &handle);
+		if (err) /* Out of memory — sufficient pressure achieved */
+			break;
+
+		handles[n++] = handle;
+		total += chunk;
+
+		p = xe_bo_map(fd, handle, chunk);
+		igt_assert(p != MAP_FAILED);
+
+		/* Fault in all pages so they actually consume memory */
+		memset(p, 0xCD, chunk);
+		munmap(p, chunk);
+	}
+
+	/* Allow shrinker time to process pressure */
+	usleep(100000);
+
+	for (int i = 0; i < n; i++)
+		gem_close(fd, handles[i]);
+
+	free(handles);
+
+	xe_vm_destroy(fd, vm);
+}
+
+/**
+ * purgeable_mark_and_verify_purged - Mark DONTNEED, pressure, check purged
+ * @fd: DRM file descriptor
+ * @vm: VM handle
+ * @addr: Virtual address of the BO
+ * @size: Size of the BO
+ *
+ * Returns true if the BO was purged under memory pressure.
+ */
+static bool purgeable_mark_and_verify_purged(int fd, uint32_t vm, uint64_t addr, size_t size)
+{
+	uint32_t retained;
+
+	/* Mark as DONTNEED */
+	retained = xe_vm_madvise_purgeable(fd, vm, addr, size,
+					   DRM_XE_VMA_PURGEABLE_STATE_DONTNEED);
+	if (retained == 0)
+		return true; /* Already purged */
+
+	/* Trigger memory pressure */
+	trigger_memory_pressure(fd);
+
+	/* Verify purged */
+	retained = xe_vm_madvise_purgeable(fd, vm, addr, size,
+					   DRM_XE_VMA_PURGEABLE_STATE_WILLNEED);
+	return retained == 0;
+}
+
+/**
+ * SUBTEST: purged-mmap-blocked
+ * Description: After BO is purged, verify mmap() fails with -EINVAL
+ * Test category: functionality test
+ */
+static void test_purged_mmap_blocked(int fd)
+{
+	uint32_t bo, vm;
+	uint64_t addr = PURGEABLE_ADDR;
+	size_t bo_size = PURGEABLE_BO_SIZE;
+	struct drm_xe_gem_mmap_offset mmo = {};
+	void *ptr;
+
+	purgeable_setup_simple_bo(fd, &vm, &bo, addr, bo_size, false);
+	if (!purgeable_mark_and_verify_purged(fd, vm, addr, bo_size)) {
+		gem_close(fd, bo);
+		xe_vm_destroy(fd, vm);
+		igt_skip("Unable to induce purge on this platform/config");
+	}
+
+	/*
+	 * Getting the mmap offset is always allowed regardless of purgeable
+	 * state - the blocking happens at mmap() time (xe_gem_object_mmap).
+	 * For a purged BO, mmap() must fail with -EINVAL (no backing store).
+	 */
+	mmo.handle = bo;
+	igt_assert_eq(igt_ioctl(fd, DRM_IOCTL_XE_GEM_MMAP_OFFSET, &mmo), 0);
+
+	ptr = mmap(NULL, bo_size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, mmo.offset);
+	igt_assert_eq_u64((uint64_t)ptr, (uint64_t)MAP_FAILED);
+	igt_assert_eq(errno, EINVAL);
+
+	gem_close(fd, bo);
+	xe_vm_destroy(fd, vm);
+}
+
 /**
  * SUBTEST: dontneed-before-mmap
  * Description: Mark BO as DONTNEED before mmap, verify mmap() fails with -EBUSY
@@ -115,6 +245,12 @@ int igt_main()
 			break;
 		}
 
+	igt_subtest("purged-mmap-blocked")
+		xe_for_each_engine(fd, hwe) {
+			test_purged_mmap_blocked(fd);
+			break;
+		}
+
 	igt_fixture() {
 		xe_device_put(fd);
 		drm_close_driver(fd);
-- 
2.43.0