cxl/test: Enforce PMD alignment for volatile mock regions

cxl_test allocates synthetic CFMWS HPA windows from a gen_pool with
SZ_256M alignment. On arm64 with CONFIG_ARM64_64K_PAGES=y and
CONFIG_PGTABLE_LEVELS=3, PMD_SIZE is 512M, so every CXL region carved
from a volatile window inherits a non-PMD-aligned start, and
cxl_dax_region_probe() -> alloc_dax_region() fails:

"""
    cxl_dax_region dax_region1: probe with driver cxl_dax_region failed
                                with error -12
"""

Enforce that every volatile mock CFMWS is PMD-aligned in both start and
size

Reviewed-by: Dave Jiang <dave.jiang@intel.com>
Acked-by: Kai-Heng Feng <kaihengf@nvidia.com>
Signed-off-by: Richard Cheng <icheng@nvidia.com>
Reviewed-by: Alison Schofield <alison.schofield@intel.com>
Link: https://patch.msgid.link/20260527090332.30002-1-icheng@nvidia.com
Signed-off-by: Dave Jiang <dave.jiang@intel.com>

diff --git a/tools/testing/cxl/test/cxl.c b/tools/testing/cxl/test/cxl.c
index 296516eecfd6af1aff7b2604ba32985b1fc0f101..4281d34cd0e7498f6aeb10ac155a729fd2fbf05b 100644 (file)
--- a/tools/testing/cxl/test/cxl.c
+++ b/tools/testing/cxl/test/cxl.c
@@ -318,7 +318,7 @@ static struct {
                        .restrictions = ACPI_CEDT_CFMWS_RESTRICT_HOSTONLYMEM |
                                        ACPI_CEDT_CFMWS_RESTRICT_VOLATILE,
                        .qtg_id = FAKE_QTG_ID,
-                       .window_size = SZ_256M,
+                       .window_size = SZ_256M > PMD_SIZE ? SZ_256M : PMD_SIZE,
                },
                .target = { 3 },
        },
@@ -495,9 +495,12 @@ static int populate_cedt(void)
 
        for (i = cfmws_start; i <= cfmws_end; i++) {
                struct acpi_cedt_cfmws *window = mock_cfmws[i];
+               int align = SZ_256M;
 
                cfmws_elc_update(window, i);
-               res = alloc_mock_res(window->window_size, SZ_256M);
+               if (window->restrictions & ACPI_CEDT_CFMWS_RESTRICT_VOLATILE)
+                       align = max_t(int, SZ_256M, PMD_SIZE);
+               res = alloc_mock_res(window->window_size, align);
                if (!res)
                        return -ENOMEM;
                window->base_hpa = res->range.start;
@@ -1819,6 +1822,12 @@ static __init int cxl_test_init(void)
        int rc, i;
        struct range mappable;
 
+       if (!IS_ALIGNED(mock_auto_region_size, PMD_SIZE)) {
+               pr_err_once("mock_auto_region_size %d must be PMD-aligned\n",
+                           mock_auto_region_size);
+               return -EINVAL;
+       }
+
        cxl_acpi_test();
        cxl_core_test();
        cxl_mem_test();