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[WIP] usdm: add hugepage allocation fallback for VFIO #145

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gcabiddu wants to merge 1 commit into from
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[WIP] usdm: add hugepage allocation fallback for VFIO #145

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2 changes: 1 addition & 1 deletion quickassist/utilities/libusdm_drv/user_space/qae_mem_common.c
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Original file line number Diff line number Diff line change
Expand Up @@ -413,7 +413,7 @@ void *__qae_alloc_addr(size_t size,
p_ctrl_blk->virt_addr,
p_ctrl_blk->phy_addr,
p_ctrl_blk->size,
__qae_hugepage_enabled());
HUGE_PAGE == p_ctrl_blk->type);

if (LARGE == mem_type)
{
Expand Down
3 changes: 3 additions & 0 deletions quickassist/utilities/libusdm_drv/user_space/qae_mem_hugepage_utils.h
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Original file line number Diff line number Diff line change
Expand Up @@ -57,4 +57,7 @@ int __qae_vfio_init_hugepages(void);

API_LOCAL
int __qae_hugepage_enabled(void);

API_LOCAL
int __qae_vfio_disable_hugepages(void);
#endif
44 changes: 44 additions & 0 deletions quickassist/utilities/libusdm_drv/user_space/vfio/qae_mem_hugepage_utils_vfio.c
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Original file line number Diff line number Diff line change
Expand Up @@ -41,6 +41,7 @@
#endif

static bool g_hugepages_enabled = false;
static bool g_hugepages_allocated = false;
static size_t g_num_hugepages = 0;
static const char sys_dir_path[] = "/sys/kernel/mm/hugepages";
extern int vfio_container_fd;
Expand Down Expand Up @@ -197,10 +198,30 @@ STATIC int mem_virt2phy(const void *virtaddr, uint64_t *physaddr_ptr)
API_LOCAL
int __qae_vfio_init_hugepages()
{
char free_hp_path[HUGEPAGE_SYSFS_PATH_SIZE] = { };
unsigned long free_hp = 0;
int ret = 0;

if (get_num_hugepages_per_system(HUGEPAGE_SYS_NODE))
return -EIO;

if (g_num_hugepages > 0)
{
/*
* Check if any hugepages are actually free.
* If all hugepages are consumed (e.g. by DPDK), do not enable
* hugepage mode to avoid allocation failures at runtime.
*/
snprintf(free_hp_path, sizeof(free_hp_path), "%s/%s/free_hugepages",
sys_dir_path, HUGEPAGE_SYS_NODE);
if (parse_sysfs_value(free_hp_path, &free_hp) == 0 && free_hp == 0)
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@fionatrahe fionatrahe Mar 3, 2026

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If the parse fails (returns -1) g_num_hugepages will not be set to 0 here. Shouldn't the logic be:

if (parse... == 0)
    {
    if (free_hp == 0)
        g_num_hugepages = 0;
    }
else // failed to parse the free_hugepages value
    {
    g_num_hugepages = 0;
    }

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@gcabiddu gcabiddu Mar 3, 2026

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Yes, right. Can be written:

ret = parse_sysfs_value(free_hp_path, &free_hp);
if (ret || ret == 0 && free_hp == 0) {
    g_num_hugepages = 0;
}

This way the return value can be preserved and returned to the calleer.

{
CMD_DEBUG("No free hugepages available (nr_hugepages=%zu). "
"Disabling hugepage mode.\n", g_num_hugepages);
g_num_hugepages = 0;
}
}

if (g_num_hugepages > 0)
{
g_hugepages_enabled = true;
Expand All @@ -224,6 +245,27 @@ int __qae_hugepage_enabled()
return g_hugepages_enabled;
}

API_LOCAL
int __qae_vfio_disable_hugepages()
{
if (g_hugepages_allocated)
{
CMD_ERROR("Hugepage allocation failed but hugepage slabs already "
"exist. Cannot fall back to regular memory.\n");
return 0;
}

CMD_DEBUG("Hugepage allocation failed, disabling hugepage mode. "
"Falling back to regular memory allocation.\n");

g_hugepages_enabled = false;
__qae_set_free_page_table_fptr(free_page_table);
__qae_set_loadaddr_fptr(load_addr);
__qae_set_loadkey_fptr(load_key);

return 1;
}

STATIC void *__qae_vfio_hugepage_mmap_addr(const size_t size)
{
void *addr = NULL;
Expand Down Expand Up @@ -350,6 +392,7 @@ dev_mem_info_t *__qae_vfio_hugepage_alloc_slab(const int fd,
save_slab_to_tmp_list(slab);
#endif
/* This is required for adding into hash table.*/
g_hugepages_allocated = true;
return slab;
}

Expand Down Expand Up @@ -377,6 +420,7 @@ dev_mem_info_t *__qae_vfio_hugepage_alloc_slab(const int fd,
slab->flag_pinned = PINNED;
#endif

g_hugepages_allocated = true;
return slab;

error:
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4 changes: 4 additions & 0 deletions quickassist/utilities/libusdm_drv/user_space/vfio/qae_mem_utils_vfio.c
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Original file line number Diff line number Diff line change
Expand Up @@ -548,6 +548,8 @@ dev_mem_info_t *__qae_alloc_slab(const int fd,
if (HUGE_PAGE == type)
{
slab = __qae_vfio_hugepage_alloc_slab(fd, size, node, type, alignment);
if (!slab && __qae_vfio_disable_hugepages())
slab = ioctl_alloc_slab(fd, size, alignment, node, SMALL);
}
else
{
Expand Down Expand Up @@ -580,6 +582,8 @@ dev_mem_info_t *__qae_alloc_slab(const int fd,
if (HUGE_PAGE == type)
{
slab = __qae_vfio_hugepage_alloc_slab(fd, size, node, type, alignment);
if (!slab && __qae_vfio_disable_hugepages())
slab = ioctl_alloc_slab(fd, size, alignment, node, SMALL);
}
else
{
Expand Down
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