[PATCH v12 2/4] drm/xe/vf: Shifting GGTT area post migration
Tomasz Lis
tomasz.lis at intel.com
Fri Apr 18 14:10:33 UTC 2025
We have only one GGTT for all IOV functions, with each VF having assigned
a range of addresses for its use. After migration, a VF can receive a
different range of addresses than it had initially.
This implements shifting GGTT addresses within drm_mm nodes, so that
VMAs stay valid after migration. This will make the driver use new
addresses when accessing GGTT from the moment the shifting ends.
By taking the ggtt->lock for the period of VMA fixups, this change
also adds constraint on that mutex. Any locks used during the recovery
cannot ever wait for hardware response - because after migration,
the hardware will not do anything until fixups are finished.
v2: Moved some functs to xe_ggtt.c; moved shift computation to just
after querying; improved documentation; switched some warns to asserts;
skipping fixups when GGTT shift eq 0; iterating through tiles (Michal)
v3: Updated kerneldocs, removed unused funct, properly allocate
balloning nodes if non existent
v4: Re-used ballooning functions from VF init, used bool in place of
standard error codes
v5: Renamed one function
v6: Subject tag change, several kerneldocs updated, some functions
renamed, some moved, added several asserts, shuffled declarations
of variables, revealed more detail in high level functions
v7: Fixed typos, added `_locked` suffix to some functs, improved
readability of asserts, removed unneeded conditional
v8: Moved one function, removed implementation detail from kerneldoc,
added asserts
v9: Code shuffling without much change, and one param rename
v10: Minor error path change, added printing the shift via debugfs
Signed-off-by: Tomasz Lis <tomasz.lis at intel.com>
Reviewed-by: Michal Wajdeczko <michal.wajdeczko at intel.com>
Cc: Michal Wajdeczko <michal.wajdeczko at intel.com>
---
drivers/gpu/drm/xe/xe_ggtt.c | 50 +++++++++++
drivers/gpu/drm/xe/xe_ggtt.h | 1 +
drivers/gpu/drm/xe/xe_gt_sriov_vf.c | 104 ++++++++++++++++++++++
drivers/gpu/drm/xe/xe_gt_sriov_vf.h | 2 +
drivers/gpu/drm/xe/xe_gt_sriov_vf_types.h | 2 +
drivers/gpu/drm/xe/xe_sriov_vf.c | 22 +++++
6 files changed, 181 insertions(+)
diff --git a/drivers/gpu/drm/xe/xe_ggtt.c b/drivers/gpu/drm/xe/xe_ggtt.c
index 5a37233f2420..af8e53014b87 100644
--- a/drivers/gpu/drm/xe/xe_ggtt.c
+++ b/drivers/gpu/drm/xe/xe_ggtt.c
@@ -484,6 +484,56 @@ void xe_ggtt_node_remove_balloon_locked(struct xe_ggtt_node *node)
drm_mm_remove_node(&node->base);
}
+static void xe_ggtt_assert_fit(struct xe_ggtt *ggtt, u64 start, u64 size)
+{
+ struct xe_tile *tile = ggtt->tile;
+ struct xe_device *xe = tile_to_xe(tile);
+ u64 __maybe_unused wopcm = xe_wopcm_size(xe);
+
+ xe_tile_assert(tile, start >= wopcm);
+ xe_tile_assert(tile, start + size < ggtt->size - wopcm);
+}
+
+/**
+ * xe_ggtt_shift_nodes_locked - Shift GGTT nodes to adjust for a change in usable address range.
+ * @ggtt: the &xe_ggtt struct instance
+ * @shift: change to the location of area provisioned for current VF
+ *
+ * This function moves all nodes from the GGTT VM, to a temp list. These nodes are expected
+ * to represent allocations in range formerly assigned to current VF, before the range changed.
+ * When the GGTT VM is completely clear of any nodes, they are re-added with shifted offsets.
+ *
+ * The function has no ability of failing - because it shifts existing nodes, without
+ * any additional processing. If the nodes were successfully existing at the old address,
+ * they will do the same at the new one. A fail inside this function would indicate that
+ * the list of nodes was either already damaged, or that the shift brings the address range
+ * outside of valid bounds. Both cases justify an assert rather than error code.
+ */
+void xe_ggtt_shift_nodes_locked(struct xe_ggtt *ggtt, s64 shift)
+{
+ struct xe_tile *tile __maybe_unused = ggtt->tile;
+ struct drm_mm_node *node, *tmpn;
+ LIST_HEAD(temp_list_head);
+
+ lockdep_assert_held(&ggtt->lock);
+
+ if (IS_ENABLED(CONFIG_DRM_XE_DEBUG))
+ drm_mm_for_each_node_safe(node, tmpn, &ggtt->mm)
+ xe_ggtt_assert_fit(ggtt, node->start + shift, node->size);
+
+ drm_mm_for_each_node_safe(node, tmpn, &ggtt->mm) {
+ drm_mm_remove_node(node);
+ list_add(&node->node_list, &temp_list_head);
+ }
+
+ list_for_each_entry_safe(node, tmpn, &temp_list_head, node_list) {
+ list_del(&node->node_list);
+ node->start += shift;
+ drm_mm_reserve_node(&ggtt->mm, node);
+ xe_tile_assert(tile, drm_mm_node_allocated(node));
+ }
+}
+
/**
* xe_ggtt_node_insert_locked - Locked version to insert a &xe_ggtt_node into the GGTT
* @node: the &xe_ggtt_node to be inserted
diff --git a/drivers/gpu/drm/xe/xe_ggtt.h b/drivers/gpu/drm/xe/xe_ggtt.h
index d468af96b465..4337a279ff3b 100644
--- a/drivers/gpu/drm/xe/xe_ggtt.h
+++ b/drivers/gpu/drm/xe/xe_ggtt.h
@@ -18,6 +18,7 @@ void xe_ggtt_node_fini(struct xe_ggtt_node *node);
int xe_ggtt_node_insert_balloon_locked(struct xe_ggtt_node *node,
u64 start, u64 size);
void xe_ggtt_node_remove_balloon_locked(struct xe_ggtt_node *node);
+void xe_ggtt_shift_nodes_locked(struct xe_ggtt *ggtt, s64 shift);
int xe_ggtt_node_insert(struct xe_ggtt_node *node, u32 size, u32 align);
int xe_ggtt_node_insert_locked(struct xe_ggtt_node *node,
diff --git a/drivers/gpu/drm/xe/xe_gt_sriov_vf.c b/drivers/gpu/drm/xe/xe_gt_sriov_vf.c
index f82ddff79b3b..4ff7ae1a5f16 100644
--- a/drivers/gpu/drm/xe/xe_gt_sriov_vf.c
+++ b/drivers/gpu/drm/xe/xe_gt_sriov_vf.c
@@ -415,6 +415,7 @@ static int vf_get_ggtt_info(struct xe_gt *gt)
xe_gt_sriov_dbg_verbose(gt, "GGTT %#llx-%#llx = %lluK\n",
start, start + size - 1, size / SZ_1K);
+ config->ggtt_shift = start - (s64)config->ggtt_base;
config->ggtt_base = start;
config->ggtt_size = size;
@@ -560,6 +561,24 @@ u64 xe_gt_sriov_vf_lmem(struct xe_gt *gt)
return gt->sriov.vf.self_config.lmem_size;
}
+/**
+ * xe_gt_sriov_vf_ggtt_shift - Return shift in GGTT range due to VF migration
+ * @gt: the &xe_gt struct instance
+ *
+ * This function is for VF use only.
+ *
+ * Return: The shift value; could be negative
+ */
+s64 xe_gt_sriov_vf_ggtt_shift(struct xe_gt *gt)
+{
+ struct xe_gt_sriov_vf_selfconfig *config = >->sriov.vf.self_config;
+
+ xe_gt_assert(gt, IS_SRIOV_VF(gt_to_xe(gt)));
+ xe_gt_assert(gt, !xe_gt_is_media_type(gt));
+
+ return config->ggtt_shift;
+}
+
static int vf_init_ggtt_balloons(struct xe_gt *gt)
{
struct xe_tile *tile = gt_to_tile(gt);
@@ -817,6 +836,89 @@ int xe_gt_sriov_vf_connect(struct xe_gt *gt)
return err;
}
+/**
+ * DOC: GGTT nodes shifting during VF post-migration recovery
+ *
+ * The first fixup applied to the VF KMD structures as part of post-migration
+ * recovery is shifting nodes within &xe_ggtt instance. The nodes are moved
+ * from range previously assigned to this VF, into newly provisioned area.
+ * The changes include balloons, which are resized accordingly.
+ *
+ * The balloon nodes are there to eliminate unavailable ranges from use: one
+ * reserves the GGTT area below the range for current VF, and another one
+ * reserves area above.
+ *
+ * Below is a GGTT layout of example VF, with a certain address range assigned to
+ * said VF, and inaccessible areas above and below:
+ *
+ * 0 4GiB
+ * |<--------------------------- Total GGTT size ----------------------------->|
+ * WOPCM GUC_TOP
+ * |<-------------- Area mappable by xe_ggtt instance ---------------->|
+ *
+ * +---+---------------------------------+----------+----------------------+---+
+ * |\\\|/////////////////////////////////| VF mem |//////////////////////|\\\|
+ * +---+---------------------------------+----------+----------------------+---+
+ *
+ * Hardware enforced access rules before migration:
+ *
+ * |<------- inaccessible for VF ------->|<VF owned>|<-- inaccessible for VF ->|
+ *
+ * GGTT nodes used for tracking allocations:
+ *
+ * |<---------- balloon ------------>|<- nodes->|<----- balloon ------>|
+ *
+ * After the migration, GGTT area assigned to the VF might have shifted, either
+ * to lower or to higher address. But we expect the total size and extra areas to
+ * be identical, as migration can only happen between matching platforms.
+ * Below is an example of GGTT layout of the VF after migration. Content of the
+ * GGTT for VF has been moved to a new area, and we receive its address from GuC:
+ *
+ * +---+----------------------+----------+---------------------------------+---+
+ * |\\\|//////////////////////| VF mem |/////////////////////////////////|\\\|
+ * +---+----------------------+----------+---------------------------------+---+
+ *
+ * Hardware enforced access rules after migration:
+ *
+ * |<- inaccessible for VF -->|<VF owned>|<------- inaccessible for VF ------->|
+ *
+ * So the VF has a new slice of GGTT assigned, and during migration process, the
+ * memory content was copied to that new area. But the &xe_ggtt nodes are still
+ * tracking allocations using the old addresses. The nodes within VF owned area
+ * have to be shifted, and balloon nodes need to be resized to properly mask out
+ * areas not owned by the VF.
+ *
+ * Fixed &xe_ggtt nodes used for tracking allocations:
+ *
+ * |<------ balloon ------>|<- nodes->|<----------- balloon ----------->|
+ *
+ * Due to use of GPU profiles, we do not expect the old and new GGTT ares to
+ * overlap; but our node shifting will fix addresses properly regardless.
+ */
+
+/**
+ * xe_gt_sriov_vf_fixup_ggtt_nodes - Shift GGTT allocations to match assigned range.
+ * @gt: the &xe_gt struct instance
+ * @shift: the shift value
+ *
+ * Since Global GTT is not virtualized, each VF has an assigned range
+ * within the global space. This range might have changed during migration,
+ * which requires all memory addresses pointing to GGTT to be shifted.
+ */
+void xe_gt_sriov_vf_fixup_ggtt_nodes(struct xe_gt *gt, s64 shift)
+{
+ struct xe_tile *tile = gt_to_tile(gt);
+ struct xe_ggtt *ggtt = tile->mem.ggtt;
+
+ xe_gt_assert(gt, !xe_gt_is_media_type(gt));
+
+ mutex_lock(&ggtt->lock);
+ xe_gt_sriov_vf_deballoon_ggtt_locked(gt);
+ xe_ggtt_shift_nodes_locked(ggtt, shift);
+ xe_gt_sriov_vf_balloon_ggtt_locked(gt);
+ mutex_unlock(&ggtt->lock);
+}
+
/**
* xe_gt_sriov_vf_migrated_event_handler - Start a VF migration recovery,
* or just mark that a GuC is ready for it.
@@ -1103,6 +1205,8 @@ void xe_gt_sriov_vf_print_config(struct xe_gt *gt, struct drm_printer *p)
string_get_size(config->ggtt_size, 1, STRING_UNITS_2, buf, sizeof(buf));
drm_printf(p, "GGTT size:\t%llu (%s)\n", config->ggtt_size, buf);
+ drm_printf(p, "GGTT shift on last restore:\t%lld\n", config->ggtt_shift);
+
if (IS_DGFX(xe) && !xe_gt_is_media_type(gt)) {
string_get_size(config->lmem_size, 1, STRING_UNITS_2, buf, sizeof(buf));
drm_printf(p, "LMEM size:\t%llu (%s)\n", config->lmem_size, buf);
diff --git a/drivers/gpu/drm/xe/xe_gt_sriov_vf.h b/drivers/gpu/drm/xe/xe_gt_sriov_vf.h
index d717deb8af91..9db41afddd5a 100644
--- a/drivers/gpu/drm/xe/xe_gt_sriov_vf.h
+++ b/drivers/gpu/drm/xe/xe_gt_sriov_vf.h
@@ -20,6 +20,8 @@ int xe_gt_sriov_vf_query_runtime(struct xe_gt *gt);
int xe_gt_sriov_vf_prepare_ggtt(struct xe_gt *gt);
int xe_gt_sriov_vf_balloon_ggtt_locked(struct xe_gt *gt);
void xe_gt_sriov_vf_deballoon_ggtt_locked(struct xe_gt *gt);
+s64 xe_gt_sriov_vf_ggtt_shift(struct xe_gt *gt);
+void xe_gt_sriov_vf_fixup_ggtt_nodes(struct xe_gt *gt, s64 shift);
int xe_gt_sriov_vf_notify_resfix_done(struct xe_gt *gt);
void xe_gt_sriov_vf_migrated_event_handler(struct xe_gt *gt);
diff --git a/drivers/gpu/drm/xe/xe_gt_sriov_vf_types.h b/drivers/gpu/drm/xe/xe_gt_sriov_vf_types.h
index a57f13b5afcd..5ccbdf8d08b6 100644
--- a/drivers/gpu/drm/xe/xe_gt_sriov_vf_types.h
+++ b/drivers/gpu/drm/xe/xe_gt_sriov_vf_types.h
@@ -40,6 +40,8 @@ struct xe_gt_sriov_vf_selfconfig {
u64 ggtt_base;
/** @ggtt_size: assigned size of the GGTT region. */
u64 ggtt_size;
+ /** @ggtt_shift: difference in ggtt_base on last migration */
+ s64 ggtt_shift;
/** @lmem_size: assigned size of the LMEM. */
u64 lmem_size;
/** @num_ctxs: assigned number of GuC submission context IDs. */
diff --git a/drivers/gpu/drm/xe/xe_sriov_vf.c b/drivers/gpu/drm/xe/xe_sriov_vf.c
index c1275e64aa9c..e70f1ceabbb3 100644
--- a/drivers/gpu/drm/xe/xe_sriov_vf.c
+++ b/drivers/gpu/drm/xe/xe_sriov_vf.c
@@ -7,6 +7,7 @@
#include "xe_assert.h"
#include "xe_device.h"
+#include "xe_gt.h"
#include "xe_gt_sriov_printk.h"
#include "xe_gt_sriov_vf.h"
#include "xe_pm.h"
@@ -170,6 +171,25 @@ static bool vf_post_migration_imminent(struct xe_device *xe)
work_pending(&xe->sriov.vf.migration.worker);
}
+static bool vf_post_migration_fixup_ggtt_nodes(struct xe_device *xe)
+{
+ bool need_fixups = false;
+ struct xe_tile *tile;
+ unsigned int id;
+
+ for_each_tile(tile, xe, id) {
+ struct xe_gt *gt = tile->primary_gt;
+ s64 shift;
+
+ shift = xe_gt_sriov_vf_ggtt_shift(gt);
+ if (shift) {
+ need_fixups = true;
+ xe_gt_sriov_vf_fixup_ggtt_nodes(gt, shift);
+ }
+ }
+ return need_fixups;
+}
+
/*
* Notify all GuCs about resource fixups apply finished.
*/
@@ -191,6 +211,7 @@ static void vf_post_migration_notify_resfix_done(struct xe_device *xe)
static void vf_post_migration_recovery(struct xe_device *xe)
{
+ bool need_fixups;
int err;
drm_dbg(&xe->drm, "migration recovery in progress\n");
@@ -201,6 +222,7 @@ static void vf_post_migration_recovery(struct xe_device *xe)
if (unlikely(err))
goto fail;
+ need_fixups = vf_post_migration_fixup_ggtt_nodes(xe);
/* FIXME: add the recovery steps */
vf_post_migration_notify_resfix_done(xe);
xe_pm_runtime_put(xe);
--
2.25.1
More information about the Intel-xe
mailing list