drm/xe/vf: Use only assigned GGTT region

Each VF is assigned a limited range of the GGTT address space.
To ensure that the VF driver does not use GGTT allocations outside
of the assigned region, explicitly reserve GGTT space below and
above this region when initializing GGTT.

Signed-off-by: Michal Wajdeczko <[e-mail]>
Reviewed-by: Michał Winiarski <[e-mail]>
Link: https://patchwork.freedesktop.org/patch/msgid/[e-mail]

drivers/gpu/drm/xe/xe_device_types.h

···
 		struct {
 			/** @sriov.vf.memirq: Memory Based Interrupts. */
 			struct xe_memirq memirq;
+
+			/** @sriov.vf.ggtt_balloon: GGTT regions excluded from use. */
+			struct drm_mm_node ggtt_balloon[2];
 		} vf;
 	} sriov;
 

drivers/gpu/drm/xe/xe_ggtt.c

···
 #include "xe_device.h"
 #include "xe_gt.h"
 #include "xe_gt_printk.h"
+#include "xe_gt_sriov_vf.h"
 #include "xe_gt_tlb_invalidation.h"
 #include "xe_map.h"
 #include "xe_pm.h"
···
 	struct xe_device *xe = tile_to_xe(ggtt->tile);
 	struct pci_dev *pdev = to_pci_dev(xe->drm.dev);
 	unsigned int gsm_size;
+	int err;
 
 	if (IS_SRIOV_VF(xe))
 		gsm_size = SZ_8M; /* GGTT is expected to be 4GiB */
···
 	mutex_init(&ggtt->lock);
 	primelockdep(ggtt);
 
-	return drmm_add_action_or_reset(&xe->drm, ggtt_fini_early, ggtt);
+	err = drmm_add_action_or_reset(&xe->drm, ggtt_fini_early, ggtt);
+	if (err)
+		return err;
+
+	if (IS_SRIOV_VF(xe)) {
+		err = xe_gt_sriov_vf_prepare_ggtt(xe_tile_get_gt(ggtt->tile, 0));
+		if (err)
+			return err;
+	}
+
+	return 0;
 }
 
 static void xe_ggtt_invalidate(struct xe_ggtt *ggtt);

drivers/gpu/drm/xe/xe_gt_sriov_vf.c

···
 #include "abi/guc_klvs_abi.h"
 #include "abi/guc_relay_actions_abi.h"
 #include "regs/xe_gt_regs.h"
+#include "regs/xe_gtt_defs.h"
 
 #include "xe_assert.h"
 #include "xe_device.h"
+#include "xe_ggtt.h"
 #include "xe_gt_sriov_printk.h"
 #include "xe_gt_sriov_vf.h"
 #include "xe_gt_sriov_vf_types.h"
···
 #include "xe_guc_relay.h"
 #include "xe_mmio.h"
 #include "xe_sriov.h"
+#include "xe_uc_fw.h"
+#include "xe_wopcm.h"
 
 #define make_u64_from_u32(hi, lo) ((u64)((u64)(u32)(hi) << 32 | (u32)(lo)))
 
···
 	xe_gt_assert(gt, gt->sriov.vf.self_config.num_ctxs);
 
 	return gt->sriov.vf.self_config.num_ctxs;
+}
+
+static int vf_balloon_ggtt(struct xe_gt *gt)
+{
+	struct xe_gt_sriov_vf_selfconfig *config = &gt->sriov.vf.self_config;
+	struct xe_tile *tile = gt_to_tile(gt);
+	struct xe_ggtt *ggtt = tile->mem.ggtt;
+	struct xe_device *xe = gt_to_xe(gt);
+	u64 start, end;
+	int err;
+
+	xe_gt_assert(gt, IS_SRIOV_VF(xe));
+	xe_gt_assert(gt, !xe_gt_is_media_type(gt));
+
+	if (!config->ggtt_size)
+		return -ENODATA;
+
+	/*
+	 * VF can only use part of the GGTT as allocated by the PF:
+	 *
+	 *      WOPCM                                  GUC_GGTT_TOP
+	 *      |<------------ Total GGTT size ------------------>|
+	 *
+	 *           VF GGTT base -->|<- size ->|
+	 *
+	 *      +--------------------+----------+-----------------+
+	 *      |////////////////////|   block  |\\\\\\\\\\\\\\\\\|
+	 *      +--------------------+----------+-----------------+
+	 *
+	 *      |<--- balloon[0] --->|<-- VF -->|<-- balloon[1] ->|
+	 */
+
+	start = xe_wopcm_size(xe);
+	end = config->ggtt_base;
+	if (end != start) {
+		err = xe_ggtt_balloon(ggtt, start, end, &tile->sriov.vf.ggtt_balloon[0]);
+		if (err)
+			goto failed;
+	}
+
+	start = config->ggtt_base + config->ggtt_size;
+	end = GUC_GGTT_TOP;
+	if (end != start) {
+		err = xe_ggtt_balloon(ggtt, start, end, &tile->sriov.vf.ggtt_balloon[1]);
+		if (err)
+			goto deballoon;
+	}
+
+	return 0;
+
+deballoon:
+	xe_ggtt_deballoon(ggtt, &tile->sriov.vf.ggtt_balloon[0]);
+failed:
+	return err;
+}
+
+static void deballoon_ggtt(struct drm_device *drm, void *arg)
+{
+	struct xe_tile *tile = arg;
+	struct xe_ggtt *ggtt = tile->mem.ggtt;
+
+	xe_tile_assert(tile, IS_SRIOV_VF(tile_to_xe(tile)));
+	xe_ggtt_deballoon(ggtt, &tile->sriov.vf.ggtt_balloon[1]);
+	xe_ggtt_deballoon(ggtt, &tile->sriov.vf.ggtt_balloon[0]);
+}
+
+/**
+ * xe_gt_sriov_vf_prepare_ggtt - Prepare a VF's GGTT configuration.
+ * @gt: the &xe_gt
+ *
+ * This function is for VF use only.
+ *
+ * Return: 0 on success or a negative error code on failure.
+ */
+int xe_gt_sriov_vf_prepare_ggtt(struct xe_gt *gt)
+{
+	struct xe_tile *tile = gt_to_tile(gt);
+	struct xe_device *xe = tile_to_xe(tile);
+	int err;
+
+	if (xe_gt_is_media_type(gt))
+		return 0;
+
+	err = vf_balloon_ggtt(gt);
+	if (err)
+		return err;
+
+	return drmm_add_action_or_reset(&xe->drm, deballoon_ggtt, tile);
 }
 
 static int relay_action_handshake(struct xe_gt *gt, u32 *major, u32 *minor)

drivers/gpu/drm/xe/xe_gt_sriov_vf.h

···
 int xe_gt_sriov_vf_query_config(struct xe_gt *gt);
 int xe_gt_sriov_vf_connect(struct xe_gt *gt);
 int xe_gt_sriov_vf_query_runtime(struct xe_gt *gt);
+int xe_gt_sriov_vf_prepare_ggtt(struct xe_gt *gt);
 
 u32 xe_gt_sriov_vf_gmdid(struct xe_gt *gt);
 u16 xe_gt_sriov_vf_guc_ids(struct xe_gt *gt);