drm/xe/vf: Use register values obtained from the PF

As part of the its initialization, the VF driver has already
obtained a list of the runtime (fuse) register values from the
PF driver. When VF driver is attempting to read register that is
inaccessible to the VF, use the values from this list instead.
Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Reviewed-by: Matt Roper <matthew.d.roper@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240523192240.844-2-michal.wajdeczko@intel.com

drivers/gpu/drm/xe/xe_gt_sriov_vf.c

@@ -4,6 +4,7 @@
  */
 
 #include <linux/bitfield.h>
+#include <linux/bsearch.h>
 
 #include <drm/drm_managed.h>
 #include <drm/drm_print.h>
@@ -21,6 +22,7 @@
 #include "xe_guc.h"
 #include "xe_guc_hxg_helpers.h"
 #include "xe_guc_relay.h"
+#include "xe_mmio.h"
 #include "xe_sriov.h"
 
 #define make_u64_from_u32(hi, lo) ((u64)((u64)(u32)(hi) << 32 | (u32)(lo)))
@@ -677,6 +679,57 @@ int xe_gt_sriov_vf_query_runtime(struct xe_gt *gt)
 	return err;
 }
 
+static int vf_runtime_reg_cmp(const void *a, const void *b)
+{
+	const struct vf_runtime_reg *ra = a;
+	const struct vf_runtime_reg *rb = b;
+
+	return (int)ra->offset - (int)rb->offset;
+}
+
+static struct vf_runtime_reg *vf_lookup_reg(struct xe_gt *gt, u32 addr)
+{
+	struct xe_gt_sriov_vf_runtime *runtime = &gt->sriov.vf.runtime;
+	struct vf_runtime_reg key = { .offset = addr };
+
+	xe_gt_assert(gt, IS_SRIOV_VF(gt_to_xe(gt)));
+
+	return bsearch(&key, runtime->regs, runtime->regs_size, sizeof(key),
+		       vf_runtime_reg_cmp);
+}
+
+/**
+ * xe_gt_sriov_vf_read32 - Get a register value from the runtime data.
+ * @gt: the &xe_gt
+ * @reg: the register to read
+ *
+ * This function is for VF use only.
+ * This function shall be called after VF has connected to PF.
+ * This function is dedicated for registers that VFs can't read directly.
+ *
+ * Return: register value obtained from the PF or 0 if not found.
+ */
+u32 xe_gt_sriov_vf_read32(struct xe_gt *gt, struct xe_reg reg)
+{
+	u32 addr = xe_mmio_adjusted_addr(gt, reg.addr);
+	struct vf_runtime_reg *rr;
+
+	xe_gt_assert(gt, IS_SRIOV_VF(gt_to_xe(gt)));
+	xe_gt_assert(gt, gt->sriov.vf.pf_version.major);
+	xe_gt_assert(gt, !reg.vf);
+
+	rr = vf_lookup_reg(gt, addr);
+	if (!rr) {
+		xe_gt_WARN(gt, IS_ENABLED(CONFIG_DRM_XE_DEBUG),
+			   "VF is trying to read an inaccessible register %#x+%#x\n",
+			   reg.addr, addr - reg.addr);
+		return 0;
+	}
+
+	xe_gt_sriov_dbg_verbose(gt, "runtime[%#x] = %#x\n", addr, rr->value);
+	return rr->value;
+}
+
 /**
  * xe_gt_sriov_vf_print_config - Print VF self config.
  * @gt: the &xe_gt

drivers/gpu/drm/xe/xe_gt_sriov_vf.h

@@ -10,6 +10,7 @@
 
 struct drm_printer;
 struct xe_gt;
+struct xe_reg;
 
 int xe_gt_sriov_vf_bootstrap(struct xe_gt *gt);
 int xe_gt_sriov_vf_query_config(struct xe_gt *gt);
@@ -17,6 +18,7 @@ int xe_gt_sriov_vf_connect(struct xe_gt *gt);
 int xe_gt_sriov_vf_query_runtime(struct xe_gt *gt);
 
 u16 xe_gt_sriov_vf_guc_ids(struct xe_gt *gt);
+u32 xe_gt_sriov_vf_read32(struct xe_gt *gt, struct xe_reg reg);
 
 void xe_gt_sriov_vf_print_config(struct xe_gt *gt, struct drm_printer *p);
 void xe_gt_sriov_vf_print_runtime(struct xe_gt *gt, struct drm_printer *p);

drivers/gpu/drm/xe/xe_mmio.c

@@ -22,6 +22,7 @@
 #include "xe_gt.h"
 #include "xe_gt_mcr.h"
 #include "xe_gt_printk.h"
+#include "xe_gt_sriov_vf.h"
 #include "xe_macros.h"
 #include "xe_module.h"
 #include "xe_sriov.h"
@@ -479,6 +480,9 @@ u32 xe_mmio_read32(struct xe_gt *gt, struct xe_reg reg)
 	struct xe_tile *tile = gt_to_tile(gt);
 	u32 addr = xe_mmio_adjusted_addr(gt, reg.addr);
 
+	if (!reg.vf && IS_SRIOV_VF(gt_to_xe(gt)))
+		return xe_gt_sriov_vf_read32(gt, reg);
+
 	return readl((reg.ext ? tile->mmio_ext.regs : tile->mmio.regs) + addr);
 }