drm/xe/vf: Provide early access to GMDID register

VFs do not have direct access to the GMDID register and must obtain
its value from the GuC. Since we need GMDID value very early in the
driver probe flow, before we even start the full setup of GT and GuC
data structures, we must do some early initializations ourselves.

Additionally, since we also need GMDID for the media GT, which isn't
created yet, temporarly tweak the root GT type into MEDIA to allow
communication with the correct GuC, as only it can provide the value
of the media GMDID register.

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/20240523223042.888-1-michal.wajdeczko@intel.com

diff --git a/drivers/gpu/drm/xe/xe_pci.c b/drivers/gpu/drm/xe/xe_pci.c
index d65f05fa7b1ba6bf8dfb9f4d5aca15275eaf8c0f..90ca97894a0947dcde377cd688242e021cbf594c 100644 (file)
--- a/drivers/gpu/drm/xe/xe_pci.c
+++ b/drivers/gpu/drm/xe/xe_pci.c
@@ -20,6 +20,8 @@
 #include "xe_device.h"
 #include "xe_drv.h"
 #include "xe_gt.h"
+#include "xe_gt_sriov_vf.h"
+#include "xe_guc.h"
 #include "xe_macros.h"
 #include "xe_mmio.h"
 #include "xe_module.h"
@@ -469,10 +471,52 @@ static void read_gmdid(struct xe_device *xe, enum xe_gmdid_type type, u32 *ver,
 
        KUNIT_STATIC_STUB_REDIRECT(read_gmdid, xe, type, ver, revid);
 
-       if (type == GMDID_MEDIA)
-               gmdid_reg.addr += MEDIA_GT_GSI_OFFSET;
+       if (IS_SRIOV_VF(xe)) {
+               /*
+                * To get the value of the GMDID register, VFs must obtain it
+                * from the GuC using MMIO communication.
+                *
+                * Note that at this point the xe_gt is not fully uninitialized
+                * and only basic access to MMIO registers is possible. To use
+                * our existing GuC communication functions we must perform at
+                * least basic xe_gt and xe_guc initialization.
+                *
+                * Since to obtain the value of GMDID_MEDIA we need to use the
+                * media GuC, temporarly tweak the gt type.
+                */
+               xe_gt_assert(gt, gt->info.type == XE_GT_TYPE_UNINITIALIZED);
+
+               if (type == GMDID_MEDIA) {
+                       gt->info.id = 1;
+                       gt->info.type = XE_GT_TYPE_MEDIA;
+               } else {
+                       gt->info.id = 0;
+                       gt->info.type = XE_GT_TYPE_MAIN;
+               }
+
+               xe_guc_comm_init_early(&gt->uc.guc);
+
+               /* Don't bother with GMDID if failed to negotiate the GuC ABI */
+               val = xe_gt_sriov_vf_bootstrap(gt) ? 0 : xe_gt_sriov_vf_gmdid(gt);
+
+               /*
+                * Only undo xe_gt.info here, the remaining changes made above
+                * will be overwritten as part of the regular initialization.
+                */
+               gt->info.id = 0;
+               gt->info.type = XE_GT_TYPE_UNINITIALIZED;
+       } else {
+               /*
+                * We need to apply the GSI offset explicitly here as at this
+                * point the xe_gt is not fully uninitialized and only basic
+                * access to MMIO registers is possible.
+                */
+               if (type == GMDID_MEDIA)
+                       gmdid_reg.addr += MEDIA_GT_GSI_OFFSET;
+
+               val = xe_mmio_read32(gt, gmdid_reg);
+       }
 
-       val = xe_mmio_read32(gt, gmdid_reg);
        *ver = REG_FIELD_GET(GMD_ID_ARCH_MASK, val) * 100 + REG_FIELD_GET(GMD_ID_RELEASE_MASK, val);
        *revid = REG_FIELD_GET(GMD_ID_REVID, val);
 }