drm/xe/pf: Trigger explicit FLR while disabling VFs

We attempt to unprovision all VFs GuC when disabling them, but
GuC may reject such request if the target VF was previously active
but VF driver didn't unload with explicit VF reset H2G action or
the VMM has not started the VF FLR.

To avoid mismatches between configs maintained the PF and GuC,
trigger an explicit FLR sequences just before releasing resources.
Signed-off-by: Michal Wajdeczko <michal.wajdeczko@intel.com>
Reviewed-by: Piotr Piórkowski <piotr.piorkowski@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240625194546.1301-2-michal.wajdeczko@intel.comSigned-off-by: Rodrigo Vivi <rodrigo.vivi@intel.com>

drivers/gpu/drm/xe/xe_gt_sriov_pf_control.c

@@ -129,6 +129,27 @@ int xe_gt_sriov_pf_control_stop_vf(struct xe_gt *gt, unsigned int vfid)
 	return pf_send_vf_stop(gt, vfid);
 }
 
+/**
+ * xe_gt_sriov_pf_control_trigger_flr - Start a VF FLR sequence.
+ * @gt: the &xe_gt
+ * @vfid: the VF identifier
+ *
+ * This function is for PF only.
+ *
+ * Return: 0 on success or a negative error code on failure.
+ */
+int xe_gt_sriov_pf_control_trigger_flr(struct xe_gt *gt, unsigned int vfid)
+{
+	int err;
+
+	/* XXX pf_send_vf_flr_start() expects ct->lock */
+	mutex_lock(&gt->uc.guc.ct.lock);
+	err = pf_send_vf_flr_start(gt, vfid);
+	mutex_unlock(&gt->uc.guc.ct.lock);
+
+	return err;
+}
+
 /**
  * DOC: The VF FLR Flow with GuC
  *

drivers/gpu/drm/xe/xe_gt_sriov_pf_control.h

@@ -14,6 +14,7 @@ struct xe_gt;
 int xe_gt_sriov_pf_control_pause_vf(struct xe_gt *gt, unsigned int vfid);
 int xe_gt_sriov_pf_control_resume_vf(struct xe_gt *gt, unsigned int vfid);
 int xe_gt_sriov_pf_control_stop_vf(struct xe_gt *gt, unsigned int vfid);
+int xe_gt_sriov_pf_control_trigger_flr(struct xe_gt *gt, unsigned int vfid);
 
 #ifdef CONFIG_PCI_IOV
 int xe_gt_sriov_pf_control_process_guc2pf(struct xe_gt *gt, const u32 *msg, u32 len);

drivers/gpu/drm/xe/xe_pci_sriov.c

@@ -6,6 +6,7 @@
 #include "xe_assert.h"
 #include "xe_device.h"
 #include "xe_gt_sriov_pf_config.h"
+#include "xe_gt_sriov_pf_control.h"
 #include "xe_pci_sriov.h"
 #include "xe_pm.h"
 #include "xe_sriov.h"
@@ -37,6 +38,17 @@ static void pf_unprovision_vfs(struct xe_device *xe, unsigned int num_vfs)
 			xe_gt_sriov_pf_config_release(gt, n, true);
 }
 
+static void pf_reset_vfs(struct xe_device *xe, unsigned int num_vfs)
+{
+	struct xe_gt *gt;
+	unsigned int id;
+	unsigned int n;
+
+	for_each_gt(gt, xe, id)
+		for (n = 1; n <= num_vfs; n++)
+			xe_gt_sriov_pf_control_trigger_flr(gt, n);
+}
+
 static int pf_enable_vfs(struct xe_device *xe, int num_vfs)
 {
 	struct pci_dev *pdev = to_pci_dev(xe->drm.dev);
@@ -94,6 +106,8 @@ static int pf_disable_vfs(struct xe_device *xe)
 
 	pci_disable_sriov(pdev);
 
+	pf_reset_vfs(xe, num_vfs);
+
 	pf_unprovision_vfs(xe, num_vfs);
 
 	/* not needed anymore - see pf_enable_vfs() */