[PATCH] drm/xe/vf: Don't try to trigger a full GT reset if VF

[Lucas De Marchi]

On Fri, Jan 31, 2025 at 07:25:02PM +0100, Michal Wajdeczko wrote:
>VFs don't have access to the GDRST(0x941c) register that driver
>uses to reset a GT. Attempt to trigger a reset using debugfs:
>
> $ cat /sys/kernel/debug/dri/0000:00:02.1/gt0/force_reset
>
>or due to a hang condition detected by the driver leads to:
>
> [ ] xe 0000:00:02.1: [drm] GT0: trying reset from force_reset [xe]
> [ ] xe 0000:00:02.1: [drm] GT0: reset queued
> [ ] xe 0000:00:02.1: [drm] GT0: reset started
> [ ] ------------[ cut here ]------------
> [ ] xe 0000:00:02.1: [drm] GT0: VF is trying to write 0x1 to an inaccessible register 0x941c+0x0
> [ ] WARNING: CPU: 3 PID: 3069 at drivers/gpu/drm/xe/xe_gt_sriov_vf.c:996 xe_gt_sriov_vf_write32+0xc6/0x580 [xe]
> [ ] RIP: 0010:xe_gt_sriov_vf_write32+0xc6/0x580 [xe]
> [ ] Call Trace:
> [ ]  <TASK>
> [ ]  ? show_regs+0x6c/0x80
> [ ]  ? __warn+0x93/0x1c0
> [ ]  ? xe_gt_sriov_vf_write32+0xc6/0x580 [xe]
> [ ]  ? report_bug+0x182/0x1b0
> [ ]  ? handle_bug+0x6e/0xb0
> [ ]  ? exc_invalid_op+0x18/0x80
> [ ]  ? asm_exc_invalid_op+0x1b/0x20
> [ ]  ? xe_gt_sriov_vf_write32+0xc6/0x580 [xe]
> [ ]  ? xe_gt_sriov_vf_write32+0xc6/0x580 [xe]
> [ ]  ? xe_gt_tlb_invalidation_reset+0xef/0x110 [xe]
> [ ]  ? __mutex_unlock_slowpath+0x41/0x2e0
> [ ]  xe_mmio_write32+0x64/0x150 [xe]
> [ ]  do_gt_reset+0x2f/0xa0 [xe]
> [ ]  gt_reset_worker+0x14e/0x1e0 [xe]
> [ ]  process_one_work+0x21c/0x740
> [ ]  worker_thread+0x1db/0x3c0
>
>Fix that by sending H2G VF_RESET(0x5507) action instead.
>
>Closes: https://gitlab.freedesktop.org/drm/xe/kernel/-/issues/4078
>Signed-off-by: Michal Wajdeczko <michal.wajdeczko at intel.com>
>---
>Cc: Michał Winiarski <michal.winiarski at intel.com>
>Cc: Jakub Kolakowski <jakub1.kolakowski at intel.com>
>---
> drivers/gpu/drm/xe/xe_gt.c          |  4 ++++
> drivers/gpu/drm/xe/xe_gt_sriov_vf.c | 16 ++++++++++++++++
> drivers/gpu/drm/xe/xe_gt_sriov_vf.h |  1 +
> 3 files changed, 21 insertions(+)
>
>diff --git a/drivers/gpu/drm/xe/xe_gt.c b/drivers/gpu/drm/xe/xe_gt.c
>index 01a4a852b8f4..9fb8f1e678dc 100644
>--- a/drivers/gpu/drm/xe/xe_gt.c
>+++ b/drivers/gpu/drm/xe/xe_gt.c
>@@ -32,6 +32,7 @@
> #include "xe_gt_pagefault.h"
> #include "xe_gt_printk.h"
> #include "xe_gt_sriov_pf.h"
>+#include "xe_gt_sriov_vf.h"
> #include "xe_gt_sysfs.h"
> #include "xe_gt_tlb_invalidation.h"
> #include "xe_gt_topology.h"
>@@ -679,6 +680,9 @@ static int do_gt_reset(struct xe_gt *gt)
> {
> 	int err;
>
>+	if (IS_SRIOV_VF(gt_to_xe(gt)))
>+		return xe_gt_sriov_vf_reset(gt);
>+
> 	xe_gsc_wa_14015076503(gt, true);
>
> 	xe_mmio_write32(&gt->mmio, GDRST, GRDOM_FULL);
>diff --git a/drivers/gpu/drm/xe/xe_gt_sriov_vf.c b/drivers/gpu/drm/xe/xe_gt_sriov_vf.c
>index 6671030439fd..4831549da319 100644
>--- a/drivers/gpu/drm/xe/xe_gt_sriov_vf.c
>+++ b/drivers/gpu/drm/xe/xe_gt_sriov_vf.c
>@@ -58,6 +58,22 @@ static int vf_reset_guc_state(struct xe_gt *gt)
> 	return err;
> }
>
>+/**
>+ * xe_gt_sriov_vf_reset - Reset GuC VF internal state.
>+ * @gt: the &xe_gt
>+ *
>+ * It requires functional `GuC MMIO based communication`_.
>+ *
>+ * Return: 0 on success or a negative error code on failure.
>+ */
>+int xe_gt_sriov_vf_reset(struct xe_gt *gt)
>+{
>+	if (!xe_device_uc_enabled(gt_to_xe(gt)))

I don't think this condition is ever true when driver is loaded in VF
mode, is it? Anyway, looks good:


Reviewed-by: Lucas De Marchi <lucas.demarchi at intel.com>


Lucas De Marchi

>+		return -ENODEV;
>+
>+	return vf_reset_guc_state(gt);
>+}
>+
> static int guc_action_match_version(struct xe_guc *guc,
> 				    u32 wanted_branch, u32 wanted_major, u32 wanted_minor,
> 				    u32 *branch, u32 *major, u32 *minor, u32 *patch)
>diff --git a/drivers/gpu/drm/xe/xe_gt_sriov_vf.h b/drivers/gpu/drm/xe/xe_gt_sriov_vf.h
>index 912d20814261..ba6c5d74e326 100644
>--- a/drivers/gpu/drm/xe/xe_gt_sriov_vf.h
>+++ b/drivers/gpu/drm/xe/xe_gt_sriov_vf.h
>@@ -12,6 +12,7 @@ struct drm_printer;
> struct xe_gt;
> struct xe_reg;
>
>+int xe_gt_sriov_vf_reset(struct xe_gt *gt);
> int xe_gt_sriov_vf_bootstrap(struct xe_gt *gt);
> int xe_gt_sriov_vf_query_config(struct xe_gt *gt);
> int xe_gt_sriov_vf_connect(struct xe_gt *gt);
>-- 
>2.47.1
>