drm/xe/pxp/uapi: Add a query for PXP status

PXP prerequisites (SW proxy and HuC auth via GSC) are completed
asynchronously from driver load, which means that userspace can start
submitting before we're ready to start a PXP session. Therefore, we need
a query that userspace can use to check not only if PXP is supported but
also to wait until the prerequisites are done.

v2: Improve doc, do not report TYPE_NONE as supported (José)
v3: Better comments, remove unneeded copy_from_user (John)

Signed-off-by: Daniele Ceraolo Spurio <daniele.ceraolospurio@intel.com>
Cc: José Roberto de Souza <jose.souza@intel.com>
Cc: John Harrison <John.C.Harrison@Intel.com>
Reviewed-by: John Harrison <John.C.Harrison@Intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20250129174140.948829-10-daniele.ceraolospurio@intel.com

Author: dceraolo

drivers/gpu/drm/xe/xe_pxp.c

@@ -80,6 +80,38 @@ static bool pxp_prerequisites_done(const struct xe_pxp *pxp)
 	return ready;
 }
 
+/**
+ * xe_pxp_get_readiness_status - check whether PXP is ready for userspace use
+ * @pxp: the xe_pxp pointer (can be NULL if PXP is disabled)
+ *
+ * Returns: 0 if PXP is not ready yet, 1 if it is ready, a negative errno value
+ * if PXP is not supported/enabled or if something went wrong in the
+ * initialization of the prerequisites. Note that the return values of this
+ * function follow the uapi (see drm_xe_query_pxp_status), so they can be used
+ * directly in the query ioctl.
+ */
+int xe_pxp_get_readiness_status(struct xe_pxp *pxp)
+{
+	int ret = 0;
+
+	if (!xe_pxp_is_enabled(pxp))
+		return -ENODEV;
+
+	/* if the GSC or HuC FW are in an error state, PXP will never work */
+	if (xe_uc_fw_status_to_error(pxp->gt->uc.huc.fw.status) ||
+	    xe_uc_fw_status_to_error(pxp->gt->uc.gsc.fw.status))
+		return -EIO;
+
+	xe_pm_runtime_get(pxp->xe);
+
+	/* PXP requires both HuC loaded and GSC proxy initialized */
+	if (pxp_prerequisites_done(pxp))
+		ret = 1;
+
+	xe_pm_runtime_put(pxp->xe);
+	return ret;
+}
+
 static bool pxp_session_is_in_play(struct xe_pxp *pxp, u32 id)
 {
 	struct xe_gt *gt = pxp->gt;

drivers/gpu/drm/xe/xe_pxp.h

@@ -14,6 +14,7 @@ struct xe_pxp;
 
 bool xe_pxp_is_supported(const struct xe_device *xe);
 bool xe_pxp_is_enabled(const struct xe_pxp *pxp);
+int xe_pxp_get_readiness_status(struct xe_pxp *pxp);
 
 int xe_pxp_init(struct xe_device *xe);
 void xe_pxp_irq_handler(struct xe_device *xe, u16 iir);

drivers/gpu/drm/xe/xe_query.c

@@ -24,6 +24,7 @@
 #include "xe_macros.h"
 #include "xe_mmio.h"
 #include "xe_oa.h"
+#include "xe_pxp.h"
 #include "xe_ttm_vram_mgr.h"
 #include "xe_wa.h"
 
@@ -698,6 +699,33 @@ static int query_oa_units(struct xe_device *xe,
 	return ret ? -EFAULT : 0;
 }
 
+static int query_pxp_status(struct xe_device *xe, struct drm_xe_device_query *query)
+{
+	struct drm_xe_query_pxp_status __user *query_ptr = u64_to_user_ptr(query->data);
+	size_t size = sizeof(struct drm_xe_query_pxp_status);
+	struct drm_xe_query_pxp_status resp = { 0 };
+	int ret;
+
+	if (query->size == 0) {
+		query->size = size;
+		return 0;
+	} else if (XE_IOCTL_DBG(xe, query->size != size)) {
+		return -EINVAL;
+	}
+
+	ret = xe_pxp_get_readiness_status(xe->pxp);
+	if (ret < 0)
+		return ret;
+
+	resp.status = ret;
+	resp.supported_session_types = BIT(DRM_XE_PXP_TYPE_HWDRM);
+
+	if (copy_to_user(query_ptr, &resp, size))
+		return -EFAULT;
+
+	return 0;
+}
+
 static int (* const xe_query_funcs[])(struct xe_device *xe,
 				      struct drm_xe_device_query *query) = {
 	query_engines,
@@ -709,6 +737,7 @@ static int (* const xe_query_funcs[])(struct xe_device *xe,
 	query_engine_cycles,
 	query_uc_fw_version,
 	query_oa_units,
+	query_pxp_status,
 };
 
 int xe_query_ioctl(struct drm_device *dev, void *data, struct drm_file *file)

include/uapi/drm/xe_drm.h

@@ -629,6 +629,39 @@ struct drm_xe_query_uc_fw_version {
 	__u64 reserved;
 };
 
+/**
+ * struct drm_xe_query_pxp_status - query if PXP is ready
+ *
+ * If PXP is enabled and no fatal error has occurred, the status will be set to
+ * one of the following values:
+ * 0: PXP init still in progress
+ * 1: PXP init complete
+ *
+ * If PXP is not enabled or something has gone wrong, the query will be failed
+ * with one of the following error codes:
+ * -ENODEV: PXP not supported or disabled;
+ * -EIO: fatal error occurred during init, so PXP will never be enabled;
+ * -EINVAL: incorrect value provided as part of the query;
+ * -EFAULT: error copying the memory between kernel and userspace.
+ *
+ * The status can only be 0 in the first few seconds after driver load. If
+ * everything works as expected, the status will transition to init complete in
+ * less than 1 second, while in case of errors the driver might take longer to
+ * start returning an error code, but it should still take less than 10 seconds.
+ *
+ * The supported session type bitmask is based on the values in
+ * enum drm_xe_pxp_session_type. TYPE_NONE is always supported and therefore
+ * is not reported in the bitmask.
+ *
+ */
+struct drm_xe_query_pxp_status {
+	/** @status: current PXP status */
+	__u32 status;
+
+	/** @supported_session_types: bitmask of supported PXP session types */
+	__u32 supported_session_types;
+};
+
 /**
  * struct drm_xe_device_query - Input of &DRM_IOCTL_XE_DEVICE_QUERY - main
  * structure to query device information
@@ -648,6 +681,7 @@ struct drm_xe_query_uc_fw_version {
  *    attributes.
  *  - %DRM_XE_DEVICE_QUERY_GT_TOPOLOGY
  *  - %DRM_XE_DEVICE_QUERY_ENGINE_CYCLES
+ *  - %DRM_XE_DEVICE_QUERY_PXP_STATUS
  *
  * If size is set to 0, the driver fills it with the required size for
  * the requested type of data to query. If size is equal to the required
@@ -700,6 +734,7 @@ struct drm_xe_device_query {
 #define DRM_XE_DEVICE_QUERY_ENGINE_CYCLES	6
 #define DRM_XE_DEVICE_QUERY_UC_FW_VERSION	7
 #define DRM_XE_DEVICE_QUERY_OA_UNITS		8
+#define DRM_XE_DEVICE_QUERY_PXP_STATUS		9
 	/** @query: The type of data to query */
 	__u32 query;