Hi Timur,
thanks for re-working this patch!
On 2/26/24 22:02, Timur Tabi wrote:
The LOGINIT, LOGINTR, LOGRM, and LOGPMU buffers are circular buffers
that have printf-like logs from GSP-RM and PMU encoded in them.
LOGINIT, LOGINTR, and LOGRM are allocated by Nouveau and their DMA
addresses are passed to GSP-RM during initialization. The buffers are
required for GSP-RM to initialize properly.
LOGPMU is also allocated by Nouveau, but its contents are updated
when Nouveau receives an NV_VGPU_MSG_EVENT_UCODE_LIBOS_PRINT RPC from
GSP-RM. Nouveau then copies the RPC to the buffer.
The messages are encoded as an array of variable-length structures that
contain the parameters to an NV_PRINTF call. The format string and
parameter count are stored in a special ELF image that contains only
logging strings. This image is not currently shipped with the Nvidia
driver.
There are two methods to extract the logs.
OpenRM tries to load the logging ELF, and if present, parses the log
buffers in real time and outputs the strings to the kernel console.
Alternatively, and this is the method used by this patch, the buffers
can be exposed to user space, and a user-space tool (along with the
logging ELF image) can parse the buffer and dump the logs.
This method has the advantage that it allows the buffers to be parsed
even when the logging ELF file is not available to the user. However,
it has the disadvantage the debubfs entries need to remain until the
Typo in "debugfs".
driver is unloaded.
The buffers are exposed via debugfs. The debugfs entries must be
created before GSP-RM is started, to ensure that they are available
during GSP-RM initialization.
Generally agree. Just wondering why you are pointing this out
explicitly.
What if we'd create them directly after GSP init? Is there anything
subtle to that?
If GSP-RM fails to initialize, then Nouveau immediately shuts down
the GSP interface. This would normally also deallocate the logging
buffers, thereby preventing the user from capturing the debug logs.
To avoid this, use the keep-gsp-logging command line parameter. If
"introduce the keep-gsp-logging command line parameter"
specified, and if at least one logging buffer has contents, then
Nouveau will migrate these buffers into new debugfs entries that are
retained until the driver unloads.
An end-user can capture the logs using the following commands:
cp /sys/kernel/debug/dri/<path>/loginit loginit
cp /sys/kernel/debug/dri/<path>/logrm logrm
cp /sys/kernel/debug/dri/<path>/logintr logintr
cp /sys/kernel/debug/dri/<path>/logpmu logpmu
where <path> is the PCI ID of the GPU (e.g. 0000:65:00.0).
Since LOGPMU is not needed for normal GSP-RM operation, it is only
created if debugfs is available. Otherwise, the
NV_VGPU_MSG_EVENT_UCODE_LIBOS_PRINT RPCs are ignored.
The commit message and some DOC comments contains trailing spaces
between words.
Signed-off-by: Timur Tabi <ttabi@xxxxxxxxxx>
---
.../gpu/drm/nouveau/include/nvkm/subdev/gsp.h | 25 ++
drivers/gpu/drm/nouveau/nouveau_drm.c | 13 +
.../gpu/drm/nouveau/nvkm/subdev/gsp/r535.c | 340 +++++++++++++++++-
3 files changed, 377 insertions(+), 1 deletion(-)
diff --git a/drivers/gpu/drm/nouveau/include/nvkm/subdev/gsp.h b/drivers/gpu/drm/nouveau/include/nvkm/subdev/gsp.h
index a9be0d86e412..e2f8ff58d408 100644
--- a/drivers/gpu/drm/nouveau/include/nvkm/subdev/gsp.h
+++ b/drivers/gpu/drm/nouveau/include/nvkm/subdev/gsp.h
@@ -5,6 +5,8 @@
#include <core/falcon.h>
#include <core/firmware.h>
+#include <linux/debugfs.h>
+
#define GSP_PAGE_SHIFT 12
#define GSP_PAGE_SIZE BIT(GSP_PAGE_SHIFT)
@@ -27,6 +29,20 @@ typedef int (*nvkm_gsp_msg_ntfy_func)(void *priv, u32 fn, void *repv, u32 repc);
struct nvkm_gsp_event;
typedef void (*nvkm_gsp_event_func)(struct nvkm_gsp_event *, void *repv, u32 repc);
+/**
+ * nvkm_gsp_log - structure for tracking GSP-RM logging buffers
+ * @head: list head
+ * @shutdown: pointer to function to call to clean up
+ *
+ * One of these is created for each GPU upon GSP shutdown if the
+ * "keep_gsp_logging" command-line parameter is specified. This is used to
+ * track the alternative debugfs entries for the GSP-RM logs.
+ */
+struct nvkm_gsp_log {
Maybe better to name this structure nvif_log instead and move it to
include/nvif/log.h for consistency. It's not really limited GSP,
although I don't see what else it could ever be used for.
+ struct list_head head;
+ void (*shutdown)(struct nvkm_gsp_log *);
+};
+
struct nvkm_gsp {
const struct nvkm_gsp_func *func;
struct nvkm_subdev subdev;
@@ -218,6 +234,15 @@ struct nvkm_gsp {
/* The size of the registry RPC */
size_t registry_rpc_size;
+
+ /*
+ * Logging buffers in debugfs. The wrapper objects need to remain
+ * in memory until the dentry is deleted.
+ */
+ struct debugfs_blob_wrapper blob_init;
+ struct debugfs_blob_wrapper blob_intr;
+ struct debugfs_blob_wrapper blob_rm;
+ struct debugfs_blob_wrapper blob_pmu;
};
static inline bool
diff --git a/drivers/gpu/drm/nouveau/nouveau_drm.c b/drivers/gpu/drm/nouveau/nouveau_drm.c
index a947e1d5f309..a258e02a16af 100644
--- a/drivers/gpu/drm/nouveau/nouveau_drm.c
+++ b/drivers/gpu/drm/nouveau/nouveau_drm.c
@@ -113,6 +113,10 @@ static struct drm_driver driver_stub;
static struct drm_driver driver_pci;
static struct drm_driver driver_platform;
+#ifdef CONFIG_DEBUG_FS
+LIST_HEAD(gsp_logs);
+#endif
+
static u64
nouveau_pci_name(struct pci_dev *pdev)
{
@@ -1446,6 +1450,15 @@ nouveau_drm_exit(void)
#endif
if (IS_ENABLED(CONFIG_DRM_NOUVEAU_SVM))
mmu_notifier_synchronize();
+
+#ifdef CONFIG_DEBUG_FS
+ if (!list_empty(&gsp_logs)) {
+ struct nvkm_gsp_log *log;
+
+ list_for_each_entry(log, &gsp_logs, head)
+ log->shutdown(log);
+ }
+#endif
}
module_init(nouveau_drm_init);
diff --git a/drivers/gpu/drm/nouveau/nvkm/subdev/gsp/r535.c b/drivers/gpu/drm/nouveau/nvkm/subdev/gsp/r535.c
index 1eb1bc5df39a..f69afd5ea263 100644
--- a/drivers/gpu/drm/nouveau/nvkm/subdev/gsp/r535.c
+++ b/drivers/gpu/drm/nouveau/nvkm/subdev/gsp/r535.c
@@ -26,6 +26,7 @@
#include <subdev/vfn.h>
#include <engine/fifo/chan.h>
#include <engine/sec2.h>
+#include <drm/drm_device.h>
#include <nvfw/fw.h>
@@ -2077,6 +2078,149 @@ r535_gsp_rmargs_init(struct nvkm_gsp *gsp, bool resume)
return 0;
}
+#ifdef CONFIG_DEBUG_FS
+
+#define NV_GSP_MSG_EVENT_UCODE_LIBOS_CLASS_PMU 0xf3d722
+
+/**
+ * r535_gsp_msg_libos_print - capture log message from the PMU
+ * @priv: gsp pointer
+ * @fn: function number (ignored)
+ * @repv: pointer to libos print RPC
+ * @repc: message size
+ *
+ * See _kgspRpcUcodeLibosPrint
+ */
+static int r535_gsp_msg_libos_print(void *priv, u32 fn, void *repv, u32 repc)
+{
+ struct nvkm_gsp *gsp = priv;
+ struct nvkm_subdev *subdev = &gsp->subdev;
+ struct {
+ u32 ucodeEngDesc;
+ u32 libosPrintBufSize;
+ u8 libosPrintBuf[];
+ } *rpc = repv;
+ unsigned int class = rpc->ucodeEngDesc >> 8;
+
+ nvkm_debug(subdev, "received libos print from class 0x%x for %u bytes\n",
+ class, rpc->libosPrintBufSize);
+
+ if (class != NV_GSP_MSG_EVENT_UCODE_LIBOS_CLASS_PMU) {
+ nvkm_warn(subdev,
+ "received libos print from unknown class 0x%x\n",
+ class);
+ return -ENOMSG;
+ }
+ if (rpc->libosPrintBufSize > GSP_PAGE_SIZE) {
+ nvkm_error(subdev, "libos print is too large (%u bytes)\n",
+ rpc->libosPrintBufSize);
+ return -E2BIG;
+
+ }
+ memcpy(gsp->blob_pmu.data, rpc->libosPrintBuf, rpc->libosPrintBufSize);
+
+ return 0;
+}
+
+/**
+ * r535_gsp_libos_debugfs_init - create logging debugfs entries
+ * @gsp: gsp pointer
+ *
+ * Create the debugfs entries. This exposes the log buffers to
+ * userspace so that an external tool can parse it.
+ *
+ * The 'logpmu' contains exception dumps from the PMU. It is written via an
+ * RPC sent from GSP-RM and must be only 4KB. We create it here because it's
+ * only useful if there is a debugfs entry to expose it. If we get the PMU
+ * logging RPC and there is no debugfs entry, the RPC is just ignored.
+ *
+ * The blob_init, blob_rm, and blob_pmu objects can't be transient
+ * because debugfs_create_blob doesn't copy them.
+ *
+ * NOTE: OpenRM loads the logging elf image and prints the log messages
+ * in real-time. We may add that capability in the future, but that
+ * requires loading an ELF images that are not distributed with the driver,
+ * and adding the parsing code to Nouveau.
+ *
+ * Ideally, this should be part of nouveau_debugfs_init(), but that function
+ * is called too late. We really want to create these debugfs entries before
+ * r535_gsp_booter_load() is called, so that if GSP-RM fails to initialize,
+ * there could still be a log to capture.
+ */
+static void r535_gsp_libos_debugfs_init(struct nvkm_gsp *gsp)
+{
+ struct dentry *dir, *dir_init, *dir_intr, *dir_rm, *dir_pmu;
+ struct device *dev = gsp->subdev.device->dev;
+
+ /* Each GPU has a subdir based on its device name, so find it */
+ struct drm_device *drm_dev = dev_get_drvdata(dev);
+
+ if (!drm_dev || !drm_dev->debugfs_root) {
+ nvkm_error(&gsp->subdev, "could not find debugfs path\n");
+ return;
+ }
+
+ dir = drm_dev->debugfs_root;
+
+ gsp->blob_init.data = gsp->loginit.data;
+ gsp->blob_init.size = gsp->loginit.size;
+ gsp->blob_intr.data = gsp->logintr.data;
+ gsp->blob_intr.size = gsp->logintr.size;
+ gsp->blob_rm.data = gsp->logrm.data;
+ gsp->blob_rm.size = gsp->logrm.size;
+
+ dir_init = debugfs_create_blob("loginit", 0444, dir, &gsp->blob_init);
+ if (IS_ERR(dir_init)) {
+ nvkm_error(&gsp->subdev, "failed to create loginit debugfs entry\n");
+ goto error;
If we hit this, dir_intr and dir_rm are uninitialized.
+ }
+
+ dir_intr = debugfs_create_blob("logintr", 0444, dir, &gsp->blob_intr);
+ if (IS_ERR(dir_intr)) {
+ nvkm_error(&gsp->subdev, "failed to create logintr debugfs entry\n");
+ goto error;
+ }
+
+ dir_rm = debugfs_create_blob("logrm", 0444, dir, &gsp->blob_rm);
+ if (IS_ERR(dir_rm)) {
+ nvkm_error(&gsp->subdev, "failed to create logrm debugfs entry\n");
+ goto error;
+ }
+
+ /*
+ * Since the PMU buffer is copied from an RPC, it doesn't need to be
+ * a DMA buffer.
+ */
+ gsp->blob_pmu.size = GSP_PAGE_SIZE;
+ gsp->blob_pmu.data = kzalloc(gsp->blob_pmu.size, GFP_KERNEL);
+ if (!gsp->blob_pmu.data)
+ goto error;
+
+ dir_pmu = debugfs_create_blob("logpmu", 0444, dir, &gsp->blob_pmu);
+ if (IS_ERR(dir_pmu)) {
+ nvkm_error(&gsp->subdev, "failed to create logpmu debugfs entry\n");
+ kfree(gsp->blob_pmu.data);
+ goto error;
+ }
+
+ i_size_write(d_inode(dir_init), gsp->blob_init.size);
+ i_size_write(d_inode(dir_intr), gsp->blob_intr.size);
+ i_size_write(d_inode(dir_rm), gsp->blob_rm.size);
+ i_size_write(d_inode(dir_pmu), gsp->blob_pmu.size);
+
+ r535_gsp_msg_ntfy_add(gsp, 0x0000100C, r535_gsp_msg_libos_print, gsp);
+
+ nvkm_debug(&gsp->subdev, "created debugfs GSP-RM logging entries\n");
+ return;
+
+error:
+ debugfs_remove(dir_init);
+ debugfs_remove(dir_intr);
+ debugfs_remove(dir_rm);
+}
+
+#endif
+
static inline u64
r535_gsp_libos_id8(const char *name)
{
@@ -2127,7 +2271,11 @@ static void create_pte_array(u64 *ptes, dma_addr_t addr, size_t size)
* written to directly by GSP-RM and can be any multiple of GSP_PAGE_SIZE.
*
* The physical address map for the log buffer is stored in the buffer
- * itself, starting with offset 1. Offset 0 contains the "put" pointer.
+ * itself, starting with offset 1. Offset 0 contains the "put" pointer (pp).
+ * Initially, pp is equal to 0. If the buffer has valid logging data in it,
+ * then pp points to index into the buffer where the next logging entry will
+ * be written. Therefore, the logging data is valid if:
+ * 1 <= pp < sizeof(buffer)/sizeof(u64)
*
* The GSP only understands 4K pages (GSP_PAGE_SIZE), so even if the kernel is
* configured for a larger page size (e.g. 64K pages), we need to give
@@ -2198,6 +2346,11 @@ r535_gsp_libos_init(struct nvkm_gsp *gsp)
args[3].size = gsp->rmargs.size;
args[3].kind = LIBOS_MEMORY_REGION_CONTIGUOUS;
args[3].loc = LIBOS_MEMORY_REGION_LOC_SYSMEM;
+
+#ifdef CONFIG_DEBUG_FS
+ r535_gsp_libos_debugfs_init(gsp);
+#endif
+
return 0;
}
@@ -2483,6 +2636,182 @@ r535_gsp_dtor_fws(struct nvkm_gsp *gsp)
gsp->fws.rm = NULL;
}
+#ifdef CONFIG_DEBUG_FS
+
+/*
+ * If GSP-RM load fails, then the GSP nvkm object will be deleted, the
+ * logging debugfs entries will be deleted, and it will not be possible to
+ * debug the load failure. The keep_gsp_logging parameter tells Nouveau
+ * to copy the logging buffers to new debugfs entries, and these entries are
+ * retained until the driver unloads.
+ */
+static bool keep_gsp_logging;
+module_param(keep_gsp_logging, bool, 0444);
+MODULE_PARM_DESC(keep_gsp_logging,
+ "Migrate the GSP-RM logging debugfs entries upon exit");
What if we start supporting multiple firmware versions? I think we
should move this module_param() either into nouveau_drm.c and pipe it
through nvkm_device_ctor() or move to nvkm/engine/device/base.c and add
it to struct nvkm_device there.
+
+// FIXME: This should be in a header file
+extern struct list_head gsp_logs;
What about include/nvif/log.h? :-)
+
+struct r535_gsp_log {
Guess we need this abstraction, since we expect that a different
firmware version might change the available log buffers?
+ struct nvkm_gsp_log log;
+
+ /*
+ * Logging buffers in debugfs. The wrapper objects need to remain
+ * in memory until the dentry is deleted.
+ */
+ struct dentry *debugfs_logging_dir;
+ struct debugfs_blob_wrapper blob_init;
+ struct debugfs_blob_wrapper blob_intr;
+ struct debugfs_blob_wrapper blob_rm;
+ struct debugfs_blob_wrapper blob_pmu;
+};
+
+static void r535_debugfs_shutdown(struct nvkm_gsp_log *_log)
+{
+ struct r535_gsp_log *log = container_of(_log, struct r535_gsp_log, log);
+
+ debugfs_remove(log->debugfs_logging_dir);
+
+ kfree(log->blob_init.data);
+ kfree(log->blob_intr.data);
+ kfree(log->blob_rm.data);
+ kfree(log->blob_pmu.data);
+}
+
+/**
+ * is_empty - return true if the logging buffer was never written to
+ * @b: blob wrapper with ->data field pointing to logging buffer
+ *
+ * The first 64-bit field of loginit, and logintr, and logrm is the 'put'
+ * pointer, and it is initialized to 0. If the pointer is still 0 when
+ * GSP-RM is shut down, that means that it was never written do, so it
+ * can be ignored.
+ *
+ * This test also works for logpmu, even though it doesn't have a put pointer.
+ */
+static bool is_empty(struct debugfs_blob_wrapper *b)
+{
+ uint64_t *put = b->data;
Better use u64.
+
+ return *put == 0;
+}
+
+static int r535_gsp_copy_log(struct dentry *parent,
+ const char *name,
+ struct debugfs_blob_wrapper *s,
+ struct debugfs_blob_wrapper *d)
+{
+ struct dentry *dir;
+
+ /* If the buffer is empty, just skip it. */
+ if (is_empty(s))
+ return 0;
+
+ d->data = kmemdup(s->data, s->size, GFP_KERNEL);
+ if (!d->data)
+ return -ENOMEM;
+
+ d->size = s->size;
+ dir = debugfs_create_blob(name, 0444, parent, d);
+ if (IS_ERR(dir)) {
+ kfree(d->data);
+ memset(d, 0, sizeof(*d));
+ return PTR_ERR(dir);
+ }
+
+ i_size_write(d_inode(dir), d->size);
+
+ return 0;
+}
+
+/**
+ * r535_gsp_retain_logging - copy logging buffers to new debugfs root
+ * @gsp: gsp pointer
+ *
+ * If keep_gsp_logging is enabled, then we want to preserve the GSP-RM logging
+ * buffers and their debugfs entries, but all those objects would normally
+ * deleted if GSP-RM fails to load. So we create a new debugfs root, allocate
+ * new buffers, then and copy contents of the logging buffers to them.
+ *
+ * These buffers and dentries are not associated with nvkm_gsp and will be
+ * retained until the driver unloads.
+ */
+static void r535_gsp_retain_logging(struct nvkm_gsp *gsp)
+{
+ struct device *dev = gsp->subdev.device->dev;
+ struct dentry *root, *dir;
+ struct r535_gsp_log *log;
+ int ret;
+
+ /* Check to make sure at least one buffer has data. */
+ if (is_empty(&gsp->blob_init) && is_empty(&gsp->blob_intr) &&
+ is_empty(&gsp->blob_rm) && is_empty(&gsp->blob_rm)) {
+ nvkm_warn(&gsp->subdev, "all logging buffers are empty\n");
+ return;
+ }
+
+ /* Find the 'dri' root debugfs entry. Every GPU has a dentry under it */
+ root = debugfs_lookup("dri", NULL);
+ if (IS_ERR(root)) {
+ /* No debugfs, or no root dentry for DRM */
Maybe print a warning as well?
+ return;
+ }
+
+ /* Create a new debugfs root. It has the same name as the old one */
+ dir = debugfs_create_dir(dev_name(dev), root);
+ dput(root);
+ if (IS_ERR(dir)) {
+ nvkm_error(&gsp->subdev,
+ "failed to create %s debugfs entry\n", dev_name(dev));
+ return;
+ }
+
+ log = devm_kzalloc(dev, sizeof(*log), GFP_KERNEL);
What if the PCI device is removed before the module is removed?
I think we should just free it in nouveau_drm_exit(). As long as
we keep the convention that struct nvif_log is the first member we
should be fine. Otherwise we could also just add ::free() callback,
like we have ::shutdown(), which seems to be safer.
+ if (!log) {
+ debugfs_remove(dir);
+ return;
+ }
+
+ ret = r535_gsp_copy_log(dir, "loginit", &gsp->blob_init, &log->blob_init);
+ if (ret)
+ goto error;
+
+ ret = r535_gsp_copy_log(dir, "logintr", &gsp->blob_intr, &log->blob_intr);
+ if (ret)
+ goto error;
+
+ ret = r535_gsp_copy_log(dir, "logrm", &gsp->blob_rm, &log->blob_rm);
+ if (ret)
+ goto error;
+
+ ret = r535_gsp_copy_log(dir, "logpmu", &gsp->blob_pmu, &log->blob_pmu);
+ if (ret)
+ goto error;
+
+ log->debugfs_logging_dir = dir;
+ log->log.shutdown = r535_debugfs_shutdown;
+ list_add(&log->log.head, &gsp_logs);
+
+ nvkm_warn(&gsp->subdev,
+ "logging buffers migrated to /sys/kernel/debug/dri/%s\n",
+ dev_name(dev));
+
+ return;
+
+error:
+ nvkm_warn(&gsp->subdev, "failed to migrate logging buffers\n");
+
+ debugfs_remove(log->debugfs_logging_dir);
+ kfree(log->blob_init.data);
+ kfree(log->blob_intr.data);
+ kfree(log->blob_rm.data);
+ kfree(log->blob_pmu.data);
+ kfree(log);
+}
+
+#endif
+
void
r535_gsp_dtor(struct nvkm_gsp *gsp)
{
@@ -2502,6 +2831,15 @@ r535_gsp_dtor(struct nvkm_gsp *gsp)
r535_gsp_dtor_fws(gsp);
nvkm_gsp_mem_dtor(&gsp->shm.mem);
+
+#ifdef CONFIG_DEBUG_FS
+ if (keep_gsp_logging)
+ r535_gsp_retain_logging(gsp);
+#endif
+
+ kfree(gsp->blob_pmu.data);
+ gsp->blob_pmu.data = NULL;
+
nvkm_gsp_mem_dtor(&gsp->loginit);
nvkm_gsp_mem_dtor(&gsp->logintr);
nvkm_gsp_mem_dtor(&gsp->logrm);
