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drm/nouveau: exec: report max pushs through getparam

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Report the maximum number of IBs that can be pushed with a single
DRM_IOCTL_NOUVEAU_EXEC through DRM_IOCTL_NOUVEAU_GETPARAM.

While the maximum number of IBs per ring might vary between chipsets,
the kernel will make sure that userspace can only push a fraction of the
maximum number of IBs per ring per job, such that we avoid a situation
where there's only a single job occupying the ring, which could
potentially lead to the ring run dry.

Using DRM_IOCTL_NOUVEAU_GETPARAM to report the maximum number of IBs
that can be pushed with a single DRM_IOCTL_NOUVEAU_EXEC implies that
all channels of a given device have the same ring size.

Reviewed-by: Dave Airlie <airlied@redhat.com>
Reviewed-by: Lyude Paul <lyude@redhat.com>
Acked-by: Faith Ekstrand <faith.ekstrand@collabora.com>
Signed-off-by: Danilo Krummrich <dakr@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20231002135008.10651-3-dakr@redhat.com
This commit is contained in:
Danilo Krummrich 2023-10-02 15:46:48 +02:00
parent bbe08a0e11
commit d59e75eef5
6 changed files with 49 additions and 4 deletions
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21
drivers/gpu/drm/nouveau/nouveau_abi16.c
View File

@ -31,6 +31,7 @@
#include "nouveau_drv.h"
#include "nouveau_dma.h"
#include "nouveau_exec.h"
#include "nouveau_gem.h"
#include "nouveau_chan.h"
#include "nouveau_abi16.h"
@ -183,6 +184,20 @@ nouveau_abi16_fini(struct nouveau_abi16 *abi16)
cli->abi16 = NULL;
}
static inline int
getparam_dma_ib_max(struct nvif_device *device)
{
const struct nvif_mclass dmas[] = {
{ NV03_CHANNEL_DMA, 0 },
{ NV10_CHANNEL_DMA, 0 },
{ NV17_CHANNEL_DMA, 0 },
{ NV40_CHANNEL_DMA, 0 },
{}
};
return nvif_mclass(&device->object, dmas) < 0 ? NV50_DMA_IB_MAX : 0;
}
int
nouveau_abi16_ioctl_getparam(ABI16_IOCTL_ARGS)
{
@ -247,6 +262,12 @@ nouveau_abi16_ioctl_getparam(ABI16_IOCTL_ARGS)
case NOUVEAU_GETPARAM_GRAPH_UNITS:
getparam->value = nvkm_gr_units(gr);
break;
case NOUVEAU_GETPARAM_EXEC_PUSH_MAX: {
int ib_max = getparam_dma_ib_max(device);
getparam->value = nouveau_exec_push_max_from_ib_max(ib_max);
break;
}
default:
NV_PRINTK(dbg, cli, "unknown parameter %lld\n", getparam->param);
return -EINVAL;

2
drivers/gpu/drm/nouveau/nouveau_chan.c
View File

@ -454,7 +454,7 @@ nouveau_channel_init(struct nouveau_channel *chan, u32 vram, u32 gart)
chan->user_get = 0x44;
chan->user_get_hi = 0x60;
chan->dma.ib_base = 0x10000 / 4;
chan->dma.ib_max = (0x02000 / 8) - 1;
chan->dma.ib_max = NV50_DMA_IB_MAX;
chan->dma.ib_put = 0;
chan->dma.ib_free = chan->dma.ib_max - chan->dma.ib_put;
chan->dma.max = chan->dma.ib_base;

3
drivers/gpu/drm/nouveau/nouveau_dma.h
View File

@ -49,6 +49,9 @@ void nv50_dma_push(struct nouveau_channel *, u64 addr, u32 length,
/* Maximum push buffer size. */
#define NV50_DMA_PUSH_MAX_LENGTH 0x7fffff
/* Maximum IBs per ring. */
#define NV50_DMA_IB_MAX ((0x02000 / 8) - 1)
/* Object handles - for stuff that's doesn't use handle == oclass. */
enum {
NvDmaFB = 0x80000002,

7
drivers/gpu/drm/nouveau/nouveau_exec.c
View File

@ -379,7 +379,7 @@ nouveau_exec_ioctl_exec(struct drm_device *dev,
struct nouveau_channel *chan = NULL;
struct nouveau_exec_job_args args = {};
struct drm_nouveau_exec *req = data;
int ret = 0;
int push_max, ret = 0;
if (unlikely(!abi16))
return -ENOMEM;
@ -404,9 +404,10 @@ nouveau_exec_ioctl_exec(struct drm_device *dev,
if (!chan->dma.ib_max)
return nouveau_abi16_put(abi16, -ENOSYS);
if (unlikely(req->push_count > NOUVEAU_GEM_MAX_PUSH)) {
push_max = nouveau_exec_push_max_from_ib_max(chan->dma.ib_max);
if (unlikely(req->push_count > push_max)) {
NV_PRINTK(err, cli, "pushbuf push count exceeds limit: %d max %d\n",
req->push_count, NOUVEAU_GEM_MAX_PUSH);
req->push_count, push_max);
return nouveau_abi16_put(abi16, -EINVAL);
}

10
drivers/gpu/drm/nouveau/nouveau_exec.h
View File

@ -51,4 +51,14 @@ int nouveau_exec_job_init(struct nouveau_exec_job **job,
int nouveau_exec_ioctl_exec(struct drm_device *dev, void *data,
struct drm_file *file_priv);
static inline unsigned int
nouveau_exec_push_max_from_ib_max(int ib_max)
{
/* Limit the number of IBs per job to half the size of the ring in order
* to avoid the ring running dry between submissions and preserve one
* more slot for the job's HW fence.
*/
return ib_max > 1 ? ib_max / 2 - 1 : 0;
}
#endif

10
include/uapi/drm/nouveau_drm.h
View File

@ -44,6 +44,16 @@ extern "C" {
#define NOUVEAU_GETPARAM_PTIMER_TIME 14
#define NOUVEAU_GETPARAM_HAS_BO_USAGE 15
#define NOUVEAU_GETPARAM_HAS_PAGEFLIP 16
/**
* @NOUVEAU_GETPARAM_EXEC_PUSH_MAX
*
* Query the maximum amount of IBs that can be pushed through a single
* &drm_nouveau_exec structure and hence a single &DRM_IOCTL_NOUVEAU_EXEC
* ioctl().
*/
#define NOUVEAU_GETPARAM_EXEC_PUSH_MAX 17
struct drm_nouveau_getparam {
__u64 param;
__u64 value;