Re: [igt-dev] [PATCH i-g-t] lib/i915: add mmap_offset support

Chris Wilson
2019-02-22T22:14:17Z

Quoting Antonio Argenziano (2019-02-22 22:01:43)
>
>
> On 22/02/19 13:59, Antonio Argenziano wrote:
> > From: "Kalamarz, Lukasz" <lukasz.kalamarz@intel.com>
> >
> > With recently proposed changes, IGT need to start supporting new
> > way of mmaping object, which will be used from now by default.
> > This patch modify gem_mmap_wc and gem_mmap functions to be
> > in sync with those changes.
> >
> > v2:
> > - Fix IOCTL number. (Daniele)
> > - Move wrappers to new file. (Chris)
>
> Not sure how much of the other stuff we might want to bring over so I've
> moved only the new wrappers for now.

It's a sensible chunk to review, so no worries, more can come later.

> > Signed-off-by: Lukasz Kalamarz <lukasz.kalamarz@intel.com>
> > Cc: Janulgue Abdiel <abdiel.janulgue@intel.com>
> > Cc: Matthew Auld <matthew.auld@intel.com>
> > Cc: Michal Winiarski <michal.winiarski@intel.com>
> > Cc: Antonio Argenziano <antonio.argenziano@intel.com>
> > Cc: Daniele Spurio Ceraolo <daniele.ceraolospurio@intel.com>
> > Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
> > Cc: Chris Wilson <chris@chris-wilson.co.uk>
> > Signed-off-by: Antonio Argenziano <antonio.argenziano@intel.com>
> > ---
> > lib/i915/gem_mman.c | 87 ++++++++++++++++++++++++++++++++++++++++++++
> > lib/i915/gem_mman.h | 61 +++++++++++++++++++++++++++++++
> > lib/ioctl_wrappers.c | 67 +++++++++++++++++++++++-----------
> > lib/ioctl_wrappers.h | 1 +
> > lib/meson.build | 1 +
> > 5 files changed, 196 insertions(+), 21 deletions(-)
> > create mode 100644 lib/i915/gem_mman.c
> > create mode 100644 lib/i915/gem_mman.h
> >
> > diff --git a/lib/i915/gem_mman.c b/lib/i915/gem_mman.c
> > new file mode 100644
> > index 00000000..fb949f44
> > --- /dev/null
> > +++ b/lib/i915/gem_mman.c
> > @@ -0,0 +1,87 @@
> > +/*
> > + * Copyright © 2007, 2011, 2013, 2014, 2019 Intel Corporation
> > + *
> > + * Permission is hereby granted, free of charge, to any person obtaining a
> > + * copy of this software and associated documentation files (the "Software"),
> > + * to deal in the Software without restriction, including without limitation
> > + * the rights to use, copy, modify, merge, publish, distribute, sublicense,
> > + * and/or sell copies of the Software, and to permit persons to whom the
> > + * Software is furnished to do so, subject to the following conditions:
> > + *
> > + * The above copyright notice and this permission notice (including the next
> > + * paragraph) shall be included in all copies or substantial portions of the
> > + * Software.
> > + *
> > + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
> > + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
> > + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
> > + * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
> > + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
> > + * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
> > + * IN THE SOFTWARE.
> > + *
> > + */
> > +
> > +#include <stdbool.h>
> > +#include <sys/ioctl.h>
> > +
> > +#include "igt_core.h"
> > +#include "ioctl_wrappers.h"
> > +
> > +#include "gem_mman.h"
> > +
> > +
> > +bool has_mmap_offset(int fd)
> > +{
> > + static int has_mmap_offset = -1;
> > +
> > + if (has_mmap_offset == -1) {
> > + struct drm_i915_getparam gp;
> > +
> > + has_mmap_offset = 0;
> > +
> > + memset(&gp, 0, sizeof(gp));
> > + gp.param = 0x55; /* I915_PARAM_MMAP_OFFSET_VERSION */
> > + gp.value = &has_mmap_offset;
> > + ioctl(fd, DRM_IOCTL_I915_GETPARAM, &gp);
> > + }
> > +
> > + return has_mmap_offset > 0;
> > +}
> > +
> > +/**
> > + * __gem_mmap_offset:
> > + * @fd: open i915 drm file descriptor
> > + * @handle: gem buffer object handle
> > + * @offset: offset in the gem buffer of the mmap arena
> > + * @size: size of the mmap arena
> > + * @prot: memory protection bits as used by mmap()
> > + * @flags: flags used to determine caching
> > + *
> > + * Similar to __gem_mmap but use MMAP_OFFSET IOCTL.
> > + *
> > + * Returns: A pointer to the created memory mapping, NULL on failure.
> > + */
> > +void
> > +*__gem_mmap_offset(int fd, uint32_t handle, uint64_t offset, uint64_t size, unsigned int prot, uint64_t flags)
> > +{
> > + struct local_drm_i915_gem_mmap_offset arg;
> > + void *ptr;
> > +
> > + memset(&arg, 0, sizeof(arg));
> > + arg.handle = handle;
> > + arg.offset = offset;
> > + arg.flags = flags;
> > +
> > + if (igt_ioctl(fd, LOCAL_DRM_IOCTL_I915_GEM_MMAP_OFFSET, &arg))
> > + return NULL;
> > +
> > + ptr = mmap64(0, size, prot, MAP_SHARED, fd, arg.offset);
> > +
> > + if (ptr == MAP_FAILED)
> > + ptr = NULL;
> > + else
> > + errno = 0;
> > +
> > + return ptr;
> > +}
> > diff --git a/lib/i915/gem_mman.h b/lib/i915/gem_mman.h
> > new file mode 100644
> > index 00000000..2f24ca99
> > --- /dev/null
> > +++ b/lib/i915/gem_mman.h
> > @@ -0,0 +1,61 @@
> > +/*
> > + * Copyright © 2007, 2011, 2013, 2014, 2019 Intel Corporation
> > + *
> > + * Permission is hereby granted, free of charge, to any person obtaining a
> > + * copy of this software and associated documentation files (the "Software"),
> > + * to deal in the Software without restriction, including without limitation
> > + * the rights to use, copy, modify, merge, publish, distribute, sublicense,
> > + * and/or sell copies of the Software, and to permit persons to whom the
> > + * Software is furnished to do so, subject to the following conditions:
> > + *
> > + * The above copyright notice and this permission notice (including the next
> > + * paragraph) shall be included in all copies or substantial portions of the
> > + * Software.
> > + *
> > + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
> > + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
> > + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
> > + * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
> > + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
> > + * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
> > + * IN THE SOFTWARE.
> > + *
> > + */
> > +
> > +#ifndef GEM_MMAN_H
> > +#define GEM_MMAN_H
> > +
> > +struct local_drm_i915_gem_mmap_offset {
> > + /** Handle for the object being mapped. */
> > + __u32 handle;
> > + __u32 pad;
> > + /**
> > + * Fake offset to use for subsequent mmap call
> > + *
> > + * This is a fixed-size type for 32/64 compatibility.
> > + */
> > + __u64 offset;
> > +
> > + /**
> > + * Flags for extended behaviour.
> > + *
> > + * It is mandatory that either one of the _WC/_WB flags
> > + * should be passed here.
> > + */
> > + __u64 flags;
> > +};
> > +
> > +#define LOCAL_DRM_I915_GEM_MMAP_OFFSET 0x24
> > +#define LOCAL_I915_MMAP_OFFSET_WC (1 << 0)
> > +#define LOCAL_I915_MMAP_OFFSET_WB (1 << 1)
> > +#define LOCAL_I915_MMAP_OFFSET_UC (1 << 2)
> > +
> > +#define LOCAL_DRM_IOCTL_I915_GEM_MMAP_OFFSET \
> > + DRM_IOWR(DRM_COMMAND_BASE + LOCAL_DRM_I915_GEM_MMAP_OFFSET, struct local_drm_i915_gem_mmap_offset)
> > +
> > +bool has_mmap_offset(int fd);
> > +
> > +void *__gem_mmap_offset(int fd, uint32_t handle, uint64_t offset, uint64_t size, unsigned int prot, uint64_t flags);
> > +
> > +#endif /* GEM_MMAN_H */
> > +
> > diff --git a/lib/ioctl_wrappers.c b/lib/ioctl_wrappers.c
> > index 404c2fbf..c11b0146 100644
> > --- a/lib/ioctl_wrappers.c
> > +++ b/lib/ioctl_wrappers.c
> > @@ -707,35 +707,50 @@ bool gem_mmap__has_wc(int fd)
> > static int has_wc = -1;
> >
> > if (has_wc == -1) {
> > - struct drm_i915_getparam gp;
> > - int mmap_version = -1;
> > - int gtt_version = -1;
> >
> > has_wc = 0;
> >
> > - memset(&gp, 0, sizeof(gp));
> > - gp.param = I915_PARAM_MMAP_GTT_VERSION;
> > - gp.value = &gtt_version;
> > - ioctl(fd, DRM_IOCTL_I915_GETPARAM, &gp);
> > -
> > - memset(&gp, 0, sizeof(gp));
> > - gp.param = I915_PARAM_MMAP_VERSION;
> > - gp.value = &mmap_version;
> > - ioctl(fd, DRM_IOCTL_I915_GETPARAM, &gp);
> > -
> > - /* Do we have the new mmap_ioctl with DOMAIN_WC? */
> > - if (mmap_version >= 1 && gtt_version >= 2) {
> > - struct drm_i915_gem_mmap arg;
> > + /* Do we have the new mmap_offset ioctl? */
> > + if (has_mmap_offset(fd)) {
> > + struct local_drm_i915_gem_mmap_offset arg;
> >
> > /* Does this device support wc-mmaps ? */
> > memset(&arg, 0, sizeof(arg));
> > arg.handle = gem_create(fd, 4096);
> > arg.offset = 0;
> > - arg.size = 4096;
> > - arg.flags = I915_MMAP_WC;
> > - has_wc = igt_ioctl(fd, DRM_IOCTL_I915_GEM_MMAP, &arg) == 0;
> > + arg.flags = LOCAL_I915_MMAP_OFFSET_WC;
> > + has_wc = igt_ioctl(fd, LOCAL_DRM_IOCTL_I915_GEM_MMAP_OFFSET, &arg) == 0;
> > gem_close(fd, arg.handle);
> > + } else {
> > + struct drm_i915_getparam gp;
> > + int mmap_version = -1;
> > + int gtt_version = -1;
> > +
> > + memset(&gp, 0, sizeof(gp));
> > + gp.param = I915_PARAM_MMAP_GTT_VERSION;
> > + gp.value = &gtt_version;
> > + ioctl(fd, DRM_IOCTL_I915_GETPARAM, &gp);
> > +
> > + memset(&gp, 0, sizeof(gp));
> > + gp.param = I915_PARAM_MMAP_VERSION;
> > + gp.value = &mmap_version;
> > + ioctl(fd, DRM_IOCTL_I915_GETPARAM, &gp);
> > +
> > + /* Do we have the mmap_ioctl with DOMAIN_WC? */
> > + if (mmap_version >= 1 && gtt_version >= 2) {
> > + struct drm_i915_gem_mmap arg;
> > +
> > + /* Does this device support wc-mmaps ? */
> > + memset(&arg, 0, sizeof(arg));
> > + arg.handle = gem_create(fd, 4096);
> > + arg.offset = 0;
> > + arg.size = 4096;
> > + arg.flags = I915_MMAP_WC;
> > + has_wc = igt_ioctl(fd, DRM_IOCTL_I915_GEM_MMAP, &arg) == 0;
> > + gem_close(fd, arg.handle);
> > + }
> > }
> > +
> > errno = 0;
> > }
> >
> > @@ -795,7 +810,10 @@ static void
> > */
> > void *__gem_mmap__wc(int fd, uint32_t handle, uint64_t offset, uint64_t size, unsigned prot)
> > {
> > - return __gem_mmap(fd, handle, offset, size, prot, I915_MMAP_WC);
> > + if (has_mmap_offset(fd))
> > + return __gem_mmap_offset(fd, handle, offset, size, prot, LOCAL_I915_MMAP_OFFSET_WC);
> > + else
> > + return __gem_mmap(fd, handle, offset, size, prot, I915_MMAP_WC);

So this is basically,

if (__gem_mmap_offset())
return __gem_mmap();

because statics are bad!

For the purposes of API testing, we want to be able to still call
__gem_mmap__wc without any magic, and similarly __gem_mmap__offset
directly.

I would suggest that we only put the magic fallback handling into
gem_mmap__wc() and keep __gem_mmap__wc around for the explicit tests of
that ioctl. Same for __gem_mmap__cpu.

The only problem will be some callers of __gem_mmap__wc would like the
nice automagic conversion. But hopefully they are few and far in between
and can be converted to the igt_assert wielding variants instead -- or
we find some other compromise.
-Chris