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author | Maarten Lankhorst <maarten.lankhorst@linux.intel.com> | 2020-08-19 16:08:43 +0200 |
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committer | Joonas Lahtinen <joonas.lahtinen@linux.intel.com> | 2020-09-07 14:29:16 +0300 |
commit | fd1500fcd4420eee06e2c7f3aa6067b78ac05871 (patch) | |
tree | 432b6c7f285b0d376f516aad22aaadda19aaff43 /drivers/gpu/drm | |
parent | 50ae6c61a17ce12c81fb1aa8b1bd21c284b81768 (diff) | |
download | linux-fd1500fcd4420eee06e2c7f3aa6067b78ac05871.tar.bz2 |
Revert "drm/i915/gem: Drop relocation slowpath".
This reverts commit 7dc8f1143778 ("drm/i915/gem: Drop relocation
slowpath"). We need the slowpath relocation for taking ww-mutex
inside the page fault handler, and we will take this mutex when
pinning all objects.
We also functionally revert ef398881d27d ("drm/i915/gem: Limit
struct_mutex to eb_reserve"), as we need the struct_mutex in
the slowpath as well, and a tiny part of 003d8b9143a6 ("drm/i915/gem:
Only call eb_lookup_vma once during execbuf ioctl"). Specifically,
we make the -EAGAIN handling part of fallback to slowpath again.
With this, we have a proper working slowpath again, which
will allow us to do fault handling with WW locks held.
[mlankhorst: Adjusted for reloc_gpu_flush() changes]
Cc: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Matthew Auld <matthew.auld@intel.com>
Signed-off-by: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
[mlankhorst: Removed extra reloc_gpu_flush()]
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/20200819140904.1708856-4-maarten.lankhorst@linux.intel.com
Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Diffstat (limited to 'drivers/gpu/drm')
-rw-r--r-- | drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c | 262 |
1 files changed, 252 insertions, 10 deletions
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c index 6acbd08f82f0..e8d713f78323 100644 --- a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c +++ b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c @@ -707,7 +707,7 @@ static int eb_reserve(struct i915_execbuffer *eb) if (err) break; } - if (!(err == -ENOSPC || err == -EAGAIN)) + if (err != -ENOSPC) break; /* Resort *all* the objects into priority order */ @@ -738,13 +738,6 @@ static int eb_reserve(struct i915_execbuffer *eb) } list_splice_tail(&last, &eb->unbound); - if (err == -EAGAIN) { - mutex_unlock(&eb->i915->drm.struct_mutex); - flush_workqueue(eb->i915->mm.userptr_wq); - mutex_lock(&eb->i915->drm.struct_mutex); - continue; - } - switch (pass++) { case 0: break; @@ -1626,7 +1619,9 @@ static int eb_relocate_vma(struct i915_execbuffer *eb, struct eb_vma *ev) * we would try to acquire the struct mutex again. Obviously * this is bad and so lockdep complains vehemently. */ - copied = __copy_from_user(r, urelocs, count * sizeof(r[0])); + pagefault_disable(); + copied = __copy_from_user_inatomic(r, urelocs, count * sizeof(r[0])); + pagefault_enable(); if (unlikely(copied)) { remain = -EFAULT; goto out; @@ -1674,6 +1669,250 @@ out: return remain; } +static int +eb_relocate_vma_slow(struct i915_execbuffer *eb, struct eb_vma *ev) +{ + const struct drm_i915_gem_exec_object2 *entry = ev->exec; + struct drm_i915_gem_relocation_entry *relocs = + u64_to_ptr(typeof(*relocs), entry->relocs_ptr); + unsigned int i; + int err; + + for (i = 0; i < entry->relocation_count; i++) { + u64 offset = eb_relocate_entry(eb, ev, &relocs[i]); + + if ((s64)offset < 0) { + err = (int)offset; + goto err; + } + } + err = 0; +err: + reloc_cache_reset(&eb->reloc_cache); + return err; +} + +static int check_relocations(const struct drm_i915_gem_exec_object2 *entry) +{ + const char __user *addr, *end; + unsigned long size; + char __maybe_unused c; + + size = entry->relocation_count; + if (size == 0) + return 0; + + if (size > N_RELOC(ULONG_MAX)) + return -EINVAL; + + addr = u64_to_user_ptr(entry->relocs_ptr); + size *= sizeof(struct drm_i915_gem_relocation_entry); + if (!access_ok(addr, size)) + return -EFAULT; + + end = addr + size; + for (; addr < end; addr += PAGE_SIZE) { + int err = __get_user(c, addr); + if (err) + return err; + } + return __get_user(c, end - 1); +} + +static int eb_copy_relocations(const struct i915_execbuffer *eb) +{ + struct drm_i915_gem_relocation_entry *relocs; + const unsigned int count = eb->buffer_count; + unsigned int i; + int err; + + for (i = 0; i < count; i++) { + const unsigned int nreloc = eb->exec[i].relocation_count; + struct drm_i915_gem_relocation_entry __user *urelocs; + unsigned long size; + unsigned long copied; + + if (nreloc == 0) + continue; + + err = check_relocations(&eb->exec[i]); + if (err) + goto err; + + urelocs = u64_to_user_ptr(eb->exec[i].relocs_ptr); + size = nreloc * sizeof(*relocs); + + relocs = kvmalloc_array(size, 1, GFP_KERNEL); + if (!relocs) { + err = -ENOMEM; + goto err; + } + + /* copy_from_user is limited to < 4GiB */ + copied = 0; + do { + unsigned int len = + min_t(u64, BIT_ULL(31), size - copied); + + if (__copy_from_user((char *)relocs + copied, + (char __user *)urelocs + copied, + len)) + goto end; + + copied += len; + } while (copied < size); + + /* + * As we do not update the known relocation offsets after + * relocating (due to the complexities in lock handling), + * we need to mark them as invalid now so that we force the + * relocation processing next time. Just in case the target + * object is evicted and then rebound into its old + * presumed_offset before the next execbuffer - if that + * happened we would make the mistake of assuming that the + * relocations were valid. + */ + if (!user_access_begin(urelocs, size)) + goto end; + + for (copied = 0; copied < nreloc; copied++) + unsafe_put_user(-1, + &urelocs[copied].presumed_offset, + end_user); + user_access_end(); + + eb->exec[i].relocs_ptr = (uintptr_t)relocs; + } + + return 0; + +end_user: + user_access_end(); +end: + kvfree(relocs); + err = -EFAULT; +err: + while (i--) { + relocs = u64_to_ptr(typeof(*relocs), eb->exec[i].relocs_ptr); + if (eb->exec[i].relocation_count) + kvfree(relocs); + } + return err; +} + +static int eb_prefault_relocations(const struct i915_execbuffer *eb) +{ + const unsigned int count = eb->buffer_count; + unsigned int i; + + for (i = 0; i < count; i++) { + int err; + + err = check_relocations(&eb->exec[i]); + if (err) + return err; + } + + return 0; +} + +static noinline int eb_relocate_slow(struct i915_execbuffer *eb) +{ + bool have_copy = false; + struct eb_vma *ev; + int err = 0; + +repeat: + if (signal_pending(current)) { + err = -ERESTARTSYS; + goto out; + } + + /* + * We take 3 passes through the slowpatch. + * + * 1 - we try to just prefault all the user relocation entries and + * then attempt to reuse the atomic pagefault disabled fast path again. + * + * 2 - we copy the user entries to a local buffer here outside of the + * local and allow ourselves to wait upon any rendering before + * relocations + * + * 3 - we already have a local copy of the relocation entries, but + * were interrupted (EAGAIN) whilst waiting for the objects, try again. + */ + if (!err) { + err = eb_prefault_relocations(eb); + } else if (!have_copy) { + err = eb_copy_relocations(eb); + have_copy = err == 0; + } else { + cond_resched(); + err = 0; + } + + flush_workqueue(eb->i915->mm.userptr_wq); + + if (err) + goto out; + + err = mutex_lock_interruptible(&eb->i915->drm.struct_mutex); + if (err) + goto out; + + list_for_each_entry(ev, &eb->relocs, reloc_link) { + if (!have_copy) { + pagefault_disable(); + err = eb_relocate_vma(eb, ev); + pagefault_enable(); + if (err) + break; + } else { + err = eb_relocate_vma_slow(eb, ev); + if (err) + break; + } + } + + mutex_unlock(&eb->i915->drm.struct_mutex); + if (err && !have_copy) + goto repeat; + + if (err) + goto err; + + /* + * Leave the user relocations as are, this is the painfully slow path, + * and we want to avoid the complication of dropping the lock whilst + * having buffers reserved in the aperture and so causing spurious + * ENOSPC for random operations. + */ + +err: + if (err == -EAGAIN) + goto repeat; + +out: + if (have_copy) { + const unsigned int count = eb->buffer_count; + unsigned int i; + + for (i = 0; i < count; i++) { + const struct drm_i915_gem_exec_object2 *entry = + &eb->exec[i]; + struct drm_i915_gem_relocation_entry *relocs; + + if (!entry->relocation_count) + continue; + + relocs = u64_to_ptr(typeof(*relocs), entry->relocs_ptr); + kvfree(relocs); + } + } + + return err; +} + static int eb_relocate(struct i915_execbuffer *eb) { int err; @@ -1695,8 +1934,11 @@ static int eb_relocate(struct i915_execbuffer *eb) list_for_each_entry(ev, &eb->relocs, reloc_link) { err = eb_relocate_vma(eb, ev); if (err) - return err; + break; } + + if (err) + return eb_relocate_slow(eb); } return 0; |