From: John Stultz <john.stultz@linaro.org>
To: lkml <linux-kernel@vger.kernel.org>
Cc: "John Stultz" <john.stultz@linaro.org>,
"Sumit Semwal" <sumit.semwal@linaro.org>,
"Liam Mark" <lmark@codeaurora.org>,
"Laura Abbott" <labbott@kernel.org>,
"Brian Starkey" <Brian.Starkey@arm.com>,
"Hridya Valsaraju" <hridya@google.com>,
"Suren Baghdasaryan" <surenb@google.com>,
"Sandeep Patil" <sspatil@google.com>,
"Daniel Mentz" <danielmentz@google.com>,
"Chris Goldsworthy" <cgoldswo@codeaurora.org>,
"Ørjan Eide" <orjan.eide@arm.com>,
"Robin Murphy" <robin.murphy@arm.com>,
"Ezequiel Garcia" <ezequiel@collabora.com>,
"Simon Ser" <contact@emersion.fr>,
"James Jones" <jajones@nvidia.com>,
linux-media@vger.kernel.org, dri-devel@lists.freedesktop.org
Subject: [PATCH v4 4/7] dma-buf: heaps: Skip sync if not mapped
Date: Thu, 29 Oct 2020 00:16:21 +0000 [thread overview]
Message-ID: <20201029001624.17513-5-john.stultz@linaro.org> (raw)
In-Reply-To: <20201029001624.17513-1-john.stultz@linaro.org>
This patch is basically a port of Ørjan Eide's similar patch for ION
https://lore.kernel.org/lkml/20200414134629.54567-1-orjan.eide@arm.com/
Only sync the sg-list of dma-buf heap attachment when the attachment
is actually mapped on the device.
dma-bufs may be synced at any time. It can be reached from user space
via DMA_BUF_IOCTL_SYNC, so there are no guarantees from callers on when
syncs may be attempted, and dma_buf_end_cpu_access() and
dma_buf_begin_cpu_access() may not be paired.
Since the sg_list's dma_address isn't set up until the buffer is used
on the device, and dma_map_sg() is called on it, the dma_address will be
NULL if sync is attempted on the dma-buf before it's mapped on a device.
Before v5.0 (commit 55897af63091 ("dma-direct: merge swiotlb_dma_ops
into the dma_direct code")) this was a problem as the dma-api (at least
the swiotlb_dma_ops on arm64) would use the potentially invalid
dma_address. How that failed depended on how the device handled physical
address 0. If 0 was a valid address to physical ram, that page would get
flushed a lot, while the actual pages in the buffer would not get synced
correctly. While if 0 is an invalid physical address it may cause a
fault and trigger a crash.
In v5.0 this was incidentally fixed by commit 55897af63091 ("dma-direct:
merge swiotlb_dma_ops into the dma_direct code"), as this moved the
dma-api to use the page pointer in the sg_list, and (for Ion buffers at
least) this will always be valid if the sg_list exists at all.
But, this issue is re-introduced in v5.3 with
commit 449fa54d6815 ("dma-direct: correct the physical addr in
dma_direct_sync_sg_for_cpu/device") moves the dma-api back to the old
behaviour and picks the dma_address that may be invalid.
dma-buf core doesn't ensure that the buffer is mapped on the device, and
thus have a valid sg_list, before calling the exporter's
begin_cpu_access.
Logic and commit message originally by: Ørjan Eide <orjan.eide@arm.com>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: Liam Mark <lmark@codeaurora.org>
Cc: Laura Abbott <labbott@kernel.org>
Cc: Brian Starkey <Brian.Starkey@arm.com>
Cc: Hridya Valsaraju <hridya@google.com>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Sandeep Patil <sspatil@google.com>
Cc: Daniel Mentz <danielmentz@google.com>
Cc: Chris Goldsworthy <cgoldswo@codeaurora.org>
Cc: Ørjan Eide <orjan.eide@arm.com>
Cc: Robin Murphy <robin.murphy@arm.com>
Cc: Ezequiel Garcia <ezequiel@collabora.com>
Cc: Simon Ser <contact@emersion.fr>
Cc: James Jones <jajones@nvidia.com>
Cc: linux-media@vger.kernel.org
Cc: dri-devel@lists.freedesktop.org
Reviewed-by: Brian Starkey <brian.starkey@arm.com>
Signed-off-by: John Stultz <john.stultz@linaro.org>
---
drivers/dma-buf/heaps/cma_heap.c | 10 ++++++++++
drivers/dma-buf/heaps/system_heap.c | 10 ++++++++++
2 files changed, 20 insertions(+)
diff --git a/drivers/dma-buf/heaps/cma_heap.c b/drivers/dma-buf/heaps/cma_heap.c
index 5341e5e226d5..028f1e8d6041 100644
--- a/drivers/dma-buf/heaps/cma_heap.c
+++ b/drivers/dma-buf/heaps/cma_heap.c
@@ -43,6 +43,7 @@ struct dma_heap_attachment {
struct device *dev;
struct sg_table table;
struct list_head list;
+ bool mapped;
};
static int cma_heap_attach(struct dma_buf *dmabuf,
@@ -67,6 +68,7 @@ static int cma_heap_attach(struct dma_buf *dmabuf,
a->dev = attachment->dev;
INIT_LIST_HEAD(&a->list);
+ a->mapped = false;
attachment->priv = a;
@@ -101,6 +103,7 @@ static struct sg_table *cma_heap_map_dma_buf(struct dma_buf_attachment *attachme
ret = dma_map_sgtable(attachment->dev, table, direction, 0);
if (ret)
return ERR_PTR(-ENOMEM);
+ a->mapped = true;
return table;
}
@@ -108,6 +111,9 @@ static void cma_heap_unmap_dma_buf(struct dma_buf_attachment *attachment,
struct sg_table *table,
enum dma_data_direction direction)
{
+ struct dma_heap_attachment *a = attachment->priv;
+
+ a->mapped = false;
dma_unmap_sgtable(attachment->dev, table, direction, 0);
}
@@ -122,6 +128,8 @@ static int cma_heap_dma_buf_begin_cpu_access(struct dma_buf *dmabuf,
mutex_lock(&buffer->lock);
list_for_each_entry(a, &buffer->attachments, list) {
+ if (!a->mapped)
+ continue;
dma_sync_sgtable_for_cpu(a->dev, &a->table, direction);
}
mutex_unlock(&buffer->lock);
@@ -140,6 +148,8 @@ static int cma_heap_dma_buf_end_cpu_access(struct dma_buf *dmabuf,
mutex_lock(&buffer->lock);
list_for_each_entry(a, &buffer->attachments, list) {
+ if (!a->mapped)
+ continue;
dma_sync_sgtable_for_device(a->dev, &a->table, direction);
}
mutex_unlock(&buffer->lock);
diff --git a/drivers/dma-buf/heaps/system_heap.c b/drivers/dma-buf/heaps/system_heap.c
index 5c44f9c06807..15b36bc862b1 100644
--- a/drivers/dma-buf/heaps/system_heap.c
+++ b/drivers/dma-buf/heaps/system_heap.c
@@ -37,6 +37,7 @@ struct dma_heap_attachment {
struct device *dev;
struct sg_table *table;
struct list_head list;
+ bool mapped;
};
static struct sg_table *dup_sg_table(struct sg_table *table)
@@ -84,6 +85,7 @@ static int system_heap_attach(struct dma_buf *dmabuf,
a->table = table;
a->dev = attachment->dev;
INIT_LIST_HEAD(&a->list);
+ a->mapped = false;
attachment->priv = a;
@@ -120,6 +122,7 @@ static struct sg_table *system_heap_map_dma_buf(struct dma_buf_attachment *attac
if (ret)
return ERR_PTR(ret);
+ a->mapped = true;
return table;
}
@@ -127,6 +130,9 @@ static void system_heap_unmap_dma_buf(struct dma_buf_attachment *attachment,
struct sg_table *table,
enum dma_data_direction direction)
{
+ struct dma_heap_attachment *a = attachment->priv;
+
+ a->mapped = false;
dma_unmap_sgtable(attachment->dev, table, direction, 0);
}
@@ -142,6 +148,8 @@ static int system_heap_dma_buf_begin_cpu_access(struct dma_buf *dmabuf,
invalidate_kernel_vmap_range(buffer->vaddr, buffer->len);
list_for_each_entry(a, &buffer->attachments, list) {
+ if (!a->mapped)
+ continue;
dma_sync_sgtable_for_cpu(a->dev, a->table, direction);
}
mutex_unlock(&buffer->lock);
@@ -161,6 +169,8 @@ static int system_heap_dma_buf_end_cpu_access(struct dma_buf *dmabuf,
flush_kernel_vmap_range(buffer->vaddr, buffer->len);
list_for_each_entry(a, &buffer->attachments, list) {
+ if (!a->mapped)
+ continue;
dma_sync_sgtable_for_device(a->dev, a->table, direction);
}
mutex_unlock(&buffer->lock);
--
2.17.1
next prev parent reply other threads:[~2020-10-29 0:18 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-29 0:16 [RESEND][PATCH v4 0/7] dma-buf: Performance improvements for system heap & a system-uncached implementation John Stultz
2020-10-29 0:16 ` [PATCH v4 1/7] dma-buf: system_heap: Rework system heap to use sgtables instead of pagelists John Stultz
2020-10-29 0:16 ` [PATCH v4 2/7] dma-buf: heaps: Move heap-helper logic into the cma_heap implementation John Stultz
2020-10-29 0:16 ` [PATCH v4 3/7] dma-buf: heaps: Remove heap-helpers code John Stultz
2020-10-29 0:16 ` John Stultz [this message]
2020-10-29 0:16 ` [PATCH v4 5/7] dma-buf: system_heap: Allocate higher order pages if available John Stultz
[not found] ` <20201029070221.2856-1-hdanton@sina.com>
2020-10-29 19:34 ` John Stultz
2020-10-29 0:16 ` [PATCH v4 6/7] dma-buf: dma-heap: Keep track of the heap device struct John Stultz
2020-10-29 0:16 ` [PATCH v4 7/7] dma-buf: system_heap: Add a system-uncached heap re-using the system heap John Stultz
[not found] ` <20201029071037.2913-1-hdanton@sina.com>
2020-10-29 22:28 ` John Stultz
-- strict thread matches above, loose matches on Subject: below --
2020-10-17 1:32 [PATCH v4 0/7] dma-buf: Performance improvements for system heap & a system-uncached implementation John Stultz
2020-10-17 1:32 ` [PATCH v4 4/7] dma-buf: heaps: Skip sync if not mapped John Stultz
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