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From: Daniel Vetter <daniel.vetter@ffwll.ch>
To: Intel Graphics Development <intel-gfx@lists.freedesktop.org>
Cc: "DRI Development" <dri-devel@lists.freedesktop.org>,
	"Daniel Vetter" <daniel.vetter@ffwll.ch>,
	"Christian König" <christian.koenig@amd.com>,
	"Jason Gunthorpe" <jgg@ziepe.ca>,
	"Suren Baghdasaryan" <surenb@google.com>,
	"Matthew Wilcox" <willy@infradead.org>,
	"John Stultz" <john.stultz@linaro.org>,
	"Daniel Vetter" <daniel.vetter@intel.com>,
	"Sumit Semwal" <sumit.semwal@linaro.org>,
	linux-media@vger.kernel.org, linaro-mm-sig@lists.linaro.org
Subject: [PATCH v3 1/4] dma-buf: Require VM_PFNMAP vma for mmap
Date: Thu,  3 Jun 2021 18:41:10 +0200	[thread overview]
Message-ID: <20210603164113.1433476-2-daniel.vetter@ffwll.ch> (raw)
In-Reply-To: <20210603164113.1433476-1-daniel.vetter@ffwll.ch>

tldr; DMA buffers aren't normal memory, expecting that you can use
them like that (like calling get_user_pages works, or that they're
accounting like any other normal memory) cannot be guaranteed.

Since some userspace only runs on integrated devices, where all
buffers are actually all resident system memory, there's a huge
temptation to assume that a struct page is always present and useable
like for any more pagecache backed mmap. This has the potential to
result in a uapi nightmare.

To stop this gap require that DMA buffer mmaps are VM_PFNMAP, which
blocks get_user_pages and all the other struct page based
infrastructure for everyone. In spirit this is the uapi counterpart to
the kernel-internal CONFIG_DMABUF_DEBUG.

Motivated by a recent patch which wanted to swich the system dma-buf
heap to vm_insert_page instead of vm_insert_pfn.

v2:

Jason brought up that we also want to guarantee that all ptes have the
pte_special flag set, to catch fast get_user_pages (on architectures
that support this). Allowing VM_MIXEDMAP (like VM_SPECIAL does) would
still allow vm_insert_page, but limiting to VM_PFNMAP will catch that.

From auditing the various functions to insert pfn pte entires
(vm_insert_pfn_prot, remap_pfn_range and all it's callers like
dma_mmap_wc) it looks like VM_PFNMAP is already required anyway, so
this should be the correct flag to check for.

References: https://lore.kernel.org/lkml/CAKMK7uHi+mG0z0HUmNt13QCCvutuRVjpcR0NjRL12k-WbWzkRg@mail.gmail.com/
Acked-by: Christian König <christian.koenig@amd.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: John Stultz <john.stultz@linaro.org>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: "Christian König" <christian.koenig@amd.com>
Cc: linux-media@vger.kernel.org
Cc: linaro-mm-sig@lists.linaro.org
--
Resending this so I can test the next two patches for vgem/shmem in
intel-gfx-ci. Last round failed somehow, but I can't repro that at all
locally here.

No immediate plans to merge this patch here since ttm isn't addressed
yet (and there we have the hugepte issue, for which I don't think we
have a clear consensus yet).
-Daniel
---
 drivers/dma-buf/dma-buf.c | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
index eadd1eaa2fb5..dda583fb1f03 100644
--- a/drivers/dma-buf/dma-buf.c
+++ b/drivers/dma-buf/dma-buf.c
@@ -127,6 +127,7 @@ static struct file_system_type dma_buf_fs_type = {
 static int dma_buf_mmap_internal(struct file *file, struct vm_area_struct *vma)
 {
 	struct dma_buf *dmabuf;
+	int ret;
 
 	if (!is_dma_buf_file(file))
 		return -EINVAL;
@@ -142,7 +143,11 @@ static int dma_buf_mmap_internal(struct file *file, struct vm_area_struct *vma)
 	    dmabuf->size >> PAGE_SHIFT)
 		return -EINVAL;
 
-	return dmabuf->ops->mmap(dmabuf, vma);
+	ret = dmabuf->ops->mmap(dmabuf, vma);
+
+	WARN_ON(!(vma->vm_flags & VM_PFNMAP));
+
+	return ret;
 }
 
 static loff_t dma_buf_llseek(struct file *file, loff_t offset, int whence)
@@ -1244,6 +1249,8 @@ EXPORT_SYMBOL_GPL(dma_buf_end_cpu_access);
 int dma_buf_mmap(struct dma_buf *dmabuf, struct vm_area_struct *vma,
 		 unsigned long pgoff)
 {
+	int ret;
+
 	if (WARN_ON(!dmabuf || !vma))
 		return -EINVAL;
 
@@ -1264,7 +1271,11 @@ int dma_buf_mmap(struct dma_buf *dmabuf, struct vm_area_struct *vma,
 	vma_set_file(vma, dmabuf->file);
 	vma->vm_pgoff = pgoff;
 
-	return dmabuf->ops->mmap(dmabuf, vma);
+	ret = dmabuf->ops->mmap(dmabuf, vma);
+
+	WARN_ON(!(vma->vm_flags & VM_PFNMAP));
+
+	return ret;
 }
 EXPORT_SYMBOL_GPL(dma_buf_mmap);
 
-- 
2.31.0


WARNING: multiple messages have this Message-ID (diff)
From: Daniel Vetter <daniel.vetter@ffwll.ch>
To: Intel Graphics Development <intel-gfx@lists.freedesktop.org>
Cc: "Daniel Vetter" <daniel.vetter@ffwll.ch>,
	"Matthew Wilcox" <willy@infradead.org>,
	linaro-mm-sig@lists.linaro.org, "Jason Gunthorpe" <jgg@ziepe.ca>,
	"DRI Development" <dri-devel@lists.freedesktop.org>,
	"Daniel Vetter" <daniel.vetter@intel.com>,
	"Suren Baghdasaryan" <surenb@google.com>,
	"Christian König" <christian.koenig@amd.com>,
	linux-media@vger.kernel.org
Subject: [PATCH v3 1/4] dma-buf: Require VM_PFNMAP vma for mmap
Date: Thu,  3 Jun 2021 18:41:10 +0200	[thread overview]
Message-ID: <20210603164113.1433476-2-daniel.vetter@ffwll.ch> (raw)
In-Reply-To: <20210603164113.1433476-1-daniel.vetter@ffwll.ch>

tldr; DMA buffers aren't normal memory, expecting that you can use
them like that (like calling get_user_pages works, or that they're
accounting like any other normal memory) cannot be guaranteed.

Since some userspace only runs on integrated devices, where all
buffers are actually all resident system memory, there's a huge
temptation to assume that a struct page is always present and useable
like for any more pagecache backed mmap. This has the potential to
result in a uapi nightmare.

To stop this gap require that DMA buffer mmaps are VM_PFNMAP, which
blocks get_user_pages and all the other struct page based
infrastructure for everyone. In spirit this is the uapi counterpart to
the kernel-internal CONFIG_DMABUF_DEBUG.

Motivated by a recent patch which wanted to swich the system dma-buf
heap to vm_insert_page instead of vm_insert_pfn.

v2:

Jason brought up that we also want to guarantee that all ptes have the
pte_special flag set, to catch fast get_user_pages (on architectures
that support this). Allowing VM_MIXEDMAP (like VM_SPECIAL does) would
still allow vm_insert_page, but limiting to VM_PFNMAP will catch that.

From auditing the various functions to insert pfn pte entires
(vm_insert_pfn_prot, remap_pfn_range and all it's callers like
dma_mmap_wc) it looks like VM_PFNMAP is already required anyway, so
this should be the correct flag to check for.

References: https://lore.kernel.org/lkml/CAKMK7uHi+mG0z0HUmNt13QCCvutuRVjpcR0NjRL12k-WbWzkRg@mail.gmail.com/
Acked-by: Christian König <christian.koenig@amd.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: John Stultz <john.stultz@linaro.org>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: "Christian König" <christian.koenig@amd.com>
Cc: linux-media@vger.kernel.org
Cc: linaro-mm-sig@lists.linaro.org
--
Resending this so I can test the next two patches for vgem/shmem in
intel-gfx-ci. Last round failed somehow, but I can't repro that at all
locally here.

No immediate plans to merge this patch here since ttm isn't addressed
yet (and there we have the hugepte issue, for which I don't think we
have a clear consensus yet).
-Daniel
---
 drivers/dma-buf/dma-buf.c | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
index eadd1eaa2fb5..dda583fb1f03 100644
--- a/drivers/dma-buf/dma-buf.c
+++ b/drivers/dma-buf/dma-buf.c
@@ -127,6 +127,7 @@ static struct file_system_type dma_buf_fs_type = {
 static int dma_buf_mmap_internal(struct file *file, struct vm_area_struct *vma)
 {
 	struct dma_buf *dmabuf;
+	int ret;
 
 	if (!is_dma_buf_file(file))
 		return -EINVAL;
@@ -142,7 +143,11 @@ static int dma_buf_mmap_internal(struct file *file, struct vm_area_struct *vma)
 	    dmabuf->size >> PAGE_SHIFT)
 		return -EINVAL;
 
-	return dmabuf->ops->mmap(dmabuf, vma);
+	ret = dmabuf->ops->mmap(dmabuf, vma);
+
+	WARN_ON(!(vma->vm_flags & VM_PFNMAP));
+
+	return ret;
 }
 
 static loff_t dma_buf_llseek(struct file *file, loff_t offset, int whence)
@@ -1244,6 +1249,8 @@ EXPORT_SYMBOL_GPL(dma_buf_end_cpu_access);
 int dma_buf_mmap(struct dma_buf *dmabuf, struct vm_area_struct *vma,
 		 unsigned long pgoff)
 {
+	int ret;
+
 	if (WARN_ON(!dmabuf || !vma))
 		return -EINVAL;
 
@@ -1264,7 +1271,11 @@ int dma_buf_mmap(struct dma_buf *dmabuf, struct vm_area_struct *vma,
 	vma_set_file(vma, dmabuf->file);
 	vma->vm_pgoff = pgoff;
 
-	return dmabuf->ops->mmap(dmabuf, vma);
+	ret = dmabuf->ops->mmap(dmabuf, vma);
+
+	WARN_ON(!(vma->vm_flags & VM_PFNMAP));
+
+	return ret;
 }
 EXPORT_SYMBOL_GPL(dma_buf_mmap);
 
-- 
2.31.0


WARNING: multiple messages have this Message-ID (diff)
From: Daniel Vetter <daniel.vetter@ffwll.ch>
To: Intel Graphics Development <intel-gfx@lists.freedesktop.org>
Cc: "Daniel Vetter" <daniel.vetter@ffwll.ch>,
	"Matthew Wilcox" <willy@infradead.org>,
	"Sumit Semwal" <sumit.semwal@linaro.org>,
	linaro-mm-sig@lists.linaro.org, "Jason Gunthorpe" <jgg@ziepe.ca>,
	"John Stultz" <john.stultz@linaro.org>,
	"DRI Development" <dri-devel@lists.freedesktop.org>,
	"Daniel Vetter" <daniel.vetter@intel.com>,
	"Suren Baghdasaryan" <surenb@google.com>,
	"Christian König" <christian.koenig@amd.com>,
	linux-media@vger.kernel.org
Subject: [Intel-gfx] [PATCH v3 1/4] dma-buf: Require VM_PFNMAP vma for mmap
Date: Thu,  3 Jun 2021 18:41:10 +0200	[thread overview]
Message-ID: <20210603164113.1433476-2-daniel.vetter@ffwll.ch> (raw)
In-Reply-To: <20210603164113.1433476-1-daniel.vetter@ffwll.ch>

tldr; DMA buffers aren't normal memory, expecting that you can use
them like that (like calling get_user_pages works, or that they're
accounting like any other normal memory) cannot be guaranteed.

Since some userspace only runs on integrated devices, where all
buffers are actually all resident system memory, there's a huge
temptation to assume that a struct page is always present and useable
like for any more pagecache backed mmap. This has the potential to
result in a uapi nightmare.

To stop this gap require that DMA buffer mmaps are VM_PFNMAP, which
blocks get_user_pages and all the other struct page based
infrastructure for everyone. In spirit this is the uapi counterpart to
the kernel-internal CONFIG_DMABUF_DEBUG.

Motivated by a recent patch which wanted to swich the system dma-buf
heap to vm_insert_page instead of vm_insert_pfn.

v2:

Jason brought up that we also want to guarantee that all ptes have the
pte_special flag set, to catch fast get_user_pages (on architectures
that support this). Allowing VM_MIXEDMAP (like VM_SPECIAL does) would
still allow vm_insert_page, but limiting to VM_PFNMAP will catch that.

From auditing the various functions to insert pfn pte entires
(vm_insert_pfn_prot, remap_pfn_range and all it's callers like
dma_mmap_wc) it looks like VM_PFNMAP is already required anyway, so
this should be the correct flag to check for.

References: https://lore.kernel.org/lkml/CAKMK7uHi+mG0z0HUmNt13QCCvutuRVjpcR0NjRL12k-WbWzkRg@mail.gmail.com/
Acked-by: Christian König <christian.koenig@amd.com>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: John Stultz <john.stultz@linaro.org>
Signed-off-by: Daniel Vetter <daniel.vetter@intel.com>
Cc: Sumit Semwal <sumit.semwal@linaro.org>
Cc: "Christian König" <christian.koenig@amd.com>
Cc: linux-media@vger.kernel.org
Cc: linaro-mm-sig@lists.linaro.org
--
Resending this so I can test the next two patches for vgem/shmem in
intel-gfx-ci. Last round failed somehow, but I can't repro that at all
locally here.

No immediate plans to merge this patch here since ttm isn't addressed
yet (and there we have the hugepte issue, for which I don't think we
have a clear consensus yet).
-Daniel
---
 drivers/dma-buf/dma-buf.c | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/drivers/dma-buf/dma-buf.c b/drivers/dma-buf/dma-buf.c
index eadd1eaa2fb5..dda583fb1f03 100644
--- a/drivers/dma-buf/dma-buf.c
+++ b/drivers/dma-buf/dma-buf.c
@@ -127,6 +127,7 @@ static struct file_system_type dma_buf_fs_type = {
 static int dma_buf_mmap_internal(struct file *file, struct vm_area_struct *vma)
 {
 	struct dma_buf *dmabuf;
+	int ret;
 
 	if (!is_dma_buf_file(file))
 		return -EINVAL;
@@ -142,7 +143,11 @@ static int dma_buf_mmap_internal(struct file *file, struct vm_area_struct *vma)
 	    dmabuf->size >> PAGE_SHIFT)
 		return -EINVAL;
 
-	return dmabuf->ops->mmap(dmabuf, vma);
+	ret = dmabuf->ops->mmap(dmabuf, vma);
+
+	WARN_ON(!(vma->vm_flags & VM_PFNMAP));
+
+	return ret;
 }
 
 static loff_t dma_buf_llseek(struct file *file, loff_t offset, int whence)
@@ -1244,6 +1249,8 @@ EXPORT_SYMBOL_GPL(dma_buf_end_cpu_access);
 int dma_buf_mmap(struct dma_buf *dmabuf, struct vm_area_struct *vma,
 		 unsigned long pgoff)
 {
+	int ret;
+
 	if (WARN_ON(!dmabuf || !vma))
 		return -EINVAL;
 
@@ -1264,7 +1271,11 @@ int dma_buf_mmap(struct dma_buf *dmabuf, struct vm_area_struct *vma,
 	vma_set_file(vma, dmabuf->file);
 	vma->vm_pgoff = pgoff;
 
-	return dmabuf->ops->mmap(dmabuf, vma);
+	ret = dmabuf->ops->mmap(dmabuf, vma);
+
+	WARN_ON(!(vma->vm_flags & VM_PFNMAP));
+
+	return ret;
 }
 EXPORT_SYMBOL_GPL(dma_buf_mmap);
 
-- 
2.31.0

_______________________________________________
Intel-gfx mailing list
Intel-gfx@lists.freedesktop.org
https://lists.freedesktop.org/mailman/listinfo/intel-gfx

  reply	other threads:[~2021-06-03 16:42 UTC|newest]

Thread overview: 21+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-06-03 16:41 [PATCH v3 0/4] shmem helpers for vgem Daniel Vetter
2021-06-03 16:41 ` [Intel-gfx] " Daniel Vetter
2021-06-03 16:41 ` Daniel Vetter [this message]
2021-06-03 16:41   ` [Intel-gfx] [PATCH v3 1/4] dma-buf: Require VM_PFNMAP vma for mmap Daniel Vetter
2021-06-03 16:41   ` Daniel Vetter
2021-06-03 16:41 ` [PATCH v3 2/4] drm/shmem-helper: Switch to vmf_insert_pfn Daniel Vetter
2021-06-03 16:41   ` [Intel-gfx] " Daniel Vetter
2021-06-03 21:08   ` [PATCH] " Daniel Vetter
2021-06-03 21:08     ` [Intel-gfx] " Daniel Vetter
2021-07-13 13:44     ` Daniel Vetter
2021-07-13 13:44       ` [Intel-gfx] " Daniel Vetter
2021-06-03 16:41 ` [PATCH v3 3/4] drm/shmem-helper: Align to page size in dumb_create Daniel Vetter
2021-06-03 16:41   ` [Intel-gfx] " Daniel Vetter
2021-06-03 16:41 ` [PATCH v3 4/4] drm/vgem: use shmem helpers Daniel Vetter
2021-06-03 16:41   ` [Intel-gfx] " Daniel Vetter
2021-06-03 21:09   ` [PATCH] " Daniel Vetter
2021-06-03 21:09     ` [Intel-gfx] " Daniel Vetter
2021-06-03 19:18 ` [Intel-gfx] ✗ Fi.CI.CHECKPATCH: warning for shmem helpers for vgem (rev3) Patchwork
2021-06-03 19:50 ` [Intel-gfx] ✗ Fi.CI.BAT: failure " Patchwork
2021-06-03 21:16 ` [Intel-gfx] ✗ Fi.CI.CHECKPATCH: warning for shmem helpers for vgem (rev5) Patchwork
2021-06-03 21:48 ` [Intel-gfx] ✗ Fi.CI.BAT: failure " Patchwork

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