[PATCH v4 0/3] Add vm_bind param check to ensure no overlap with kbo AS carveout

[PATCH v4 0/3] Add vm_bind param check to ensure no overlap with kbo AS carveout

[Adrián Larumbe]

Just a quick check to make sure user-supplied vm_bind regions aren't
clashing with the region reserved for kernel bo's.

I tried to introduce a similar check for panthor_vm_alloc_va(), to throw
back an error when mappings of kernel bo's against specific addresses fall
within the auto_va region. However that is not possible, since there's one
FW region that must be mapped right at CSF_MCU_SHARED_REGION_START. That
is usually not a problem, since drm_mm_insert_node_in_range() will pick
the next one available.

v3 also comes with an early bind range overflow check for sparse mappings.

Signed-off-by: Adrián Larumbe <adrian.larumbe@collabora.com>
---
Changes in v4:
- Deleted commit that passes single operation to panthor_vm_prepare_unmap_op_ctx.
- Moved overflow check one step above in the call stack.
- Rearranged the commits in the series.
- Link to v3: https://patch.msgid.link/20260629-vm_bind_checks-v3-0-85e6740f6c2e@collabora.com

Changes in v3:
- Fixed off-by-one error for user va range calculations.
- Added new commit for panthor_vm_prepare_unmap_op_ctx to take a whole operation.
- Added commit with bind range early overflow check.
- Link to v2: https://patch.msgid.link/20260619-vm_bind_checks-v2-0-b51abab35f71@collabora.com

Changes in v2:
- Simplified user VA range with kernel BO range overlap to a single statement.
- Link to v1: https://patch.msgid.link/20260616-vm_bind_checks-v1-0-956198602ae3@collabora.com

To: Boris Brezillon <boris.brezillon@collabora.com>
To: Steven Price <steven.price@arm.com>
To: Liviu Dudau <liviu.dudau@arm.com>
To: Maarten Lankhorst <maarten.lankhorst@linux.intel.com>
To: Maxime Ripard <mripard@kernel.org>
To: Thomas Zimmermann <tzimmermann@suse.de>
To: David Airlie <airlied@gmail.com>
To: Simona Vetter <simona@ffwll.ch>
To: Heiko Stuebner <heiko@sntech.de>
To: Grant Likely <grant.likely@linaro.org>
To: Adrián Larumbe <adrian.larumbe@collabora.com>
Cc: dri-devel@lists.freedesktop.org
Cc: linux-kernel@vger.kernel.org

---
Adrián Larumbe (3):
      drm/panthor: Check for sparse binding range overflow
      drm/panthor: Add vm_bind region with kbo range overlap check
      drm/panthor: Fix comment to reflect actual struct field name

 drivers/gpu/drm/panthor/panthor_mmu.c | 15 ++++++++++++++-
 1 file changed, 14 insertions(+), 1 deletion(-)
---
base-commit: 8fca3d8dbebf8d960dad7b10db3cb4a61139454b
change-id: 20260614-vm_bind_checks-46075ba069a0

Best regards,
--  
Adrián Larumbe <adrian.larumbe@collabora.com>

[PATCH v4 1/3] drm/panthor: Check for sparse binding range overflow

[Adrián Larumbe]

This check is being already carried out further down the call stack inside
drm_gpuvm_sm_map -> drm_gpuvm_range_valid, but it's best to fail early in
the driver before GPUVM functions are invoked so that we won't waste time
allocating vm_bind context resources.

Reported-by: Sashiko <noreply@sashiko.dev>
Closes: https://sashiko.dev/#/message/20260623204220.CDB1B1F000E9%40smtp.kernel.org
Fixes: 12cf826bf1dd ("drm/panthor: Support sparse mappings")
Signed-off-by: Adrián Larumbe <adrian.larumbe@collabora.com>
---
 drivers/gpu/drm/panthor/panthor_mmu.c | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/drivers/gpu/drm/panthor/panthor_mmu.c b/drivers/gpu/drm/panthor/panthor_mmu.c
index 31cc57029c12..163231c1703d 100644
--- a/drivers/gpu/drm/panthor/panthor_mmu.c
+++ b/drivers/gpu/drm/panthor/panthor_mmu.c
@@ -2975,12 +2975,16 @@ panthor_vm_bind_prepare_op_ctx(struct drm_file *file,
 {
 	ssize_t vm_pgsz = panthor_vm_page_size(vm);
 	struct drm_gem_object *gem;
+	u64 end;
 	int ret;
 
 	/* Aligned on page size. */
 	if (!IS_ALIGNED(op->va | op->size | op->bo_offset, vm_pgsz))
 		return -EINVAL;
 
+	if (check_add_overflow(op->va, op->size, &end))
+		return -EINVAL;
+
 	switch (op->flags & DRM_PANTHOR_VM_BIND_OP_TYPE_MASK) {
 	case DRM_PANTHOR_VM_BIND_OP_TYPE_MAP:
 		if (!(op->flags & DRM_PANTHOR_VM_BIND_OP_MAP_SPARSE)) {

-- 
2.55.0

[PATCH v4 2/3] drm/panthor: Add vm_bind region with kbo range overlap check

[Adrián Larumbe]

When a VM is created, caller has to specify the range of the address space
carve-out set aside for mapping kernel BO's. That means vm_bind mappings of
UM-exposed BO's should not intersect with that region, but at the moment
we're not checking this.

At first, I thought of giving these values to drm_gpuvm_init() through its
reserve_{offset, range} arguments, but it turns out that is meant for VM
address spans that are not managed through the usual drm_gpuvm split/merge
circuit, so storing the end of the user VA range at VM creation time and
doing a quick check in the vm_bind ioctl path was the simplest workaround.

Fixes: tag and reference the relevant sparse binding support commit.
Fixes: 647810ec2476 ("drm/panthor: Add the MMU/VM logical block")
Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>
Signed-off-by: Adrián Larumbe <adrian.larumbe@collabora.com>
---
 drivers/gpu/drm/panthor/panthor_mmu.c | 9 +++++++++
 1 file changed, 9 insertions(+)

diff --git a/drivers/gpu/drm/panthor/panthor_mmu.c b/drivers/gpu/drm/panthor/panthor_mmu.c
index 163231c1703d..662a2c13b467 100644
--- a/drivers/gpu/drm/panthor/panthor_mmu.c
+++ b/drivers/gpu/drm/panthor/panthor_mmu.c
@@ -310,6 +310,9 @@ struct panthor_vm {
 		u64 end;
 	} kernel_auto_va;
 
+	/** @user_va_range: Upper boundary of VAs VM users can map objects against. */
+	u64 user_va_range;
+
 	/** @as: Address space related fields. */
 	struct {
 		/**
@@ -2893,6 +2896,8 @@ panthor_vm_create(struct panthor_device *ptdev, bool for_mcu,
 		va_range = full_va_range;
 	}
 
+	vm->user_va_range = kernel_va_start;
+
 	mutex_init(&vm->mm_lock);
 	drm_mm_init(&vm->mm, kernel_va_start, kernel_va_size);
 	vm->kernel_auto_va.start = auto_kernel_va_start;
@@ -2985,6 +2990,10 @@ panthor_vm_bind_prepare_op_ctx(struct drm_file *file,
 	if (check_add_overflow(op->va, op->size, &end))
 		return -EINVAL;
 
+	/* We don't allow mappings that overlap with kbo's reserved range */
+	if (end > vm->user_va_range)
+		return -EINVAL;
+
 	switch (op->flags & DRM_PANTHOR_VM_BIND_OP_TYPE_MASK) {
 	case DRM_PANTHOR_VM_BIND_OP_TYPE_MAP:
 		if (!(op->flags & DRM_PANTHOR_VM_BIND_OP_MAP_SPARSE)) {

-- 
2.55.0

[PATCH v4 3/3] drm/panthor: Fix comment to reflect actual struct field name

[Adrián Larumbe]

The mismatch would pop up when building the kernel with W=1.

Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>
Reviewed-by: Steven Price <steven.price@arm.com>
Signed-off-by: Adrián Larumbe <adrian.larumbe@collabora.com>
---
 drivers/gpu/drm/panthor/panthor_mmu.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/panthor/panthor_mmu.c b/drivers/gpu/drm/panthor/panthor_mmu.c
index 662a2c13b467..d09d5641e6c0 100644
--- a/drivers/gpu/drm/panthor/panthor_mmu.c
+++ b/drivers/gpu/drm/panthor/panthor_mmu.c
@@ -306,7 +306,7 @@ struct panthor_vm {
 		/** @kernel_auto_va.start: Start of the automatic VA-range for kernel BOs. */
 		u64 start;
 
-		/** @kernel_auto_va.size: Size of the automatic VA-range for kernel BOs. */
+		/** @kernel_auto_va.end: End of the automatic VA-range for kernel BOs. */
 		u64 end;
 	} kernel_auto_va;
 

-- 
2.55.0

Re: [PATCH v4 1/3] drm/panthor: Check for sparse binding range overflow

[Liviu Dudau]

On Sat, Jul 04, 2026 at 05:46:44AM +0100, Adrián Larumbe wrote:
> This check is being already carried out further down the call stack inside
> drm_gpuvm_sm_map -> drm_gpuvm_range_valid, but it's best to fail early in
> the driver before GPUVM functions are invoked so that we won't waste time
> allocating vm_bind context resources.
> 
> Reported-by: Sashiko <noreply@sashiko.dev>
> Closes: https://sashiko.dev/#/message/20260623204220.CDB1B1F000E9%40smtp.kernel.org
> Fixes: 12cf826bf1dd ("drm/panthor: Support sparse mappings")
> Signed-off-by: Adrián Larumbe <adrian.larumbe@collabora.com>

Reviewed-by: Liviu Dudau <liviu.dudau@arm.com>

Best regards,
Liviu

> ---
>  drivers/gpu/drm/panthor/panthor_mmu.c | 4 ++++
>  1 file changed, 4 insertions(+)
> 
> diff --git a/drivers/gpu/drm/panthor/panthor_mmu.c b/drivers/gpu/drm/panthor/panthor_mmu.c
> index 31cc57029c12..163231c1703d 100644
> --- a/drivers/gpu/drm/panthor/panthor_mmu.c
> +++ b/drivers/gpu/drm/panthor/panthor_mmu.c
> @@ -2975,12 +2975,16 @@ panthor_vm_bind_prepare_op_ctx(struct drm_file *file,
>  {
>  	ssize_t vm_pgsz = panthor_vm_page_size(vm);
>  	struct drm_gem_object *gem;
> +	u64 end;
>  	int ret;
>  
>  	/* Aligned on page size. */
>  	if (!IS_ALIGNED(op->va | op->size | op->bo_offset, vm_pgsz))
>  		return -EINVAL;
>  
> +	if (check_add_overflow(op->va, op->size, &end))
> +		return -EINVAL;
> +
>  	switch (op->flags & DRM_PANTHOR_VM_BIND_OP_TYPE_MASK) {
>  	case DRM_PANTHOR_VM_BIND_OP_TYPE_MAP:
>  		if (!(op->flags & DRM_PANTHOR_VM_BIND_OP_MAP_SPARSE)) {
> 
> -- 
> 2.55.0
> 

-- 
====================
| I would like to |
| fix the world,  |
| but they're not |
| giving me the   |
 \ source code!  /
  ---------------
    ¯\_(ツ)_/¯

Re: [PATCH v4 2/3] drm/panthor: Add vm_bind region with kbo range overlap check

[Liviu Dudau]

On Sat, Jul 04, 2026 at 05:46:45AM +0100, Adrián Larumbe wrote:
> When a VM is created, caller has to specify the range of the address space
> carve-out set aside for mapping kernel BO's. That means vm_bind mappings of
> UM-exposed BO's should not intersect with that region, but at the moment
> we're not checking this.
> 
> At first, I thought of giving these values to drm_gpuvm_init() through its
> reserve_{offset, range} arguments, but it turns out that is meant for VM
> address spans that are not managed through the usual drm_gpuvm split/merge
> circuit, so storing the end of the user VA range at VM creation time and
> doing a quick check in the vm_bind ioctl path was the simplest workaround.
> 
> Fixes: tag and reference the relevant sparse binding support commit.
> Fixes: 647810ec2476 ("drm/panthor: Add the MMU/VM logical block")
> Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>
> Signed-off-by: Adrián Larumbe <adrian.larumbe@collabora.com>

Reviewed-by: Liviu Dudau <liviu.dudau@arm.com>

Best regards,
Liviu

> ---
>  drivers/gpu/drm/panthor/panthor_mmu.c | 9 +++++++++
>  1 file changed, 9 insertions(+)
> 
> diff --git a/drivers/gpu/drm/panthor/panthor_mmu.c b/drivers/gpu/drm/panthor/panthor_mmu.c
> index 163231c1703d..662a2c13b467 100644
> --- a/drivers/gpu/drm/panthor/panthor_mmu.c
> +++ b/drivers/gpu/drm/panthor/panthor_mmu.c
> @@ -310,6 +310,9 @@ struct panthor_vm {
>  		u64 end;
>  	} kernel_auto_va;
>  
> +	/** @user_va_range: Upper boundary of VAs VM users can map objects against. */
> +	u64 user_va_range;
> +
>  	/** @as: Address space related fields. */
>  	struct {
>  		/**
> @@ -2893,6 +2896,8 @@ panthor_vm_create(struct panthor_device *ptdev, bool for_mcu,
>  		va_range = full_va_range;
>  	}
>  
> +	vm->user_va_range = kernel_va_start;
> +
>  	mutex_init(&vm->mm_lock);
>  	drm_mm_init(&vm->mm, kernel_va_start, kernel_va_size);
>  	vm->kernel_auto_va.start = auto_kernel_va_start;
> @@ -2985,6 +2990,10 @@ panthor_vm_bind_prepare_op_ctx(struct drm_file *file,
>  	if (check_add_overflow(op->va, op->size, &end))
>  		return -EINVAL;
>  
> +	/* We don't allow mappings that overlap with kbo's reserved range */
> +	if (end > vm->user_va_range)
> +		return -EINVAL;
> +
>  	switch (op->flags & DRM_PANTHOR_VM_BIND_OP_TYPE_MASK) {
>  	case DRM_PANTHOR_VM_BIND_OP_TYPE_MAP:
>  		if (!(op->flags & DRM_PANTHOR_VM_BIND_OP_MAP_SPARSE)) {
> 
> -- 
> 2.55.0
> 

-- 
====================
| I would like to |
| fix the world,  |
| but they're not |
| giving me the   |
 \ source code!  /
  ---------------
    ¯\_(ツ)_/¯

Re: [PATCH v4 3/3] drm/panthor: Fix comment to reflect actual struct field name

[Liviu Dudau]

On Sat, Jul 04, 2026 at 05:46:46AM +0100, Adrián Larumbe wrote:
> The mismatch would pop up when building the kernel with W=1.
> 
> Reviewed-by: Boris Brezillon <boris.brezillon@collabora.com>
> Reviewed-by: Steven Price <steven.price@arm.com>
> Signed-off-by: Adrián Larumbe <adrian.larumbe@collabora.com>

Reviewed-by: Liviu Dudau <liviu.dudau@arm.com>

Best regards,
Liviu

> ---
>  drivers/gpu/drm/panthor/panthor_mmu.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/panthor/panthor_mmu.c b/drivers/gpu/drm/panthor/panthor_mmu.c
> index 662a2c13b467..d09d5641e6c0 100644
> --- a/drivers/gpu/drm/panthor/panthor_mmu.c
> +++ b/drivers/gpu/drm/panthor/panthor_mmu.c
> @@ -306,7 +306,7 @@ struct panthor_vm {
>  		/** @kernel_auto_va.start: Start of the automatic VA-range for kernel BOs. */
>  		u64 start;
>  
> -		/** @kernel_auto_va.size: Size of the automatic VA-range for kernel BOs. */
> +		/** @kernel_auto_va.end: End of the automatic VA-range for kernel BOs. */
>  		u64 end;
>  	} kernel_auto_va;
>  
> 
> -- 
> 2.55.0
> 

-- 
====================
| I would like to |
| fix the world,  |
| but they're not |
| giving me the   |
 \ source code!  /
  ---------------
    ¯\_(ツ)_/¯

Re: [PATCH v4 2/3] drm/panthor: Add vm_bind region with kbo range overlap check

[Adrián Larumbe]

On Sat, 04 Jul 2026 05:46:45 +0100, Adrián Larumbe <adrian.larumbe@collabora.com> wrote:
> When a VM is created, caller has to specify the range of the address space
> carve-out set aside for mapping kernel BO's. That means vm_bind mappings of
> UM-exposed BO's should not intersect with that region, but at the moment
> we're not checking this.
> 
> At first, I thought of giving these values to drm_gpuvm_init() through its
> reserve_{offset, range} arguments, but it turns out that is meant for VM
> address spans that are not managed through the usual drm_gpuvm split/merge
> circuit, so storing the end of the user VA range at VM creation time and
> doing a quick check in the vm_bind ioctl path was the simplest workaround.
> 
> Fixes: tag and reference the relevant sparse binding support commit.

Just realised this was a placeholder I left before I went looking for the
right commit hash for the following tag. Seems that checkpatch.pl wouldn't
catch it either.

-- 
Adrián Larumbe <adrian.larumbe@collabora.com>