[PATCH] drm/panthor: Fix firmware initialization on systems with a page size > 4k

[PATCH] drm/panthor: Fix firmware initialization on systems with a page size > 4k

[Boris Brezillon]

The system and GPU MMU page size might differ, which becomes a
problem for FW sections that need to be mapped at explicit address
since our PAGE_SIZE alignment might cover a VA range that's
expected to be used for another section.

Make sure we never map more than we need.

Fixes: 2718d91816ee ("drm/panthor: Add the FW logical block")
Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
---
 drivers/gpu/drm/panthor/panthor_fw.c  |  3 +--
 drivers/gpu/drm/panthor/panthor_gem.c | 11 ++++++++---
 drivers/gpu/drm/panthor/panthor_mmu.c |  6 +++---
 3 files changed, 12 insertions(+), 8 deletions(-)

diff --git a/drivers/gpu/drm/panthor/panthor_fw.c b/drivers/gpu/drm/panthor/panthor_fw.c
index ef232c0c2049..293846400296 100644
--- a/drivers/gpu/drm/panthor/panthor_fw.c
+++ b/drivers/gpu/drm/panthor/panthor_fw.c
@@ -515,8 +515,7 @@ static int panthor_fw_load_section_entry(struct panthor_device *ptdev,
 		return -EINVAL;
 	}
 
-	if ((hdr.va.start & ~PAGE_MASK) != 0 ||
-	    (hdr.va.end & ~PAGE_MASK) != 0) {
+	if (!IS_ALIGNED(hdr.va.start, SZ_4K) || !IS_ALIGNED(hdr.va.end, SZ_4K)) {
 		drm_err(&ptdev->base, "Firmware corrupted, virtual addresses not page aligned: 0x%x-0x%x\n",
 			hdr.va.start, hdr.va.end);
 		return -EINVAL;
diff --git a/drivers/gpu/drm/panthor/panthor_gem.c b/drivers/gpu/drm/panthor/panthor_gem.c
index c60b599665d8..2c8d6e2c7232 100644
--- a/drivers/gpu/drm/panthor/panthor_gem.c
+++ b/drivers/gpu/drm/panthor/panthor_gem.c
@@ -44,8 +44,7 @@ void panthor_kernel_bo_destroy(struct panthor_kernel_bo *bo)
 			to_panthor_bo(bo->obj)->exclusive_vm_root_gem != panthor_vm_root_gem(vm)))
 		goto out_free_bo;
 
-	ret = panthor_vm_unmap_range(vm, bo->va_node.start,
-				     panthor_kernel_bo_size(bo));
+	ret = panthor_vm_unmap_range(vm, bo->va_node.start, bo->va_node.size);
 	if (ret)
 		goto out_free_bo;
 
@@ -95,10 +94,16 @@ panthor_kernel_bo_create(struct panthor_device *ptdev, struct panthor_vm *vm,
 	}
 
 	bo = to_panthor_bo(&obj->base);
-	size = obj->base.size;
 	kbo->obj = &obj->base;
 	bo->flags = bo_flags;
 
+	/* The system and GPU MMU page size might differ, which becomes a
+	 * problem for FW sections that need to be mapped at explicit address
+	 * since our PAGE_SIZE alignment might cover a VA range that's
+	 * expected to be used for another section.
+	 * Make sure we never map more than we need.
+	 */
+	size = ALIGN(size, SZ_4K);
 	ret = panthor_vm_alloc_va(vm, gpu_va, size, &kbo->va_node);
 	if (ret)
 		goto err_put_obj;
diff --git a/drivers/gpu/drm/panthor/panthor_mmu.c b/drivers/gpu/drm/panthor/panthor_mmu.c
index 3cd2bce59edc..e53d131c53cc 100644
--- a/drivers/gpu/drm/panthor/panthor_mmu.c
+++ b/drivers/gpu/drm/panthor/panthor_mmu.c
@@ -1027,10 +1027,10 @@ panthor_vm_alloc_va(struct panthor_vm *vm, u64 va, u64 size,
 {
 	int ret;
 
-	if (!size || (size & ~PAGE_MASK))
+	if (!size || !IS_ALIGNED(size, SZ_4K))
 		return -EINVAL;
 
-	if (va != PANTHOR_VM_KERNEL_AUTO_VA && (va & ~PAGE_MASK))
+	if (va != PANTHOR_VM_KERNEL_AUTO_VA && !IS_ALIGNED(va, SZ_4K))
 		return -EINVAL;
 
 	mutex_lock(&vm->mm_lock);
@@ -2370,7 +2370,7 @@ panthor_vm_bind_prepare_op_ctx(struct drm_file *file,
 	int ret;
 
 	/* Aligned on page size. */
-	if ((op->va | op->size) & ~PAGE_MASK)
+	if (!IS_ALIGNED(op->va | op->size, SZ_4K))
 		return -EINVAL;
 
 	switch (op->flags & DRM_PANTHOR_VM_BIND_OP_TYPE_MASK) {
-- 
2.46.2

Re: [PATCH] drm/panthor: Fix firmware initialization on systems with a page size > 4k

[Steven Price]

On 08/10/2024 09:47, Boris Brezillon wrote:
> The system and GPU MMU page size might differ, which becomes a
> problem for FW sections that need to be mapped at explicit address
> since our PAGE_SIZE alignment might cover a VA range that's
> expected to be used for another section.
> 
> Make sure we never map more than we need.
> 
> Fixes: 2718d91816ee ("drm/panthor: Add the FW logical block")
> Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>

Reviewed-by: Steven Price <steven.price@arm.com>

> ---
>  drivers/gpu/drm/panthor/panthor_fw.c  |  3 +--
>  drivers/gpu/drm/panthor/panthor_gem.c | 11 ++++++++---
>  drivers/gpu/drm/panthor/panthor_mmu.c |  6 +++---
>  3 files changed, 12 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/gpu/drm/panthor/panthor_fw.c b/drivers/gpu/drm/panthor/panthor_fw.c
> index ef232c0c2049..293846400296 100644
> --- a/drivers/gpu/drm/panthor/panthor_fw.c
> +++ b/drivers/gpu/drm/panthor/panthor_fw.c
> @@ -515,8 +515,7 @@ static int panthor_fw_load_section_entry(struct panthor_device *ptdev,
>  		return -EINVAL;
>  	}
>  
> -	if ((hdr.va.start & ~PAGE_MASK) != 0 ||
> -	    (hdr.va.end & ~PAGE_MASK) != 0) {
> +	if (!IS_ALIGNED(hdr.va.start, SZ_4K) || !IS_ALIGNED(hdr.va.end, SZ_4K)) {
>  		drm_err(&ptdev->base, "Firmware corrupted, virtual addresses not page aligned: 0x%x-0x%x\n",
>  			hdr.va.start, hdr.va.end);
>  		return -EINVAL;
> diff --git a/drivers/gpu/drm/panthor/panthor_gem.c b/drivers/gpu/drm/panthor/panthor_gem.c
> index c60b599665d8..2c8d6e2c7232 100644
> --- a/drivers/gpu/drm/panthor/panthor_gem.c
> +++ b/drivers/gpu/drm/panthor/panthor_gem.c
> @@ -44,8 +44,7 @@ void panthor_kernel_bo_destroy(struct panthor_kernel_bo *bo)
>  			to_panthor_bo(bo->obj)->exclusive_vm_root_gem != panthor_vm_root_gem(vm)))
>  		goto out_free_bo;
>  
> -	ret = panthor_vm_unmap_range(vm, bo->va_node.start,
> -				     panthor_kernel_bo_size(bo));
> +	ret = panthor_vm_unmap_range(vm, bo->va_node.start, bo->va_node.size);
>  	if (ret)
>  		goto out_free_bo;
>  
> @@ -95,10 +94,16 @@ panthor_kernel_bo_create(struct panthor_device *ptdev, struct panthor_vm *vm,
>  	}
>  
>  	bo = to_panthor_bo(&obj->base);
> -	size = obj->base.size;
>  	kbo->obj = &obj->base;
>  	bo->flags = bo_flags;
>  
> +	/* The system and GPU MMU page size might differ, which becomes a
> +	 * problem for FW sections that need to be mapped at explicit address
> +	 * since our PAGE_SIZE alignment might cover a VA range that's
> +	 * expected to be used for another section.
> +	 * Make sure we never map more than we need.
> +	 */
> +	size = ALIGN(size, SZ_4K);
>  	ret = panthor_vm_alloc_va(vm, gpu_va, size, &kbo->va_node);
>  	if (ret)
>  		goto err_put_obj;
> diff --git a/drivers/gpu/drm/panthor/panthor_mmu.c b/drivers/gpu/drm/panthor/panthor_mmu.c
> index 3cd2bce59edc..e53d131c53cc 100644
> --- a/drivers/gpu/drm/panthor/panthor_mmu.c
> +++ b/drivers/gpu/drm/panthor/panthor_mmu.c
> @@ -1027,10 +1027,10 @@ panthor_vm_alloc_va(struct panthor_vm *vm, u64 va, u64 size,
>  {
>  	int ret;
>  
> -	if (!size || (size & ~PAGE_MASK))
> +	if (!size || !IS_ALIGNED(size, SZ_4K))
>  		return -EINVAL;
>  
> -	if (va != PANTHOR_VM_KERNEL_AUTO_VA && (va & ~PAGE_MASK))
> +	if (va != PANTHOR_VM_KERNEL_AUTO_VA && !IS_ALIGNED(va, SZ_4K))
>  		return -EINVAL;
>  
>  	mutex_lock(&vm->mm_lock);
> @@ -2370,7 +2370,7 @@ panthor_vm_bind_prepare_op_ctx(struct drm_file *file,
>  	int ret;
>  
>  	/* Aligned on page size. */
> -	if ((op->va | op->size) & ~PAGE_MASK)
> +	if (!IS_ALIGNED(op->va | op->size, SZ_4K))
>  		return -EINVAL;
>  
>  	switch (op->flags & DRM_PANTHOR_VM_BIND_OP_TYPE_MASK) {

Re: [PATCH] drm/panthor: Fix firmware initialization on systems with a page size > 4k

[Adrián Larumbe]

Hi Boris,

On 09.10.2024 09:10, Steven Price wrote:
> On 08/10/2024 09:47, Boris Brezillon wrote:
> > The system and GPU MMU page size might differ, which becomes a
> > problem for FW sections that need to be mapped at explicit address
> > since our PAGE_SIZE alignment might cover a VA range that's
> > expected to be used for another section.
> > 
> > Make sure we never map more than we need.
> > 
> > Fixes: 2718d91816ee ("drm/panthor: Add the FW logical block")
> > Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
> 
> Reviewed-by: Steven Price <steven.price@arm.com>
> 
> > ---
> >  drivers/gpu/drm/panthor/panthor_fw.c  |  3 +--
> >  drivers/gpu/drm/panthor/panthor_gem.c | 11 ++++++++---
> >  drivers/gpu/drm/panthor/panthor_mmu.c |  6 +++---
> >  3 files changed, 12 insertions(+), 8 deletions(-)
> > 
> > diff --git a/drivers/gpu/drm/panthor/panthor_fw.c b/drivers/gpu/drm/panthor/panthor_fw.c
> > index ef232c0c2049..293846400296 100644
> > --- a/drivers/gpu/drm/panthor/panthor_fw.c
> > +++ b/drivers/gpu/drm/panthor/panthor_fw.c
> > @@ -515,8 +515,7 @@ static int panthor_fw_load_section_entry(struct panthor_device *ptdev,
> >  		return -EINVAL;
> >  	}
> >  
> > -	if ((hdr.va.start & ~PAGE_MASK) != 0 ||
> > -	    (hdr.va.end & ~PAGE_MASK) != 0) {
> > +	if (!IS_ALIGNED(hdr.va.start, SZ_4K) || !IS_ALIGNED(hdr.va.end, SZ_4K)) {
> >  		drm_err(&ptdev->base, "Firmware corrupted, virtual addresses not page aligned: 0x%x-0x%x\n",
> >  			hdr.va.start, hdr.va.end);
> >  		return -EINVAL;
> > diff --git a/drivers/gpu/drm/panthor/panthor_gem.c b/drivers/gpu/drm/panthor/panthor_gem.c
> > index c60b599665d8..2c8d6e2c7232 100644
> > --- a/drivers/gpu/drm/panthor/panthor_gem.c
> > +++ b/drivers/gpu/drm/panthor/panthor_gem.c
> > @@ -44,8 +44,7 @@ void panthor_kernel_bo_destroy(struct panthor_kernel_bo *bo)
> >  			to_panthor_bo(bo->obj)->exclusive_vm_root_gem != panthor_vm_root_gem(vm)))
> >  		goto out_free_bo;
> >  
> > -	ret = panthor_vm_unmap_range(vm, bo->va_node.start,
> > -				     panthor_kernel_bo_size(bo));
> > +	ret = panthor_vm_unmap_range(vm, bo->va_node.start, bo->va_node.size);
> >  	if (ret)
> >  		goto out_free_bo;
> >  
> > @@ -95,10 +94,16 @@ panthor_kernel_bo_create(struct panthor_device *ptdev, struct panthor_vm *vm,
> >  	}
> >  	bo = to_panthor_bo(&obj->base);
> > -	size = obj->base.size;
> >  	kbo->obj = &obj->base;
> >  	bo->flags = bo_flags;
> >  
> > +	/* The system and GPU MMU page size might differ, which becomes a
> > +	 * problem for FW sections that need to be mapped at explicit address
> > +	 * since our PAGE_SIZE alignment might cover a VA range that's
> > +	 * expected to be used for another section.
> > +	 * Make sure we never map more than we need.
> > +	 */

I was wondering, this must be a relatively common situation for other DRM
drivers, so maybe the DRM shmem core should have a BO creation function that
lets you specify an exact page alignment?

> > +	size = ALIGN(size, SZ_4K);

I was thinking, if we know that the FW's page size is always 4KiB, maybe we could do

#define CSF_FW_PAGESIZE SZ_4K

somewhere in panthor_fw.h to make things clearer?

Cheers,
Adrian

Reviewed-by: Adrian Larumbe <adrian.larumbe@collabora.com>

> >  	ret = panthor_vm_alloc_va(vm, gpu_va, size, &kbo->va_node);
> >  	if (ret)
> >  		goto err_put_obj;
> > diff --git a/drivers/gpu/drm/panthor/panthor_mmu.c b/drivers/gpu/drm/panthor/panthor_mmu.c
> > index 3cd2bce59edc..e53d131c53cc 100644
> > --- a/drivers/gpu/drm/panthor/panthor_mmu.c
> > +++ b/drivers/gpu/drm/panthor/panthor_mmu.c
> > @@ -1027,10 +1027,10 @@ panthor_vm_alloc_va(struct panthor_vm *vm, u64 va, u64 size,
> >  {
> >  	int ret;
> >  
> > -	if (!size || (size & ~PAGE_MASK))
> > +	if (!size || !IS_ALIGNED(size, SZ_4K))
> >  		return -EINVAL;
> >  
> > -	if (va != PANTHOR_VM_KERNEL_AUTO_VA && (va & ~PAGE_MASK))
> > +	if (va != PANTHOR_VM_KERNEL_AUTO_VA && !IS_ALIGNED(va, SZ_4K))
> >  		return -EINVAL;
> >  
> >  	mutex_lock(&vm->mm_lock);
> > @@ -2370,7 +2370,7 @@ panthor_vm_bind_prepare_op_ctx(struct drm_file *file,
> >  	int ret;
> >  
> >  	/* Aligned on page size. */
> > -	if ((op->va | op->size) & ~PAGE_MASK)
> > +	if (!IS_ALIGNED(op->va | op->size, SZ_4K))
> >  		return -EINVAL;
> >  
> >  	switch (op->flags & DRM_PANTHOR_VM_BIND_OP_TYPE_MASK) {

Re: [PATCH] drm/panthor: Fix firmware initialization on systems with a page size > 4k

[Liviu Dudau]

On Fri, Oct 11, 2024 at 06:58:45PM +0100, Adrián Larumbe wrote:
> Hi Boris,
> 
> On 09.10.2024 09:10, Steven Price wrote:
> > On 08/10/2024 09:47, Boris Brezillon wrote:
> > > The system and GPU MMU page size might differ, which becomes a
> > > problem for FW sections that need to be mapped at explicit address
> > > since our PAGE_SIZE alignment might cover a VA range that's
> > > expected to be used for another section.
> > > 
> > > Make sure we never map more than we need.
> > > 
> > > Fixes: 2718d91816ee ("drm/panthor: Add the FW logical block")
> > > Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
> > 
> > Reviewed-by: Steven Price <steven.price@arm.com>

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

> > 
> > > ---
> > >  drivers/gpu/drm/panthor/panthor_fw.c  |  3 +--
> > >  drivers/gpu/drm/panthor/panthor_gem.c | 11 ++++++++---
> > >  drivers/gpu/drm/panthor/panthor_mmu.c |  6 +++---
> > >  3 files changed, 12 insertions(+), 8 deletions(-)
> > > 
> > > diff --git a/drivers/gpu/drm/panthor/panthor_fw.c b/drivers/gpu/drm/panthor/panthor_fw.c
> > > index ef232c0c2049..293846400296 100644
> > > --- a/drivers/gpu/drm/panthor/panthor_fw.c
> > > +++ b/drivers/gpu/drm/panthor/panthor_fw.c
> > > @@ -515,8 +515,7 @@ static int panthor_fw_load_section_entry(struct panthor_device *ptdev,
> > >  		return -EINVAL;
> > >  	}
> > >  
> > > -	if ((hdr.va.start & ~PAGE_MASK) != 0 ||
> > > -	    (hdr.va.end & ~PAGE_MASK) != 0) {
> > > +	if (!IS_ALIGNED(hdr.va.start, SZ_4K) || !IS_ALIGNED(hdr.va.end, SZ_4K)) {
> > >  		drm_err(&ptdev->base, "Firmware corrupted, virtual addresses not page aligned: 0x%x-0x%x\n",
> > >  			hdr.va.start, hdr.va.end);
> > >  		return -EINVAL;
> > > diff --git a/drivers/gpu/drm/panthor/panthor_gem.c b/drivers/gpu/drm/panthor/panthor_gem.c
> > > index c60b599665d8..2c8d6e2c7232 100644
> > > --- a/drivers/gpu/drm/panthor/panthor_gem.c
> > > +++ b/drivers/gpu/drm/panthor/panthor_gem.c
> > > @@ -44,8 +44,7 @@ void panthor_kernel_bo_destroy(struct panthor_kernel_bo *bo)
> > >  			to_panthor_bo(bo->obj)->exclusive_vm_root_gem != panthor_vm_root_gem(vm)))
> > >  		goto out_free_bo;
> > >  
> > > -	ret = panthor_vm_unmap_range(vm, bo->va_node.start,
> > > -				     panthor_kernel_bo_size(bo));
> > > +	ret = panthor_vm_unmap_range(vm, bo->va_node.start, bo->va_node.size);
> > >  	if (ret)
> > >  		goto out_free_bo;
> > >  
> > > @@ -95,10 +94,16 @@ panthor_kernel_bo_create(struct panthor_device *ptdev, struct panthor_vm *vm,
> > >  	}
> > >  	bo = to_panthor_bo(&obj->base);
> > > -	size = obj->base.size;
> > >  	kbo->obj = &obj->base;
> > >  	bo->flags = bo_flags;
> > >  
> > > +	/* The system and GPU MMU page size might differ, which becomes a
> > > +	 * problem for FW sections that need to be mapped at explicit address
> > > +	 * since our PAGE_SIZE alignment might cover a VA range that's
> > > +	 * expected to be used for another section.
> > > +	 * Make sure we never map more than we need.
> > > +	 */
> 
> I was wondering, this must be a relatively common situation for other DRM
> drivers, so maybe the DRM shmem core should have a BO creation function that
> lets you specify an exact page alignment?

There are probably not that many DRM drivers that need specific alignment, but I think
it's not a bad idea to add a function like that in a separate patch.

> 
> > > +	size = ALIGN(size, SZ_4K);
> 
> I was thinking, if we know that the FW's page size is always 4KiB, maybe we could do
> 
> #define CSF_FW_PAGESIZE SZ_4K
> 
> somewhere in panthor_fw.h to make things clearer?

Until future comes in and the firmware page size changes :)
But yeah, it could help in the future to search for firmware's page size when we will need to update it.

Best regards,
Liviu

> 
> Cheers,
> Adrian
> 
> Reviewed-by: Adrian Larumbe <adrian.larumbe@collabora.com>
> 
> > >  	ret = panthor_vm_alloc_va(vm, gpu_va, size, &kbo->va_node);
> > >  	if (ret)
> > >  		goto err_put_obj;
> > > diff --git a/drivers/gpu/drm/panthor/panthor_mmu.c b/drivers/gpu/drm/panthor/panthor_mmu.c
> > > index 3cd2bce59edc..e53d131c53cc 100644
> > > --- a/drivers/gpu/drm/panthor/panthor_mmu.c
> > > +++ b/drivers/gpu/drm/panthor/panthor_mmu.c
> > > @@ -1027,10 +1027,10 @@ panthor_vm_alloc_va(struct panthor_vm *vm, u64 va, u64 size,
> > >  {
> > >  	int ret;
> > >  
> > > -	if (!size || (size & ~PAGE_MASK))
> > > +	if (!size || !IS_ALIGNED(size, SZ_4K))
> > >  		return -EINVAL;
> > >  
> > > -	if (va != PANTHOR_VM_KERNEL_AUTO_VA && (va & ~PAGE_MASK))
> > > +	if (va != PANTHOR_VM_KERNEL_AUTO_VA && !IS_ALIGNED(va, SZ_4K))
> > >  		return -EINVAL;
> > >  
> > >  	mutex_lock(&vm->mm_lock);
> > > @@ -2370,7 +2370,7 @@ panthor_vm_bind_prepare_op_ctx(struct drm_file *file,
> > >  	int ret;
> > >  
> > >  	/* Aligned on page size. */
> > > -	if ((op->va | op->size) & ~PAGE_MASK)
> > > +	if (!IS_ALIGNED(op->va | op->size, SZ_4K))
> > >  		return -EINVAL;
> > >  
> > >  	switch (op->flags & DRM_PANTHOR_VM_BIND_OP_TYPE_MASK) {
> 

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

Re: [PATCH] drm/panthor: Fix firmware initialization on systems with a page size > 4k

[Boris Brezillon]

On Fri, 11 Oct 2024 18:58:45 +0100
Adrián Larumbe <adrian.larumbe@collabora.com> wrote:

> Hi Boris,
> 
> On 09.10.2024 09:10, Steven Price wrote:
> > On 08/10/2024 09:47, Boris Brezillon wrote:  
> > > The system and GPU MMU page size might differ, which becomes a
> > > problem for FW sections that need to be mapped at explicit address
> > > since our PAGE_SIZE alignment might cover a VA range that's
> > > expected to be used for another section.
> > > 
> > > Make sure we never map more than we need.
> > > 
> > > Fixes: 2718d91816ee ("drm/panthor: Add the FW logical block")
> > > Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>  
> > 
> > Reviewed-by: Steven Price <steven.price@arm.com>
> >   
> > > ---
> > >  drivers/gpu/drm/panthor/panthor_fw.c  |  3 +--
> > >  drivers/gpu/drm/panthor/panthor_gem.c | 11 ++++++++---
> > >  drivers/gpu/drm/panthor/panthor_mmu.c |  6 +++---
> > >  3 files changed, 12 insertions(+), 8 deletions(-)
> > > 
> > > diff --git a/drivers/gpu/drm/panthor/panthor_fw.c b/drivers/gpu/drm/panthor/panthor_fw.c
> > > index ef232c0c2049..293846400296 100644
> > > --- a/drivers/gpu/drm/panthor/panthor_fw.c
> > > +++ b/drivers/gpu/drm/panthor/panthor_fw.c
> > > @@ -515,8 +515,7 @@ static int panthor_fw_load_section_entry(struct panthor_device *ptdev,
> > >  		return -EINVAL;
> > >  	}
> > >  
> > > -	if ((hdr.va.start & ~PAGE_MASK) != 0 ||
> > > -	    (hdr.va.end & ~PAGE_MASK) != 0) {
> > > +	if (!IS_ALIGNED(hdr.va.start, SZ_4K) || !IS_ALIGNED(hdr.va.end, SZ_4K)) {
> > >  		drm_err(&ptdev->base, "Firmware corrupted, virtual addresses not page aligned: 0x%x-0x%x\n",
> > >  			hdr.va.start, hdr.va.end);
> > >  		return -EINVAL;
> > > diff --git a/drivers/gpu/drm/panthor/panthor_gem.c b/drivers/gpu/drm/panthor/panthor_gem.c
> > > index c60b599665d8..2c8d6e2c7232 100644
> > > --- a/drivers/gpu/drm/panthor/panthor_gem.c
> > > +++ b/drivers/gpu/drm/panthor/panthor_gem.c
> > > @@ -44,8 +44,7 @@ void panthor_kernel_bo_destroy(struct panthor_kernel_bo *bo)
> > >  			to_panthor_bo(bo->obj)->exclusive_vm_root_gem != panthor_vm_root_gem(vm)))
> > >  		goto out_free_bo;
> > >  
> > > -	ret = panthor_vm_unmap_range(vm, bo->va_node.start,
> > > -				     panthor_kernel_bo_size(bo));
> > > +	ret = panthor_vm_unmap_range(vm, bo->va_node.start, bo->va_node.size);
> > >  	if (ret)
> > >  		goto out_free_bo;
> > >  
> > > @@ -95,10 +94,16 @@ panthor_kernel_bo_create(struct panthor_device *ptdev, struct panthor_vm *vm,
> > >  	}
> > >  	bo = to_panthor_bo(&obj->base);
> > > -	size = obj->base.size;
> > >  	kbo->obj = &obj->base;
> > >  	bo->flags = bo_flags;
> > >  
> > > +	/* The system and GPU MMU page size might differ, which becomes a
> > > +	 * problem for FW sections that need to be mapped at explicit address
> > > +	 * since our PAGE_SIZE alignment might cover a VA range that's
> > > +	 * expected to be used for another section.
> > > +	 * Make sure we never map more than we need.
> > > +	 */  
> 
> I was wondering, this must be a relatively common situation for other DRM
> drivers, so maybe the DRM shmem core should have a BO creation function that
> lets you specify an exact page alignment?

So, there's a difference between the MMU page granularity and the system
page size. The BO allocation granularity will always be the system page
size, because gem_shmem can't allocate partial pages.

> 
> > > +	size = ALIGN(size, SZ_4K);  
> 
> I was thinking, if we know that the FW's page size is always 4KiB, maybe we could do
> 
> #define CSF_FW_PAGESIZE SZ_4K
> 
> somewhere in panthor_fw.h to make things clearer?

That I can do. If we want it to be fully dynamic, we can even make it a
panthor_mmu_get_page_size() helper which queries the pgsize_bitmap of
the io_pgtable to get the minimum granularity.