[PATCH 0/2] mm, drm/ttm: Fix pte insertion with customized protection

[PATCH 0/2] mm, drm/ttm: Fix pte insertion with customized protection

[Thomas Hellström (VMware)]

From: Thomas Hellstrom <thellstrom@vmware.com>

The drm/ttm module is using a modified on-stack copy of the
struct vm_area_struct to be able to set a page protection with customized
caching. Fix that by adding a vmf_insert_mixed_prot() function similar
to the existing vmf_insert_pfn_prot() for use with drm/ttm.

I'd like to merge this through a drm tree.


Thomas Hellstrom (2):
  mm: Add and export vmf_insert_mixed_prot()
  drm/ttm: Fix vm page protection handling

 drivers/gpu/drm/ttm/ttm_bo_vm.c | 14 +++++++-------
 include/linux/mm.h              |  2 ++
 mm/memory.c                     | 15 +++++++++++----
 3 files changed, 20 insertions(+), 11 deletions(-)

Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Cc: "Jérôme Glisse" <jglisse@redhat.com>
Cc: "Christian König" <christian.koenig@amd.com>

-- 
2.21.0

[PATCH 1/2] mm: Add and export vmf_insert_mixed_prot()

[Thomas Hellström (VMware)]

From: Thomas Hellstrom <thellstrom@vmware.com>

The TTM module today uses a hack to be able to set a different page
protection than struct vm_area_struct::vm_page_prot. To be able to do
this properly, add and export vmf_insert_mixed_prot().

Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Cc: "Jérôme Glisse" <jglisse@redhat.com>
Cc: "Christian König" <christian.koenig@amd.com>
Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Acked-by: Christian König <christian.koenig@amd.com>
---
 include/linux/mm.h |  2 ++
 mm/memory.c        | 15 +++++++++++----
 2 files changed, 13 insertions(+), 4 deletions(-)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index cc292273e6ba..29575d3c1e47 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2548,6 +2548,8 @@ vm_fault_t vmf_insert_pfn_prot(struct vm_area_struct *vma, unsigned long addr,
 			unsigned long pfn, pgprot_t pgprot);
 vm_fault_t vmf_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
 			pfn_t pfn);
+vm_fault_t vmf_insert_mixed_prot(struct vm_area_struct *vma, unsigned long addr,
+			pfn_t pfn, pgprot_t pgprot);
 vm_fault_t vmf_insert_mixed_mkwrite(struct vm_area_struct *vma,
 		unsigned long addr, pfn_t pfn);
 int vm_iomap_memory(struct vm_area_struct *vma, phys_addr_t start, unsigned long len);
diff --git a/mm/memory.c b/mm/memory.c
index b1ca51a079f2..28f162e28144 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1719,9 +1719,9 @@ static bool vm_mixed_ok(struct vm_area_struct *vma, pfn_t pfn)
 }
 
 static vm_fault_t __vm_insert_mixed(struct vm_area_struct *vma,
-		unsigned long addr, pfn_t pfn, bool mkwrite)
+	        unsigned long addr, pfn_t pfn, pgprot_t pgprot,
+		bool mkwrite)
 {
-	pgprot_t pgprot = vma->vm_page_prot;
 	int err;
 
 	BUG_ON(!vm_mixed_ok(vma, pfn));
@@ -1764,10 +1764,17 @@ static vm_fault_t __vm_insert_mixed(struct vm_area_struct *vma,
 	return VM_FAULT_NOPAGE;
 }
 
+vm_fault_t vmf_insert_mixed_prot(struct vm_area_struct *vma, unsigned long addr,
+				 pfn_t pfn, pgprot_t pgprot)
+{
+	return __vm_insert_mixed(vma, addr, pfn, pgprot, false);
+}
+EXPORT_SYMBOL(vmf_insert_mixed_prot);
+
 vm_fault_t vmf_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
 		pfn_t pfn)
 {
-	return __vm_insert_mixed(vma, addr, pfn, false);
+	return __vm_insert_mixed(vma, addr, pfn, vma->vm_page_prot, false);
 }
 EXPORT_SYMBOL(vmf_insert_mixed);
 
@@ -1779,7 +1786,7 @@ EXPORT_SYMBOL(vmf_insert_mixed);
 vm_fault_t vmf_insert_mixed_mkwrite(struct vm_area_struct *vma,
 		unsigned long addr, pfn_t pfn)
 {
-	return __vm_insert_mixed(vma, addr, pfn, true);
+	return __vm_insert_mixed(vma, addr, pfn, vma->vm_page_prot, true);
 }
 EXPORT_SYMBOL(vmf_insert_mixed_mkwrite);
 
-- 
2.21.0

[PATCH 2/2] drm/ttm: Fix vm page protection handling

[Thomas Hellström (VMware)]

From: Thomas Hellstrom <thellstrom@vmware.com>

We were using an ugly hack to set the page protection correctly.
Fix that and instead use vmf_insert_mixed_prot() and / or
vmf_insert_pfn_prot().
Also get the default page protection from
struct vm_area_struct::vm_page_prot rather than using vm_get_page_prot().
This way we catch modifications done by the vm system for drivers that
want write-notification.

Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Cc: "Jérôme Glisse" <jglisse@redhat.com>
Cc: "Christian König" <christian.koenig@amd.com>
Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
---
 drivers/gpu/drm/ttm/ttm_bo_vm.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/drivers/gpu/drm/ttm/ttm_bo_vm.c b/drivers/gpu/drm/ttm/ttm_bo_vm.c
index e6495ca2630b..2098f8d4dfc5 100644
--- a/drivers/gpu/drm/ttm/ttm_bo_vm.c
+++ b/drivers/gpu/drm/ttm/ttm_bo_vm.c
@@ -173,7 +173,6 @@ vm_fault_t ttm_bo_vm_fault_reserved(struct vm_fault *vmf,
 				    pgoff_t num_prefault)
 {
 	struct vm_area_struct *vma = vmf->vma;
-	struct vm_area_struct cvma = *vma;
 	struct ttm_buffer_object *bo = vma->vm_private_data;
 	struct ttm_bo_device *bdev = bo->bdev;
 	unsigned long page_offset;
@@ -244,7 +243,7 @@ vm_fault_t ttm_bo_vm_fault_reserved(struct vm_fault *vmf,
 		goto out_io_unlock;
 	}
 
-	cvma.vm_page_prot = ttm_io_prot(bo->mem.placement, prot);
+	prot = ttm_io_prot(bo->mem.placement, prot);
 	if (!bo->mem.bus.is_iomem) {
 		struct ttm_operation_ctx ctx = {
 			.interruptible = false,
@@ -260,7 +259,7 @@ vm_fault_t ttm_bo_vm_fault_reserved(struct vm_fault *vmf,
 		}
 	} else {
 		/* Iomem should not be marked encrypted */
-		cvma.vm_page_prot = pgprot_decrypted(cvma.vm_page_prot);
+		prot = pgprot_decrypted(prot);
 	}
 
 	/*
@@ -284,10 +283,11 @@ vm_fault_t ttm_bo_vm_fault_reserved(struct vm_fault *vmf,
 		}
 
 		if (vma->vm_flags & VM_MIXEDMAP)
-			ret = vmf_insert_mixed(&cvma, address,
-					__pfn_to_pfn_t(pfn, PFN_DEV));
+			ret = vmf_insert_mixed_prot(vma, address,
+						    __pfn_to_pfn_t(pfn, PFN_DEV),
+						    prot);
 		else
-			ret = vmf_insert_pfn(&cvma, address, pfn);
+			ret = vmf_insert_pfn_prot(vma, address, pfn, prot);
 
 		/* Never error on prefaulted PTEs */
 		if (unlikely((ret & VM_FAULT_ERROR))) {
@@ -319,7 +319,7 @@ vm_fault_t ttm_bo_vm_fault(struct vm_fault *vmf)
 	if (ret)
 		return ret;
 
-	prot = vm_get_page_prot(vma->vm_flags);
+	prot = vma->vm_page_prot;
 	ret = ttm_bo_vm_fault_reserved(vmf, prot, TTM_BO_VM_NUM_PREFAULT);
 	if (ret == VM_FAULT_RETRY && !(vmf->flags & FAULT_FLAG_RETRY_NOWAIT))
 		return ret;
-- 
2.21.0

Re: [PATCH 2/2] drm/ttm: Fix vm page protection handling

[Kirill A. Shutemov]

On Tue, Dec 03, 2019 at 08:54:46AM +0100, Thomas Hellström (VMware) wrote:
> From: Thomas Hellstrom <thellstrom@vmware.com>
> 
> We were using an ugly hack to set the page protection correctly.
> Fix that and instead use vmf_insert_mixed_prot() and / or
> vmf_insert_pfn_prot().
> Also get the default page protection from
> struct vm_area_struct::vm_page_prot rather than using vm_get_page_prot().
> This way we catch modifications done by the vm system for drivers that
> want write-notification.

Hm. Why doesn't your VMA have the right prot flags in the first place? Why
do you need to override them? More context, please.

-- 
 Kirill A. Shutemov

Re: [PATCH 2/2] drm/ttm: Fix vm page protection handling

[Christian König]

Am 03.12.19 um 10:55 schrieb Kirill A. Shutemov:
> On Tue, Dec 03, 2019 at 08:54:46AM +0100, Thomas Hellström (VMware) wrote:
>> From: Thomas Hellstrom <thellstrom@vmware.com>
>>
>> We were using an ugly hack to set the page protection correctly.
>> Fix that and instead use vmf_insert_mixed_prot() and / or
>> vmf_insert_pfn_prot().
>> Also get the default page protection from
>> struct vm_area_struct::vm_page_prot rather than using vm_get_page_prot().
>> This way we catch modifications done by the vm system for drivers that
>> want write-notification.
> Hm. Why doesn't your VMA have the right prot flags in the first place? Why
> do you need to override them? More context, please.

TTM allows for graphics buffer to move between system and IO memory. So 
the prot flags can change on the fly for a VMA.

Regards,
Christian.

Re: [PATCH 2/2] drm/ttm: Fix vm page protection handling

[Thomas Hellström (VMware)]

On 12/3/19 10:58 AM, Christian König wrote:
> Am 03.12.19 um 10:55 schrieb Kirill A. Shutemov:
>> On Tue, Dec 03, 2019 at 08:54:46AM +0100, Thomas Hellström (VMware) 
>> wrote:
>>> From: Thomas Hellstrom <thellstrom@vmware.com>
>>>
>>> We were using an ugly hack to set the page protection correctly.
>>> Fix that and instead use vmf_insert_mixed_prot() and / or
>>> vmf_insert_pfn_prot().
>>> Also get the default page protection from
>>> struct vm_area_struct::vm_page_prot rather than using 
>>> vm_get_page_prot().
>>> This way we catch modifications done by the vm system for drivers that
>>> want write-notification.
>> Hm. Why doesn't your VMA have the right prot flags in the first 
>> place? Why
>> do you need to override them? More context, please.
>
> TTM allows for graphics buffer to move between system and IO memory. 
> So the prot flags can change on the fly for a VMA.
>
I'll add that and some additional info to the commit message. And fix 
that CC'd dri-devel address.

Thanks,
Thomas





> Regards,
> Christian.

Re: [PATCH 1/2] mm: Add and export vmf_insert_mixed_prot()

[Christian König]

Am 26.11.19 um 21:27 schrieb Thomas Hellström (VMware):
> From: Thomas Hellstrom <thellstrom@vmware.com>
>
> The TTM module today uses a hack to be able to set a different page
> protection than struct vm_area_struct::vm_page_prot. To be able to do
> this properly, add and export vmf_insert_mixed_prot().
>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Michal Hocko <mhocko@suse.com>
> Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>
> Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
> Cc: Ralph Campbell <rcampbell@nvidia.com>
> Cc: "Jérôme Glisse" <jglisse@redhat.com>
> Cc: "Christian König" <christian.koenig@amd.com>
> Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>

Acked-by: Christian König <christian.koenig@amd.com>

> ---
>   include/linux/mm.h |  2 ++
>   mm/memory.c        | 15 +++++++++++----
>   2 files changed, 13 insertions(+), 4 deletions(-)
>
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index cc292273e6ba..29575d3c1e47 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -2548,6 +2548,8 @@ vm_fault_t vmf_insert_pfn_prot(struct vm_area_struct *vma, unsigned long addr,
>   			unsigned long pfn, pgprot_t pgprot);
>   vm_fault_t vmf_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
>   			pfn_t pfn);
> +vm_fault_t vmf_insert_mixed_prot(struct vm_area_struct *vma, unsigned long addr,
> +			pfn_t pfn, pgprot_t pgprot);
>   vm_fault_t vmf_insert_mixed_mkwrite(struct vm_area_struct *vma,
>   		unsigned long addr, pfn_t pfn);
>   int vm_iomap_memory(struct vm_area_struct *vma, phys_addr_t start, unsigned long len);
> diff --git a/mm/memory.c b/mm/memory.c
> index b1ca51a079f2..28f162e28144 100644
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -1719,9 +1719,9 @@ static bool vm_mixed_ok(struct vm_area_struct *vma, pfn_t pfn)
>   }
>   
>   static vm_fault_t __vm_insert_mixed(struct vm_area_struct *vma,
> -		unsigned long addr, pfn_t pfn, bool mkwrite)
> +		unsigned long addr, pfn_t pfn, pgprot_t pgprot,
> +		bool mkwrite)
>   {
> -	pgprot_t pgprot = vma->vm_page_prot;
>   	int err;
>   
>   	BUG_ON(!vm_mixed_ok(vma, pfn));
> @@ -1764,10 +1764,17 @@ static vm_fault_t __vm_insert_mixed(struct vm_area_struct *vma,
>   	return VM_FAULT_NOPAGE;
>   }
>   
> +vm_fault_t vmf_insert_mixed_prot(struct vm_area_struct *vma, unsigned long addr,
> +				 pfn_t pfn, pgprot_t pgprot)
> +{
> +	return __vm_insert_mixed(vma, addr, pfn, pgprot, false);
> +}
> +EXPORT_SYMBOL(vmf_insert_mixed_prot);
> +
>   vm_fault_t vmf_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
>   		pfn_t pfn)
>   {
> -	return __vm_insert_mixed(vma, addr, pfn, false);
> +	return __vm_insert_mixed(vma, addr, pfn, vma->vm_page_prot, false);
>   }
>   EXPORT_SYMBOL(vmf_insert_mixed);
>   
> @@ -1779,7 +1786,7 @@ EXPORT_SYMBOL(vmf_insert_mixed);
>   vm_fault_t vmf_insert_mixed_mkwrite(struct vm_area_struct *vma,
>   		unsigned long addr, pfn_t pfn)
>   {
> -	return __vm_insert_mixed(vma, addr, pfn, true);
> +	return __vm_insert_mixed(vma, addr, pfn, vma->vm_page_prot, true);
>   }
>   EXPORT_SYMBOL(vmf_insert_mixed_mkwrite);
>   

[PATCH 1/2] mm: Add and export vmf_insert_mixed_prot()

[Thomas Hellström (VMware)]

From: Thomas Hellstrom <thellstrom@vmware.com>

The TTM module today uses a hack to be able to set a different page
protection than struct vm_area_struct::vm_page_prot. To be able to do
this properly, add and export vmf_insert_mixed_prot().

Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Cc: "Jérôme Glisse" <jglisse@redhat.com>
Cc: "Christian König" <christian.koenig@amd.com>
Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
---
 include/linux/mm.h |  2 ++
 mm/memory.c        | 15 +++++++++++----
 2 files changed, 13 insertions(+), 4 deletions(-)

diff --git a/include/linux/mm.h b/include/linux/mm.h
index cc292273e6ba..29575d3c1e47 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -2548,6 +2548,8 @@ vm_fault_t vmf_insert_pfn_prot(struct vm_area_struct *vma, unsigned long addr,
 			unsigned long pfn, pgprot_t pgprot);
 vm_fault_t vmf_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
 			pfn_t pfn);
+vm_fault_t vmf_insert_mixed_prot(struct vm_area_struct *vma, unsigned long addr,
+			pfn_t pfn, pgprot_t pgprot);
 vm_fault_t vmf_insert_mixed_mkwrite(struct vm_area_struct *vma,
 		unsigned long addr, pfn_t pfn);
 int vm_iomap_memory(struct vm_area_struct *vma, phys_addr_t start, unsigned long len);
diff --git a/mm/memory.c b/mm/memory.c
index b1ca51a079f2..28f162e28144 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -1719,9 +1719,9 @@ static bool vm_mixed_ok(struct vm_area_struct *vma, pfn_t pfn)
 }
 
 static vm_fault_t __vm_insert_mixed(struct vm_area_struct *vma,
-		unsigned long addr, pfn_t pfn, bool mkwrite)
+		unsigned long addr, pfn_t pfn, pgprot_t pgprot,
+		bool mkwrite)
 {
-	pgprot_t pgprot = vma->vm_page_prot;
 	int err;
 
 	BUG_ON(!vm_mixed_ok(vma, pfn));
@@ -1764,10 +1764,17 @@ static vm_fault_t __vm_insert_mixed(struct vm_area_struct *vma,
 	return VM_FAULT_NOPAGE;
 }
 
+vm_fault_t vmf_insert_mixed_prot(struct vm_area_struct *vma, unsigned long addr,
+				 pfn_t pfn, pgprot_t pgprot)
+{
+	return __vm_insert_mixed(vma, addr, pfn, pgprot, false);
+}
+EXPORT_SYMBOL(vmf_insert_mixed_prot);
+
 vm_fault_t vmf_insert_mixed(struct vm_area_struct *vma, unsigned long addr,
 		pfn_t pfn)
 {
-	return __vm_insert_mixed(vma, addr, pfn, false);
+	return __vm_insert_mixed(vma, addr, pfn, vma->vm_page_prot, false);
 }
 EXPORT_SYMBOL(vmf_insert_mixed);
 
@@ -1779,7 +1786,7 @@ EXPORT_SYMBOL(vmf_insert_mixed);
 vm_fault_t vmf_insert_mixed_mkwrite(struct vm_area_struct *vma,
 		unsigned long addr, pfn_t pfn)
 {
-	return __vm_insert_mixed(vma, addr, pfn, true);
+	return __vm_insert_mixed(vma, addr, pfn, vma->vm_page_prot, true);
 }
 EXPORT_SYMBOL(vmf_insert_mixed_mkwrite);
 
-- 
2.21.0