diff mbox series

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

Message ID 20191203075446.60197-3-thomas_os@shipmail.org (mailing list archive)
State New, archived
Headers show
Series mm, drm/ttm: Fix pte insertion with customized protection | expand

Commit Message

Thomas Hellström (Intel) Dec. 3, 2019, 7:54 a.m. UTC 
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(-)

Comments

Kirill A. Shutemov Dec. 3, 2019, 9:55 a.m. UTC | #1 
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.
Christian König Dec. 3, 2019, 9:58 a.m. UTC | #2 
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.
Thomas Hellström (Intel) Dec. 3, 2019, 10:19 a.m. UTC | #3 
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.
diff mbox series

Patch

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;