[PATCH 4/7] drm/amdgpu/virt: add function to check MMIO accessing

[Ding, Pixel]

It works with current MMIO blocking policy, while all pages are blocked expect the one containing mailbox registers. But actually it’s not a good approach, as commented we should add interaction between host and guest for MMIO blocking check in future.

By now I can add more comments here, is it OK?
— 
Sincerely Yours,
Pixel







On 24/10/2017, 12:33 AM, "Deucher, Alexander" <Alexander.Deucher at amd.com> wrote:

>> -----Original Message-----
>> From: amd-gfx [mailto:amd-gfx-bounces at lists.freedesktop.org] On Behalf
>> Of Pixel Ding
>> Sent: Monday, October 23, 2017 6:03 AM
>> To: amd-gfx at lists.freedesktop.org
>> Cc: Sun, Gary; Ding, Pixel; Li, Bingley
>> Subject: [PATCH 4/7] drm/amdgpu/virt: add function to check MMIO
>> accessing
>> 
>> From: pding <Pixel.Ding at amd.com>
>> 
>> MMIO space can be blocked on virtualised device. Add this function
>> to check if MMIO is blocked or not.
>> 
>> Todo: need a reliable method such like communation with hypervisor.
>> 
>> Signed-off-by: pding <Pixel.Ding at amd.com>
>> ---
>>  drivers/gpu/drm/amd/amdgpu/amdgpu_virt.c | 5 +++++
>>  drivers/gpu/drm/amd/amdgpu/amdgpu_virt.h | 1 +
>>  2 files changed, 6 insertions(+)
>> 
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_virt.c
>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_virt.c
>> index e97f80f..33dac7e 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_virt.c
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_virt.c
>> @@ -24,6 +24,11 @@
>>  #include "amdgpu.h"
>>  #define MAX_KIQ_REG_WAIT	100000000 /* in usecs */
>> 
>> +bool amdgpu_virt_mmio_blocked(struct amdgpu_device *adev)
>> +{
>> +	return RREG32_NO_KIQ(0xc040) == 0xffffffff;
>> +}
>
>Is this safe?  Won't accessing non-instanced registers cause a problem?  Probably also worth commenting that register this is and a note for future asics in case the register map changes.
>
>Alex
>
>> +
>>  int amdgpu_allocate_static_csa(struct amdgpu_device *adev)
>>  {
>>  	int r;
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_virt.h
>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_virt.h
>> index b89d37f..81efb9d 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_virt.h
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_virt.h
>> @@ -276,6 +276,7 @@ static inline bool is_virtual_machine(void)
>>  }
>> 
>>  struct amdgpu_vm;
>> +bool amdgpu_virt_mmio_blocked(struct amdgpu_device *adev);
>>  int amdgpu_allocate_static_csa(struct amdgpu_device *adev);
>>  int amdgpu_map_static_csa(struct amdgpu_device *adev, struct
>> amdgpu_vm *vm,
>>  			  struct amdgpu_bo_va **bo_va);
>> --
>> 2.9.5
>> 
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