[PATCH] drm/amdgpu: Add kernel parameter to force no xgmi

[Sierra Guiza, Alejandro (Alex)]

[AMD Public Use]

Please ignore this patch, it should be in a different branch. As PCIe p2p is not supported in upstream.

Regards,
Alex Sierra

> -----Original Message-----
> From: amd-gfx <amd-gfx-bounces at lists.freedesktop.org> On Behalf Of
> Sierra Guiza, Alejandro (Alex)
> Sent: Wednesday, October 28, 2020 1:09 PM
> To: Koenig, Christian <Christian.Koenig at amd.com>; amd-
> gfx at lists.freedesktop.org
> Subject: Re: [PATCH] drm/amdgpu: Add kernel parameter to force no xgmi
> 
> 
> On 10/28/2020 9:58 AM, Christian König wrote:
> > Am 28.10.20 um 15:55 schrieb Alex Sierra:
> >> By enabling this parameter, the system will be forced to use pcie
> >> interface only for p2p transactions.
> >
> > Better name that amdgpu_xgmi with a default value of enabled.
> >
> > Or maybe add another bit value for amdgpu_vm_debug instead.
> 
> Ack
> 
> Regards,
> Alex Sierra
> 
> >
> >
> >>
> >> Signed-off-by: Alex Sierra <alex.sierra at amd.com>
> >> ---
> >>   drivers/gpu/drm/amd/amdgpu/amdgpu.h        | 1 +
> >>   drivers/gpu/drm/amd/amdgpu/amdgpu_device.c | 2 +-
> >>   drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c    | 9 +++++++++
> >>   3 files changed, 11 insertions(+), 1 deletion(-)
> >>
> >> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
> >> b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
> >> index ba65d4f2ab67..3645f00e9f61 100644
> >> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu.h
> >> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu.h
> >> @@ -188,6 +188,7 @@ extern int amdgpu_discovery;
> >>   extern int amdgpu_mes;
> >>   extern int amdgpu_noretry;
> >>   extern int amdgpu_force_asic_type;
> >> +extern int amdgpu_force_no_xgmi;
> >>   #ifdef CONFIG_HSA_AMD
> >>   extern int sched_policy;
> >>   extern bool debug_evictions;
> >> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> >> b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> >> index 1fe850e0a94d..0a5d97a84017 100644
> >> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> >> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> >> @@ -2257,7 +2257,7 @@ static int amdgpu_device_ip_init(struct
> >> amdgpu_device *adev)
> >>       if (r)
> >>           goto init_failed;
> >>   -    if (adev->gmc.xgmi.num_physical_nodes > 1)
> >> +    if (!amdgpu_force_no_xgmi && adev-
> >gmc.xgmi.num_physical_nodes >
> >> +1)
> >
> > Mhm, this will most likely cause problems. You still need to add the
> > device to the hive because otherwise GPU won't work.
> 
> What kind of problems? So far, I have validated this using a system with
> multiple devices and running ./rocm_bandwidth_test -t. With and without
> the parameter set.
> 
> Regards,
> Alex Sierra
> 
> >
> > Apart from that sounds like a good idea in general.
> >
> > Christian.
> >
> >>           amdgpu_xgmi_add_device(adev);
> >>       amdgpu_amdkfd_device_init(adev);
> >>   diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
> >> b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
> >> index 4b78ecfd35f7..22485067cf31 100644
> >> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
> >> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_drv.c
> >> @@ -160,6 +160,7 @@ int amdgpu_force_asic_type = -1;
> >>   int amdgpu_tmz = 0;
> >>   int amdgpu_reset_method = -1; /* auto */
> >>   int amdgpu_num_kcq = -1;
> >> +int amdgpu_force_no_xgmi = 0;
> >>     struct amdgpu_mgpu_info mgpu_info = {
> >>       .mutex = __MUTEX_INITIALIZER(mgpu_info.mutex),
> >> @@ -522,6 +523,14 @@ module_param_named(ras_enable,
> >> amdgpu_ras_enable, int, 0444);
> >>   MODULE_PARM_DESC(ras_mask, "Mask of RAS features to enable
> (default
> >> 0xffffffff), only valid when ras_enable == 1");
> >>   module_param_named(ras_mask, amdgpu_ras_mask, uint, 0444);
> >>   +/**
> >> + * DOC: force_no_xgmi (uint)
> >> + * Forces not to use xgmi interface (0 = disable, 1 = enable).
> >> + * Default is 0 (disabled).
> >> + */
> >> +MODULE_PARM_DESC(force_no_xgmi, "Force not to use xgmi
> interface");
> >> +module_param_named(force_no_xgmi, amdgpu_force_no_xgmi, int,
> 0600);
> >> +
> >>   /**
> >>    * DOC: si_support (int)
> >>    * Set SI support driver. This parameter works after set config
> >> CONFIG_DRM_AMDGPU_SI. For SI asic, when radeon driver is enabled,
> >
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