AMD General
Hi, Christian.
This version of the patch is not host-platform dependent; all host platforms
follow the same path.
I verified this patch with KVM in my local environment and with ESXi on a
borrowed server.
Distinguishing the host platform was a mistake,
and I have explained the situation at the end of the patch email.
I have pasted the content below:
Hi, Christian and Lijo.
Sorry, I made a mistake.
Host access to the VF FB is not platform-dependent. After the host
driver sets VF_FB_EN in response to GPU_INIT_DATA, the host can access the VF
FB.
I borrowed an ESXi server and tested this patch there.
The amdgpu driver works normally.
I rewrote the background. Is anything still unclear?
Thanks,
Chong.
-----Original Message-----
From: Koenig, Christian <[email protected]>
Sent: Wednesday, July 8, 2026 5:05 PM
To: Li, Chong(Alan) <[email protected]>; [email protected]
Cc: Deng, Emily <[email protected]>; Chang, HaiJun <[email protected]>;
Skvortsov, Victor <[email protected]>; Lazar, Lijo <[email protected]>;
Cursor <[email protected]>
Subject: Re: [PATCH] drm/amdgpu: improve the amdgpu device init progress in
sriov mode
On 7/8/26 10:25, chong li wrote:
> v2:
> Some legacy ASICs do not send amdgpu_virt_request_init_data().
> Only keep the full GPU access request early when request_init_data is not
> sent.
>
> v1:
> Move the initialization of non-GPU resources out of the full GPU
> access region during AMDGPU device initialization.
>
> Background:
> In SR-IOV, the guest sends GPU_INIT_DATA, then the host enables
> VF_FB_EN and places early initialization data, such as IP discovery,
> VBIOS, and PF-VF exchange data, in the VF FB. The guest should then be
> able to read this data before requesting full GPU access.
>
> Before this patch, the VF still requested full GPU access in
> amdgpu_device_ip_early_init(). At that point TTM is not initialized
> yet, so the normal VRAM aperture mapping is unavailable and the guest
> falls back to MM_INDEX/MM_DATA register access. That register path
> requires full GPU access.
>
> Use the BAR0 framebuffer read path, amdgpu_device_read_fb_via_bar0(),
> for the early init-data copy instead of MM_INDEX/MM_DATA. This lets
> the driver delay the full GPU access request until after the early
> init data has been copied.
That looks like it goes into the right direction, but as far as I can see it is
still an ESXi specific change.
So once more: We can't adjust the driver to the hypervisor!
Either this works on all hypervisors or I have to reject the change.
Regards,
Christian.
>
> Signed-off-by: chong li <[email protected]>
> Co-authored-by: Cursor <[email protected]>
> ---
> drivers/gpu/drm/amd/amdgpu/amdgpu_device.c | 21 +++++++++++++++++----
> drivers/gpu/drm/amd/amdgpu/mxgpu_ai.c | 4 ++--
> 2 files changed, 19 insertions(+), 6 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> index 610d82b79de3..ac66796e8634 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
> @@ -38,6 +38,10 @@
> #include <linux/apple-gmux.h>
> #include <linux/nospec.h>
>
> +#ifdef CONFIG_X86
> +#include <asm/hypervisor.h>
> +#endif
> +
> #include <drm/drm_atomic_helper.h>
> #include <drm/drm_client_event.h>
> #include <drm/drm_crtc_helper.h>
> @@ -1987,16 +1991,19 @@ static int amdgpu_device_ip_early_init(struct
> amdgpu_device *adev) {
> struct amdgpu_ip_block *ip_block;
> struct pci_dev *parent;
> - bool total, skip_bios;
> + bool total, skip_bios, early_full_gpu_access = false;
> uint32_t bios_flags;
> int i, r;
>
> amdgpu_device_enable_virtual_display(adev);
>
> if (amdgpu_sriov_vf(adev)) {
> - r = amdgpu_virt_request_full_gpu(adev, true);
> - if (r)
> - return r;
> + early_full_gpu_access = (adev->virt.req_init_data_ver == 0);
> + if (early_full_gpu_access) {
> + r = amdgpu_virt_request_full_gpu(adev, true);
> + if (r)
> + return r;
> + }
>
> r = amdgpu_virt_init_critical_region(adev);
> if (r)
> @@ -2159,6 +2166,12 @@ static int amdgpu_device_ip_early_init(struct
> amdgpu_device *adev)
> if (!total)
> return -ENODEV;
>
> + if (amdgpu_sriov_vf(adev) && !early_full_gpu_access) {
> + r = amdgpu_virt_request_full_gpu(adev, true);
> + if (r)
> + return r;
> + }
> +
> if (adev->gmc.xgmi.supported)
> amdgpu_xgmi_early_init(adev);
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/mxgpu_ai.c
> b/drivers/gpu/drm/amd/amdgpu/mxgpu_ai.c
> index 9a40107a0869..340703d89d6b 100644
> --- a/drivers/gpu/drm/amd/amdgpu/mxgpu_ai.c
> +++ b/drivers/gpu/drm/amd/amdgpu/mxgpu_ai.c
> @@ -185,8 +185,8 @@ static int xgpu_ai_send_access_requests(struct
> amdgpu_device *adev,
> } else if (req == IDH_REQ_GPU_INIT_DATA){
> /* Dummy REQ_GPU_INIT_DATA handling */
> r = xgpu_ai_poll_msg(adev, IDH_REQ_GPU_INIT_DATA_READY);
> - /* version set to 0 since dummy */
> - adev->virt.req_init_data_ver = 0;
> + /* Version is set to 1 since GPU_CRIT_REGION_V1 */
> + adev->virt.req_init_data_ver = GPU_CRIT_REGION_V1;
> }
>
> return 0;
