Re: [EXTERNAL] [PATCH 2/2] drm/amdkfd: Add PCIe Hotplug Support for AMDKFD

[Shuotao Xu <shuotaoxu@xxxxxxxxxxxxx>]

On Apr 11, 2022, at 11:52 PM, Andrey Grodzovsky <andrey.grodzovsky@xxxxxxx> wrote:

[Some people who received this message don't often get email from andrey.grodzovsky@xxxxxxx. Learn why this is important at http://aka.ms/LearnAboutSenderIdentification.]

On 2022-04-08 21:28, Shuotao Xu wrote:

On Apr 8, 2022, at 11:28 PM, Andrey Grodzovsky <andrey.grodzovsky@xxxxxxx> wrote:

[Some people who received this message don't often get email from andrey.grodzovsky@xxxxxxx. Learn why this is important at http://aka.ms/LearnAboutSenderIdentification.]

On 2022-04-08 04:45, Shuotao Xu wrote:

Adding PCIe Hotplug Support for AMDKFD: the support of hot-plug of GPU
devices can open doors for many advanced applications in data center
in the next few years, such as for GPU resource
disaggregation. Current AMDKFD does not support hotplug out b/o the
following reasons:

1. During PCIe removal, decrement KFD lock which was incremented at
the beginning of hw fini; otherwise kfd_open later is going to
fail.

I assumed you read my comment last time, still you do same approach.
More in details bellow

Aha, I like your fix:) I was not familiar with drm APIs so just only half understood your comment last time.

BTW, I tried hot-plugging out a GPU when rocm application is still running.
From dmesg, application is still trying to access the removed kfd device, and are met with some errors.

Application us supposed to keep running, it holds the drm_device
reference as long as it has an open
FD to the device and final cleanup will come only after the app will die
thus releasing the FD and the last
drm_device reference.

Application would hang and not exiting in this case.

Actually I tried kill -7 $pid, and the process exists. The dmesg has some warning though.

[  711.769977] WARNING: CPU: 23 PID: 344 at .../amdgpu-rocm5.0.2/src/amd/amdgpu/amdgpu_object.c:1336 amdgpu_bo_release_notify+0x150/0x160 [amdgpu]

[  711.770528] Modules linked in: amdgpu(OE) amdttm(OE) amd_sched(OE) amdkcl(OE) iommu_v2 nf_conntrack_netlink nfnetlink xfrm_user xfrm_algo xt_addrtype br_netfilter xt_CHECKSUM iptable_mangle xt_MASQUERADE iptable_nat nf_nat xt_conntrack nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 ipt_REJECT nf_reject_ipv4 xt_tcpudp bridge stp llc ebtable_filter ebtables ip6table_filter ip6_tables iptable_filter overlay binfmt_misc intel_rapl_msr i40iw intel_rapl_common skx_edac nfit x86_pkg_temp_thermal intel_powerclamp coretemp kvm_intel rpcrdma kvm sunrpc ipmi_ssif ib_umad ib_ipoib rdma_ucm irqbypass rapl joydev acpi_ipmi input_leds intel_cstate ipmi_si ipmi_devintf mei_me mei intel_pch_thermal ipmi_msghandler ioatdma mac_hid lpc_ich dca acpi_power_meter acpi_pad sch_fq_codel ib_iser rdma_cm iw_cm ib_cm iscsi_tcp libiscsi_tcp libiscsi scsi_transport_iscsi pci_stub ip_tables x_tables autofs4 btrfs blake2b_generic zstd_compress raid10 raid456 async_raid6_recov async_memcpy async_pq async_xor async_tx xor

[  711.779359]  raid6_pq libcrc32c raid1 raid0 multipath linear mlx5_ib ib_uverbs ib_core ast drm_vram_helper i2c_algo_bit drm_ttm_helper ttm drm_kms_helper syscopyarea crct10dif_pclmul crc32_pclmul ghash_clmulni_intel sysfillrect uas hid_generic sysimgblt aesni_intel mlx5_core fb_sys_fops crypto_simd usbhid cryptd drm i40e pci_hyperv_intf usb_storage glue_helper mlxfw hid ahci libahci wmi

[  711.779752] CPU: 23 PID: 344 Comm: kworker/23:1 Tainted: G        W  OE     5.11.0+ #1

[  711.779755] Hardware name: Supermicro SYS-4029GP-TRT2/X11DPG-OT-CPU, BIOS 2.1 08/14/2018

[  711.779756] Workqueue: kfd_process_wq kfd_process_wq_release [amdgpu]

[  711.779955] RIP: 0010:amdgpu_bo_release_notify+0x150/0x160 [amdgpu]

[  711.780141] Code: e8 b5 af 34 f4 e9 1f ff ff ff 48 39 c2 74 07 0f 0b e9 69 ff ff ff 4c 89 e7 e8 3c b4 16 00 e9 5c ff ff ff e8 a2 ce fd f3 eb cf <0f> 0b eb cb e8 d7 02 34 f4 0f 1f 80 00 00 00 00 0f 1f 44 00 00 55

[  711.780143] RSP: 0018:ffffa8100dd67c30 EFLAGS: 00010282

[  711.780145] RAX: 00000000ffffffea RBX: ffff89980e792058 RCX: 0000000000000000

[  711.780147] RDX: 0000000000000000 RSI: ffff89a8f9ad8870 RDI: ffff89a8f9ad8870

[  711.780148] RBP: ffffa8100dd67c50 R08: 0000000000000000 R09: fffffffffff99b18

[  711.780149] R10: ffffa8100dd67bd0 R11: ffffa8100dd67908 R12: ffff89980e792000

[  711.780151] R13: ffff89980e792058 R14: ffff89980e7921bc R15: dead000000000100

[  711.780152] FS:  0000000000000000(0000) GS:ffff89a8f9ac0000(0000) knlGS:0000000000000000

[  711.780154] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033

[  711.780156] CR2: 00007ffddac6f71f CR3: 00000030bb80a003 CR4: 00000000007706e0

[  711.780157] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000

[  711.780159] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400

[  711.780160] PKRU: 55555554

[  711.780161] Call Trace:

[  711.780163]  ttm_bo_release+0x2ae/0x320 [amdttm]

[  711.780169]  amdttm_bo_put+0x30/0x40 [amdttm]

[  711.780357]  amdgpu_bo_unref+0x1e/0x30 [amdgpu]

[  711.780543]  amdgpu_gem_object_free+0x8b/0x160 [amdgpu]

[  711.781119]  drm_gem_object_free+0x1d/0x30 [drm]

[  711.781489]  amdgpu_amdkfd_gpuvm_free_memory_of_gpu+0x34a/0x380 [amdgpu]

[  711.782044]  kfd_process_device_free_bos+0xe0/0x130 [amdgpu]

[  711.782611]  kfd_process_wq_release+0x286/0x380 [amdgpu]

[  711.783172]  process_one_work+0x236/0x420

[  711.783543]  worker_thread+0x34/0x400

[  711.783911]  ? process_one_work+0x420/0x420

[  711.784279]  kthread+0x126/0x140

[  711.784653]  ? kthread_park+0x90/0x90

[  711.785018]  ret_from_fork+0x22/0x30

[  711.785387] ---[ end trace d8f50f6594817c84 ]---

[  711.798716] [drm] amdgpu: ttm finalized

For graphic apps what i usually see is a crash because of sigsev when
the app tries to access
an unmapped MMIO region on the device. I haven't tested for compute
stack and so there might
be something I haven't covered. Hang could mean for example waiting on a
fence which is not being
signaled - please provide full dmesg from this case.

Do you have any good suggestions on how to fix it down the line? (HIP runtime/libhsakmt or driver)

[64036.631333] amdgpu: amdgpu_vm_bo_update failed
[64036.631702] amdgpu: validate_invalid_user_pages: update PTE failed
[64036.640754] amdgpu: amdgpu_vm_bo_update failed
[64036.641120] amdgpu: validate_invalid_user_pages: update PTE failed
[64036.650394] amdgpu: amdgpu_vm_bo_update failed
[64036.650765] amdgpu: validate_invalid_user_pages: update PTE failed

The full dmesg will just the repetition of those two messages,

[186885.764079] amdgpu 0000:43:00.0: amdgpu: amdgpu: finishing device.

[186885.766916] [drm] free PSP TMR buffer

[186893.868173] amdgpu: amdgpu_vm_bo_update failed

[186893.868235] amdgpu: validate_invalid_user_pages: update PTE failed

[186893.876154] amdgpu: amdgpu_vm_bo_update failed

[186893.876190] amdgpu: validate_invalid_user_pages: update PTE failed

[186893.884150] amdgpu: amdgpu_vm_bo_update failed

[186893.884185] amdgpu: validate_invalid_user_pages: update PTE failed

This just probably means trying to update PTEs after the physical device
is gone - we usually avoid this by
first trying to do all HW shutdowns early before PCI remove completion
but when it's really tricky by
protecting HW access sections with drm_dev_enter/exit scope.

For this particular error it would be the best to flush
info->restore_userptr_work before the end of
amdgpu_pci_remove (rejecting new process creation and calling
cancel_delayed_work_sync(&process_info->restore_userptr_work) for all
running processes)
somewhere in amdgpu_pci_remove.

I tried something like *kfd_process_ref_release* which I think did what you described, but it did not work.

Instead I tried to kill the process from the kernel, but the amdgpu could **only** be hot-plugged in back successfully only if there was no rocm kernel running when it was plugged out. If not, amdgpu_probe will just hang later. (Maybe because amdgpu was plugged out while running state, it leaves a bad HW state which causes probe to hang).

I don’t know if this is a viable solution worth pursuing, but I attached the diff anyway.

Another solution could be let compute stack user mode detect a topology change via generation_count change, and abort gracefully there.

diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_device.c b/drivers/gpu/drm/amd/amdkfd/kfd_device.c

index 4e7d9cb09a69..79b4c9b84cd0 100644

--- a/drivers/gpu/drm/amd/amdkfd/kfd_device.c

+++ b/drivers/gpu/drm/amd/amdkfd/kfd_device.c

@@ -697,12 +697,15 @@ void kgd2kfd_suspend(struct kfd_dev *kfd, bool run_pm, bool force)

                return;

        /* for runtime suspend, skip locking kfd */

-       if (!run_pm) {

+       if (!run_pm && !drm_dev_is_unplugged(kfd->ddev)) {

                /* For first KFD device suspend all the KFD processes */

                if (atomic_inc_return(&kfd_locked) == 1)

                        kfd_suspend_all_processes(force);

        }

+       if (drm_dev_is_unplugged(kfd->ddev))

+               kfd_kill_all_user_processes();

+

        kfd->dqm->ops.stop(kfd->dqm);

        kfd_iommu_suspend(kfd);

 }

diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_priv.h b/drivers/gpu/drm/amd/amdkfd/kfd_priv.h

index 55c9e1922714..84cbcd857856 100644

--- a/drivers/gpu/drm/amd/amdkfd/kfd_priv.h

+++ b/drivers/gpu/drm/amd/amdkfd/kfd_priv.h

@@ -1065,6 +1065,7 @@ void kfd_unref_process(struct kfd_process *p);

 int kfd_process_evict_queues(struct kfd_process *p, bool force);

 int kfd_process_restore_queues(struct kfd_process *p);

 void kfd_suspend_all_processes(bool force);

+void kfd_kill_all_user_processes(void);

 /*

  * kfd_resume_all_processes:

  *     bool sync: If kfd_resume_all_processes() should wait for the

diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_process.c b/drivers/gpu/drm/amd/amdkfd/kfd_process.c

index 6cdc855abb6d..fb0c753b682c 100644

--- a/drivers/gpu/drm/amd/amdkfd/kfd_process.c

+++ b/drivers/gpu/drm/amd/amdkfd/kfd_process.c

@@ -2206,6 +2206,24 @@ void kfd_suspend_all_processes(bool force)

        srcu_read_unlock(&kfd_processes_srcu, idx);

 }

+

+void kfd_kill_all_user_processes(void)

+{

+       struct kfd_process *p;

+       struct amdkfd_process_info *p_info;

+       unsigned int temp;

+       int idx = srcu_read_lock(&kfd_processes_srcu);

+

+       pr_info("Killing all processes\n");

+       hash_for_each_rcu(kfd_processes_table, temp, p, kfd_processes) {

+               p_info = p->kgd_process_info;

+               pr_info("Killing  processes, pid = %d", pid_nr(p_info->pid));

+               kill_pid(p_info->pid, SIGBUS, 1);

+       }

+       srcu_read_unlock(&kfd_processes_srcu, idx);

+}

+

+

 int kfd_resume_all_processes(bool sync)

 {

        struct kfd_process *p;

Andrey

Really appreciate your help!

Best,
Shuotao

2. Remove redudant p2p/io links in sysfs when device is hotplugged
out.

3. New kfd node_id is not properly assigned after a new device is
added after a gpu is hotplugged out in a system. libhsakmt will
find this anomaly, (i.e. node_from != <dev node id> in iolinks),
when taking a topology_snapshot, thus returns fault to the rocm
stack.

-- This patch fixes issue 1; another patch by Mukul fixes issues 2&3.
-- Tested on a 4-GPU MI100 gpu nodes with kernel 5.13.0-kfd; kernel
5.16.0-kfd is unstable out of box for MI100.
---
drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.c | 5 +++++
drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.h | 7 +++++++
drivers/gpu/drm/amd/amdgpu/amdgpu_device.c | 1 +
drivers/gpu/drm/amd/amdkfd/kfd_device.c | 13 +++++++++++++
4 files changed, 26 insertions(+)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.c
index c18c4be1e4ac..d50011bdb5c4 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.c
@@ -213,6 +213,11 @@ int amdgpu_amdkfd_resume(struct amdgpu_device *adev, bool run_pm)
return r;
}

+int amdgpu_amdkfd_resume_processes(void)
+{
+ return kgd2kfd_resume_processes();
+}
+
int amdgpu_amdkfd_pre_reset(struct amdgpu_device *adev)
{
int r = 0;
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.h b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.h
index f8b9f27adcf5..803306e011c3 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.h
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.h
@@ -140,6 +140,7 @@ void amdgpu_amdkfd_fini(void);
void amdgpu_amdkfd_suspend(struct amdgpu_device *adev, bool run_pm);
int amdgpu_amdkfd_resume_iommu(struct amdgpu_device *adev);
int amdgpu_amdkfd_resume(struct amdgpu_device *adev, bool run_pm);
+int amdgpu_amdkfd_resume_processes(void);
void amdgpu_amdkfd_interrupt(struct amdgpu_device *adev,
const void *ih_ring_entry);
void amdgpu_amdkfd_device_probe(struct amdgpu_device *adev);
@@ -347,6 +348,7 @@ void kgd2kfd_device_exit(struct kfd_dev *kfd);
void kgd2kfd_suspend(struct kfd_dev *kfd, bool run_pm);
int kgd2kfd_resume_iommu(struct kfd_dev *kfd);
int kgd2kfd_resume(struct kfd_dev *kfd, bool run_pm);
+int kgd2kfd_resume_processes(void);
int kgd2kfd_pre_reset(struct kfd_dev *kfd);
int kgd2kfd_post_reset(struct kfd_dev *kfd);
void kgd2kfd_interrupt(struct kfd_dev *kfd, const void *ih_ring_entry);
@@ -393,6 +395,11 @@ static inline int kgd2kfd_resume(struct kfd_dev *kfd, bool run_pm)
return 0;
}

+static inline int kgd2kfd_resume_processes(void)
+{
+ return 0;
+}
+
static inline int kgd2kfd_pre_reset(struct kfd_dev *kfd)
{
return 0;
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
index fa4a9f13c922..5827b65b7489 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
@@ -4004,6 +4004,7 @@ void amdgpu_device_fini_hw(struct amdgpu_device *adev)
if (drm_dev_is_unplugged(adev_to_drm(adev)))
amdgpu_device_unmap_mmio(adev);

+ amdgpu_amdkfd_resume_processes();
}

void amdgpu_device_fini_sw(struct amdgpu_device *adev)
diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_device.c b/drivers/gpu/drm/amd/amdkfd/kfd_device.c
index 62aa6c9d5123..ef05aae9255e 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_device.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_device.c
@@ -714,6 +714,19 @@ int kgd2kfd_resume(struct kfd_dev *kfd, bool run_pm)
return ret;
}

+/* for non-runtime resume only */
+int kgd2kfd_resume_processes(void)
+{
+ int count;
+
+ count = atomic_dec_return(&kfd_locked);
+ WARN_ONCE(count < 0, "KFD suspend / resume ref. error");
+ if (count == 0)
+ return kfd_resume_all_processes();
+
+ return 0;
+}

It doesn't make sense to me to just increment kfd_locked in
kgd2kfd_suspend to only decrement it again a few functions down the
road.

I suggest this instead - you only incrmemnt if not during PCI remove

diff --git a/drivers/gpu/drm/amd/amdkfd/kfd_device.c
b/drivers/gpu/drm/amd/amdkfd/kfd_device.c
index 1c2cf3a33c1f..7754f77248a4 100644
--- a/drivers/gpu/drm/amd/amdkfd/kfd_device.c
+++ b/drivers/gpu/drm/amd/amdkfd/kfd_device.c
@@ -952,11 +952,12 @@ bool kfd_is_locked(void)

void kgd2kfd_suspend(struct kfd_dev *kfd, bool run_pm)
{
+
if (!kfd->init_complete)
return;

/* for runtime suspend, skip locking kfd */
- if (!run_pm) {
+ if (!run_pm && !drm_dev_is_unplugged(kfd->ddev)) {
/* For first KFD device suspend all the KFD processes */
if (atomic_inc_return(&kfd_locked) == 1)
kfd_suspend_all_processes();


Andrey

+
int kgd2kfd_resume_iommu(struct kfd_dev *kfd)
{
int err = 0;