[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-ID: <op.2pkbj8lbwjvjmi@hhuan26-mobl.amr.corp.intel.com>
Date: Tue, 18 Jun 2024 07:56:22 -0500
From: "Haitao Huang" <haitao.huang@...ux.intel.com>
To: "chenridong@...wei.com" <chenridong@...wei.com>,
"linux-sgx@...r.kernel.org" <linux-sgx@...r.kernel.org>,
"cgroups@...r.kernel.org" <cgroups@...r.kernel.org>, "mkoutny@...e.com"
<mkoutny@...e.com>, "dave.hansen@...ux.intel.com"
<dave.hansen@...ux.intel.com>, "tim.c.chen@...ux.intel.com"
<tim.c.chen@...ux.intel.com>, "linux-kernel@...r.kernel.org"
<linux-kernel@...r.kernel.org>, "mingo@...hat.com" <mingo@...hat.com>,
"tglx@...utronix.de" <tglx@...utronix.de>, "tj@...nel.org" <tj@...nel.org>,
"jarkko@...nel.org" <jarkko@...nel.org>, "Mehta, Sohil"
<sohil.mehta@...el.com>, "hpa@...or.com" <hpa@...or.com>, "bp@...en8.de"
<bp@...en8.de>, "x86@...nel.org" <x86@...nel.org>, "Huang, Kai"
<kai.huang@...el.com>
Cc: "mikko.ylinen@...ux.intel.com" <mikko.ylinen@...ux.intel.com>,
"seanjc@...gle.com" <seanjc@...gle.com>, "anakrish@...rosoft.com"
<anakrish@...rosoft.com>, "Zhang, Bo" <zhanb@...rosoft.com>,
"kristen@...ux.intel.com" <kristen@...ux.intel.com>, "yangjie@...rosoft.com"
<yangjie@...rosoft.com>, "Li, Zhiquan1" <zhiquan1.li@...el.com>,
"chrisyan@...rosoft.com" <chrisyan@...rosoft.com>
Subject: Re: [PATCH v15 05/14] x86/sgx: Implement basic EPC misc cgroup
functionality
On Tue, 18 Jun 2024 06:31:09 -0500, Huang, Kai <kai.huang@...el.com> wrote:
>
>> @@ -921,7 +956,8 @@ static int __init sgx_init(void)
>> if (!sgx_page_cache_init())
>> return -ENOMEM;
>>
>> - if (!sgx_page_reclaimer_init()) {
>> + if (!sgx_page_reclaimer_init() || !sgx_cgroup_init()) {
>> + misc_cg_set_capacity(MISC_CG_RES_SGX_EPC, 0);
>> ret = -ENOMEM;
>> goto err_page_cache;
>> }
>
> This code change is wrong due to two reasons:
>
> 1) If sgx_page_reclaimer_init() was successful, but sgx_cgroup_init()
> failed, you actually need to 'goto err_kthread' because the ksgxd()
> kernel
> thread is already created and is running.
>
> 2) There are other cases after here that can also result in sgx_init() to
> fail completely, e.g., registering sgx_dev_provision mics device. We
> need
> to reset the capacity to 0 for those cases as well.
>
> AFAICT, you need something like:
>
> diff --git a/arch/x86/kernel/cpu/sgx/main.c
> b/arch/x86/kernel/cpu/sgx/main.c
> index 27892e57c4ef..46f9c26992a7 100644
> --- a/arch/x86/kernel/cpu/sgx/main.c
> +++ b/arch/x86/kernel/cpu/sgx/main.c
> @@ -930,6 +930,10 @@ static int __init sgx_init(void)
> if (ret)
> goto err_kthread;
> + ret = sgx_cgroup_init();
> + if (ret)
> + goto err_provision;
> +
> /*
> * Always try to initialize the native *and* KVM drivers.
> * The KVM driver is less picky than the native one and
> @@ -941,10 +945,12 @@ static int __init sgx_init(void)
> ret = sgx_drv_init();
> if (sgx_vepc_init() && ret)
> - goto err_provision;
> + goto err_cgroup;
> return 0;
> +err_cgroup:
> + /* SGX EPC cgroup cleanup */
> err_provision:
> misc_deregister(&sgx_dev_provision);
> @@ -952,6 +958,8 @@ static int __init sgx_init(void)
> kthread_stop(ksgxd_tsk);
> err_page_cache:
> + misc_misc_cg_set_capacity(MISC_CG_RES_SGX_EPC, 0);
> +
> for (i = 0; i < sgx_nr_epc_sections; i++) {
> vfree(sgx_epc_sections[i].pages);
> memunmap(sgx_epc_sections[i].virt_addr);
>
>
> I put the sgx_cgroup_init() before sgx_drv_init() and sgx_vepc_init(),
> otherwise you will need sgx_drv_cleanup() and sgx_vepc_cleanup()
> respectively when sgx_cgroup_init() fails.
>
Yes, good catch.
> This looks a little bit weird too, though:
>
> Calling misc_misc_cg_set_capacity() to reset capacity to 0 is done at end
> of sgx_init() error path, because the "set capacity" part is done in
> sgx_epc_cache_init().
> But logically, both "set capacity" and "reset capacity to 0" should be
> SGX
> EPC cgroup operation, so it's more reasonable to do "set capacity" in
> sgx_cgroup_init() and do "reset to 0" in the
>
> /* SGX EPC cgroup cleanup */
>
> as shown above.
>
> Eventually, you will need to do EPC cgroup cleanup anyway, e.g., to free
> the workqueue, so it's odd to have two places to handle EPC cgroup
> cleanup.
>
> I understand the reason "set capacity" part is done in
> sgx_page_cache_init() now is because in that function you can easily get
> the capacity. But the fact is @sgx_numa_nodes also tracks EPC size for
> each node, so you can also get the total EPC size from @sgx_numa_node in
> sgx_cgroup_init() and set capacity there.
>
> In this case, you can put "reset capacity to 0" and "free workqueue"
> together as the "SGX EPC cgroup cleanup", which is way more clear IMHO.
>
Okay, will expose @sgx_numa_nodes to epc_cgroup.c and do the calculations
in sgx_cgroup_init().
Thanks
Haitao
Powered by blists - more mailing lists