linux-kernel - Re: [PATCH v4] x86/sgx: Do not consider unsanitized pages an error

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Message-ID: <Ywkh+ChYvUW3zwfD@kernel.org>
Date:   Fri, 26 Aug 2022 22:41:44 +0300
From:   Jarkko Sakkinen <jarkko@...nel.org>
To:     Paul Menzel <pmenzel@...gen.mpg.de>
Cc:     Dave Hansen <dave.hansen@...ux.intel.com>,
        linux-sgx@...r.kernel.org,
        Haitao Huang <haitao.huang@...ux.intel.com>,
        Reinette Chatre <reinette.chatre@...el.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Ingo Molnar <mingo@...hat.com>, Borislav Petkov <bp@...en8.de>,
        x86@...nel.org, "H. Peter Anvin" <hpa@...or.com>,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4] x86/sgx: Do not consider unsanitized pages an error

On Fri, Aug 26, 2022 at 07:21:44PM +0200, Paul Menzel wrote:
> Dear Jarkko,
> 
> 
> Am 26.08.22 um 14:51 schrieb Paul Menzel:
> 
> […]
> 
> > Am 26.08.22 um 03:41 schrieb Jarkko Sakkinen:
> > > In sgx_init(), if misc_register() for the provision device fails, and
> > > neither sgx_drv_init() nor sgx_vepc_init() succeeds, then ksgxd will be
> > > prematurely stopped.
> > > 
> > > This triggers WARN_ON() because sgx_dirty_page_list ends up being
> > > non-empty. Ultimately this can crash the kernel, depending on the kernel
> > > command line, which is not correct behavior because SGX driver is not
> > > working incorrectly.
> > 
> > Maybe paste the WARN_ON trace, so `git log` can be searched for the
> > trace too.
> > 
> > > Print simple warning instead, and improve the output by printing the
> > > number of unsanitized pages.
> > 
> > See below, but no warning seems to be logged in my case now. (I should
> > test Linus’ current master too.)
> 
> Just for the record, the problem still exists in Linus’ master branch:
> 
> ```
> [    0.000000] Linux version 6.0.0-rc2 (root@...b429beb4a) (gcc (Debian
> 11.3.0-3) 11.3.0, GNU ld (GNU Binutils for Debian) 2.38) #382 SMP
> PREEMPT_DYNAMIC Fri Aug 26 12:52:15 UTC 2022
> [    0.000000] Command line: BOOT_IMAGE=/vmlinuz-6.0.0-rc2
> root=UUID=56f398e0-1e25-4fda-aa9f-611dece4b333 ro quiet
> module_blacklist=psmouse initcall_debug log_buf_len=4M cryptomgr.notests
> […]
> [    0.268089] calling  sgx_init+0x0/0x409 @ 1
> [    0.268103] sgx: EPC section 0x40200000-0x45f7ffff
> [    0.268591] ------------[ cut here ]------------
> [    0.268592] WARNING: CPU: 6 PID: 83 at arch/x86/kernel/cpu/sgx/main.c:401
> ksgxd+0x1b7/0x1d0
> [    0.268598] Modules linked in:
> [    0.268600] CPU: 6 PID: 83 Comm: ksgxd Not tainted 6.0.0-rc2 #382
> [    0.268603] Hardware name: Dell Inc. XPS 13 9370/0RMYH9, BIOS 1.21.0
> 07/06/2022
> [    0.268604] RIP: 0010:ksgxd+0x1b7/0x1d0
> [    0.268607] Code: ff e9 f2 fe ff ff 48 89 df e8 75 07 0e 00 84 c0 0f 84
> c3 fe ff ff 31 ff e8 e6 07 0e 00 84 c0 0f 85 94 fe ff ff e9 af fe ff ff <0f>
> 0b e9 7f fe ff ff e8 dd 9c 95 00 66 66 2e 0f 1f 84 00 00 00 00
> [    0.268608] RSP: 0000:ffffb6c7404f3ed8 EFLAGS: 00010287
> [    0.268610] RAX: ffffb6c740431a10 RBX: ffff8dcd8117b400 RCX:
> 0000000000000000
> [    0.268612] RDX: 0000000080000000 RSI: ffffb6c7404319d0 RDI:
> 00000000ffffffff
> [    0.268613] RBP: ffff8dcd820a4d80 R08: ffff8dcd820a4180 R09:
> ffff8dcd820a4180
> [    0.268614] R10: 0000000000000000 R11: 0000000000000006 R12:
> ffffb6c74006bce0
> [    0.268615] R13: ffff8dcd80e63880 R14: ffffffffa8a60f10 R15:
> 0000000000000000
> [    0.268616] FS:  0000000000000000(0000) GS:ffff8dcf25580000(0000)
> knlGS:0000000000000000
> [    0.268617] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> [    0.268619] CR2: 0000000000000000 CR3: 0000000213410001 CR4:
> 00000000003706e0
> [    0.268620] DR0: 0000000000000000 DR1: 0000000000000000 DR2:
> 0000000000000000
> [    0.268621] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7:
> 0000000000000400
> [    0.268622] Call Trace:
> [    0.268624]  <TASK>
> [    0.268627]  ? _raw_spin_lock_irqsave+0x24/0x60
> [    0.268632]  ? _raw_spin_unlock_irqrestore+0x23/0x40
> [    0.268634]  ? __kthread_parkme+0x36/0x90
> [    0.268637]  kthread+0xe5/0x110
> [    0.268639]  ? kthread_complete_and_exit+0x20/0x20
> [    0.268642]  ret_from_fork+0x1f/0x30
> [    0.268647]  </TASK>
> [    0.268648] ---[ end trace 0000000000000000 ]---
> [    0.268694] initcall sgx_init+0x0/0x409 returned -19 after 603 usecs
> ```
> 
> Tested-by: Paul Menzel <pmenzel@...gen.mpg.de>

Thank you.

BR, Jarkko