Messages in this thread Patch in this message | | | Date | Fri, 26 Aug 2022 19:21:44 +0200 | Subject | Re: [PATCH v4] x86/sgx: Do not consider unsanitized pages an error | From | Paul Menzel <> |
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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@4beb429beb4a) (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@molgen.mpg.de>
>> Link: https://lore.kernel.org/linux-sgx/20220825051827.246698-1-jarkko@kernel.org/T/#u >> Reported-by: Paul Menzel <pmenzel@molgen.mpg.de> >> Fixes: 51ab30eb2ad4 ("x86/sgx: Replace section->init_laundry_list with sgx_dirty_page_list") >> Signed-off-by: Jarkko Sakkinen <jarkko@kernel.org> >> --- >> Cc: Haitao Huang <haitao.huang@linux.intel.com> >> Cc: Dave Hansen <dave.hansen@linux.intel.com> >> Cc: Reinette Chatre <reinette.chatre@intel.com> >> >> v4: >> - Explain expectations for dirty_page_list in the function header, >> instead >> of an inline comment. >> - Improve commit message to explain the conditions better. >> - Return the number of pages left dirty to ksgxd() and print warning >> after >> the 2nd call, if there are any. >> >> v3: >> - Remove WARN_ON(). >> - Tuned comments and the commit message a bit. >> >> v2: >> - Replaced WARN_ON() with optional pr_info() inside >> __sgx_sanitize_pages(). >> - Rewrote the commit message. >> - Added the fixes tag. >> --- >> arch/x86/kernel/cpu/sgx/main.c | 19 +++++++++++++------ >> 1 file changed, 13 insertions(+), 6 deletions(-) >> >> diff --git a/arch/x86/kernel/cpu/sgx/main.c >> b/arch/x86/kernel/cpu/sgx/main.c >> index 515e2a5f25bb..903100fcfce3 100644 >> --- a/arch/x86/kernel/cpu/sgx/main.c >> +++ b/arch/x86/kernel/cpu/sgx/main.c >> @@ -49,17 +49,20 @@ static LIST_HEAD(sgx_dirty_page_list); >> * Reset post-kexec EPC pages to the uninitialized state. The pages are removed >> * from the input list, and made available for the page allocator. SECS pages >> * prepending their children in the input list are left intact. >> + * >> + * Contents of the @dirty_page_list must be thread-local, i.e. >> + * not shared by multiple threads. >> */ >> -static void __sgx_sanitize_pages(struct list_head *dirty_page_list) >> +static int __sgx_sanitize_pages(struct list_head *dirty_page_list) >> { >> struct sgx_epc_page *page; >> + int left_dirty = 0; >> LIST_HEAD(dirty); >> int ret; >> - /* dirty_page_list is thread-local, no need for a lock: */ >> while (!list_empty(dirty_page_list)) { >> if (kthread_should_stop()) >> - return; >> + break; >> page = list_first_entry(dirty_page_list, struct >> sgx_epc_page, list); >> @@ -92,12 +95,14 @@ static void __sgx_sanitize_pages(struct list_head >> *dirty_page_list) >> } else { >> /* The page is not yet clean - move to the dirty list. */ >> list_move_tail(&page->list, &dirty); >> + left_dirty++; >> } >> cond_resched(); >> } >> list_splice(&dirty, dirty_page_list); >> + return left_dirty; >> } >> static bool sgx_reclaimer_age(struct sgx_epc_page *epc_page) >> @@ -388,6 +393,8 @@ void sgx_reclaim_direct(void) >> static int ksgxd(void *p) >> { >> + int left_dirty; >> + >> set_freezable(); >> /* >> @@ -395,10 +402,10 @@ static int ksgxd(void *p) >> * required for SECS pages, whose child pages blocked EREMOVE. >> */ >> __sgx_sanitize_pages(&sgx_dirty_page_list); >> - __sgx_sanitize_pages(&sgx_dirty_page_list); >> - /* sanity check: */ >> - WARN_ON(!list_empty(&sgx_dirty_page_list)); >> + left_dirty = __sgx_sanitize_pages(&sgx_dirty_page_list); >> + if (left_dirty) >> + pr_warn("%d unsanitized pages\n", left_dirty); >> while (!kthread_should_stop()) { >> if (try_to_freeze()) > > I tested this on top of commit 4c612826bec1 (Merge tag 'net-6.0-rc3' of > git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net) and the > warning trace is gone. > > [ 0.255192] calling sgx_init+0x0/0x409 @ 1 > [ 0.255207] sgx: EPC section 0x40200000-0x45f7ffff > [ 0.255747] initcall sgx_init+0x0/0x409 returned -19 after 552 usecs > > (OT: If -19 suggests something failed, a message, why sgx_init() failed > would be nice.) > > Please find the whole output of `dmesg` attached. > > > Kind regards, > > Paul
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