Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932814AbdDFGXU (ORCPT ); Thu, 6 Apr 2017 02:23:20 -0400 Received: from mx2.suse.de ([195.135.220.15]:48963 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754270AbdDFGXN (ORCPT ); Thu, 6 Apr 2017 02:23:13 -0400 Subject: Re: [PATCH] arm64: xen: Implement EFI reset_system callback To: Boris Ostrovsky , Julien Grall , xen-devel@lists.xen.org References: <20170405181417.15985-1-julien.grall@arm.com> Cc: sstabellini@kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Daniel Kiper From: Juergen Gross Message-ID: Date: Thu, 6 Apr 2017 08:23:10 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:45.0) Gecko/20100101 Thunderbird/45.8.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 8098 Lines: 152 On 05/04/17 21:49, Boris Ostrovsky wrote: > On 04/05/2017 02:14 PM, Julien Grall wrote: >> When rebooting DOM0 with ACPI, the kernel is crashing with the stack trace [1]. >> >> This is happening because when EFI runtimes are enabled, the reset code >> (see machin_restart) will first try to use EFI restart method. >> >> However, the EFI restart code is expecting the reset_system callback to >> be always set. This is not the case for Xen and will lead to crash. >> >> Looking at the reboot path, it is expected to fallback on an alternative >> reboot method if one does not work. So implement reset_system callback >> as a NOP for Xen. >> >> [ 36.999270] reboot: Restarting system >> [ 37.002921] Internal error: Attempting to execute userspace memory: 86000004 [#1] PREEMPT SMP >> [ 37.011460] Modules linked in: >> [ 37.014598] CPU: 0 PID: 1 Comm: systemd-shutdow Not tainted 4.11.0-rc1-00003-g1e248b60a39b-dirty #506 >> [ 37.023903] Hardware name: (null) (DT) >> [ 37.027734] task: ffff800902068000 task.stack: ffff800902064000 >> [ 37.033739] PC is at 0x0 >> [ 37.036359] LR is at efi_reboot+0x94/0xd0 >> [ 37.040438] pc : [<0000000000000000>] lr : [] pstate: 404001c5 >> [ 37.047920] sp : ffff800902067cf0 >> [ 37.051314] x29: ffff800902067cf0 x28: ffff800902068000 >> [ 37.056709] x27: ffff000008992000 x26: 000000000000008e >> [ 37.062104] x25: 0000000000000123 x24: 0000000000000015 >> [ 37.067499] x23: 0000000000000000 x22: ffff000008e6e250 >> [ 37.072894] x21: ffff000008e6e000 x20: 0000000000000000 >> [ 37.078289] x19: ffff000008e5d4c8 x18: 0000000000000010 >> [ 37.083684] x17: 0000ffffa7c27470 x16: 00000000deadbeef >> [ 37.089079] x15: 0000000000000006 x14: ffff000088f42bef >> [ 37.094474] x13: ffff000008f42bfd x12: ffff000008e706c0 >> [ 37.099870] x11: ffff000008e70000 x10: 0000000005f5e0ff >> [ 37.105265] x9 : ffff800902067a50 x8 : 6974726174736552 >> [ 37.110660] x7 : ffff000008cc6fb8 x6 : ffff000008cc6fb0 >> [ 37.116055] x5 : ffff000008c97dd8 x4 : 0000000000000000 >> [ 37.121453] x3 : 0000000000000000 x2 : 0000000000000000 >> [ 37.126845] x1 : 0000000000000000 x0 : 0000000000000000 >> [ 37.132239] >> [ 37.133808] Process systemd-shutdow (pid: 1, stack limit = 0xffff800902064000) >> [ 37.141118] Stack: (0xffff800902067cf0 to 0xffff800902068000) >> [ 37.146949] 7ce0: ffff800902067d40 ffff000008085334 >> [ 37.154869] 7d00: 0000000000000000 ffff000008f3b000 ffff800902067d40 ffff0000080852e0 >> [ 37.162787] 7d20: ffff000008cc6fb0 ffff000008cc6fb8 ffff000008c7f580 ffff000008c97dd8 >> [ 37.170706] 7d40: ffff800902067d60 ffff0000080e2c2c 0000000000000000 0000000001234567 >> [ 37.178624] 7d60: ffff800902067d80 ffff0000080e2ee8 0000000000000000 ffff0000080e2df4 >> [ 37.186544] 7d80: 0000000000000000 ffff0000080830f0 0000000000000000 00008008ff1c1000 >> [ 37.194462] 7da0: ffffffffffffffff 0000ffffa7c4b1cc 0000000000000000 0000000000000024 >> [ 37.202380] 7dc0: ffff800902067dd0 0000000000000005 0000fffff24743c8 0000000000000004 >> [ 37.210299] 7de0: 0000fffff2475f03 0000000000000010 0000fffff2474418 0000000000000005 >> [ 37.218218] 7e00: 0000fffff2474578 000000000000000a 0000aaaad6b722c0 0000000000000001 >> [ 37.226136] 7e20: 0000000000000123 0000000000000038 ffff800902067e50 ffff0000081e7294 >> [ 37.234055] 7e40: ffff800902067e60 ffff0000081e935c ffff800902067e60 ffff0000081e9388 >> [ 37.241973] 7e60: ffff800902067eb0 ffff0000081ea388 0000000000000000 00008008ff1c1000 >> [ 37.249892] 7e80: ffffffffffffffff 0000ffffa7c4a79c 0000000000000000 ffff000000020000 >> [ 37.257810] 7ea0: 0000010000000004 0000000000000000 0000000000000000 ffff0000080830f0 >> [ 37.265729] 7ec0: fffffffffee1dead 0000000028121969 0000000001234567 0000000000000000 >> [ 37.273651] 7ee0: ffffffffffffffff 8080000000800000 0000800000008080 feffa9a9d4ff2d66 >> [ 37.281567] 7f00: 000000000000008e feffa9a9d5b60e0f 7f7fffffffff7f7f 0101010101010101 >> [ 37.289485] 7f20: 0000000000000010 0000000000000008 000000000000003a 0000ffffa7ccf588 >> [ 37.297404] 7f40: 0000aaaad6b87d00 0000ffffa7c4b1b0 0000fffff2474be0 0000aaaad6b88000 >> [ 37.305326] 7f60: 0000fffff2474fb0 0000000001234567 0000000000000000 0000000000000000 >> [ 37.313240] 7f80: 0000000000000000 0000000000000001 0000aaaad6b70d4d 0000000000000000 >> [ 37.321159] 7fa0: 0000000000000001 0000fffff2474ea0 0000aaaad6b5e2e0 0000fffff2474e80 >> [ 37.329078] 7fc0: 0000ffffa7c4b1cc 0000000000000000 fffffffffee1dead 000000000000008e >> [ 37.336997] 7fe0: 0000000000000000 0000000000000000 9ce839cffee77eab fafdbf9f7ed57f2f >> [ 37.344911] Call trace: >> [ 37.347437] Exception stack(0xffff800902067b20 to 0xffff800902067c50) >> [ 37.353970] 7b20: ffff000008e5d4c8 0001000000000000 0000000080f82000 0000000000000000 >> [ 37.361883] 7b40: ffff800902067b60 ffff000008e17000 ffff000008f44c68 00000001081081b4 >> [ 37.369802] 7b60: ffff800902067bf0 ffff000008108478 0000000000000000 ffff000008c235b0 >> [ 37.377721] 7b80: ffff800902067ce0 0000000000000000 0000000000000000 0000000000000015 >> [ 37.385643] 7ba0: 0000000000000123 000000000000008e ffff000008992000 ffff800902068000 >> [ 37.393557] 7bc0: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 >> [ 37.401477] 7be0: 0000000000000000 ffff000008c97dd8 ffff000008cc6fb0 ffff000008cc6fb8 >> [ 37.409396] 7c00: 6974726174736552 ffff800902067a50 0000000005f5e0ff ffff000008e70000 >> [ 37.417318] 7c20: ffff000008e706c0 ffff000008f42bfd ffff000088f42bef 0000000000000006 >> [ 37.425234] 7c40: 00000000deadbeef 0000ffffa7c27470 >> [ 37.430190] [< (null)>] (null) >> [ 37.434982] [] machine_restart+0x6c/0x70 >> [ 37.440550] [] kernel_restart+0x6c/0x78 >> [ 37.446030] [] SyS_reboot+0x130/0x228 >> [ 37.451337] [] el0_svc_naked+0x24/0x28 >> [ 37.456737] Code: bad PC value >> [ 37.459891] ---[ end trace 76e2fc17e050aecd ]--- >> >> Signed-off-by: Julien Grall >> Cc: Boris Ostrovsky >> Cc: Juergen Gross >> >> -- >> >> The x86 code has theoritically a similar issue, altought EFI does not >> seem to be the preferred method. I have left it unimplemented on x86 and >> CCed Linux Xen x86 maintainers to know their view here. > > (+Daniel) > > This could be a problem for x86 as well, at least theoretically. > xen_machine_power_off() may call pm_power_off(), which is efi.reset_system. > > So I think we should have a similar routine there. +1 I don't see any problem with such a routine added, in contrast to potential "reboots" instead of power off without it. So I think this dummy xen_efi_reset_system() should be added to drivers/xen/efi.c instead. >> This should also probably be fixed in stable tree. Yes. Juergen >> --- >> arch/arm/xen/efi.c | 10 +++++++++- >> 1 file changed, 9 insertions(+), 1 deletion(-) >> >> diff --git a/arch/arm/xen/efi.c b/arch/arm/xen/efi.c >> index 16db419f9e90..3b29788c29e9 100644 >> --- a/arch/arm/xen/efi.c >> +++ b/arch/arm/xen/efi.c >> @@ -19,6 +19,14 @@ >> #include >> #include >> >> +static void xen_efi_reset_system(int reset_type, >> + efi_status_t status, >> + unsigned long data_size, >> + efi_char16_t *data) >> +{ >> + /* NOP implementation, reset will fallback on an alternative method */ >> +} >> + >> /* Set XEN EFI runtime services function pointers. Other fields of struct efi, >> * e.g. efi.systab, will be set like normal EFI. >> */ >> @@ -35,6 +43,6 @@ void __init xen_efi_runtime_setup(void) >> efi.update_capsule = xen_efi_update_capsule; >> efi.query_capsule_caps = xen_efi_query_capsule_caps; >> efi.get_next_high_mono_count = xen_efi_get_next_high_mono_count; >> - efi.reset_system = NULL; /* Functionality provided by Xen. */ >> + efi.reset_system = xen_efi_reset_system; >> } >> EXPORT_SYMBOL_GPL(xen_efi_runtime_setup); > >