From: "M. Vefa Bicakci" <m.v.b@runbox.com>
To: Boris Ostrovsky <boris.ostrovsky@oracle.com>,
linux-kernel@vger.kernel.org
Cc: Dominik Brodowski <linux@dominikbrodowski.net>,
Andy Lutomirski <luto@kernel.org>, Ingo Molnar <mingo@redhat.com>,
"H. Peter Anvin" <hpa@zytor.com>,
Thomas Gleixner <tglx@linutronix.de>,
Juergen Gross <jgross@suse.com>,
xen-devel@lists.xenproject.org, x86@kernel.org,
stable@vger.kernel.org
Subject: Re: [PATCH 1/2] x86/entry/64: Do not clear %rbx under Xen
Date: Sat, 21 Jul 2018 19:18:42 -0400 [thread overview]
Message-ID: <6426e7a4-2da0-9a36-298a-89e956e98812@runbox.com> (raw)
In-Reply-To: <5a21b844-36a9-8fe4-c6cd-6fade3dfa941@oracle.com>
On 07/21/2018 05:19 PM, Boris Ostrovsky wrote:
> On 07/21/2018 03:49 PM, M. Vefa Bicakci wrote:
>> diff --git a/arch/x86/entry/entry_64.S b/arch/x86/entry/entry_64.S
>> index c7449f377a77..96e8ff34129e 100644
>> --- a/arch/x86/entry/entry_64.S
>> +++ b/arch/x86/entry/entry_64.S
>> @@ -1129,7 +1129,7 @@ ENTRY(xen_failsafe_callback)
>> addq $0x30, %rsp
>> UNWIND_HINT_IRET_REGS
>> pushq $-1 /* orig_ax = -1 => not a system call */
>> - PUSH_AND_CLEAR_REGS
>> + PUSH_AND_CLEAR_REGS clear_rbx=0
>
>
> Do we need this at all? We are returning from the hypervisor here.
>
> -boris
>
>> ENCODE_FRAME_POINTER
>> jmp error_exit
>> END(xen_failsafe_callback)
Hello Boris,
If you are referring to the PUSH_AND_CLEAR_REGS macro itself, I am not sure;
however, not clearing the RBX register seemed to resolve the issues mentioned
in the commit message for me. Given Andy's comment though, I believe that the
approach in this patch may not be correct.
Thank you,
Vefa
next prev parent reply other threads:[~2018-07-21 23:19 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-07-21 19:49 M. Vefa Bicakci
2018-07-21 19:49 ` [PATCH 2/2] xen/pv: Call get_cpu_address_sizes to set x86_virt/phys_bits M. Vefa Bicakci
2018-07-21 21:25 ` Boris Ostrovsky
2018-07-21 23:17 ` M. Vefa Bicakci
2018-07-22 15:57 ` M. Vefa Bicakci
2018-07-23 15:04 ` Boris Ostrovsky
2018-07-24 12:42 ` M. Vefa Bicakci
2018-07-24 12:45 ` [PATCH v2] " M. Vefa Bicakci
2018-07-24 14:08 ` Boris Ostrovsky
2018-07-26 3:56 ` [PATCH v3] " M. Vefa Bicakci
2018-08-06 20:15 ` [PATCH v2] " Boris Ostrovsky
2018-08-06 20:16 ` Thomas Gleixner
2018-08-06 21:27 ` Boris Ostrovsky
2018-08-07 9:50 ` Ingo Molnar
2018-07-21 21:19 ` [PATCH 1/2] x86/entry/64: Do not clear %rbx under Xen Boris Ostrovsky
2018-07-21 23:18 ` M. Vefa Bicakci [this message]
2018-07-23 14:56 ` Boris Ostrovsky
2018-07-21 21:45 ` Andy Lutomirski
2018-07-21 23:19 ` M. Vefa Bicakci
2018-07-21 23:30 ` Andy Lutomirski
2018-07-21 23:37 ` M. Vefa Bicakci
2018-07-22 1:20 ` M. Vefa Bicakci
2018-07-22 17:56 ` Andy Lutomirski
2018-07-22 18:32 ` [Xen-devel] " Andrew Cooper
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