linux-kernel - Re: [Qemu-devel] [PATCH 0/2 v3] kvm: notify host when guest panicked

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:	Wed, 21 Mar 2012 14:12:50 -0500
From:	Anthony Liguori <anthony@...emonkey.ws>
To:	Avi Kivity <avi@...hat.com>
CC:	Jan Kiszka <jan.kiszka@...mens.com>,
	Gleb Natapov <gleb@...hat.com>,
	qemu-devel <qemu-devel@...gnu.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Eric Northup <digitaleric@...gle.com>,
	kvm list <kvm@...r.kernel.org>,
	Amit Shah <amit.shah@...hat.com>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
Subject: Re: [Qemu-devel] [PATCH 0/2 v3] kvm: notify host when guest panicked

On 03/15/2012 06:46 AM, Avi Kivity wrote:
> On 03/15/2012 01:25 PM, Jan Kiszka wrote:
>>>>
>>> There was such vm exit (KVM_EXIT_HYPERCALL), but it was deemed to be a
>>> bad idea.
>>
>> BTW, this would help a lot in emulating hypercalls of other hypervisors
>> (or of KVM's VAPIC in the absence of in-kernel irqchip - I had to jump
>> through hoops therefore) in user space. Not all those hypercall handlers
>> actually have to reside in the KVM module.
>>
>
> That is true.  On the other hand the hypercall ABI might go to pieces if
> there was no central implementation.

Just declare that outl 0x505 is a megaultracall and s/vmcall/outb/g and call it 
a day.

The performance difference between vmcall and outl is so tiny compared to the 
cost of dropping to userspace that it really doesn't matter which instruction is 
used.

Regards,

Anthony Liguori

>

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/