linux-kernel - Re: [PATCH 2/2] KVM: MMU: Use base

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, 15 Sep 2010 11:48:01 -0300
From:	Marcelo Tosatti <mtosatti@...hat.com>
To:	"Roedel, Joerg" <Joerg.Roedel@....com>
Cc:	Avi Kivity <avi@...hat.com>,
	"kvm@...r.kernel.org" <kvm@...r.kernel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/2] KVM: MMU: Use base_role.nxe for mmu.nx

On Wed, Sep 15, 2010 at 10:48:33AM +0200, Roedel, Joerg wrote:
> On Tue, Sep 14, 2010 at 06:08:37PM -0400, Marcelo Tosatti wrote:
> > 
> > For tdp better set base_role.nxe to zero, otherwise duplicate tdp
> > pagetables can be created if the guest switches between nx/non-nx.
> >
> 
> This does not work because bit 63 is marked as reserved if base_role.nxe
> is 0. If the walk_addr_generic function then runs with tdp enabled it
> would report a set nx bit as a rsvd fault.

Ah, OK.

> We also can't use is_nx() in those path because it does not distinguish
> between l1 and l2 nx. Are there guests that switch the efer.nx bit
> regularly enough so that it matters? If so I would suggest to drop this
> patch and keep mmu.nx.

Well, i don't think it would be a common scenario. Ignore me.

--
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/