From mboxrd@z Thu Jan  1 00:00:00 1970
From: Kevin Wolf <kwolf@redhat.com>
Subject: Re: [PATCH 1/3] KVM: x86 emulator: Fix task switch privilege checks
Date: Tue, 24 Jan 2012 15:15:13 +0100
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References: <1327335048-31925-1-git-send-email-kwolf@redhat.com> <1327335048-31925-2-git-send-email-kwolf@redhat.com> <20120124140316.GD19255@amd.com>
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Cc: kvm@vger.kernel.org, gleb@redhat.com,
	yoshikawa.takuya@oss.ntt.co.jp, avi@redhat.com, mtosatti@redhat.com
To: Joerg Roedel <joerg.roedel@amd.com>
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Am 24.01.2012 15:03, schrieb Joerg Roedel:
> On Mon, Jan 23, 2012 at 05:10:46PM +0100, Kevin Wolf wrote:
>> This patch fixes the problem for VMX. For SVM, the logic used to
>> determine the source of the task switch is buggy, so we can't pass
>> useful information to the emulator there and just disable the check in
>> all cases.
> 
> Actually, SVM isn't buggy :) For SVM you do not need to do any
> priviledge checks in software because the hardware already takes care of
> that.
> In other words, KVM only gets a task-switch intercept if the priviledges
> are all checked and correct.

Okay, that's good to hear. The current code is still buggy because as
Gleb noted it checks against the TSS DPL. We need to disable that check
for SVM then. Also all checks for TASK_SWITCH_GATE indicate that
something is wrong because it will never happen.

Are you going to rewrite task_switch_interception() on top of this series?

Kevin