[Lucid][SRU][PATCH] UBUNTU: SAUCE: (no-up) Fix up KVM: VMX: Fix host userspace gsbase corruption

[Steve Conklin]

On Tue, 2011-05-24 at 12:24 -0700, Leann Ogasawara wrote:
> SRU Justification:
> 
> http://bugs.launchpad.net/bugs/787675
> 
> I've clearly buggered up a backported patch on Lucid that came in as an
> aside for the 2.6.32.26+drm33.11 stable patch set (See bug 681132). The
> patch in question is:
> 
>     KVM: VMX: Fix host userspace gsbase corruption
> 
>     We now use load_gs_index() to load gs safely; unfortunately this also
>     changes MSR_KERNEL_GS_BASE, which we managed separately. This resulted
>     in confusion and breakage running 32-bit host userspace on a 64-bit kernel.
> 
> The original thread regarding this patch can be read at:
> 
> https://lists.ubuntu.com/archives/kernel-team/2010-November/013655.html
> 
> The attached patch correctly fixes up the accidental deletion of a line
> of code, and correctly removes the intended line. Please apply to Lucid.
> I've also built a test kernel and referenced it in the bug.  I'm hoping
> for testing feedback from Jiang who originally brought the mistake to my
> attention.
> 
> Thanks,
> Leann
> 
> The following changes since commit 800e98aaa03cf2134fb3b1a7c11f59e93fa97c23:
>   Thomas Schlichter (1):
>         UBUNTU: SAUCE: vesafb: enable mtrr WC by default
> 
> are available in the git repository at:
> 
>   git://kernel.ubuntu.com/ogasawara/ubuntu-lucid.git lp787675
> 
> Leann Ogasawara (1):
>       UBUNTU: SAUCE: (no-up) Fix up KVM: VMX: Fix host userspace gsbase corruption
> 
>  arch/x86/kvm/vmx.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
> 
> From 7766255c19171ecd6961ea9b6455d0de11245d19 Mon Sep 17 00:00:00 2001
> From: Leann Ogasawara <leann.ogasawara at canonical.com>
> Date: Tue, 24 May 2011 09:40:12 -0700
> Subject: [PATCH] UBUNTU: SAUCE: (no-up) Fix up KVM: VMX: Fix host userspace gsbase corruption
> 
> BugLink: http://bugs.launchpad.net/bugs/787675
> 
> The backport for the following commit was incorrect, eg. it removed a
> line which it shouldn't have.
> 
>   commit 6cbdc7ba48dff850c233a1ea1abe87a6d0cde2dd
>   Author: Avi Kivity <avi at redhat.com>
>   Date:   Thu Nov 11 12:37:26 2010 +0200
> 
>     KVM: VMX: Fix host userspace gsbase corruption
> 
> Fix up the backport to be correct.
> 
> Signed-off-by: Leann Ogasawara <leann.ogasawara at canonical.com>
> ---
>  arch/x86/kvm/vmx.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
> 
> diff --git a/arch/x86/kvm/vmx.c b/arch/x86/kvm/vmx.c
> index 77c3287..e3222ab 100644
> --- a/arch/x86/kvm/vmx.c
> +++ b/arch/x86/kvm/vmx.c
> @@ -699,7 +699,7 @@ static void __vmx_load_host_state(struct vcpu_vmx *vmx)
>  	if (vmx->host_state.gs_ldt_reload_needed) {
>  		kvm_load_ldt(vmx->host_state.ldt_sel);
>  #ifdef CONFIG_X86_64
> -		wrmsrl(MSR_KERNEL_GS_BASE, current->thread.gs);
> +		load_gs_index(vmx->host_state.gs_sel);
>  #else
>  		loadsegment(gs, vmx->host_state.gs_sel);
>  #endif
> -- 
> 1.7.0.4
> 
> 
> 


Acked-by: Steve Conklin <sconklin at canonical.com>


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