linux-kernel - Re: [PATCH] xen: fix logical error in tlb flushing

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Date:	Fri, 24 Aug 2012 14:17:21 -0400
From:	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
To:	Jan Beulich <JBeulich@...e.com>
Cc:	Alex Shi <alex.shi@...el.com>, tglx@...utronix.de,
	mingo@...hat.com, hpa@...or.com, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] xen: fix logical error in tlb flushing

On Fri, Aug 24, 2012 at 04:16:39PM +0100, Jan Beulich wrote:
> >>> On 24.08.12 at 10:55, Alex Shi <alex.shi@...el.com> wrote:
> > While TLB_FLUSH_ALL gets passed as 'end' argument to
> > flush_tlb_others(), the Xen code was made to check its 'start'
> > parameter. That may give a incorrect op.cmd to MMUEXT_INVLPG_MULTI
> > instead of MMUEXT_TLB_FLUSH_MULTI. Then it causes some page can not
> > be flushed from TLB.
> > 
> > This patch fixed this issue.
> > 
> > Reported-by: Jan Beulich <jbeulich@...e.com>
> > Signed-off-by: Alex Shi <alex.shi@...el.com>
> 
> Acked-by: Jan Beulich <jbeulich@...e.com>

How can I reproduce this and should this also go to stable@...nel.org?
> 
> > ---
> >  arch/x86/xen/mmu.c |    2 +-
> >  1 files changed, 1 insertions(+), 1 deletions(-)
> > 
> > diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
> > index b65a761..5141d80 100644
> > --- a/arch/x86/xen/mmu.c
> > +++ b/arch/x86/xen/mmu.c
> > @@ -1283,7 +1283,7 @@ static void xen_flush_tlb_others(const struct cpumask 
> > *cpus,
> >  	cpumask_clear_cpu(smp_processor_id(), to_cpumask(args->mask));
> >  
> >  	args->op.cmd = MMUEXT_TLB_FLUSH_MULTI;
> > -	if (start != TLB_FLUSH_ALL && (end - start) <= PAGE_SIZE) {
> > +	if (end != TLB_FLUSH_ALL && (end - start) <= PAGE_SIZE) {
> >  		args->op.cmd = MMUEXT_INVLPG_MULTI;
> >  		args->op.arg1.linear_addr = start;
> >  	}
> > -- 
> > 1.7.5.4
> > 
> > .
> 
> 
> 
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