linux-kernel - Re: [PATCH 2/2] kvm, MCE, Send SRAR SIGBUS directly

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Date:	Sat, 09 Oct 2010 08:48:50 +0800
From:	Huang Ying <ying.huang@...el.com>
To:	Marcelo Tosatti <mtosatti@...hat.com>
Cc:	Avi Kivity <avi@...hat.com>,
	"kvm@...r.kernel.org" <kvm@...r.kernel.org>,
	Andi Kleen <andi@...stfloor.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Dean Nelson <dnelson@...hat.com>
Subject: Re: [PATCH 2/2] kvm, MCE, Send SRAR SIGBUS directly

On Sat, 2010-10-09 at 04:25 +0800, Marcelo Tosatti wrote:
> On Fri, Oct 08, 2010 at 04:24:15PM +0800, Huang Ying wrote:
> > Originally, SRAR SIGBUS is sent to QEMU-KVM via touching the poisoned
> > page. But commit 96054569190bdec375fe824e48ca1f4e3b53dd36 prevents the
> > signal from being sent. So now the signal is sent via
> > force_sig_info_fault directly.
> > 
> > Reported-by: Dean Nelson <dnelson@...hat.com>
> > Signed-off-by: Huang Ying <ying.huang@...el.com>
> > ---
> >  arch/x86/include/asm/signal.h |    3 +++
> >  arch/x86/kvm/mmu.c            |   15 +++------------
> >  arch/x86/mm/fault.c           |    6 +++---
> >  3 files changed, 9 insertions(+), 15 deletions(-)
> > 
> > --- a/arch/x86/include/asm/signal.h
> > +++ b/arch/x86/include/asm/signal.h
> > @@ -258,6 +258,9 @@ struct pt_regs;
> >  
> >  #define ptrace_signal_deliver(regs, cookie) do { } while (0)
> >  
> > +void force_sig_info_fault(int si_signo, int si_code, unsigned long address,
> > +			  struct task_struct *tsk);
> > +
> >  #endif /* __KERNEL__ */
> >  #endif /* __ASSEMBLY__ */
> >  
> > --- a/arch/x86/mm/fault.c
> > +++ b/arch/x86/mm/fault.c
> > @@ -158,9 +158,8 @@ is_prefetch(struct pt_regs *regs, unsign
> >  	return prefetch;
> >  }
> >  
> > -static void
> > -force_sig_info_fault(int si_signo, int si_code, unsigned long address,
> > -		     struct task_struct *tsk)
> > +void force_sig_info_fault(int si_signo, int si_code, unsigned long address,
> > +			  struct task_struct *tsk)
> >  {
> >  	siginfo_t info;
> >  
> > @@ -172,6 +171,7 @@ force_sig_info_fault(int si_signo, int s
> >  
> >  	force_sig_info(si_signo, &info, tsk);
> >  }
> > +EXPORT_SYMBOL_GPL(force_sig_info_fault);
> >  
> >  DEFINE_SPINLOCK(pgd_lock);
> >  LIST_HEAD(pgd_list);
> > --- a/arch/x86/kvm/mmu.c
> > +++ b/arch/x86/kvm/mmu.c
> > @@ -39,6 +39,7 @@
> >  #include <asm/cmpxchg.h>
> >  #include <asm/io.h>
> >  #include <asm/vmx.h>
> > +#include <asm/signal.h>
> >  
> >  /*
> >   * When setting this variable to true it enables Two-Dimensional-Paging
> > @@ -2104,22 +2105,12 @@ static int __direct_map(struct kvm_vcpu
> >  	return pt_write;
> >  }
> >  
> > -static void kvm_send_hwpoison_signal(struct kvm *kvm, gfn_t gfn)
> > -{
> > -	char buf[1];
> > -	void __user *hva;
> > -	int r;
> > -
> > -	/* Touch the page, so send SIGBUS */
> > -	hva = (void __user *)gfn_to_hva(kvm, gfn);
> > -	r = copy_from_user(buf, hva, 1);
> > -}
> > -
> >  static int kvm_handle_bad_page(struct kvm *kvm, gfn_t gfn, pfn_t pfn)
> >  {
> >  	kvm_release_pfn_clean(pfn);
> >  	if (is_hwpoison_pfn(pfn)) {
> > -		kvm_send_hwpoison_signal(kvm, gfn);
> > +		force_sig_info_fault(SIGBUS, BUS_MCEERR_AR,
> > +				     gfn_to_hva(kvm, gfn), current);
> >  		return 0;
> >  	} else if (is_fault_pfn(pfn))
> >  		return -EFAULT;
> 
> Better fill siginfo and use force_sig_info, which is already exported.

It seems that force_sig_info is not exported for now.

Best Regards,
Huang Ying


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