Re: [Xen-devel] [PATCH 3/3] x86/mm: merge ptwr and mmio_ro page fault handlers

[Wei Liu <wei.liu2@xxxxxxxxxx>]

On Wed, Aug 30, 2017 at 07:02:52PM +0100, Andrew Cooper wrote:
> On 30/08/17 18:11, Wei Liu wrote:
> > Provide a unified entry to avoid going through pte look-up, decode and
> > emulation cycle more than necessary. The path taken is determined by
> > the faulting address.
> >
> > Note that the order of checks is changed in the new function, but the
> > order of the checks is performed shouldn't matter.
> >
> > The sole caller is changed to use the new function.
> >
> > No functional change.
> >
> > Signed-off-by: Wei Liu <wei.liu2@xxxxxxxxxx>
> > ---
> > Cc: Jan Beulich <jbeulich@xxxxxxxx>
> > Cc: Andrew Cooper <andrew.cooper3@xxxxxxxxxx>
> >
> > xtf is happy with this change. Let me know if more tests can be done.
> 
> Booting dom0 is probably the best easy test going.
> 
> > diff --git a/xen/include/asm-x86/mm.h b/xen/include/asm-x86/mm.h
> > index ec7ce3c8c8..85adafdfa2 100644
> > --- a/xen/include/asm-x86/mm.h
> > +++ b/xen/include/asm-x86/mm.h
> > @@ -511,10 +511,8 @@ extern int mmcfg_intercept_write(enum x86_segment seg,
> >  int pv_emul_cpuid(uint32_t leaf, uint32_t subleaf,
> >                    struct cpuid_leaf *res, struct x86_emulate_ctxt *ctxt);
> >  
> > -int  ptwr_do_page_fault(struct vcpu *, unsigned long,
> > -                        struct cpu_user_regs *);
> > -int  mmio_ro_do_page_fault(struct vcpu *, unsigned long,
> > -                           struct cpu_user_regs *);
> > +int ptwr_or_mmio_ro_do_page_fault(struct vcpu *, unsigned long,
> > +                                  struct cpu_user_regs *);
> 
> pv_ro_page_fault() ?
> 
> >  
> >  int audit_adjust_pgtables(struct domain *d, int dir, int noisy);
> >  
> 
> I was thinking something more like this extra delta (only compile
> tested) which drops rather more code.

Your diff deleted two perfc_incr. I will modify it to restore that
behaviour.

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