Re: [Xen-devel] [PATCH v7 08/15] x86/cpu: Remove loop form vmce_save_vcpu_ctxt() func

[Alexandru Stefan ISAILA <aisaila@xxxxxxxxxxxxxxx>]

On Vi, 2018-06-08 at 08:33 +0000, Paul Durrant wrote:
> > 
> > -----Original Message-----
> > From: Alexandru Isaila [mailto:aisaila@xxxxxxxxxxxxxxx]
> > Sent: 07 June 2018 15:59
> > To: xen-devel@xxxxxxxxxxxxx
> > Cc: Ian Jackson <Ian.Jackson@xxxxxxxxxx>; Wei Liu <wei.liu2@citrix.
> > com>;
> > jbeulich@xxxxxxxx; Andrew Cooper <Andrew.Cooper3@xxxxxxxxxx>; Paul
> > Durrant <Paul.Durrant@xxxxxxxxxx>; Alexandru Isaila
> > <aisaila@xxxxxxxxxxxxxxx>
> > Subject: [PATCH v7 08/15] x86/cpu: Remove loop form
> > vmce_save_vcpu_ctxt() func
> > 
> > Signed-off-by: Alexandru Isaila <aisaila@xxxxxxxxxxxxxxx>
> > ---
> >  xen/arch/x86/cpu/mcheck/vmce.c | 27 +++++++--------------------
> >  1 file changed, 7 insertions(+), 20 deletions(-)
> > 
> > diff --git a/xen/arch/x86/cpu/mcheck/vmce.c
> > b/xen/arch/x86/cpu/mcheck/vmce.c
> > index 404f27e..ead1f73 100644
> > --- a/xen/arch/x86/cpu/mcheck/vmce.c
> > +++ b/xen/arch/x86/cpu/mcheck/vmce.c
> > @@ -349,30 +349,17 @@ int vmce_wrmsr(uint32_t msr, uint64_t val)
> >      return ret;
> >  }
> > 
> > -static void vmce_save_vcpu_ctxt_one(struct vcpu *v, struct
> > hvm_vmce_vcpu *ctxt)
> > -{
> > -    ctxt->caps = v->arch.vmce.mcg_cap;
> > -    ctxt->mci_ctl2_bank0 = v->arch.vmce.bank[0].mci_ctl2;
> > -    ctxt->mci_ctl2_bank1 = v->arch.vmce.bank[1].mci_ctl2;
> > -    ctxt->mcg_ext_ctl = v->arch.vmce.mcg_ext_ctl;
> > -}
> > -
> >  static int vmce_save_vcpu_ctxt(struct domain *d,
> > hvm_domain_context_t
> > *h)
> >  {
> > -    struct vcpu *v;
> > -    int err = 0;
> > -
> > -    for_each_vcpu ( d, v )
> > -    {
> > -        struct hvm_vmce_vcpu ctxt;
> > +    struct hvm_vmce_vcpu ctxt;
> > +    struct vcpu *v = NULL;
> > 
> > -        vmce_save_vcpu_ctxt_one(v, &ctxt);
> > -        err = hvm_save_entry(VMCE_VCPU, v->vcpu_id, h, &ctxt);
> > -        if ( err )
> > -            break;
> > -    }
> > +    ctxt.caps = v->arch.vmce.mcg_cap;
> There's a typo in the commit title (s/form/from), but I don't
> understand what you're doing here. You set v to NULL above and
> dereference it below. AFAICT, until patch #15 is applied context
> saving will be completely broken.
Yes, this is true, but it could't find a better way to split the last
patch further.

Alex
> > 
> > +    ctxt.mci_ctl2_bank0 = v->arch.vmce.bank[0].mci_ctl2;
> > +    ctxt.mci_ctl2_bank1 = v->arch.vmce.bank[1].mci_ctl2;
> > +    ctxt.mcg_ext_ctl = v->arch.vmce.mcg_ext_ctl;
> > 
> > -    return err;
> > +    return hvm_save_entry(VMCE_VCPU, v->vcpu_id, h, &ctxt);
> >  }
> > 
> >  static int vmce_load_vcpu_ctxt(struct domain *d,
> > hvm_domain_context_t
> > *h)
> > --
> > 2.7.4
> 
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