Re: [Xen-devel] [PATCH v6 08/16] x86/hvm: unify stdvga mmio intercept with standard mmio intercept

[Paul Durrant <Paul.Durrant@xxxxxxxxxx>]

> -----Original Message-----
> From: Jan Beulich [mailto:JBeulich@xxxxxxxx]
> Sent: 08 July 2015 17:17
> To: Paul Durrant
> Cc: xen-devel@xxxxxxxxxxxxxxxxxxxx; Keir (Xen.org)
> Subject: Re: [PATCH v6 08/16] x86/hvm: unify stdvga mmio intercept with
> standard mmio intercept
> 
> >>> On 03.07.15 at 18:25, <paul.durrant@xxxxxxxxxx> wrote:
> > -int stdvga_intercept_mmio(ioreq_t *p)
> > +static bool_t stdvga_mem_accept(const struct hvm_io_handler *handler,
> > +                                const ioreq_t *p)
> >  {
> > -    struct domain *d = current->domain;
> > -    struct hvm_hw_stdvga *s = &d->arch.hvm_domain.stdvga;
> > -    uint64_t start, end, count = p->count, size = p->size;
> > -    int buf = 0, rc;
> > -
> > -    if ( p->df )
> > -    {
> > -        start = (p->addr - (count - 1) * size);
> > -        end = p->addr + size;
> > -    }
> > -    else
> > -    {
> > -        start = p->addr;
> > -        end = p->addr + count * size;
> > -    }
> > -
> > -    if ( (start < VGA_MEM_BASE) || (end > (VGA_MEM_BASE +
> VGA_MEM_SIZE)) )
> > -        return X86EMUL_UNHANDLEABLE;
> > -
> > -    if ( p->size > 8 )
> > -    {
> > -        gdprintk(XENLOG_WARNING, "invalid mmio size %d\n", (int)p->size);
> > -        return X86EMUL_UNHANDLEABLE;
> > -    }
> > +    struct hvm_hw_stdvga *s = &current->domain-
> >arch.hvm_domain.stdvga;
> >
> >      spin_lock(&s->lock);
> >
> > -    if ( s->stdvga && s->cache )
> > +    if ( !s->stdvga ||
> > +         (p->addr < VGA_MEM_BASE) ||
> > +         ((p->addr + p->size) > (VGA_MEM_BASE + VGA_MEM_SIZE)) )
> > +        goto reject;
> 
> I came here just to check whether you make use of the earlier
> added hvm_mmio_{first,last}_byte(), but found that you're ignoring
> p->df now altogether. That can't be right?
> 

Yes, that's a mistake. I was forgetting that we still handle reads with count > 
1.

  Paul

> Jan


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