Re: [Xen-devel] [PATCH v3 for 4.5] ioreq-server: handle the lack of a default emulator properly

[Paul Durrant <Paul.Durrant@xxxxxxxxxx>]

> -----Original Message-----
> From: Jan Beulich [mailto:JBeulich@xxxxxxxx]
> Sent: 30 September 2014 10:49
> To: Andrew Cooper; Paul Durrant
> Cc: xen-devel@xxxxxxxxxxxxx; Keir (Xen.org)
> Subject: RE: [Xen-devel] [PATCH v3 for 4.5] ioreq-server: handle the lack of a
> default emulator properly
> 
> >>> On 30.09.14 at 11:43, <Paul.Durrant@xxxxxxxxxx> wrote:
> >>  -----Original Message-----
> >> From: Andrew Cooper
> >> Sent: 30 September 2014 10:29
> >> To: Paul Durrant; xen-devel@xxxxxxxxxxxxx
> >> Cc: Keir (Xen.org); Jan Beulich
> >> Subject: Re: [Xen-devel] [PATCH v3 for 4.5] ioreq-server: handle the lack
> of a
> >> default emulator properly
> >>
> >> On 30/09/14 10:18, Paul Durrant wrote:
> >> > I started porting QEMU over to use the new ioreq server API and hit a
> >> > problem with PCI bus enumeration. Because, with my patches, QEMU
> only
> >> > registers to handle config space accesses for the PCI device it
> implements
> >> > all other attempts by the guest to access 0xcfc go nowhere and this was
> >> > causing the vcpu to wedge up because nothing was completing the I/O.
> >> >
> >> > This patch introduces an I/O completion handler into the hypervisor for
> the
> >> > case where no ioreq server matches a particular request. Read requests
> >> are
> >> > completed with 0xf's in the data buffer, writes and all other I/O req
> types
> >> > are ignored.
> >> >
> >> > Signed-off-by: Paul Durrant <paul.durrant@xxxxxxxxxx>
> >> > Cc: Keir Fraser <keir@xxxxxxx>
> >> > Cc: Jan Beulich <jbeulich@xxxxxxxx>
> >>
> >> One bug, couple of nits.
> >>
> >> It is probably worth having a sentence in the commit message concerning
> >> the removal of list_is_singular().
> >>
> >> > ---
> >> > v3: - Fix for backwards string instruction emulation
> >> >
> >> > v2: - First non-RFC submission
> >> >     - Removed warning on unemulated MMIO accesses
> >> >
> >> >  xen/arch/x86/hvm/hvm.c |   35
> ++++++++++++++++++++++++++++++++-
> >> --
> >> >  1 file changed, 32 insertions(+), 3 deletions(-)
> >> >
> >> > diff --git a/xen/arch/x86/hvm/hvm.c b/xen/arch/x86/hvm/hvm.c
> >> > index 5c7e0a4..e6611ed 100644
> >> > --- a/xen/arch/x86/hvm/hvm.c
> >> > +++ b/xen/arch/x86/hvm/hvm.c
> >> > @@ -2386,8 +2386,7 @@ static struct hvm_ioreq_server
> >> *hvm_select_ioreq_server(struct domain *d,
> >> >      if ( list_empty(&d->arch.hvm_domain.ioreq_server.list) )
> >> >          return NULL;
> >> >
> >> > -    if ( list_is_singular(&d->arch.hvm_domain.ioreq_server.list) ||
> >> > -         (p->type != IOREQ_TYPE_COPY && p->type != IOREQ_TYPE_PIO) )
> >> > +    if ( p->type != IOREQ_TYPE_COPY && p->type != IOREQ_TYPE_PIO )
> >> >          return d->arch.hvm_domain.default_ioreq_server;
> >> >
> >> >      cf8 = d->arch.hvm_domain.pci_cf8;
> >> > @@ -2618,12 +2617,42 @@ bool_t
> >> hvm_send_assist_req_to_ioreq_server(struct hvm_ioreq_server *s,
> >> >      return 0;
> >> >  }
> >> >
> >> > +static bool_t hvm_complete_assist_req(ioreq_t *p)
> >> > +{
> >> > +    switch (p->type)
> >>
> >> Style: ( p-> type )
> >>
> >
> > <Sigh> Yes, missed that one.
> 
> And I can fix that while committing...
> 

Ok. Thanks,

  Paul

> Jan


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