Re: [Xen-devel] [PATCH v2] qemu/xen: Add 64 bits big bar support on qemu

["Hao, Xudong" <xudong.hao@xxxxxxxxx>]

> -----Original Message-----
> From: Stefano Stabellini [mailto:stefano.stabellini@xxxxxxxxxxxxx]
> Sent: Tuesday, September 25, 2012 6:52 PM
> To: Hao, Xudong
> Cc: Stefano Stabellini; xen-devel@xxxxxxxxxxxxx; qemu-devel@xxxxxxxxxx;
> Zhang, Xiantao
> Subject: Re: [PATCH v2] qemu/xen: Add 64 bits big bar support on qemu
> 
> On Tue, 25 Sep 2012, Xudong Hao wrote:
> > Changes from v1:
> > - Rebase to qemu upstream from qemu-xen
> 
> Thanks. Please run scripts/checkpatch.pl on this patch, you'll find
> some cody style issues that need to be fixed.
> 
OK, will use this scripts to check code style.

> 
> > Currently it is assumed PCI device BAR access < 4G memory. If there is such 
> > a
> > device whose BAR size is larger than 4G, it must access > 4G memory
> address.
> > This patch enable the 64bits big BAR support on qemu.
> >
> > Signed-off-by: Xudong Hao <xudong.hao@xxxxxxxxx>
> > Signed-off-by: Xiantao Zhang <xiantao.zhang@xxxxxxxxx>
> > ---
> >  hw/xen_pt.c             |   16 ++++++++--------
> >  hw/xen_pt_config_init.c |   42
> +++++++++++++++++++++++++++++-------------
> >
> > diff --git a/hw/xen_pt.c b/hw/xen_pt.c
> > index 307119a..2a8bcf3 100644
> > --- a/hw/xen_pt.c
> > +++ b/hw/xen_pt.c
> > @@ -403,21 +403,21 @@ static int
> xen_pt_register_regions(XenPCIPassthroughState *s)
> >
> >          s->bases[i].access.u = r->base_addr;
> >
> > -        if (r->type & XEN_HOST_PCI_REGION_TYPE_IO) {
> > +        if (r->type & XEN_HOST_PCI_REGION_TYPE_IO)
> >              type = PCI_BASE_ADDRESS_SPACE_IO;
> > -        } else {
> > +        else if (r->type & XEN_HOST_PCI_REGION_TYPE_MEM_64)
> > +            type = PCI_BASE_ADDRESS_MEM_TYPE_64;
> > +        else if (r->type & XEN_HOST_PCI_REGION_TYPE_PREFETCH)
> > +            type |= PCI_BASE_ADDRESS_MEM_PREFETCH;
> > +        else
> >              type = PCI_BASE_ADDRESS_SPACE_MEMORY;
> > -            if (r->type & XEN_HOST_PCI_REGION_TYPE_PREFETCH) {
> > -                type |= PCI_BASE_ADDRESS_MEM_PREFETCH;
> > -            }
> > -        }
> 
> Aside from the cody style issue here, this changes the behavior for type
> PCI_BASE_ADDRESS_SPACE_MEMORY. Before we could have:
> 
> type =
> PCI_BASE_ADDRESS_SPACE_MEMORY|PCI_BASE_ADDRESS_MEM_PREFETCH;
> 
> now we cannot anymore.
> 

Will change to:
-        if (r->type & XEN_HOST_PCI_REGION_TYPE_IO) {
+        if (r->type & XEN_HOST_PCI_REGION_TYPE_IO)
             type = PCI_BASE_ADDRESS_SPACE_IO;
-        } else {
+        else
             type = PCI_BASE_ADDRESS_SPACE_MEMORY;
-            if (r->type & XEN_HOST_PCI_REGION_TYPE_PREFETCH) {
+            if (r->type & XEN_HOST_PCI_REGION_TYPE_MEM_64)
+                type |= PCI_BASE_ADDRESS_MEM_TYPE_64;
+           else if (r->type & XEN_HOST_PCI_REGION_TYPE_PREFETCH)
                 type |= PCI_BASE_ADDRESS_MEM_PREFETCH;
-            }
-        }

> 
> >          memory_region_init_io(&s->bar[i], &ops, &s->dev,
> >                                "xen-pci-pt-bar", r->size);
> >          pci_register_bar(&s->dev, i, type, &s->bar[i]);
> >
> > -        XEN_PT_LOG(&s->dev, "IO region %i registered
> (size=0x%08"PRIx64
> > -                   " base_addr=0x%08"PRIx64" type: %#x)\n",
> > +        XEN_PT_LOG(&s->dev, "IO region %i registered
> (size=0x%lx"PRIx64
> > +                   " base_addr=0x%lx"PRIx64" type: %#x)\n",
> >                     i, r->size, r->base_addr, type);
> >      }
> >
> > diff --git a/hw/xen_pt_config_init.c b/hw/xen_pt_config_init.c
> > index e524a40..5e7ca22 100644
> > --- a/hw/xen_pt_config_init.c
> > +++ b/hw/xen_pt_config_init.c
> > @@ -342,6 +342,7 @@ static int
> xen_pt_cmd_reg_write(XenPCIPassthroughState *s, XenPTReg *cfg_entry,
> >  #define XEN_PT_BAR_IO_RO_MASK     0x00000003  /* BAR ReadOnly
> mask(I/O) */
> >  #define XEN_PT_BAR_IO_EMU_MASK    0xFFFFFFFC  /* BAR emul
> mask(I/O) */
> >
> > +static uint64_t xen_pt_get_bar_size(PCIIORegion *r);
> 
> there is just one user of xen_pt_get_bar_size, maybe you can just
> move the implementation here
> 

Ok, thanks.

> 
> >  static XenPTBarFlag xen_pt_bar_reg_parse(XenPCIPassthroughState *s,
> >                                           XenPTRegInfo *reg)
> >  {
> > @@ -366,7 +367,7 @@ static XenPTBarFlag
> xen_pt_bar_reg_parse(XenPCIPassthroughState *s,
> >
> >      /* check unused BAR */
> >      r = &d->io_regions[index];
> > -    if (r->size == 0) {
> > +    if (!xen_pt_get_bar_size(r)) {
> >          return XEN_PT_BAR_FLAG_UNUSED;
> >      }
> >
> > @@ -383,6 +384,24 @@ static XenPTBarFlag
> xen_pt_bar_reg_parse(XenPCIPassthroughState *s,
> >      }
> >  }
> >
> > +static bool is_64bit_bar(PCIIORegion *r)
> > +{
> > +    return !!(r->type & PCI_BASE_ADDRESS_MEM_TYPE_64);
> > +}
> > +
> > +static uint64_t xen_pt_get_bar_size(PCIIORegion *r)
> > +{
> > +    if (is_64bit_bar(r))
> > +    {
> > +        uint64_t size64;
> > +        size64 = (r + 1)->size;
> > +        size64 <<= 32;
> > +        size64 += r->size;
> > +        return size64;
> > +    }
> > +    return r->size;
> > +}
> > +
> >  static inline uint32_t base_address_with_flags(XenHostPCIIORegion *hr)
> >  {
> >      if (hr->type & XEN_HOST_PCI_REGION_TYPE_IO) {
> > @@ -481,7 +500,10 @@ static int
> xen_pt_bar_reg_write(XenPCIPassthroughState *s, XenPTReg *cfg_entry,
> >      switch (s->bases[index].bar_flag) {
> >      case XEN_PT_BAR_FLAG_MEM:
> >          bar_emu_mask = XEN_PT_BAR_MEM_EMU_MASK;
> > -        bar_ro_mask = XEN_PT_BAR_MEM_RO_MASK | (r_size - 1);
> > +        if (!r_size)
> > +            bar_ro_mask = XEN_PT_BAR_ALLF;
> > +        else
> > +            bar_ro_mask = XEN_PT_BAR_MEM_RO_MASK | (r_size - 1);
> >          break;
> 
> Is this an actual mistake everywhere?

It's low 32bit mask for 64 bit bars.

> There is at least another instance of
> 
> bar_ro_mask = something | (r_size - 1);
> 
> under the XEN_PT_BAR_FLAG_IO case.

Bar_ro_mask under XEN_PT_BAR_FLAG_IO already be done, I don't change IO case.

> Or is it only a problem with 64 bit bars? If so, could you please
> explain why?
> 
> 
> >      case XEN_PT_BAR_FLAG_IO:
> >          bar_emu_mask = XEN_PT_BAR_IO_EMU_MASK;
> > @@ -489,7 +511,10 @@ static int
> xen_pt_bar_reg_write(XenPCIPassthroughState *s, XenPTReg *cfg_entry,
> >          break;
> >      case XEN_PT_BAR_FLAG_UPPER:
> >          bar_emu_mask = XEN_PT_BAR_ALLF;
> > -        bar_ro_mask = 0;    /* all upper 32bit are R/W */
> > +        if (!r_size)
> > +            bar_ro_mask = 0;
> > +        else
> > +            bar_ro_mask = r_size - 1;
> >          break;
> 
> bar_ro_mask = r_size ? r_size - 1 : 0;
> 

Great. :)



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