Re: [Xen-devel] [PATCH 10/10] xen/swiotlb: Depending on after_bootmem is not correct.

[Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>]

On Fri, Sep 14, 2012 at 05:10:48PM +0100, Stefano Stabellini wrote:
> On Mon, 10 Sep 2012, Konrad Rzeszutek Wilk wrote:
> > When PCI IOMMUs are initialized it is after after_bootmem but
> > before a lot of "other" subsystems are initialized. As such
> > the check for after_bootmem is incorrect and we should
> > just use a parameter to define whether we are early or late.
> > 
> > This solves this bootup problem:
> > 
> > __ex_table already sorted, skipping sortM
> > Initializing CPU#0
> > Warning: only able to allocate 1 MB for software IO TLB
> > Xen-SWIOTLB: Lowering to 2MB
> > Warning: only able to allocate 1 MB for software IO TLB
> > Xen-SWIOTLB: Lowering to 2MB
> > Warning: only able to allocate 1 MB for software IO TLB
> > Xen-SWIOTLB: Lowering to 2MB
> > Warning: only able to allocate 1 MB for software IO TLB
> > Cannot allocate Xen-SWIOTLB buffer (rc:-12)
> > 
> > Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
> > ---
> >  arch/x86/xen/pci-swiotlb-xen.c |    4 ++--
> >  drivers/xen/swiotlb-xen.c      |   11 ++++++-----
> >  include/xen/swiotlb-xen.h      |    2 +-
> >  3 files changed, 9 insertions(+), 8 deletions(-)
> > 
> > diff --git a/arch/x86/xen/pci-swiotlb-xen.c b/arch/x86/xen/pci-swiotlb-xen.c
> > index fc0c78f..1608244 100644
> > --- a/arch/x86/xen/pci-swiotlb-xen.c
> > +++ b/arch/x86/xen/pci-swiotlb-xen.c
> > @@ -69,7 +69,7 @@ int __init pci_xen_swiotlb_detect(void)
> >  void __init pci_xen_swiotlb_init(void)
> >  {
> >     if (xen_swiotlb) {
> > -           xen_swiotlb_init(1);
> > +           xen_swiotlb_init(1, true /* early */);
> >             dma_ops = &xen_swiotlb_dma_ops;
> >  
> >             /* Make sure ACS will be enabled */
> > @@ -84,7 +84,7 @@ int pci_xen_swiotlb_init_late(void)
> >     if (xen_swiotlb)
> >             return 0;
> >  
> > -   rc = xen_swiotlb_init(1);
> > +   rc = xen_swiotlb_init(1, false /* late */);
> >     if (rc)
> >             return rc;
> >  
> > diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c
> > index 6f81994..7443e19 100644
> > --- a/drivers/xen/swiotlb-xen.c
> > +++ b/drivers/xen/swiotlb-xen.c
> > @@ -176,7 +176,7 @@ static const char *xen_swiotlb_error(enum 
> > xen_swiotlb_err err)
> >     }
> >     return "";
> >  }
> > -int __ref xen_swiotlb_init(int verbose)
> > +int __ref xen_swiotlb_init(int verbose, bool early)
> >  {
> >     unsigned long bytes, order;
> >     int rc = -ENOMEM;
> > @@ -190,7 +190,7 @@ retry:
> >     /*
> >      * Get IO TLB memory from any location.
> >      */
> > -   if (!after_bootmem)
> > +   if (early)
> >             xen_io_tlb_start = alloc_bootmem_pages(PAGE_ALIGN(bytes));
> >     else {
> >  #define SLABS_PER_PAGE (1 << (PAGE_SHIFT - IO_TLB_SHIFT))
> > @@ -220,7 +220,7 @@ retry:
> >                            bytes,
> >                            xen_io_tlb_nslabs);
> >     if (rc) {
> > -           if (!after_bootmem)
> > +           if (early)
> >                     free_bootmem(__pa(xen_io_tlb_start), PAGE_ALIGN(bytes));
> >             else {
> >                     free_pages((unsigned long)xen_io_tlb_start, order);
> > @@ -230,7 +230,8 @@ retry:
> >             goto error;
> >     }
> >     start_dma_addr = xen_virt_to_bus(xen_io_tlb_start);
> > -   if (!after_bootmem)
> > +   rc = 0;
>      ^
> why does this change belong to this patch?

Good eyes. I was being sneaky and rolled it in. But I can't recall why I needed
this. <sigh>

> 
> 
> > +   if (early)
> >             swiotlb_init_with_tbl(xen_io_tlb_start, xen_io_tlb_nslabs, 
> > verbose);
> >     else
> >             rc = swiotlb_late_init_with_tbl(xen_io_tlb_start, 
> > xen_io_tlb_nslabs);
> > @@ -244,7 +245,7 @@ error:
> >             goto retry;
> >     }
> >     pr_err("%s (rc:%d)", xen_swiotlb_error(m_ret), rc);
> > -   if (!after_bootmem)
> > +   if (early)
> >             panic("%s (rc:%d)", xen_swiotlb_error(m_ret), rc);
> >     else
> >             free_pages((unsigned long)xen_io_tlb_start, order);
> > diff --git a/include/xen/swiotlb-xen.h b/include/xen/swiotlb-xen.h
> > index a0db2b7..de8bcc6 100644
> > --- a/include/xen/swiotlb-xen.h
> > +++ b/include/xen/swiotlb-xen.h
> > @@ -3,7 +3,7 @@
> >  
> >  #include <linux/swiotlb.h>
> >  
> > -extern int xen_swiotlb_init(int verbose);
> > +extern int xen_swiotlb_init(int verbose, bool early);
> >  
> >  extern void
> >  *xen_swiotlb_alloc_coherent(struct device *hwdev, size_t size,
> > -- 
> > 1.7.7.6
> > 

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