Re: port-amd64/42980: satalink DMA fails under amd64

[Manuel Bouyer <bouyer%antioche.eu.org@localhost>]

On Tue, Mar 16, 2010 at 10:02:56PM -0400, Julian Bourne wrote:
> Further investigation: the EINVAL is being returned by the call to:
> 
> bus_dmamem_alloc(...,size=65536,
>    alignment=4096,  boundary=8192,
>    nsegs=17, flags=0x3)
> 
> from _bus_dma_alloc_bouncebuf() on line 896;
> from _bus_dmamap_create() on line 283.
> 
> This is all from: arch/x86/x86/bus_dma.c revision 1.45 (NetBSD-5.0.2).
> 
> Ultimately, this is called from dev/pci/pciide_common.c revision 1.38
> on line 597 via bus_dmamap_create() - the error is printed out a few
> lines after.

I think the bug is from _bus_dma_alloc_bouncebuf(), 
which doesn't pay enough attention to the boundary value vs size, before
calling bus_dmamem_alloc().
It seems to me that the right solution is to properly handle the boundary
in _xen_bus_dmamem_alloc_range() (the x86 version doens't need changes, this
is handled by uvm_pglistalloc()). 
I think the attached patch should do it; can you test (and make sure you
removed your patch before, of course :) ?

-- 
Manuel Bouyer <bouyer%antioche.eu.org@localhost>
     NetBSD: 26 ans d'experience feront toujours la difference
--

Index: xen_bus_dma.c
===================================================================
RCS file: /cvsroot/src/sys/arch/xen/x86/xen_bus_dma.c,v
retrieving revision 1.11.8.1
diff -u -p -u -r1.11.8.1 xen_bus_dma.c
--- xen_bus_dma.c       30 Jan 2010 19:14:20 -0000      1.11.8.1
+++ xen_bus_dma.c       18 Mar 2010 16:53:52 -0000
@@ -61,7 +61,7 @@ static inline int get_order(unsigned lon
 }
 
 static int
-_xen_alloc_contig(bus_size_t size, bus_size_t alignment, bus_size_t boundary,
+_xen_alloc_contig(bus_size_t size, bus_size_t alignment,
     struct pglist *mlistp, int flags, bus_addr_t low, bus_addr_t high)
 {
        int order, i;
@@ -75,9 +75,9 @@ _xen_alloc_contig(bus_size_t size, bus_s
 
        /*
         * When requesting a contigous memory region, the hypervisor will
-        * return a memory range aligned on size. This will automagically
-        * handle "boundary", but the only way to enforce alignment
-        * is to request a memory region of size max(alignment, size).
+        * return a memory range aligned on size. 
+        * The only way to enforce alignment is to request a memory region
+        * of size max(alignment, size).
         */
        order = max(get_order(size), get_order(alignment));
        npages = (1 << order);
@@ -252,8 +252,6 @@ _xen_bus_dmamem_alloc_range(bus_dma_tag_
        KASSERT((boundary & (boundary - 1)) == 0);
        if (alignment < PAGE_SIZE)
                alignment = PAGE_SIZE;
-       if (boundary != 0 && boundary < size)
-               return (EINVAL);
 
        /*
         * Allocate pages from the VM system.
@@ -282,10 +280,9 @@ again:
                curaddr = _BUS_VM_PAGE_TO_BUS(m);
                if (curaddr < low || curaddr >= high)
                        goto badaddr;
-               if (curaddr == (lastaddr + PAGE_SIZE)) {
+               if (curaddr == (lastaddr + PAGE_SIZE) &&
+                   (lastaddr & boundary) == (curaddr & boundary)) {
                        segs[curseg].ds_len += PAGE_SIZE;
-                       if ((lastaddr & boundary) != (curaddr & boundary))
-                               goto dorealloc;
                } else {
                        curseg++;
                        if (curseg >= nsegs || (curaddr & (alignment - 1)) != 0)
@@ -343,7 +340,7 @@ dorealloc:
                segs[curseg].ds_len = 0;
        }
        error = _xen_alloc_contig(size, alignment,
-           boundary, &mlist, flags, low, high);
+           &mlist, flags, low, high);
        if (error)
                return error;
        goto again;