| Message ID | 20190524144250.5102-1-sergey.dyasli@citrix.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | [v1] xen/swiotlb: rework early repeat code | expand |
On Fri, 24 May 2019, Sergey Dyasli wrote: > Current repeat code is plain broken for the early=true case. Xen exchanges > all DMA (<4GB) pages that it can on the first xen_swiotlb_fixup() attempt. > All further attempts with a halved region will fail immediately because > all DMA pages already belong to Dom0. > > Introduce contig_pages param for xen_swiotlb_fixup() to track the number > of pages that were made contiguous in MFN space and use the same bootmem > region while halving the memory requirements. > > Signed-off-by: Sergey Dyasli <sergey.dyasli@citrix.com> Just FYI I am touching the same code to fix another unrelated bug, see: https://marc.info/?l=xen-devel&m=155856767022893 > --- > CC: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> > CC: Boris Ostrovsky <boris.ostrovsky@oracle.com> > CC: Juergen Gross <jgross@suse.com> > CC: Stefano Stabellini <sstabellini@kernel.org> > CC: Paul Durrant <paul.durrant@citrix.com> > --- > drivers/xen/swiotlb-xen.c | 36 ++++++++++++++++++++++++++++++------ > 1 file changed, 30 insertions(+), 6 deletions(-) > > diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c > index 5dcb06fe9667..d2aba804d06c 100644 > --- a/drivers/xen/swiotlb-xen.c > +++ b/drivers/xen/swiotlb-xen.c > @@ -142,7 +142,8 @@ static int is_xen_swiotlb_buffer(dma_addr_t dma_addr) > static int max_dma_bits = 32; > > static int > -xen_swiotlb_fixup(void *buf, size_t size, unsigned long nslabs) > +xen_swiotlb_fixup(void *buf, size_t size, unsigned long nslabs, > + unsigned long *contig_pages) > { > int i, rc; > int dma_bits; > @@ -156,10 +157,13 @@ xen_swiotlb_fixup(void *buf, size_t size, unsigned long nslabs) > int slabs = min(nslabs - i, (unsigned long)IO_TLB_SEGSIZE); > > do { > + unsigned int order = get_order(slabs << IO_TLB_SHIFT); > rc = xen_create_contiguous_region( > p + (i << IO_TLB_SHIFT), > - get_order(slabs << IO_TLB_SHIFT), > + order, > dma_bits, &dma_handle); > + if (rc == 0) > + *contig_pages += 1 << order; > } while (rc && dma_bits++ < max_dma_bits); > if (rc) > return rc; > @@ -202,7 +206,7 @@ static const char *xen_swiotlb_error(enum xen_swiotlb_err err) > } > int __ref xen_swiotlb_init(int verbose, bool early) > { > - unsigned long bytes, order; > + unsigned long bytes, order, contig_pages; > int rc = -ENOMEM; > enum xen_swiotlb_err m_ret = XEN_SWIOTLB_UNKNOWN; > unsigned int repeat = 3; > @@ -244,13 +248,32 @@ int __ref xen_swiotlb_init(int verbose, bool early) > /* > * And replace that memory with pages under 4GB. > */ > + contig_pages = 0; > rc = xen_swiotlb_fixup(xen_io_tlb_start, > bytes, > - xen_io_tlb_nslabs); > + xen_io_tlb_nslabs, > + &contig_pages); > if (rc) { > - if (early) > + if (early) { > + unsigned long orig_bytes = bytes; > + while (repeat-- > 0) { > + xen_io_tlb_nslabs = max(1024UL, /* Min is 2MB */ > + (xen_io_tlb_nslabs >> 1)); > + pr_info("Lowering to %luMB\n", > + (xen_io_tlb_nslabs << IO_TLB_SHIFT) >> 20); > + bytes = xen_set_nslabs(xen_io_tlb_nslabs); > + order = get_order(xen_io_tlb_nslabs << IO_TLB_SHIFT); > + xen_io_tlb_end = xen_io_tlb_start + bytes; > + if (contig_pages >= (1ul << order)) { > + /* Enough pages were made contiguous */ > + memblock_free(__pa(xen_io_tlb_start + bytes), > + PAGE_ALIGN(orig_bytes - bytes)); > + goto fixup_done; > + } > + } > memblock_free(__pa(xen_io_tlb_start), > PAGE_ALIGN(bytes)); > + } > else { > free_pages((unsigned long)xen_io_tlb_start, order); > xen_io_tlb_start = NULL; > @@ -258,6 +281,7 @@ int __ref xen_swiotlb_init(int verbose, bool early) > m_ret = XEN_SWIOTLB_EFIXUP; > goto error; > } > +fixup_done: > start_dma_addr = xen_virt_to_bus(xen_io_tlb_start); > if (early) { > if (swiotlb_init_with_tbl(xen_io_tlb_start, xen_io_tlb_nslabs, > @@ -272,7 +296,7 @@ int __ref xen_swiotlb_init(int verbose, bool early) > > return rc; > error: > - if (repeat--) { > + if (repeat-- > 0) { > xen_io_tlb_nslabs = max(1024UL, /* Min is 2MB */ > (xen_io_tlb_nslabs >> 1)); > pr_info("Lowering to %luMB\n", > -- > 2.17.1 >
diff --git a/drivers/xen/swiotlb-xen.c b/drivers/xen/swiotlb-xen.c index 5dcb06fe9667..d2aba804d06c 100644 --- a/drivers/xen/swiotlb-xen.c +++ b/drivers/xen/swiotlb-xen.c @@ -142,7 +142,8 @@ static int is_xen_swiotlb_buffer(dma_addr_t dma_addr) static int max_dma_bits = 32; static int -xen_swiotlb_fixup(void *buf, size_t size, unsigned long nslabs) +xen_swiotlb_fixup(void *buf, size_t size, unsigned long nslabs, + unsigned long *contig_pages) { int i, rc; int dma_bits; @@ -156,10 +157,13 @@ xen_swiotlb_fixup(void *buf, size_t size, unsigned long nslabs) int slabs = min(nslabs - i, (unsigned long)IO_TLB_SEGSIZE); do { + unsigned int order = get_order(slabs << IO_TLB_SHIFT); rc = xen_create_contiguous_region( p + (i << IO_TLB_SHIFT), - get_order(slabs << IO_TLB_SHIFT), + order, dma_bits, &dma_handle); + if (rc == 0) + *contig_pages += 1 << order; } while (rc && dma_bits++ < max_dma_bits); if (rc) return rc; @@ -202,7 +206,7 @@ static const char *xen_swiotlb_error(enum xen_swiotlb_err err) } int __ref xen_swiotlb_init(int verbose, bool early) { - unsigned long bytes, order; + unsigned long bytes, order, contig_pages; int rc = -ENOMEM; enum xen_swiotlb_err m_ret = XEN_SWIOTLB_UNKNOWN; unsigned int repeat = 3; @@ -244,13 +248,32 @@ int __ref xen_swiotlb_init(int verbose, bool early) /* * And replace that memory with pages under 4GB. */ + contig_pages = 0; rc = xen_swiotlb_fixup(xen_io_tlb_start, bytes, - xen_io_tlb_nslabs); + xen_io_tlb_nslabs, + &contig_pages); if (rc) { - if (early) + if (early) { + unsigned long orig_bytes = bytes; + while (repeat-- > 0) { + xen_io_tlb_nslabs = max(1024UL, /* Min is 2MB */ + (xen_io_tlb_nslabs >> 1)); + pr_info("Lowering to %luMB\n", + (xen_io_tlb_nslabs << IO_TLB_SHIFT) >> 20); + bytes = xen_set_nslabs(xen_io_tlb_nslabs); + order = get_order(xen_io_tlb_nslabs << IO_TLB_SHIFT); + xen_io_tlb_end = xen_io_tlb_start + bytes; + if (contig_pages >= (1ul << order)) { + /* Enough pages were made contiguous */ + memblock_free(__pa(xen_io_tlb_start + bytes), + PAGE_ALIGN(orig_bytes - bytes)); + goto fixup_done; + } + } memblock_free(__pa(xen_io_tlb_start), PAGE_ALIGN(bytes)); + } else { free_pages((unsigned long)xen_io_tlb_start, order); xen_io_tlb_start = NULL; @@ -258,6 +281,7 @@ int __ref xen_swiotlb_init(int verbose, bool early) m_ret = XEN_SWIOTLB_EFIXUP; goto error; } +fixup_done: start_dma_addr = xen_virt_to_bus(xen_io_tlb_start); if (early) { if (swiotlb_init_with_tbl(xen_io_tlb_start, xen_io_tlb_nslabs, @@ -272,7 +296,7 @@ int __ref xen_swiotlb_init(int verbose, bool early) return rc; error: - if (repeat--) { + if (repeat-- > 0) { xen_io_tlb_nslabs = max(1024UL, /* Min is 2MB */ (xen_io_tlb_nslabs >> 1)); pr_info("Lowering to %luMB\n",
Current repeat code is plain broken for the early=true case. Xen exchanges all DMA (<4GB) pages that it can on the first xen_swiotlb_fixup() attempt. All further attempts with a halved region will fail immediately because all DMA pages already belong to Dom0. Introduce contig_pages param for xen_swiotlb_fixup() to track the number of pages that were made contiguous in MFN space and use the same bootmem region while halving the memory requirements. Signed-off-by: Sergey Dyasli <sergey.dyasli@citrix.com> --- CC: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> CC: Boris Ostrovsky <boris.ostrovsky@oracle.com> CC: Juergen Gross <jgross@suse.com> CC: Stefano Stabellini <sstabellini@kernel.org> CC: Paul Durrant <paul.durrant@citrix.com> --- drivers/xen/swiotlb-xen.c | 36 ++++++++++++++++++++++++++++++------ 1 file changed, 30 insertions(+), 6 deletions(-)