|
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH v3] dm_op: Add xendevicemodel_modified_memory_bulk.
>>> On 28.03.17 at 15:18, <jennifer.herbert@xxxxxxxxxx> wrote:
> --- a/xen/arch/x86/hvm/dm.c
> +++ b/xen/arch/x86/hvm/dm.c
> @@ -119,56 +119,96 @@ static int set_isa_irq_level(struct domain *d, uint8_t
> isa_irq,
> }
>
> static int modified_memory(struct domain *d,
> - struct xen_dm_op_modified_memory *data)
> + struct xen_dm_op_modified_memory *header,
> + xen_dm_op_buf_t* buf)
> {
> - xen_pfn_t last_pfn = data->first_pfn + data->nr - 1;
> - unsigned int iter = 0;
> - int rc = 0;
> -
> - if ( (data->first_pfn > last_pfn) ||
> - (last_pfn > domain_get_maximum_gpfn(d)) )
> - return -EINVAL;
> + /* Process maximum of 256 pfns before checking for continuation */
> + const unsigned int cont_check_interval = 0x100;
> + unsigned int rem_extents = header->nr_extents;
> + unsigned int batch_rem_pfns = cont_check_interval;
>
> if ( !paging_mode_log_dirty(d) )
> return 0;
>
> - while ( iter < data->nr )
> + if ( (buf->size / sizeof(struct xen_dm_op_modified_memory_extent)) <
> + rem_extents )
> + return -EINVAL;
I'm sorry for noticing this only now, but I think this together with the
open coded copy below calls for a copy_buf_from_guest_offset()
helper.
> + while ( rem_extents > 0)
> {
> - unsigned long pfn = data->first_pfn + iter;
> - struct page_info *page;
> + struct xen_dm_op_modified_memory_extent extent;
> + unsigned int batch_nr;
> + xen_pfn_t pfn;
> + xen_pfn_t end_pfn;
> + unsigned int *pfns_already_done;
Perhaps drop "already"? Personally I also wouldn't mind you
dropping the variable altogether and using header->opaque
directly, but I guess that's too "opaque" for your taste?
> - page = get_page_from_gfn(d, pfn, NULL, P2M_UNSHARE);
> - if ( page )
> + if ( copy_from_guest_offset(&extent, buf->h, rem_extents - 1, 1) )
> + return -EFAULT;
> + /*
> + * In the case of continuation, header->opaque contains the
> + * number of pfns already processed for this extent
> + */
> + pfns_already_done = &header->opaque;
If you want to keep the variable, this should be moved out of the
loop (as being loop invariant).
> + if (*pfns_already_done >= extent.nr || extent.pad)
> + return -EINVAL;
> +
> + pfn = extent.first_pfn + *pfns_already_done;
> + batch_nr = extent.nr - *pfns_already_done;
> +
> + if ( batch_nr > batch_rem_pfns )
> {
> - mfn_t gmfn = _mfn(page_to_mfn(page));
> -
> - paging_mark_dirty(d, gmfn);
> - /*
> - * These are most probably not page tables any more
> - * don't take a long time and don't die either.
> - */
> - sh_remove_shadows(d, gmfn, 1, 0);
> - put_page(page);
> + batch_nr = batch_rem_pfns;
> + *pfns_already_done += batch_nr;
> + }
> + else
> + {
> + rem_extents--;
> + *pfns_already_done = 0;
> }
>
> - iter++;
> + batch_rem_pfns -= batch_nr;
> + end_pfn = pfn + batch_nr;
> +
> + if ( (pfn >= end_pfn) ||
> + (end_pfn > domain_get_maximum_gpfn(d)) )
> + return -EINVAL;
I think these checks should be done of the extent as a whole, not
just the portion you mean to process in this batch.
> + header->nr_extents = rem_extents;
> +
> + while ( pfn < end_pfn )
> + {
> + struct page_info *page;
> + page = get_page_from_gfn(d, pfn, NULL, P2M_UNSHARE);
Either make this the initializer, or have a blank line between
declaration and statements.
> + if ( page )
> + {
> + mfn_t gmfn = _mfn(page_to_mfn(page));
> +
> + paging_mark_dirty(d, gmfn);
> + /*
> + * These are most probably not page tables any more
> + * don't take a long time and don't die either.
> + */
> + sh_remove_shadows(d, gmfn, 1, 0);
> + put_page(page);
> + }
> + pfn++;
> + }
Would you mind bringing this in for() form?
> /*
> - * Check for continuation every 256th iteration and if the
> - * iteration is not the last.
> + * Check for continuation every 256th pfn and if the
> + * pfn is not the last.
> */
> - if ( (iter < data->nr) && ((iter & 0xff) == 0) &&
> - hypercall_preempt_check() )
> + if ( (batch_rem_pfns == 0) && (rem_extents > 0) )
Looking at this again I think it would be best to drop the mention
of 256 here, instead talking about a fully handled batch or some
such.
> @@ -441,13 +481,8 @@ static int dm_op(domid_t domid,
> struct xen_dm_op_modified_memory *data =
> &op.u.modified_memory;
>
> - const_op = false;
> -
> - rc = -EINVAL;
> - if ( data->pad )
> - break;
> -
> - rc = modified_memory(d, data);
> + rc = modified_memory(d, data, &bufs[1]);
> + const_op = (rc != 0);
Isn't this wrong now, i.e. don't you need to copy back the
header now in all cases?
> --- a/xen/include/public/hvm/dm_op.h
> +++ b/xen/include/public/hvm/dm_op.h
> @@ -237,13 +237,29 @@ struct xen_dm_op_set_pci_link_route {
> * XEN_DMOP_modified_memory: Notify that a set of pages were modified by
> * an emulator.
> *
> - * NOTE: In the event of a continuation, the @first_pfn is set to the
> - * value of the pfn of the remaining set of pages and @nr reduced
> - * to the size of the remaining set.
> + * DMOP buf 1 contains an array of xen_dm_op_modified_memory_extent with
> + * @nr_extents entries.
> + * @opaque must be initially set to 0.
> + *
> + * On error, @nr_extents will contain the index+1 of the extent that
> + * had the error. It is not defined if or which pages may have been
> + * marked as dirty, in this event.
> + *
> + * @opaque must be initially set to 0.
Please say so just once.
> struct xen_dm_op_modified_memory {
> + /*
> + * IN - Number of extents to be processed
> + * OUT -returns n+1 for failing extent
> + */
> + uint32_t nr_extents;
This n+1 thing is somewhat odd, but I guess it can't be prevented
without going through extra hoops.
Jan
_______________________________________________
Xen-devel mailing list
Xen-devel@xxxxxxxxxxxxx
https://lists.xen.org/xen-devel
|
 |
Lists.xenproject.org is hosted with RackSpace, monitoring our |