| Message ID | 1489675444-34062-1-git-send-email-jennifer.herbert@citrix.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
> -----Original Message----- > From: Jennifer Herbert [mailto:jennifer.herbert@citrix.com] > Sent: 16 March 2017 14:44 > To: Xen-devel <xen-devel@lists.xen.org> > Cc: Jennifer Herbert <jennifer.herbert@citrix.com>; Jan Beulich > <jbeulich@suse.com>; Ian Jackson <Ian.Jackson@citrix.com>; Wei Liu > <wei.liu2@citrix.com>; Andrew Cooper <Andrew.Cooper3@citrix.com>; Paul > Durrant <Paul.Durrant@citrix.com> > Subject: [PATCH] dm_op: Add xendevicemodel_modified_memory_bulk. > > From: Jennifer Herbert <Jennifer.Herbert@citrix.com> > > This new lib devicemodel call allows multiple extents of pages to be > marked as modified in a single call. This is something needed for a > usecase I'm working on. > > The xen side of the modified_memory call has been modified to accept > an array of extents. The devicemodle library either provides an array > of length 1, to support the original library function, or a second > function allows an array to be provided. > > Signed-off-by: Jennifer Herbert <Jennifer.Herbert@citrix.com> > --- > Cc: Jan Beulich <jbeulich@suse.com> > Cc: Ian Jackson <ian.jackson@eu.citrix.com> > Cc: Wei Liu <wei.liu2@citrix.com> > Cc: Andrew Cooper <andrew.cooper3@citrix.com> > Cc: Paul Durrant <paul.durrant@citrix.com> > --- > tools/libs/devicemodel/core.c | 30 ++++-- > tools/libs/devicemodel/include/xendevicemodel.h | 20 +++- > xen/arch/x86/hvm/dm.c | 117 +++++++++++++++-------- > xen/include/public/hvm/dm_op.h | 12 ++- > 4 files changed, 125 insertions(+), 54 deletions(-) > > diff --git a/tools/libs/devicemodel/core.c b/tools/libs/devicemodel/core.c > index a85cb49..1f7a9dc 100644 > --- a/tools/libs/devicemodel/core.c > +++ b/tools/libs/devicemodel/core.c > @@ -434,22 +434,36 @@ int xendevicemodel_track_dirty_vram( > dirty_bitmap, (size_t)(nr + 7) / 8); > } > > -int xendevicemodel_modified_memory( > - xendevicemodel_handle *dmod, domid_t domid, uint64_t first_pfn, > - uint32_t nr) > +int xendevicemodel_modified_memory_bulk( > + xendevicemodel_handle *dmod, domid_t domid, > + struct xen_dm_op_modified_memory_extent *extents, uint32_t nr) > { > struct xen_dm_op op; > - struct xen_dm_op_modified_memory *data; > + struct xen_dm_op_modified_memory *header; > + size_t extents_size = nr * sizeof(struct > xen_dm_op_modified_memory_extent); > > memset(&op, 0, sizeof(op)); > > op.op = XEN_DMOP_modified_memory; > - data = &op.u.modified_memory; > + header = &op.u.modified_memory; > > - data->first_pfn = first_pfn; > - data->nr = nr; > + header->nr_extents = nr; > + header->offset = 0; > > - return xendevicemodel_op(dmod, domid, 1, &op, sizeof(op)); > + return xendevicemodel_op(dmod, domid, 2, &op, sizeof(op), > + extents, extents_size); > +} > + > +int xendevicemodel_modified_memory( > + xendevicemodel_handle *dmod, domid_t domid, uint64_t first_pfn, > + uint32_t nr) > +{ > + struct xen_dm_op_modified_memory_extent extent; > + > + extent.first_pfn = first_pfn; > + extent.nr = nr; > + > + return xendevicemodel_modified_memory_bulk(dmod, domid, &extent, > 1); > } > > int xendevicemodel_set_mem_type( > diff --git a/tools/libs/devicemodel/include/xendevicemodel.h > b/tools/libs/devicemodel/include/xendevicemodel.h > index b3f600e..b88d73c 100644 > --- a/tools/libs/devicemodel/include/xendevicemodel.h > +++ b/tools/libs/devicemodel/include/xendevicemodel.h > @@ -236,8 +236,8 @@ int xendevicemodel_track_dirty_vram( > uint32_t nr, unsigned long *dirty_bitmap); > > /** > - * This function notifies the hypervisor that a set of domain pages > - * have been modified. > + * This function notifies the hypervisor that a set of contiguous > + * domain pages have been modified. > * > * @parm dmod a handle to an open devicemodel interface. > * @parm domid the domain id to be serviced > @@ -249,6 +249,22 @@ int xendevicemodel_modified_memory( > xendevicemodel_handle *dmod, domid_t domid, uint64_t first_pfn, > uint32_t nr); > > + It looks like this blank line is extraneous. > +/** > + * This function notifies the hypervisor that a set of discontiguous > + * domain pages have been modified. > + * > + * @parm dmod a handle to an open devicemodel interface. > + * @parm domid the domain id to be serviced > + * @parm extents an array of extent structs, which each hold > + a start_pfn and nr (number of pfns). > + * @parm nr the number of extents in the array > + * @return 0 on success, -1 on failure. > + */ > +int xendevicemodel_modified_memory_bulk( > + xendevicemodel_handle *dmod, domid_t domid, > + struct xen_dm_op_modified_memory_extent extents[], uint32_t nr); > + > /** > * This function notifies the hypervisor that a set of domain pages > * are to be treated in a specific way. (See the definition of > diff --git a/xen/arch/x86/hvm/dm.c b/xen/arch/x86/hvm/dm.c > index 2122c45..0c4a820 100644 > --- 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; > + /* Process maximum of 255 pfns before checking for continuation */ 255 or 256? > + const uint32_t max_pfns = 0xff; > > - if ( (data->first_pfn > last_pfn) || > - (last_pfn > domain_get_maximum_gpfn(d)) ) > - return -EINVAL; > + xen_pfn_t last_pfn; > + int rc = 0; > + uint32_t offset = header->offset; > + unsigned long pfn; > + unsigned long max_pfn; > + unsigned max_nr; > + uint32_t rem_pfns = max_pfns; > > if ( !paging_mode_log_dirty(d) ) > return 0; > > - while ( iter < data->nr ) > + if ( (buf->size / sizeof(struct xen_dm_op_modified_memory_extent)) < > + header->nr_extents ) > + return -EINVAL; > + > + while ( offset < header->nr_extents ) > { > - unsigned long pfn = data->first_pfn + iter; > - struct page_info *page; > + struct xen_dm_op_modified_memory_extent extent; > > - page = get_page_from_gfn(d, pfn, NULL, P2M_UNSHARE); > - if ( page ) > + if ( copy_from_guest_offset(&extent, buf->h, offset, 1) ) > + return -EFAULT; > + > + last_pfn = extent.first_pfn + extent.nr - 1; > + > + if ( last_pfn > domain_get_maximum_gpfn(d) ) > + return -EINVAL; > + > + if ( extent.nr > rem_pfns ) > + max_nr = rem_pfns; > + else > { > - 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); > + max_nr = extent.nr; > + offset++; > } > > - iter++; > + rem_pfns -= max_nr; > + max_pfn = extent.first_pfn + max_nr; > > - /* > - * Check for continuation every 256th iteration and if the > - * iteration is not the last. > - */ > - if ( (iter < data->nr) && ((iter & 0xff) == 0) && > - hypercall_preempt_check() ) > + pfn = extent.first_pfn; > + while ( pfn < max_pfn ) > { > - data->first_pfn += iter; > - data->nr -= iter; > + struct page_info *page; > + page = get_page_from_gfn(d, pfn, NULL, P2M_UNSHARE); > + > + 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++; > + } > > - rc = -ERESTART; > - break; > + if ( max_nr < extent.nr ) > + { > + extent.first_pfn += max_nr; > + extent.nr-= max_nr; Missing space before -=. > + if ( copy_to_guest_offset(buf->h, offset, &extent, 1) ) > + return -EFAULT; > } > - } > > - return rc; > + /* > + * Check for continuation every 256th pfn and if the > + * pfn is not the last. > + */ > + > + if ( (rem_pfns == 0) && (offset <= header->nr_extents) ) > + { > + if ( hypercall_preempt_check() ) > + { > + header->offset = offset; > + rc = -ERESTART; > + break; > + } > + rem_pfns += max_pfns; > + } > + } > + return rc; > } > > static bool allow_p2m_type_change(p2m_type_t old, p2m_type_t new) > @@ -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 != -ERESTART); > break; > } > > diff --git a/xen/include/public/hvm/dm_op.h > b/xen/include/public/hvm/dm_op.h > index f54cece..1c602b1 100644 > --- a/xen/include/public/hvm/dm_op.h > +++ b/xen/include/public/hvm/dm_op.h > @@ -237,13 +237,19 @@ 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. This comment should really be transferred into a comment block for xen_dm_op_modified_memory_extent below since the extents are modified in the event of a continuation. > + * DMOP buf 1 contains an array of xen_dm_op_modified_memory_extent > with > + * nr_extent entries. > + * > + * On continuation, @offset is set to the next extent to be processed. > */ > #define XEN_DMOP_modified_memory 11 > > struct xen_dm_op_modified_memory { > + uint32_t nr_extents; /* IN - number of extents. */ > + uint32_t offset; /* Caller must set to 0. */ Again, I think it would be good to explain that this is used for continuations (to indicate the next extent to process) which is why it must be set to 0. Paul > +}; > + > +struct xen_dm_op_modified_memory_extent { > /* IN - number of contiguous pages modified */ > uint32_t nr; > uint32_t pad; > -- > 1.7.10.4
>>> On 16.03.17 at 15:44, <jennifer.herbert@citrix.com> 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; > + /* Process maximum of 255 pfns before checking for continuation */ > + const uint32_t max_pfns = 0xff; > > - if ( (data->first_pfn > last_pfn) || > - (last_pfn > domain_get_maximum_gpfn(d)) ) > - return -EINVAL; > + xen_pfn_t last_pfn; > + int rc = 0; > + uint32_t offset = header->offset; > + unsigned long pfn; > + unsigned long max_pfn; > + unsigned max_nr; > + uint32_t rem_pfns = max_pfns; Please avoid fixed width types when you don't really need them. Also "unsigned int" please instead of plain "unsigned". > if ( !paging_mode_log_dirty(d) ) > return 0; > > - while ( iter < data->nr ) > + if ( (buf->size / sizeof(struct xen_dm_op_modified_memory_extent)) < > + header->nr_extents ) Indentation. > + return -EINVAL; > + > + while ( offset < header->nr_extents ) > { > - unsigned long pfn = data->first_pfn + iter; > - struct page_info *page; > + struct xen_dm_op_modified_memory_extent extent; > > - page = get_page_from_gfn(d, pfn, NULL, P2M_UNSHARE); > - if ( page ) > + if ( copy_from_guest_offset(&extent, buf->h, offset, 1) ) > + return -EFAULT; > + > + last_pfn = extent.first_pfn + extent.nr - 1; > + > + if ( last_pfn > domain_get_maximum_gpfn(d) ) Where did the original "(data->first_pfn > last_pfn)" go? > + return -EINVAL; > + > + if ( extent.nr > rem_pfns ) > + max_nr = rem_pfns; > + else > { > - 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); > + max_nr = extent.nr; > + offset++; > } > > - iter++; > + rem_pfns -= max_nr; > + max_pfn = extent.first_pfn + max_nr; > > - /* > - * Check for continuation every 256th iteration and if the > - * iteration is not the last. > - */ > - if ( (iter < data->nr) && ((iter & 0xff) == 0) && > - hypercall_preempt_check() ) > + pfn = extent.first_pfn; > + while ( pfn < max_pfn ) The max_ prefixes chosen are somewhat problematic with a loop condition like this: "max" commonly means the maximum valid one rather than the first following item. Perhaps "end_pfn" and just "nr"? > { > - data->first_pfn += iter; > - data->nr -= iter; > + struct page_info *page; > + page = get_page_from_gfn(d, pfn, NULL, P2M_UNSHARE); > + > + 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++; > + } > > - rc = -ERESTART; > - break; > + if ( max_nr < extent.nr ) > + { > + extent.first_pfn += max_nr; > + extent.nr-= max_nr; > + if ( copy_to_guest_offset(buf->h, offset, &extent, 1) ) > + return -EFAULT; Is this copying back needed when not returning -ERESTART below? I do realize that with the current code structure it's needed for the copy_from above to read back the value, but even if this doesn't look to be a double fetch vulnerability I think it would be better if the value propagation would occur without going through guest memory. > } > - } > > - return rc; > + /* > + * Check for continuation every 256th pfn and if the > + * pfn is not the last. > + */ > + > + if ( (rem_pfns == 0) && (offset <= header->nr_extents) ) DYM < instead of <= here? > + { > + if ( hypercall_preempt_check() ) > + { > + header->offset = offset; > + rc = -ERESTART; > + break; > + } > + rem_pfns += max_pfns; rem_pfns is zero prior to this anyway: Please use = instead of += . > --- a/xen/include/public/hvm/dm_op.h > +++ b/xen/include/public/hvm/dm_op.h > @@ -237,13 +237,19 @@ 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_extent entries. > + * > + * On continuation, @offset is set to the next extent to be processed. > */ > #define XEN_DMOP_modified_memory 11 > > struct xen_dm_op_modified_memory { > + uint32_t nr_extents; /* IN - number of extents. */ > + uint32_t offset; /* Caller must set to 0. */ I think you should try to get away without this extra field: For the purpose here, incrementing the handle value together with decrementing nr_extents should be sufficient (just like done with various other batchable hypercalls). And if the field was to stay, "offset" is a bad name imo, as this leaves open whether this is byte- or extent-granular. "cur_extent" perhaps? Jan
diff --git a/tools/libs/devicemodel/core.c b/tools/libs/devicemodel/core.c index a85cb49..1f7a9dc 100644 --- a/tools/libs/devicemodel/core.c +++ b/tools/libs/devicemodel/core.c @@ -434,22 +434,36 @@ int xendevicemodel_track_dirty_vram( dirty_bitmap, (size_t)(nr + 7) / 8); } -int xendevicemodel_modified_memory( - xendevicemodel_handle *dmod, domid_t domid, uint64_t first_pfn, - uint32_t nr) +int xendevicemodel_modified_memory_bulk( + xendevicemodel_handle *dmod, domid_t domid, + struct xen_dm_op_modified_memory_extent *extents, uint32_t nr) { struct xen_dm_op op; - struct xen_dm_op_modified_memory *data; + struct xen_dm_op_modified_memory *header; + size_t extents_size = nr * sizeof(struct xen_dm_op_modified_memory_extent); memset(&op, 0, sizeof(op)); op.op = XEN_DMOP_modified_memory; - data = &op.u.modified_memory; + header = &op.u.modified_memory; - data->first_pfn = first_pfn; - data->nr = nr; + header->nr_extents = nr; + header->offset = 0; - return xendevicemodel_op(dmod, domid, 1, &op, sizeof(op)); + return xendevicemodel_op(dmod, domid, 2, &op, sizeof(op), + extents, extents_size); +} + +int xendevicemodel_modified_memory( + xendevicemodel_handle *dmod, domid_t domid, uint64_t first_pfn, + uint32_t nr) +{ + struct xen_dm_op_modified_memory_extent extent; + + extent.first_pfn = first_pfn; + extent.nr = nr; + + return xendevicemodel_modified_memory_bulk(dmod, domid, &extent, 1); } int xendevicemodel_set_mem_type( diff --git a/tools/libs/devicemodel/include/xendevicemodel.h b/tools/libs/devicemodel/include/xendevicemodel.h index b3f600e..b88d73c 100644 --- a/tools/libs/devicemodel/include/xendevicemodel.h +++ b/tools/libs/devicemodel/include/xendevicemodel.h @@ -236,8 +236,8 @@ int xendevicemodel_track_dirty_vram( uint32_t nr, unsigned long *dirty_bitmap); /** - * This function notifies the hypervisor that a set of domain pages - * have been modified. + * This function notifies the hypervisor that a set of contiguous + * domain pages have been modified. * * @parm dmod a handle to an open devicemodel interface. * @parm domid the domain id to be serviced @@ -249,6 +249,22 @@ int xendevicemodel_modified_memory( xendevicemodel_handle *dmod, domid_t domid, uint64_t first_pfn, uint32_t nr); + +/** + * This function notifies the hypervisor that a set of discontiguous + * domain pages have been modified. + * + * @parm dmod a handle to an open devicemodel interface. + * @parm domid the domain id to be serviced + * @parm extents an array of extent structs, which each hold + a start_pfn and nr (number of pfns). + * @parm nr the number of extents in the array + * @return 0 on success, -1 on failure. + */ +int xendevicemodel_modified_memory_bulk( + xendevicemodel_handle *dmod, domid_t domid, + struct xen_dm_op_modified_memory_extent extents[], uint32_t nr); + /** * This function notifies the hypervisor that a set of domain pages * are to be treated in a specific way. (See the definition of diff --git a/xen/arch/x86/hvm/dm.c b/xen/arch/x86/hvm/dm.c index 2122c45..0c4a820 100644 --- 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; + /* Process maximum of 255 pfns before checking for continuation */ + const uint32_t max_pfns = 0xff; - if ( (data->first_pfn > last_pfn) || - (last_pfn > domain_get_maximum_gpfn(d)) ) - return -EINVAL; + xen_pfn_t last_pfn; + int rc = 0; + uint32_t offset = header->offset; + unsigned long pfn; + unsigned long max_pfn; + unsigned max_nr; + uint32_t rem_pfns = max_pfns; if ( !paging_mode_log_dirty(d) ) return 0; - while ( iter < data->nr ) + if ( (buf->size / sizeof(struct xen_dm_op_modified_memory_extent)) < + header->nr_extents ) + return -EINVAL; + + while ( offset < header->nr_extents ) { - unsigned long pfn = data->first_pfn + iter; - struct page_info *page; + struct xen_dm_op_modified_memory_extent extent; - page = get_page_from_gfn(d, pfn, NULL, P2M_UNSHARE); - if ( page ) + if ( copy_from_guest_offset(&extent, buf->h, offset, 1) ) + return -EFAULT; + + last_pfn = extent.first_pfn + extent.nr - 1; + + if ( last_pfn > domain_get_maximum_gpfn(d) ) + return -EINVAL; + + if ( extent.nr > rem_pfns ) + max_nr = rem_pfns; + else { - 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); + max_nr = extent.nr; + offset++; } - iter++; + rem_pfns -= max_nr; + max_pfn = extent.first_pfn + max_nr; - /* - * Check for continuation every 256th iteration and if the - * iteration is not the last. - */ - if ( (iter < data->nr) && ((iter & 0xff) == 0) && - hypercall_preempt_check() ) + pfn = extent.first_pfn; + while ( pfn < max_pfn ) { - data->first_pfn += iter; - data->nr -= iter; + struct page_info *page; + page = get_page_from_gfn(d, pfn, NULL, P2M_UNSHARE); + + 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++; + } - rc = -ERESTART; - break; + if ( max_nr < extent.nr ) + { + extent.first_pfn += max_nr; + extent.nr-= max_nr; + if ( copy_to_guest_offset(buf->h, offset, &extent, 1) ) + return -EFAULT; } - } - return rc; + /* + * Check for continuation every 256th pfn and if the + * pfn is not the last. + */ + + if ( (rem_pfns == 0) && (offset <= header->nr_extents) ) + { + if ( hypercall_preempt_check() ) + { + header->offset = offset; + rc = -ERESTART; + break; + } + rem_pfns += max_pfns; + } + } + return rc; } static bool allow_p2m_type_change(p2m_type_t old, p2m_type_t new) @@ -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 != -ERESTART); break; } diff --git a/xen/include/public/hvm/dm_op.h b/xen/include/public/hvm/dm_op.h index f54cece..1c602b1 100644 --- a/xen/include/public/hvm/dm_op.h +++ b/xen/include/public/hvm/dm_op.h @@ -237,13 +237,19 @@ 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_extent entries. + * + * On continuation, @offset is set to the next extent to be processed. */ #define XEN_DMOP_modified_memory 11 struct xen_dm_op_modified_memory { + uint32_t nr_extents; /* IN - number of extents. */ + uint32_t offset; /* Caller must set to 0. */ +}; + +struct xen_dm_op_modified_memory_extent { /* IN - number of contiguous pages modified */ uint32_t nr; uint32_t pad;