[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] [PATCH v3 5/7] xen/memory: Improve compat XENMEM_acquire_resource handling
The frame_list is an input, or an output, depending on whether the calling domain is translated or not. The array does not need marshalling in both directions. Furthermore, the copy-in loop was very inefficient, copying 4 bytes at at time. Rewrite it to copy in all nr_frames at once, and then expand compat_pfn_t to xen_pfn_t in place. Re-position the copy-in loop to simplify continuation support in a future patch, and reduce the scope of certain variables. No change in guest observed behaviour. Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx> Reviewed-by: Paul Durrant <paul@xxxxxxx> --- CC: George Dunlap <George.Dunlap@xxxxxxxxxxxxx> CC: Ian Jackson <iwj@xxxxxxxxxxxxxx> CC: Jan Beulich <JBeulich@xxxxxxxx> CC: Stefano Stabellini <sstabellini@xxxxxxxxxx> CC: Wei Liu <wl@xxxxxxx> CC: Julien Grall <julien@xxxxxxx> CC: Paul Durrant <paul@xxxxxxx> CC: Michał Leszczyński <michal.leszczynski@xxxxxxx> CC: Hubert Jasudowicz <hubert.jasudowicz@xxxxxxx> CC: Tamas K Lengyel <tamas@xxxxxxxxxxxxx> --- xen/common/compat/memory.c | 65 ++++++++++++++++++++++++++++------------------ 1 file changed, 40 insertions(+), 25 deletions(-) diff --git a/xen/common/compat/memory.c b/xen/common/compat/memory.c index ed92e05b08..834c5e19d1 100644 --- a/xen/common/compat/memory.c +++ b/xen/common/compat/memory.c @@ -55,6 +55,8 @@ static int get_reserved_device_memory(xen_pfn_t start, xen_ulong_t nr, int compat_memory_op(unsigned int cmd, XEN_GUEST_HANDLE_PARAM(void) compat) { + struct vcpu *curr = current; + struct domain *currd = curr->domain; int split, op = cmd & MEMOP_CMD_MASK; long rc; unsigned int start_extent = cmd >> MEMOP_EXTENT_SHIFT; @@ -399,7 +401,7 @@ int compat_memory_op(unsigned int cmd, XEN_GUEST_HANDLE_PARAM(void) compat) case XENMEM_acquire_resource: { - xen_pfn_t *xen_frame_list; + xen_pfn_t *xen_frame_list = NULL; unsigned int max_nr_frames; if ( copy_from_guest(&cmp.mar, compat, 1) ) @@ -417,28 +419,10 @@ int compat_memory_op(unsigned int cmd, XEN_GUEST_HANDLE_PARAM(void) compat) if ( cmp.mar.nr_frames > max_nr_frames ) return -E2BIG; - if ( compat_handle_is_null(cmp.mar.frame_list) ) - xen_frame_list = NULL; - else - { + /* Marshal the frame list in the remainder of the xlat space. */ + if ( !compat_handle_is_null(cmp.mar.frame_list) ) xen_frame_list = (xen_pfn_t *)(nat.mar + 1); - if ( !compat_handle_okay(cmp.mar.frame_list, - cmp.mar.nr_frames) ) - return -EFAULT; - - for ( i = 0; i < cmp.mar.nr_frames; i++ ) - { - compat_pfn_t frame; - - if ( __copy_from_compat_offset( - &frame, cmp.mar.frame_list, i, 1) ) - return -EFAULT; - - xen_frame_list[i] = frame; - } - } - #define XLAT_mem_acquire_resource_HNDL_frame_list(_d_, _s_) \ set_xen_guest_handle((_d_)->frame_list, xen_frame_list) @@ -446,6 +430,31 @@ int compat_memory_op(unsigned int cmd, XEN_GUEST_HANDLE_PARAM(void) compat) #undef XLAT_mem_acquire_resource_HNDL_frame_list + if ( xen_frame_list && cmp.mar.nr_frames ) + { + /* + * frame_list is an input for translated guests, and an output + * for untranslated guests. Only copy in for translated guests. + */ + if ( paging_mode_translate(currd) ) + { + compat_pfn_t *compat_frame_list = (void *)xen_frame_list; + + if ( !compat_handle_okay(cmp.mar.frame_list, + cmp.mar.nr_frames) || + __copy_from_compat_offset( + compat_frame_list, cmp.mar.frame_list, + 0, cmp.mar.nr_frames) ) + return -EFAULT; + + /* + * Iterate backwards over compat_frame_list[] expanding + * compat_pfn_t to xen_pfn_t in place. + */ + for ( int x = cmp.mar.nr_frames - 1; x >= 0; --x ) + xen_frame_list[x] = compat_frame_list[x]; + } + } break; } default: @@ -590,8 +599,6 @@ int compat_memory_op(unsigned int cmd, XEN_GUEST_HANDLE_PARAM(void) compat) case XENMEM_acquire_resource: { - const xen_pfn_t *xen_frame_list = (xen_pfn_t *)(nat.mar + 1); - compat_pfn_t *compat_frame_list = (compat_pfn_t *)(nat.mar + 1); DEFINE_XEN_GUEST_HANDLE(compat_mem_acquire_resource_t); if ( compat_handle_is_null(cmp.mar.frame_list) ) @@ -601,9 +608,18 @@ int compat_memory_op(unsigned int cmd, XEN_GUEST_HANDLE_PARAM(void) compat) compat_mem_acquire_resource_t), nat.mar, nr_frames) ) return -EFAULT; + break; } - else + + /* + * frame_list is an input for translated guests, and an output for + * untranslated guests. Only copy out for untranslated guests. + */ + if ( !paging_mode_translate(currd) ) { + const xen_pfn_t *xen_frame_list = (xen_pfn_t *)(nat.mar + 1); + compat_pfn_t *compat_frame_list = (compat_pfn_t *)(nat.mar + 1); + /* * NOTE: the smaller compat array overwrites the native * array. @@ -625,7 +641,6 @@ int compat_memory_op(unsigned int cmd, XEN_GUEST_HANDLE_PARAM(void) compat) cmp.mar.nr_frames) ) return -EFAULT; } - break; } -- 2.11.0
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