[Spice-devel] [PATCH v2 08/12] qxl-wddm-dod: Prepare for failure to allocate memory
Yuri Benditovich
yuri.benditovich at daynix.com
Mon Apr 3 12:52:39 UTC 2017
On Mon, Apr 3, 2017 at 1:55 PM, Frediano Ziglio <fziglio at redhat.com> wrote:
> >
> > From: "yuri.benditovich at daynix.com" <yuri.benditovich at daynix.com>
> >
> > Preparation for further scenarios when memory allocation failure
> > can happen and we'll need to use fallback when possible.
> > Memory allocation can fail in following cases:
> > - when non-forced memory allocation used and the attempt to allocate
> > the memory must be as fast as possible, without waits
> > - when forced memory allocation used, but the driver already received
> > stop command and waits for thread termination. Note that in case
> > the VSync control is enabled stop command may happen even after the
> video
> > subsystem executes switch to VGA mode. In such case QEMU will not
> return
> > previously allocated objects (assuming the QXL driver already disabled
> > and ignoring callbacks from Spice server in VGA mode).
> >
>
> Just to confirm, by VGA mode you mean when Windows attempt to unload the
> driver and use VESA/VGA modes, not VgaDevice, right?
> In this case I assume the memory will be freed when the driver is
> unloaded by Windows.
> I would expect the number of commands sent in this case is small.
> Also why is not possible to just ignore the commands sent by Windows
> in this case?
>
When VSync is enabled and the system activates watchdog policy, there are 2
possible flows
related to driver stopping:
First one is regular PnP stop (for example, on disable), on stop the driver
waits until thread
finishes and the thread is able to complete all the operations, in the
worst case it will take
some time until thread allocates all the pending drawables and sends them
down.
Second one is forced stop due to long processing of presentation callback.
We do
our best to avoid this, but this is still possible, at least in theory. In
this case OS
may not not wait until the driver completes stop flow and can activate
fallback
mode and make switch to VGA mode. If the thread is processing outstanding
drawables, it needs to allocate memory (forced) and may pend until some
previously allocated
objects must be reported by QEMU/spice server to the guest. As the switch
to VGA
already happened, QEMU does not report them (assuming the guest does need
this,
which is completely correct in case of regular stop). At the moment of VGA
switch the
thread can be in the middle of allocation, so the driver shall know to
abort the allocation if
stop flow already started.
BTW, In earlier notes you mentioned possibility to use VGA memory as
alternate area for
objects allocation. I think that in stop flow due to watchdog the VGA area
may be used by
fallback video engine as frame buffer and this can corrupt the memory arena
managed by mspace code.
> > In case of forced memory allocation the allocation routine waits
> > unpredictable time until the request is satisfied. In current commit
> > we do not acquire m_MemLock mutex for all this time, but release it
> > when entering long wait to allow another caller to try allocating memory.
> >
>
> Looking at final code AllocMem can return NULL in all cases depending
> on the state of the driver however not all paths check if this function
> returns NULL. Specifically InitMonitorConfig and SetClip.
> InitMonitorConfig is called just after initializing memory so is
> unlikely to fail and SetClip is always called with clip == NULL however
> I don't like to have unexploded bombs in the code.
>
> > Signed-off-by: Yuri Benditovich <yuri.benditovich at daynix.com>
> > ---
> > qxldod/QxlDod.cpp | 86
> > +++++++++++++++++++++++++++++++++++++++++++++++++------
> > qxldod/QxlDod.h | 3 +-
> > 2 files changed, 79 insertions(+), 10 deletions(-)
> >
> > diff --git a/qxldod/QxlDod.cpp b/qxldod/QxlDod.cpp
> > index aa70f39..f8440d4 100755
> > --- a/qxldod/QxlDod.cpp
> > +++ b/qxldod/QxlDod.cpp
> > @@ -3064,6 +3064,7 @@ QxlDevice::QxlDevice(_In_ QxlDod* pQxlDod)
> > m_FreeOutputs = 0;
> > m_Pending = 0;
> > m_PresentThread = NULL;
> > + m_bActive = FALSE;
> > }
> >
> > QxlDevice::~QxlDevice(void)
> > @@ -3490,14 +3491,19 @@ NTSTATUS QxlDevice::QxlInit(DXGK_DISPLA
> Y_INFORMATION*
> > pDispInfo)
> > Status = AcquireDisplayInfo(*(pDispInfo));
> > if (NT_SUCCESS(Status))
> > {
> > + m_bActive = TRUE;
> > Status = StartPresentThread();
> > }
> > + if (!NT_SUCCESS(Status)) {
> > + m_bActive = FALSE;
> > + }
> > return Status;
> > }
> >
> > void QxlDevice::QxlClose()
> > {
> > PAGED_CODE();
> > + m_bActive = FALSE;
> > StopPresentThread();
> > DestroyMemSlots();
> > }
> > @@ -3945,14 +3951,18 @@ void QxlDevice::WaitForReleaseRing(void)
> > {
> > PAGED_CODE();
> > int wait;
> > + BOOLEAN locked;
> >
> > DbgPrint(TRACE_LEVEL_VERBOSE, ("--->%s\n", __FUNCTION__));
> >
> > + locked = WaitForObject(&m_MemLock, NULL);
> > for (;;) {
> > LARGE_INTEGER timeout;
> >
> > if (SPICE_RING_IS_EMPTY(m_ReleaseRing)) {
> > + ReleaseMutex(&m_MemLock, locked);
> > QXL_SLEEP(10);
> > + locked = WaitForObject(&m_MemLock, NULL);
> > if (!SPICE_RING_IS_EMPTY(m_ReleaseRing)) {
> > break;
> > }
> > @@ -3960,17 +3970,20 @@ void QxlDevice::WaitForReleaseRing(void)
> > }
> > SPICE_RING_CONS_WAIT(m_ReleaseRing, wait);
> >
> > - if (!wait) {
> > + if (!wait || !m_bActive) {
> > break;
> > }
> >
> > + ReleaseMutex(&m_MemLock, locked);
> > timeout.QuadPart = -30 * 1000 * 10; //30ms
> > WaitForObject(&m_DisplayEvent, &timeout);
> > + locked = WaitForObject(&m_MemLock, NULL);
> >
> > if (SPICE_RING_IS_EMPTY(m_ReleaseRing)) {
> > SyncIo(QXL_IO_NOTIFY_OOM, 0);
> > }
> > }
> > + ReleaseMutex(&m_MemLock, locked);
> > DbgPrint(TRACE_LEVEL_VERBOSE, ("%s: <---\n", __FUNCTION__));
> > }
> >
> > @@ -4052,7 +4065,16 @@ void *QxlDevice::AllocMem(UINT32 mspace_type,
> size_t
> > size, BOOL force)
> > mspace_malloc_stats(m_MSInfo[mspace_type]._mspace);
> > #endif
> >
> > - locked = WaitForObject(&m_MemLock, NULL);
> > + if (force)
> > + locked = WaitForObject(&m_MemLock, NULL);
> > + else {
> > + LARGE_INTEGER doNotWait;
> > + doNotWait.QuadPart = 0;
> > + locked = WaitForObject(&m_MemLock, &doNotWait);
> > + if (!locked) {
> > + return NULL;
> > + }
> > + }
> >
> > while (1) {
> > /* Release lots of queued resources, before allocating, as we
> > @@ -4070,17 +4092,20 @@ void *QxlDevice::AllocMem(UINT32 mspace_type,
> size_t
> > size, BOOL force)
> > continue;
> > }
> >
> > - if (force) {
> > + if (force && m_bActive) {
> > /* Ask spice to free some stuff */
> > + ReleaseMutex(&m_MemLock, locked);
> > WaitForReleaseRing();
> > + locked = WaitForObject(&m_MemLock, NULL);
> > } else {
> > /* Fail */
> > break;
> > }
> > }
> > +
> > ReleaseMutex(&m_MemLock, locked);
> >
> > - ASSERT((!ptr && !force) || (ptr >= m_MSInfo[mspace_type].mspace_start
> &&
> > + ASSERT((!ptr && (!force || !m_bActive)) || (ptr >=
> > m_MSInfo[mspace_type].mspace_start &&
> > ptr <
> > m_MSInfo[mspace_type].mspace_e
> nd));
> > DbgPrint(TRACE_LEVEL_VERBOSE, ("<---%s: ptr 0x%x\n", __FUNCTION__,
> > ptr));
> > return ptr;
> > @@ -4113,6 +4138,9 @@ QXLDrawable *QxlDevice::GetDrawable()
> > QXLOutput *output;
> >
> > output = (QXLOutput *)AllocMem(MSPACE_TYPE_VRAM, sizeof(QXLOutput) +
> > sizeof(QXLDrawable), TRUE);
> > + if (!output) {
> > + return NULL;
> > + }
> > output->num_res = 0;
> > RESOURCE_TYPE(output, RESOURCE_TYPE_DRAWABLE);
> > ((QXLDrawable *)output->data)->release_info.id = (UINT64)output;
> > @@ -4128,6 +4156,9 @@ QXLCursorCmd *QxlDevice::CursorCmd()
> >
> > DbgPrint(TRACE_LEVEL_VERBOSE, ("---> %s\n", __FUNCTION__));
> > output = (QXLOutput *)AllocMem(MSPACE_TYPE_VRAM, sizeof(QXLOutput) +
> > sizeof(QXLCursorCmd), TRUE);
> > + if (!output) {
> > + return NULL;
> > + }
> > output->num_res = 0;
> > RESOURCE_TYPE(output, RESOURCE_TYPE_CURSOR);
> > cursor_cmd = (QXLCursorCmd *)output->data;
> > @@ -4277,6 +4308,9 @@ QXLDrawable *QxlDevice::Drawable(UINT8 type, CONST
> RECT
> > *area, CONST RECT *clip,
> > DbgPrint(TRACE_LEVEL_VERBOSE, ("---> %s\n", __FUNCTION__));
> >
> > drawable = GetDrawable();
> > + if (!drawable) {
> > + return NULL;
> > + }
> > drawable->surface_id = surface_id;
> > drawable->type = type;
> > drawable->effect = QXL_EFFECT_OPAQUE;
> > @@ -4420,6 +4454,11 @@ QXLDrawable *QxlDevice::PrepareBltBits (
> > alloc_size = BITMAP_ALLOC_BASE + BITS_BUF_MAX - BITS_BUF_MAX %
> > line_size;
> > alloc_size = MIN(BITMAP_ALLOC_BASE + height * line_size,
> alloc_size);
> > image_res = (Resource*)AllocMem(MSPACE_TYPE_VRAM, alloc_size,
> TRUE);
> > + if (!image_res) {
> > + ReleaseOutput(drawable->release_info.id);
> > + DbgPrint(TRACE_LEVEL_ERROR, ("Cannot allocate bitmap for
> > drawable\n"));
> > + return NULL;
> > + }
> >
> > image_res->refs = 1;
> > image_res->free = FreeBitmapImageEx;
> > @@ -4450,8 +4489,12 @@ QXLDrawable *QxlDevice::PrepareBltBits (
> > alloc_size = height * line_size;
> >
> > for (; src != src_end; src -= pSrc->Pitch, alloc_size -= line_size)
> {
> > - PutBytesAlign(&chunk, &dest, &dest_end, src,
> > - line_size, alloc_size, line_size);
> > + if (!PutBytesAlign(&chunk, &dest, &dest_end, src,
> > + line_size, alloc_size, line_size)) {
> > + ReleaseOutput(drawable->release_info.id);
> > + DbgPrint(TRACE_LEVEL_ERROR, ("Cannot allocate additional
> bitmap
> > for drawable\n"));
> > + return NULL;
> > + }
> > }
> >
> > internal->image.bitmap.palette = 0;
> > @@ -4472,7 +4515,7 @@ QXLDrawable *QxlDevice::PrepareBltBits (
> > return drawable;
> > }
> >
> > -VOID QxlDevice::PutBytesAlign(QXLDataChunk **chunk_ptr, UINT8
> **now_ptr,
> > +BOOLEAN QxlDevice::PutBytesAlign(QXLDataChunk **chunk_ptr, UINT8
> **now_ptr,
> > UINT8 **end_ptr, UINT8 *src, int size,
> > size_t alloc_size, uint32_t alignment)
> > {
> > @@ -4490,6 +4533,9 @@ VOID QxlDevice::PutBytesAlign(QXLDataChunk
> **chunk_ptr,
> > UINT8 **now_ptr,
> > aligned_size -= aligned_size % alignment;
> >
> > void *ptr = AllocMem(MSPACE_TYPE_VRAM, size +
> > sizeof(QXLDataChunk), TRUE);
> > + if (!ptr) {
> > + return FALSE;
> > + }
> > chunk->next_chunk = PA(ptr, m_SurfaceMemSlot);
> > ((QXLDataChunk *)ptr)->prev_chunk = PA(chunk,
> m_SurfaceMemSlot);
> > chunk = (QXLDataChunk *)ptr;
> > @@ -4510,6 +4556,7 @@ VOID QxlDevice::PutBytesAlign(QXLDataChunk
> **chunk_ptr,
> > UINT8 **now_ptr,
> > *now_ptr = now;
> > *end_ptr = end;
> > DbgPrint(TRACE_LEVEL_VERBOSE, ("<--- %s\n", __FUNCTION__));
> > + return TRUE;
> > }
> >
> > VOID QxlDevice::BlackOutScreen(CURRENT_BDD_MODE* pCurrentBddMod)
> > @@ -4573,6 +4620,11 @@ NTSTATUS QxlDevice::SetPointerShape(_In_ CONST
> > DXGKARG_SETPOINTERSHAPE* pSetPoi
> > int num_images = 1;
> >
> > cursor_cmd = CursorCmd();
> > + if (!cursor_cmd) {
> > + DbgPrint(TRACE_LEVEL_ERROR, ("%s: Failed to allocate cursor
> > command\n", __FUNCTION__));
> > + return STATUS_INSUFFICIENT_RESOURCES;
> > + }
> > +
> > cursor_cmd->type = QXL_CURSOR_SET;
> >
> > cursor_cmd->u.set.visible = TRUE;
> > @@ -4580,6 +4632,12 @@ NTSTATUS QxlDevice::SetPointerShape(_In_ CONST
> > DXGKARG_SETPOINTERSHAPE* pSetPoi
> > cursor_cmd->u.set.position.y = 0;
> >
> > res = (Resource *)AllocMem(MSPACE_TYPE_VRAM, CURSOR_ALLOC_SIZE,
> TRUE);
> > + if (!res) {
> > + DbgPrint(TRACE_LEVEL_ERROR, ("%s: Failed to allocate cursor
> data\n",
> > __FUNCTION__));
> > + ReleaseOutput(cursor_cmd->release_info.id);
> > + return STATUS_INSUFFICIENT_RESOURCES;
> > + }
> > +
> > res->refs = 1;
> > res->free = FreeCursorEx;
> > res->ptr = this;
> > @@ -4616,8 +4674,13 @@ NTSTATUS QxlDevice::SetPointerShape(_In_ CONST
> > DXGKARG_SETPOINTERSHAPE* pSetPoi
> > end = (UINT8 *)res + CURSOR_ALLOC_SIZE;
> > src_end = src + (pSetPointerShape->Pitch * pSetPointerShape->Height
> *
> > num_images);
> > for (; src != src_end; src += pSetPointerShape->Pitch) {
> > - PutBytesAlign(&chunk, &now, &end, src, line_size,
> > - PAGE_SIZE, 1);
> > + if (!PutBytesAlign(&chunk, &now, &end, src, line_size,
> > + PAGE_SIZE, 1))
> > + {
> > + DbgPrint(TRACE_LEVEL_ERROR, ("%s: Failed to allocate cursor
> > bitmap\n", __FUNCTION__));
> > + ReleaseOutput(cursor_cmd->release_info.id);
> > + return STATUS_INSUFFICIENT_RESOURCES;
> > + }
> > }
> > CursorCmdAddRes(cursor_cmd, res);
> > RELEASE_RES(res);
> > @@ -4638,6 +4701,11 @@ NTSTATUS QxlDevice::SetPointerPosition(_In_ CONST
> > DXGKARG_SETPOINTERPOSITION* pS
> > pSetPointerPosition->X,
> > pSetPointerPosition->Y));
> > QXLCursorCmd *cursor_cmd = CursorCmd();
> > + if (!cursor_cmd) {
> > + DbgPrint(TRACE_LEVEL_ERROR, ("%s: Failed to allocate cursor
> > command\n", __FUNCTION__));
> > + return STATUS_INSUFFICIENT_RESOURCES;
> > + }
> > +
> > if (pSetPointerPosition->X < 0 || !pSetPointerPosition->Flags.Visible)
> {
> > cursor_cmd->type = QXL_CURSOR_HIDE;
> > } else {
> > diff --git a/qxldod/QxlDod.h b/qxldod/QxlDod.h
> > index a1e9634..cbcd11e 100755
> > --- a/qxldod/QxlDod.h
> > +++ b/qxldod/QxlDod.h
> > @@ -601,7 +601,7 @@ private:
> > void PushCmd(void);
> > void WaitForCursorRing(void);
> > void PushCursor(void);
> > - void PutBytesAlign(QXLDataChunk **chunk_ptr, UINT8 **now_ptr,
> > + BOOLEAN PutBytesAlign(QXLDataChunk **chunk_ptr, UINT8 **now_ptr,
> > UINT8 **end_ptr, UINT8 *src, int size,
> > size_t alloc_size, uint32_t alignment);
> > void AsyncIo(UCHAR Port, UCHAR Value);
> > @@ -671,6 +671,7 @@ private:
> >
> > QXLPresentOnlyRing m_PresentRing[1];
> > HANDLE m_PresentThread;
> > + BOOLEAN m_bActive;
> > };
> >
> > class QxlDod {
>
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