Fixes read after freeing error reported
https://lists.gnu.org/archive/html/qemu-devel/2017-08/msg04243.html
Message-Id: <59a56959-ca12-ea75-33fa-ff07eba1b090@redhat.com>
ich9-ahci device creates ide buses and attaches them as QOM children
at realize time, however it forgets to properly clean them up
at unrealize time and frees memory containing these children,
with following call-chain:
qdev_device_add()
object_property_set_bool('realized', true)
device_set_realized()
...
pci_qdev_realize() -> pci_ich9_ahci_realize() -> ahci_realize()
...
s->dev = g_new0(AHCIDevice, ports);
...
AHCIDevice *ad = &s->dev[i];
ide_bus_new(&ad->port, sizeof(ad->port), qdev, i, 1);
^^^ creates bus in memory allocated by above gnew()
and adds it as child propety to ahci device
...
hotplug_handler_plug(); -> goto post_realize_fail;
pci_qdev_unrealize() -> pci_ich9_uninit() -> ahci_uninit()
...
g_free(s->dev);
^^^ free memory that holds children busses
return with error from device_set_realized()
As result later when qdev_device_add() tries to unparent ich9-ahci
after failed device_set_realized(),
object_unparent() -> object_property_del_child()
iterates over existing QOM children including buses added by
ide_bus_new() and tries to unparent them, which causes access to
freed memory where they where located.
Reported-by: Thomas Huth <thuth@redhat.com>
Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Tested-by: Thomas Huth <thuth@redhat.com>
Reviewed-by: John Snow <jsnow@redhat.com>
Message-id: 1503938085-169486-1-git-send-email-imammedo@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>
Complete the split by renaming ahci_public.h --> ahci.h and
moving the current ahci.h to hw/ide/ahci_internal.h.
Adjust ahci_internal.h to now load ahci.h instead of ahci_public.h.
Finalize the split by switching external users to the new header.
Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Tested-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-id: 20170623220926.11479-4-jsnow@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>
Instead of reaching into the PCI state, allow the AHCIDevice to
respond with how many ports it has.
Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Tested-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-id: 20170623220926.11479-2-jsnow@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>
In some cases a failing VMSTATE_*_EQUAL does not mean we detected a bug,
but it's actually the best we can do. Especially in these cases a verbose
error message is required.
Let's introduce infrastructure for specifying a error hint to be used if
equal check fails. Let's do this by adding a parameter to the _EQUAL
macros called _err_hint. Also change all current users to pass NULL as
last parameter so nothing changes for them.
Signed-off-by: Halil Pasic <pasic@linux.vnet.ibm.com>
Message-Id: <20170623144823.42936-1-pasic@linux.vnet.ibm.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
This can avoid memory leak when hotunplug the ahci device.
Signed-off-by: Li Qiang <liqiang6-s@360.cn>
Message-id: 1488449293-80280-4-git-send-email-liqiang6-s@360.cn
Signed-off-by: John Snow <jsnow@redhat.com>
The AHCI emulation code supports 64-bit addressing and should advertise this
fact in the Host Capabilities register. Both Linux and Windows drivers test
this bit to decide if the upper 32 bits of various registers may be written
to, and at least some versions of Windows have a bug where DMA is attempted
with an address above 4GB but, in the absence of HOST_CAP_64, the upper 32
bits are left unititialized which leads to a memory corruption.
[Maintainer edit:
This fixes https://bugzilla.redhat.com/show_bug.cgi?id=1411105,
which affects Windows Server 2008 SP2 in some cases.]
Signed-off-by: Ladi Prosek <lprosek@redhat.com>
Message-id: 1484305370-6220-1-git-send-email-lprosek@redhat.com
[Amended commit message --js]
Signed-off-by: John Snow <jsnow@redhat.com>
The hard-coded default alignment is BDRV_SECTOR_SIZE, however this is not
necessarily the case for all platforms. Use this as the default alignment for
all current callers.
Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Reviewed-by: Eric Blake <eblake@redhat.com>
Acked-by: John Snow <jsnow@redhat.com>
Message-id: 1476445266-27503-2-git-send-email-mark.cave-ayland@ilande.co.uk
Signed-off-by: John Snow <jsnow@redhat.com>
Similar to existing fixes for IDE (87ac25fd) and ATAPI (7f951b2d), the
AIOCB must be cleared in the callback. Otherwise, we may accidentally
try to reset a dangling pointer in bdrv_aio_cancel() from a port reset.
Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 1474575040-32079-2-git-send-email-jsnow@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>
ahci-test /x86_64/ahci/io/dma/lba28/retry triggers the following leak:
Direct leak of 16 byte(s) in 1 object(s) allocated from:
#0 0x7fc4b2a25e20 in malloc (/lib64/libasan.so.3+0xc6e20)
#1 0x7fc4993bce58 in g_malloc (/lib64/libglib-2.0.so.0+0x4ee58)
#2 0x556a187d4b34 in ahci_populate_sglist hw/ide/ahci.c:896
#3 0x556a187d8237 in ahci_dma_prepare_buf hw/ide/ahci.c:1367
#4 0x556a187b5a1a in ide_dma_cb hw/ide/core.c:844
#5 0x556a187d7eec in ahci_start_dma hw/ide/ahci.c:1333
#6 0x556a187b650b in ide_start_dma hw/ide/core.c:921
#7 0x556a187b61e6 in ide_sector_start_dma hw/ide/core.c:911
#8 0x556a187b9e26 in cmd_write_dma hw/ide/core.c:1486
#9 0x556a187bd519 in ide_exec_cmd hw/ide/core.c:2027
#10 0x556a187d71c5 in handle_reg_h2d_fis hw/ide/ahci.c:1204
#11 0x556a187d7681 in handle_cmd hw/ide/ahci.c:1254
#12 0x556a187d168a in check_cmd hw/ide/ahci.c:510
#13 0x556a187d0afc in ahci_port_write hw/ide/ahci.c:314
#14 0x556a187d105d in ahci_mem_write hw/ide/ahci.c:435
#15 0x556a1831d959 in memory_region_write_accessor /home/elmarco/src/qemu/memory.c:525
#16 0x556a1831dc35 in access_with_adjusted_size /home/elmarco/src/qemu/memory.c:591
#17 0x556a18323ce3 in memory_region_dispatch_write /home/elmarco/src/qemu/memory.c:1262
#18 0x556a1828cf67 in address_space_write_continue /home/elmarco/src/qemu/exec.c:2578
#19 0x556a1828d20b in address_space_write /home/elmarco/src/qemu/exec.c:2635
#20 0x556a1828d92b in address_space_rw /home/elmarco/src/qemu/exec.c:2737
#21 0x556a1828daf7 in cpu_physical_memory_rw /home/elmarco/src/qemu/exec.c:2746
#22 0x556a183068d3 in cpu_physical_memory_write /home/elmarco/src/qemu/include/exec/cpu-common.h:72
#23 0x556a18308194 in qtest_process_command /home/elmarco/src/qemu/qtest.c:382
#24 0x556a18309999 in qtest_process_inbuf /home/elmarco/src/qemu/qtest.c:573
#25 0x556a18309a4a in qtest_read /home/elmarco/src/qemu/qtest.c:585
#26 0x556a18598b85 in qemu_chr_be_write_impl /home/elmarco/src/qemu/qemu-char.c:387
#27 0x556a18598c52 in qemu_chr_be_write /home/elmarco/src/qemu/qemu-char.c:399
#28 0x556a185a2afa in tcp_chr_read /home/elmarco/src/qemu/qemu-char.c:2902
#29 0x556a18cbaf52 in qio_channel_fd_source_dispatch io/channel-watch.c:84
Follow John Snow recommendation:
Everywhere else ncq_err is used, it is accompanied by a list cleanup
except for ncq_cb, which is the case you are fixing here.
Move the sglist destruction inside of ncq_err and then delete it from
the other two locations to keep it tidy.
Call dma_buf_commit in ide_dma_cb after the early return. Though, this
is also a little wonky because this routine does more than clear the
list, but it is at the moment the centralized "we're done with the
sglist" function and none of the other side effects that occur in
dma_buf_commit will interfere with the reset that occurs from
ide_restart_bh, I think
Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: John Snow <jsnow@redhat.com>
Each irq is referenced by the IDEBus in ide_init2(), thus we can free
the no longer used array.
Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Reviewed-by: John Snow <jsnow@redhat.com>
Acked-by: John Snow <jsnow@redhat.com>
Tracked down with an ugly, brittle and probably buggy Perl script.
Also move includes converted to <...> up so they get included before
ours where that's obviously okay.
Signed-off-by: Markus Armbruster <armbru@redhat.com>
Reviewed-by: Eric Blake <eblake@redhat.com>
Tested-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Richard Henderson <rth@twiddle.net>
If the FIS or DMA engines are already started, do not allow them to be
"restarted." As a side-effect of this change, the migration post-load
routine must be modified to cope. If the engines are listed as "on"
in the migrated registers, they must be cleared to allow the startup
routine to see the transition from "off" to "on".
As a second side-effect, the extra argument to ahci_cond_engine_start
is removed in favor of consistent behavior.
Signed-off-by: John Snow <jsnow@redhat.com>
Message-id: 1454103689-13042-5-git-send-email-jsnow@redhat.com
Currently, we let ahci_cond_start_engines reject weird configurations
where either the DMA (CLB) or FIS engines are said to be started, but
their matching on/off control bit is toggled off.
There should be no way to achieve this, since any time you toggle the
control bit off, the status bit should always follow synchronously.
Preparing for a refactor in cond_start_engines, move the rejection logic
straight up into post_load.
Signed-off-by: John Snow <jsnow@redhat.com>
Message-id: 1454103689-13042-4-git-send-email-jsnow@redhat.com
Instead of relying on ahci_cond_start_engines to maintain the
engine status indicators itself, have the lower-layer CLB and FIS mapper
helpers do it themselves.
This makes the cond_start routine slightly nicer to read, and makes sure
that the status indicators will always be correct.
Signed-off-by: John Snow <jsnow@redhat.com>
Message-id: 1454103689-13042-3-git-send-email-jsnow@redhat.com
Clean up includes so that osdep.h is included first and headers
which it implies are not included manually.
This commit was created with scripts/clean-includes.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Message-id: 1453832250-766-17-git-send-email-peter.maydell@linaro.org
When processing NCQ commands, AHCI device emulation prepares a
NCQ transfer object; To which an aio control block(aiocb) object
is assigned in 'execute_ncq_command'. In case, when the NCQ
command is invalid, the 'aiocb' object is not assigned, and NCQ
transfer object is left as 'used'. This leads to a use after
free kind of error in 'bdrv_aio_cancel_async' via 'ahci_reset_port'.
Reset NCQ transfer object to 'unused' to avoid it.
[Maintainer edit: s/ACHI/AHCI/ in the commit message. --js]
Reported-by: Qinghao Tang <luodalongde@gmail.com>
Signed-off-by: Prasad J Pandit <pjp@fedoraproject.org>
Reviewed-by: John Snow <jsnow@redhat.com>
Message-id: 1452282511-4116-1-git-send-email-ppandit@redhat.com
Signed-off-by: John Snow <jsnow@redhat.com>
Add a Sysbus AHCI subclass for the Allwinner AHCI. It has a few extra
vendor specific registers which are used for phy and power init.
Signed-off-by: Peter Crosthwaite <crosthwaite.peter@gmail.com>
Reviewed-by: John Snow <jsnow@redhat.com>
Message-id: 833b5b05ed5ade38bf69656679b0a7575e79492b.1445917756.git.crosthwaite.peter@gmail.com
[resolved patch context on pull --js]
Signed-off-by: John Snow <jsnow@redhat.com>
Do the init level tasks asap and the realize later (mainly when
num_ports is available). This allows sub-class realize routines
to work with the device post-init.
Signed-off-by: Peter Crosthwaite <crosthwaite.peter@gmail.com>
Reviewed-by: John Snow <jsnow@redhat.com>
Message-id: 1a7c7b2b32e5ccf49373a5065da5ece89730d3ac.1445917756.git.crosthwaite.peter@gmail.com
Signed-off-by: John Snow <jsnow@redhat.com>
Not that you can request a >2GiB transaction, but that's why checking
for it makes no sense anymore.
With the newer 'limit' parameter to prepare_buf, we no longer need a
static limit. The maximum limit is still 2GiB, but the limit parameter
is set to the current transaction size, which cannot surpass 32MiB
(512 * 65536). If the PRDT surpasses the transactional size, then,
we'll just carry out the normative underflow handling pathways instead
of needing an extra, strange pathway that worries about hitting some
logistical cap for the largest sglist we can support -- we'll never
even attempt to build one that big anymore.
Reported-by: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: John Snow <jsnow@redhat.com>
Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 1445902682-20051-1-git-send-email-jsnow@redhat.com
Avoid undefined behaviour from shifting left into the sign bit:
hw/ide/ahci.c:551:36: runtime error: left shift of 255 by 24 places cannot be represented in type 'int'
(Unfortunately C's promotion rules mean that in the expression
"some_uint8_t_variable << 24" the LHS gets promoted to signed
int before shifting.)
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: John Snow <jsnow@redhat.com>
with write_fis_d2h and signature generation tidied up,
let's adjust the initial d2h semantics to make more sense.
The initial d2h is considered delivered if there is guest
memory to save it to.
Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 1441140641-17631-5-git-send-email-jsnow@redhat.com
It's no longer used. We used to generate a D2H FIS based
upon the command FIS that prompted the update, but in reality,
the D2H FIS is generated purely from register state.
cmd_fis is vestigial, so get rid of it.
Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 1441140641-17631-4-git-send-email-jsnow@redhat.com
The initial register device-to-host FIS no longer needs to specially
set certain fields, as these can be handled generically by setting those
fields explicitly with the signatures we want at port reset time.
(1) Signatures are decomposed into their four component registers and
set upon (AHCI) port reset.
(2) the signature cache register is no longer set manually per-each
device type, but instead just once during ahci_init_d2h.
Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 1441140641-17631-3-git-send-email-jsnow@redhat.com
This check is dead due to an earlier conditional.
AHCI does not currently support hotplugging, so
checks to see if devices are present or not are useless.
Remove it.
Reported-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 1441140641-17631-2-git-send-email-jsnow@redhat.com
IDEState's io_buffer_offset was originally added to keep track of offsets
in AHCI rather exclusively, but it was added to IDEState instead of an
AHCI-specific structure.
AHCI fakes all PIO transfers using DMA and a scatter-gather list. When
the core or atapi layers invoke HBA-specific mechanisms for transfers,
they do not always know that it is being backed by DMA or a sglist, so
this offset is not always updated by the HBA code everywhere.
If we modify it in dma_buf_commit, however, any HBA that needs to use
this offset to manage operating on only part of a sglist will have
access to it.
This will fix ATAPI PIO transfers performed through the AHCI HBA,
which were previously not modifying this value appropriately.
This will fix ATAPI PIO transfers larger than one sector.
Reported-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Paolo Bonzini <pbonzini@redhat.com>
Tested-by: Laszlo Ersek <lersek@redhat.com>
Message-id: 1440546331-29087-2-git-send-email-jsnow@redhat.com
CC: qemu-stable@nongnu.org
Minor cleanup.
Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Gonglei <arei.gonglei@huawei.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Signed-off-by: Michael Tokarev <mjt@tls.msk.ru>
The AHCIState struct can either have AHCIPCIState or SysbusAHCIState
as a parent. The ahci_irq_lower() and ahci_irq_raise() functions
assume that it is always AHCIPCIState, which is not always the
case, which causes a seg fault. Verify what the container of AHCIState
is before setting the PCIDevice struct.
Signed-off-by: Alistair Francis <alistair.francis@xilinx.com>
Acked-by: John Snow <jsnow@redhat.com>
Reviewed-by: Peter Crosthwaite <crosthwaite.peter@gmail.com>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Pull the AHCI state structure out into the header. This allows
other containers to access the struct. This is required to add
the device to modern SoC containers.
Signed-off-by: Alistair Francis <alistair.francis@xilinx.com>
Reviewed-by: Sai Pavan Boddu <saipava@xilinx.com>
Reviewed-by: Peter Crosthwaite <crosthwaite.peter@gmail.com>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
The AHCI spec requires that the HBA sets the ICC bits to zero after the
ICC change is done. Since we don't do any ICC change, force the bits to
zero all the time.
This fixes delays with some OSs (e.g. OpenBSD) waiting for the ICC bits
to change to 0.
Signed-off-by: Stefan Fritsch <sf@sfritsch.de>
Reviewed-by: Kevin Wolf <kwolf@redhat.com>
Reviewed-by: John Snow <jsnow@redhat.com>
Message-id: E1ZFpg7-00027N-HW@eru.sfritsch.de
Signed-off-by: John Snow <jsnow@redhat.com>
There are two things to fix here:
The first one is subtle: the PxSACT register in the AHCI HBA has different
semantics from the field it is shadowing, the ACT field in the
Set Device Bits FIS.
In the HBA register, PxSACT acts as a bitfield indicating outstanding
NCQ commands where a set bit indicates a pending NCQ operation. The FIS
field however operates as an RWC register update to PxSACT, where a set
bit indicates a *successfully* completed command.
Correct the FIS semantics. At the same time, move the "clear finished"
action to the SDB FIS generation instead of the register read to mimick
how the other shadow registers work, which always just report the last
reported value from a FIS, and not the most current values which may
not have been reported by a FIS yet.
Lastly and more simply, SATA 3.2 section 13.6.4.2 (and later sections)
all specify that the Interrupt bit for the SDB FIS should always be set
to one for NCQ commands. That's currently the only time we generate this
FIS, so set it on all the time.
Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 1435767578-32743-16-git-send-email-jsnow@redhat.com
The Register D2H FIS should copy the current values of
the registers instead of just parroting back the same
values the guest sent back to it.
In this case, the SECTOR COUNT variables are actually
not generally meaningful in terms of standard commands
(See ATA8-AC3 Section 9.2 Normal Outputs), so it actually
probably doesn't matter what we put in here.
Meanwhile, we do need to use the Register update FIS from
the NCQ pathways (in error cases), so getting rid of
references to cur_cmd here is a win for AHCI concurrency.
Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 1435767578-32743-14-git-send-email-jsnow@redhat.com
Migrate the NCQ queue. This is solely for the benefit of halted commands,
since anything else should have completed and had any relevant status
flushed to the HBA registers already.
Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 1435767578-32743-13-git-send-email-jsnow@redhat.com
cur_cmd is an internal bookmark that points to the
current AHCI Command Header being processed by the
AHCI state machine. With NCQ needing to occasionally
rely on some of the same AHCI helpers, we cannot use
cur_cmd and will need to grab explicit pointers instead.
In an attempt to begin relying on the cur_cmd pointer
less, add a helper to let us specifically get the pointer
to the command header of particular interest.
Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 1435767578-32743-12-git-send-email-jsnow@redhat.com
While the rest of the AHCI device can rely on a single bookmarked
pointer for the AHCI Command Header currently being processed, NCQ
is asynchronous and may have many commands in flight simultaneously.
Add a cmdh pointer to the ncq_tfs object and make the sglist prepare
function take an AHCICmdHeader pointer so we can be explicit about
where we'd like to build SGlists from.
Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 1435767578-32743-11-git-send-email-jsnow@redhat.com
uint16_t isn't enough to hold the real sector count, since a value of
zero implies a full 64K sectors, so we need a uint32_t here.
We *could* cheat and pretend that this value is 0-based and fit it in
a uint16_t, but I'd rather waste 2 bytes instead of a future dev's
10 minutes when they forget to +1/-1 accordingly somewhere.
See SATA 3.2, section 13.6.4.1 "READ FPDMA QUEUED".
Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 1435767578-32743-9-git-send-email-jsnow@redhat.com
Handle NCQ failures for cases where we want to halt the VM on IO errors.
Upon a VM state change, retry the halted NCQ commands.
Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 1435767578-32743-7-git-send-email-jsnow@redhat.com
When we add werror=stop or rerror=stop support to NCQ,
we'll want to take a codepath where we don't actually
complete the command, so factor that out into a new routine.
Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 1435767578-32743-6-git-send-email-jsnow@redhat.com
Split off execute_ncq_command so that we can call
it separately later if we desire.
Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 1435767578-32743-5-git-send-email-jsnow@redhat.com
We already checked this in the handle_cmd phase, so just
change this to an assertion and simplify the error logic.
(Also, fix the switch indent, because checkpatch.pl yelled.)
((Sorry for churn.))
Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 1435767578-32743-4-git-send-email-jsnow@redhat.com
For migration and werror=stop/rerror=stop resume purposes,
it will be convenient to have the command handy inside of
ncq_tfs.
Eventually, we'd like to avoid reading from the FIS entirely
after the initial read, so this is a byte (hah!) sized step
in that direction.
Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 1435767578-32743-3-git-send-email-jsnow@redhat.com
prepare_buf should not always grab as many descriptors
as it can, sometimes it should self-limit.
For example, an NCQ transfer of 1 sector with a PRDT that
describes 4GiB of data should not copy 4GiB of data, it
should just transfer that first 512 bytes.
PIO is not affected, because the dma_buf_rw dma helpers
already have a byte limit built-in to them, but DMA/NCQ
will exhaust the entire list regardless of requested size.
AHCI 1.3 specifies in section 6.1.6 Command List Underflow that
NCQ is not required to detect underflow conditions. Non-NCQ
pathways signal underflow by writing to the PRDBC field, which
will already occur by writing the actual transferred byte count
to the PRDBC, signaling the underflow.
Our NCQ pathways aren't required to detect underflow, but since our DMA
backend uses the size of the PRDT to determine the size of the transer,
if our PRDT is bigger than the transaction (the underflow condition) it
doesn't cost us anything to detect it and truncate the PRDT.
This is a recoverable error and is not signaled to the guest, in either
NCQ or normal DMA cases.
For BMDMA, the existing pathways should see no guest-visible difference,
but any bytes described in the overage will no longer be transferred
before indicating to the guest that there was an underflow.
Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 1435767578-32743-2-git-send-email-jsnow@redhat.com
This value should not be size-corrected, 0 sectors does not imply
1 sector(s). This is just debug information, but it's misleading!
Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 1435016308-6150-8-git-send-email-jsnow@redhat.com
Most of the time, these bits can be safely ignored. For the purposes
of debugging however, it's nice to know that they're not being used.
Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 1435016308-6150-7-git-send-email-jsnow@redhat.com
There's no real reason to have it bundled together, and this way
is a little nicer to follow if you have the AHCI spec pulled up.
Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 1435016308-6150-6-git-send-email-jsnow@redhat.com
Don't attempt the NCQ transfer if the PRDT we were given is not big
enough to perform the entire transfer.
Signed-off-by: John Snow <jsnow@redhat.com>
Reviewed-by: Stefan Hajnoczi <stefanha@redhat.com>
Message-id: 1435016308-6150-5-git-send-email-jsnow@redhat.com
