Virtqueue notify is currently handled synchronously in userspace virtio. This
prevents the vcpu from executing guest code while hardware emulation code
handles the notify.
On systems that support KVM, the ioeventfd mechanism can be used to make
virtqueue notify a lightweight exit by deferring hardware emulation to the
iothread and allowing the VM to continue execution. This model is similar to
how vhost receives virtqueue notifies.
The result of this change is improved performance for userspace virtio devices.
Virtio-blk throughput increases especially for multithreaded scenarios and
virtio-net transmit throughput increases substantially.
Some virtio devices are known to have guest drivers which expect a notify to be
processed synchronously and spin waiting for completion.
For virtio-net, this also seems to interact with the guest stack in strange
ways so that TCP throughput for small message sizes (~200bytes)
is harmed. Only enable ioeventfd for virtio-blk for now.
Care must be taken not to interfere with vhost-net, which uses host
notifiers. If the set_host_notifier() API is used by a device
virtio-pci will disable virtio-ioeventfd and let the device deal with
host notifiers as it wishes.
Finally, there used to be a limit of 6 KVM io bus devices inside the
kernel. On such a kernel, don't use ioeventfd for virtqueue host
notification since the limit is reached too easily. This ensures that
existing vhost-net setups (which always use ioeventfd) have ioeventfds
available so they can continue to work.
After migration and on VM change state (running/paused) virtio-ioeventfd
will enable/disable itself.
* VIRTIO_CONFIG_S_DRIVER_OK -> enable virtio-ioeventfd
* !VIRTIO_CONFIG_S_DRIVER_OK -> disable virtio-ioeventfd
* virtio_pci_set_host_notifier() -> disable virtio-ioeventfd
* vm_change_state(running=0) -> disable virtio-ioeventfd
* vm_change_state(running=1) -> enable virtio-ioeventfd
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
There used to be a limit of 6 KVM io bus devices in the kernel.
On such a kernel, we can't use many ioeventfds for host notification
since the limit is reached too easily.
Add an API to test for this condition.
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Move tracking vmstate change from virtio-net to virtio.c
as it is going to be used by virito-blk and virtio-pci
for the ioeventfd support.
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
The VirtIOPCIProxy bugs field is currently used to enable workarounds
for older guests. Rename it to flags so that other per-device behavior
can be tracked.
A later patch uses the flags field to remember whether ioeventfd should
be used for virtqueue host notification.
Signed-off-by: Stefan Hajnoczi <stefanha@linux.vnet.ibm.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This patch tags all vga cards as not hotpluggable. The qemu
standard vga will never ever be hotpluggable. For cirrus + vmware
it might be possible to get that work some day. Todays we can't
handle that for a number of reasons though.
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This patch tags all pci devices which belong to the piix3/4 chipsets as
not hotpluggable (Host bridge, ISA bridge, IDE controller, ACPI bridge).
Acked-by: Aurelien Jarno <aurelien@aurel32.net>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
This patch adds a field to PCIDeviceInfo to tag devices as being
not hotpluggable. Any attempt to plug-in or -out such a device
will throw an error.
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>
Slirp code tries to be smart an avoid data copy by using pointer to
the data. This solution leads to unaligned access, in this case
preq_addr, which is a 32-bit long structure. There is no real point
of avoiding data copy in a such case, as the value itself is smaller
or the same size as a pointer.
The patch replaces pointers to the preq_addr structure by the strcture
itself, and use the address 0.0.0.0 if no address has been requested
(this is not a valid address in such a request). It compares it with
htonl(0L) for correctness reasons, in case a code checker look for such
mistakes. It also uses memcpy() for copying the data, which takes care
of alignement issues.
This fixes an unaligned access on IA64 host while requesting a DHCP
address.
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
Improve constant loading in two ways:
- On all ARM versions, it's possible to load 0xffffff00 = -0x100 using
the mvn rd, #0. Fix the conditions.
- On <= ARMv6 versions, where movw and movt are not available, load the
constants using mov and orr with rotations depending on the constant
to load. This is very useful for example to load constants where the
low byte is 0. This reduce the generated code size by about 7%.
Also fix the coding style at the same time.
Cc: Andrzej Zaborowski <balrog@zabor.org>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
SH4 is using 16-bit instructions which means most of the constants are
loaded through a constant pool at the end of the subroutine. The same
memory page is therefore accessed in exec and read mode.
With the current implementation, a QEMU TLB entry is set to read or
read/write mode after an UTLB search and to exec mode after an ITLB
search, which causes a lot of TLB exceptions to switch from read or
read/write to exec and vice versa.
This patch optimizes that by already setting the QEMU TLB entry in read
or read/write mode when an UTLB entry is copied into ITLB (during an
ITLB miss). This improve the emulation speed by about 14%.
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
Some Linux kernels seems to implement ITLB/UTLB flushing through by
writing all TLB entries through the memory mapped interface instead
of writing one to MMUCR.TI.
Implement memory mapped ITLB write interface so that such kernels can
boot. This fixes https://bugs.launchpad.net/bugs/700774 .
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
Each @section should have a menu entry and a @node entry.
Signed-off-by: Stefan Weil <weil@mail.berlios.de>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
Fix a file descriptor leak reported by cppcheck:
[/src/qemu/usb-bsd.c:392]: (error) Resource leak: bfd
[/src/qemu/usb-bsd.c:388]: (error) Resource leak: dfd
Rearrange the code to avoid descriptor leaks. Also add braces as
needed.
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
TCG on MIPS was trying to avoid changing the branch offset, but didn't
due to a stupid typo. Fix it.
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
Due to a typo, qemu_st64 doesn't properly byteswap the 32-bit low word of
a 64 bit word before saving it. This patch fixes that.
Acked-by: Andrzej Zaborowski <balrogg@gmail.com>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
QEMU uses code retranslation to restore the CPU state when an exception
happens. For it to work the retranslation must not modify the generated
code. This is what is currently implemented in ARM TCG.
However on CPU that don't have icache/dcache/memory synchronised like
ARM, this requirement is stronger and code retranslation must not modify
the generated code "atomically", as the cache line might be flushed
at any moment (interrupt, exception, task switching), even if not
triggered by QEMU. The probability for this to happen is very low, and
depends on cache size and associativiy, machine load, interrupts, so the
symptoms are might happen randomly.
This requirement is currently not followed in tcg/arm, for the
load/store code, which basically has the following structure:
1) tlb access code is written
2) conditional fast path code is written
3) branch is written with a temporary target
4) slow path code is written
5) branch target is updated
The cache lines corresponding to the retranslated code is not flushed
after code retranslation as the generated code is supposed to be the
same. However if the cache line corresponding to the branch instruction
is flushed between step 3 and 5, and is not flushed again before the
code is executed again, the branch target is wrong. In the guest, the
symptoms are MMU page fault at a random addresses, which leads to
kernel page fault or segmentation faults.
The patch fixes this issue by avoiding writing the branch target until
it is known, that is by writing only the branch instruction first, and
later only the offset.
This fixes booting linux guests on ARM hosts (tested: arm, i386, mips,
mipsel, sh4, sparc).
Acked-by: Edgar E. Iglesias <edgar.iglesias@gmail.com>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
* 'linux-user-for-upstream' of git://gitorious.org/qemu-maemo/qemu:
Remove dead code for ARM semihosting commandline handling
Fix commandline handling for ARM semihosted executables
linux-user: Fix incorrect NaN detection in ARM nwfpe emulation
softfloat: Implement floatx80_is_any_nan() and float128_is_any_nan()
linux-user: Implement FS_IOC_FIEMAP ioctl
linux-user: Support ioctls whose parameter size is not constant
linux-user: Implement sync_file_range{,2} syscalls
There are some bits in the code which were used to store the commandline for
the semihosting call. These bits are now write-only and can be removed.
Signed-off-by: Wolfgang Schildbach <wschi@dolby.com>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Riku Voipio <riku.voipio@iki.fi>
Use the copy of the command line that loader_build_argptr() sets up in guest
memory as the command line to return from the ARM SYS_GET_CMDLINE semihosting
call. Previously we were using a pointer to memory which had already been
freed before the guest program started.
This fixes https://bugs.launchpad.net/qemu/+bug/673613 .
Signed-off-by: Wolfgang Schildbach <wschi@dolby.com>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Riku Voipio <riku.voipio@iki.fi>
The code in the linux-user ARM nwfpe emulation was incorrectly
checking only for quiet NaNs when it should have been checking
for any kind of NaN. This is probably because the code in
question was taken from the Linux kernel, whose copy of the
softfloat library had been modified so that float*_is_nan()
returned true for all NaNs, not just quiet ones. The qemu
equivalent function is float*_is_any_nan(), so use that.
NB that this code is really obsolete since nobody uses FPE
for actual arithmetic now; this is just cleanup following
the recent renaming of the NaN related functions.
Acked-by: Aurelien Jarno <aurelien@aurel32.net>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Riku Voipio <riku.voipio@iki.fi>
Implement versions of float*_is_any_nan() for the floatx80 and
float128 types.
Acked-by: Aurelien Jarno <aurelien@aurel32.net>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Riku Voipio <riku.voipio@iki.fi>
Implement the FS_IOC_FIEMAP ioctl using the new support for
custom handling of ioctls; this is needed because the struct
that is passed includes a variable-length array.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Riku Voipio <riku.voipio@iki.fi>
Some ioctls (for example FS_IOC_FIEMAP) use structures whose size is
not constant. The generic argument conversion code in do_ioctl()
cannot handle this, so add support for implementing a special-case
handler for a particular ioctl which does the conversion itself.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Riku Voipio <riku.voipio@iki.fi>
Implement the missing syscalls sync_file_range and sync_file_range2.
The latter in particular is used by newer versions of apt on Ubuntu
for ARM.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Riku Voipio <riku.voipio@iki.fi>
Commit 92d675d1c1 triggered uninitialized
variables warning with GCC 4.6. Fix them by adding zero initializers.
Acked-by: Blue Swirl <blauwirbel@gmail.com>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
Wire up the new softfloat support for flushing input denormals
to zero on ARM. The FPSCR FZ bit enables flush-to-zero for
both inputs and outputs, but the reporting of when inputs are
flushed to zero is via a separate IDC bit rather than the UFC
(underflow) bit used when output denormals are flushed to zero.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Acked-by: Aurelien Jarno <aurelien@aurel32.net>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
When handling a write to the ARM FPSCR, set the softfloat cumulative
exception flags from the cumulative flags in the FPSCR, not the
exception-enable bits. Also don't apply a mask: vfp_exceptbits_to_host
will only look at the correct bits anyway.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Acked-by: Aurelien Jarno <aurelien@aurel32.net>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
Add support to softfloat for flushing input denormal float32 and float64
to zero. softfloat's existing 'flush_to_zero' flag only flushes denormals
to zero on output. Some CPUs need input denormals to be flushed before
processing as well. Implement this, using a new status flag to enable it
and a new exception status bit to indicate when it has happened. Existing
CPUs should be unaffected as there is no behaviour change unless the
mode is enabled.
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Acked-by: Aurelien Jarno <aurelien@aurel32.net>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
SMMLA and SMMLS are broken on both in normal and thumb mode, that is
both (different) implementations are wrong. They try to avoid a 64-bit
add for the rounding, which is not trivial if you want to support both
SMMLA and SMMLS with the same code.
The code below uses the same implementation for both modes, using the
code from the ARM manual. It also fixes the thumb decoding that was a
mix between normal and thumb mode.
This fixes the issues reported in
https://bugs.launchpad.net/qemu/+bug/629298
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Aurelien Jarno <aurelien@aurel32.net>
Avoid a warning with GCC 4.6.0:
/src/qemu/block.c: In function 'bdrv_img_create':
/src/qemu/block.c:2862:25: error: variable 'fmt' set but not used [-Werror=unused-but-set-variable]
CC: Kevin Wolf <kwolf@redhat.com>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
This patch replaces explicit bswaps with endianness hints to the
mmio layer.
CC: Alexander Graf <agraf@suse.de>
Signed-off-by: Blue Swirl <blauwirbel@gmail.com>
