The new MSR IA32_SPEC_CTRL MSR was introduced by a recent Intel
microcode updated and can be used by OSes to mitigate
CVE-2017-5715. Unfortunately we can't change the existing CPU
models without breaking existing setups, so users need to
explicitly update their VM configuration to use the new *-IBRS
CPU model if they want to expose IBRS to guests.
The new CPU models are simple copies of the existing CPU models,
with just CPUID_7_0_EDX_SPEC_CTRL added and model_id updated.
Cc: Jiri Denemark <jdenemar@redhat.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Message-Id: <20180109154519.25634-6-ehabkost@redhat.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Add the new feature word and the "ibpb" feature flag.
Based on a patch by Paolo Bonzini.
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Message-Id: <20180109154519.25634-5-ehabkost@redhat.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Add the feature name and a CPUID_7_0_EDX_SPEC_CTRL macro.
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Message-Id: <20180109154519.25634-4-ehabkost@redhat.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
It is valid to have a 48-character model ID on CPUID, however the
definition of X86CPUDefinition::model_id is char[48], which can
make the compiler drop the null terminator from the string.
If a CPU model happens to have 48 bytes on model_id, "-cpu help"
will print garbage and the object_property_set_str() call at
x86_cpu_load_def() will read data outside the model_id array.
We could increase the array size to 49, but this would mean the
compiler would not issue a warning if a 49-char string is used by
mistake for model_id.
To make things simpler, simply change model_id to be const char*,
and validate the string length using an assert() on
x86_register_cpudef_type().
Reported-by: "Dr. David Alan Gilbert" <dgilbert@redhat.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
Message-Id: <20180109154519.25634-2-ehabkost@redhat.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
CPUID_7_0_EBX_CLFLUSHOPT is missed in current "Skylake-Server" cpu
model. Add it to "Skylake-Server" cpu model on pc-i440fx-2.12 and
pc-q35-2.12. Keep it disabled in "Skylake-Server" cpu model on older
machine types.
Signed-off-by: Haozhong Zhang <haozhong.zhang@intel.com>
Message-Id: <20171219033730.12748-3-haozhong.zhang@intel.com>
Reviewed-by: Eduardo Habkost <ehabkost@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Eduardo Habkost <ehabkost@redhat.com>
When overwritting a valid TLB entry with a new one, the previous page
were not flushed in QEMU TLB, leading to incoherent mapping. This commit
fixes this.
Signed-off-by: Luc MICHEL <luc.michel@git.antfield.fr>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
When skiboot starts, it first clears the CPU structs for all possible
CPUs on a system :
for (i = 0; i <= cpu_max_pir; i++)
memset(&cpu_stacks[i].cpu, 0, sizeof(struct cpu_thread));
On POWER9, cpu_max_pir is quite big, 0x7fff, and the skiboot cpu_stacks
array overlaps with the memory region in which QEMU maps the initramfs
file. Move it upwards in memory to keep it safe.
Signed-off-by: Cédric Le Goater <clg@kaod.org>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
The XSCOM base address of the core chiplet was wrongly calculated. Use
the OPAL macros to fix that and do a couple of renames.
Signed-off-by: Cédric Le Goater <clg@kaod.org>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
These are useful when instantiating device models which are shared
between the POWER8 and the POWER9 processor families.
Signed-off-by: Cédric Le Goater <clg@kaod.org>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
When addressed by XSCOM, the first core has the 0x20 chiplet ID but
the CPU PIR can start at 0x0.
Signed-off-by: Cédric Le Goater <clg@kaod.org>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
commit 1ed9c8af50 ("target/ppc: Add POWER9 DD2.0 model information")
deprecated the POWER9 model v1.0.
Signed-off-by: Cédric Le Goater <clg@kaod.org>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Recent commit introduced the firmware image skiboot 5.9 which
has a different first line ouput.
Signed-off-by: Cédric Le Goater <clg@kaod.org>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
This is skiboot 5.9 (commit e0ee24c2). It brings improved POWER9
support among many other things. Built from submodule.
Signed-off-by: Cédric Le Goater <clg@kaod.org>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
fa98fbfc "PC: KVM: Support machine option to set VSMT mode" introduced the
"vsmt" parameter for the pseries machine type, which controls the spacing
of the vcpu ids of thread 0 for each virtual core. This was done to bring
some consistency and stability to how that was done, while still allowing
backwards compatibility for migration and otherwise.
The default value we used for vsmt was set to the max of the host's
advertised default number of threads and the number of vthreads per vcore
in the guest. This was done to continue running without extra parameters
on older KVM versions which don't allow the VSMT value to be changed.
Unfortunately, even that smaller than before leakage of host configuration
into guest visible configuration still breaks things. Specifically a guest
with 4 (or less) vthread/vcore will get a different vsmt value when
running on a POWER8 (vsmt==8) and POWER9 (vsmt==4) host. That means the
vcpu ids don't line up so you can't migrate between them, though you should
be able to.
Long term we really want to make vsmt == smp_threads for sufficiently
new machine types. However, that means that qemu will then require a
sufficiently recent KVM (one which supports changing VSMT) - that's still
not widely enough deployed to be really comfortable to do.
In the meantime we need some default that will work as often as
possible. This patch changes that default to 8 in all circumstances.
This does change guest visible behaviour (including for existing
machine versions) for many cases - just not the most common/important
case.
Following is case by case justification for why this is still the least
worst option. Note that any of the old behaviours can still be duplicated
after this patch, it's just that it requires manual intervention by
setting the vsmt property on the command line.
KVM HV on POWER8 host:
This is the overwhelmingly common case in production setups, and is
unchanged by design. POWER8 hosts will advertise a default VSMT mode
of 8, and > 8 vthreads/vcore isn't permitted
KVM HV on POWER7 host:
Will break, but POWER7s allowing KVM were never released to the public.
KVM HV on POWER9 host:
Not yet released to the public, breaking this now will reduce other
breakage later.
KVM HV on PowerPC 970:
Will theoretically break it, but it was barely supported to begin with
and already required various user visible hacks to work. Also so old
that I just don't care.
TCG:
This is the nastiest one; it means migration of TCG guests (without
manual vsmt setting) will break. Since TCG is rarely used in production
I think this is worth it for the other benefits. It does also remove
one more barrier to TCG<->KVM migration which could be interesting for
debugging applications.
KVM PR:
As with TCG, this will break migration of existing configurations,
without adding extra manual vsmt options. As with TCG, it is rare in
production so I think the benefits outweigh breakages.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Laurent Vivier <lvivier@redhat.com>
Reviewed-by: Jose Ricardo Ziviani <joserz@linux.vnet.ibm.com>
Reviewed-by: Greg Kurz <groug@kaod.org>
At present if we require a vsmt mode that's not equal to the kernel's
default, and the kernel doesn't let us change it (e.g. because it's an old
kernel without support) then we always fail.
But in fact we can cope with the kernel having a different vsmt as long as
a) it's >= the actual number of vthreads/vcore (so that guest threads
that are supposed to be on the same core act like it)
b) it's a submultiple of the requested vsmt mode (so that guest threads
spaced by the vsmt value will act like they're on different cores)
Allowing this case gives us a bit more freedom to adjust the vsmt behaviour
without breaking existing cases.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Laurent Vivier <lvivier@redhat.com>
Tested-by: Greg Kurz <groug@kaod.org>
Reviewed-by: Greg Kurz <groug@kaod.org>
We recently had some discussions that were sidetracked for a while, because
nearly everyone misapprehended the purpose of the 'max_threads' field in
the compatiblity modes table. It's all about guest expectations, not host
expectations or support (that's handled elsewhere).
In an attempt to avoid a repeat of that confusion, rename the field to
'max_vthreads' and add an explanatory comment.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Laurent Vivier <lvivier@redhat.com>
Reviewed-by: Greg Kurz <groug@kaod.org>
Reviewed-by: Jose Ricardo Ziviani <joserz@linux.vnet.ibm.com>
Increases the max smt mode to 8 for Power9. That's because KVM supports
smt emulation in this platform so QEMU should allow users to use it as
well.
Today if we try to pass -smp ...,threads=8, QEMU will silently truncate
it to smt4 mode and may cause a crash if we try to perform a cpu
hotplug.
Signed-off-by: Jose Ricardo Ziviani <joserz@linux.vnet.ibm.com>
[dwg: Added an explanatory comment]
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
The options field here is intended to list the available values for the
capability. It's not used yet, because the existing capabilities are
boolean.
We're going to add capabilities that aren't, but in that case the info on
the possible values can be folded into the .description field.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Currently spapr_caps are tied to boolean values (on or off). This patch
reworks the caps so that they can have any uint8 value. This allows more
capabilities with various values to be represented in the same way
internally. Capabilities are numbered in ascending order. The internal
representation of capability values is an array of uint8s in the
sPAPRMachineState, indexed by capability number.
Capabilities can have their own name, description, options, getter and
setter functions, type and allow functions. They also each have their own
section in the migration stream. Capabilities are only migrated if they
were explictly set on the command line, with the assumption that
otherwise the default will match.
On migration we ensure that the capability value on the destination
is greater than or equal to the capability value from the source. So
long at this remains the case then the migration is considered
compatible and allowed to continue.
This patch implements generic getter and setter functions for boolean
capabilities. It also converts the existings cap-htm, cap-vsx and
cap-dfp capabilities to this new format.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Decimal Floating Point has been available on POWER7 and later (server)
cpus. However, it can be disabled on the hypervisor, meaning that it's
not available to guests.
We currently handle this by conditionally advertising DFP support in the
device tree depending on whether the guest CPU model supports it - which
can also depend on what's allowed in the host for -cpu host. That can lead
to confusion on migration, since host properties are silently affecting
guest visible properties.
This patch handles it by treating it as an optional capability for the
pseries machine type.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Greg Kurz <groug@kaod.org>
We currently have some conditionals in the spapr device tree code to decide
whether or not to advertise the availability of the VMX (aka Altivec) and
VSX vector extensions to the guest, based on whether the guest cpu has
those features.
This can lead to confusion and subtle failures on migration, since it makes
a guest visible change based only on host capabilities. We now have a
better mechanism for this, in spapr capabilities flags, which explicitly
depend on user options rather than host capabilities.
Rework the advertisement of VSX and VMX based on a new VSX capability. We
no longer bother with a conditional for VMX support, because every CPU
that's ever been supported by the pseries machine type supports VMX.
NOTE: Some userspace distributions (e.g. RHEL7.4) already rely on
availability of VSX in libc, so using cap-vsx=off may lead to a fatal
SIGILL in init.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Greg Kurz <groug@kaod.org>
When constructing the "host" cpu class we modify whether the VMX and VSX
vector extensions and DFP (Decimal Floating Point) are available
based on whether KVM can support those instructions. This can depend on
policy in the host kernel as well as on the actual host cpu capabilities.
However, the way we probe for this is not very nice: we explicitly check
the host's device tree. That works in practice, but it's not really
correct, since the device tree is a property of the host kernel's platform
which we don't really know about. We get away with it because the only
modern POWER platforms happen to encode VMX, VSX and DFP availability in
the device tree in the same way.
Arguably we should have an explicit KVM capability for this, but we haven't
needed one so far. Barring specific KVM policies which don't yet exist,
each of these instruction classes will be available in the guest if and
only if they're available in the qemu userspace process. We can determine
that from the ELF AUX vector we're supplied with.
Once reworked like this, there are no more callers for kvmppc_get_vmx() and
kvmppc_get_dfp() so remove them.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Greg Kurz <groug@kaod.org>
Now that the "pseries" machine type implements optional capabilities (well,
one so far) there's the possibility of having different capabilities
available at either end of a migration. Although arguably a user error,
it would be nice to catch this situation and fail as gracefully as we can.
This adds code to migrate the capabilities flags. These aren't pulled
directly into the destination's configuration since what the user has
specified on the destination command line should take precedence. However,
they are checked against the destination capabilities.
If the source was using a capability which is absent on the destination,
we fail the migration, since that could easily cause a guest crash or other
bad behaviour. If the source lacked a capability which is present on the
destination we warn, but allow the migration to proceed.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Greg Kurz <groug@kaod.org>
This adds an spapr capability bit for Hardware Transactional Memory. It is
enabled by default for pseries-2.11 and earlier machine types. with POWER8
or later CPUs (as it must be, since earlier qemu versions would implicitly
allow it). However it is disabled by default for the latest pseries-2.12
machine type.
This means that with the latest machine type, HTM will not be available,
regardless of CPU, unless it is explicitly enabled on the command line.
That change is made on the basis that:
* This way running with -M pseries,accel=tcg will start with whatever cpu
and will provide the same guest visible model as with accel=kvm.
- More specifically, this means existing make check tests don't have
to be modified to use cap-htm=off in order to run with TCG
* We hope to add a new "HTM without suspend" feature in the not too
distant future which could work on both POWER8 and POWER9 cpus, and
could be enabled by default.
* Best guesses suggest that future POWER cpus may well only support the
HTM-without-suspend model, not the (frankly, horribly overcomplicated)
POWER8 style HTM with suspend.
* Anecdotal evidence suggests problems with HTM being enabled when it
wasn't wanted are more common than being missing when it was.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Greg Kurz <groug@kaod.org>
Because PAPR is a paravirtual environment access to certain CPU (or other)
facilities can be blocked by the hypervisor. PAPR provides ways to
advertise in the device tree whether or not those features are available to
the guest.
In some places we automatically determine whether to make a feature
available based on whether our host can support it, in most cases this is
based on limitations in the available KVM implementation.
Although we correctly advertise this to the guest, it means that host
factors might make changes to the guest visible environment which is bad:
as well as generaly reducing reproducibility, it means that a migration
between different host environments can easily go bad.
We've mostly gotten away with it because the environments considered mature
enough to be well supported (basically, KVM on POWER8) have had consistent
feature availability. But, it's still not right and some limitations on
POWER9 is going to make it more of an issue in future.
This introduces an infrastructure for defining "sPAPR capabilities". These
are set by default based on the machine version, masked by the capabilities
of the chosen cpu, but can be overriden with machine properties.
The intention is at reset time we verify that the requested capabilities
can be supported on the host (considering TCG, KVM and/or host cpu
limitations). If not we simply fail, rather than silently modifying the
advertised featureset to the guest.
This does mean that certain configurations that "worked" may now fail, but
such configurations were already more subtly broken.
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
Reviewed-by: Greg Kurz <groug@kaod.org>
As stated in the 1ad9f0a464 commit log, the returned entries are not
a whole PTEG. It was not a problem before 1ad9f0a464 as it would read
a single record assuming it contains a whole PTEG but now the code tries
reading the entire PTEG and "if ((n - i) < invalid)" produces negative
values which then are converted to size_t for memset() and that throws
seg fault.
This fixes the math.
While here, fix the last @i increment as well.
Fixes: 1ad9f0a464 "target/ppc: Fix KVM-HV HPTE accessors"
Signed-off-by: Alexey Kardashevskiy <aik@ozlabs.ru>
Signed-off-by: David Gibson <david@gibson.dropbear.id.au>
We recently relaxed the limit of the number of opcodes that can
appear in a TranslationBlock. In certain cases this has resulted
in relocation overflow.
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
The code sequence we were generating was only good for unsigned
comparisons. For signed comparisions, use the sequence from gcc.
Fixes booting of ppc64 firmware, with a patch changing the code
sequence for ppc comparisons.
Tested-by: Michael Roth <mdroth@linux.vnet.ibm.com>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
* SDHCI: cleanups and minor bug fixes
* target/arm: minor refactor preparatory to fp16 support
* omap_ssd, ssi-sd, pl181, milkymist-memcard: reset the SD
card on controller reset (fixes migration failures)
* target/arm: Handle page table walk load failures correctly
* hw/arm/virt: Add virt-2.12 machine type
* get_phys_addr_pmsav7: Support AP=0b111 for v7M
* hw/intc/armv7m: Support byte and halfword accesses to CFSR
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Merge remote-tracking branch 'remotes/pmaydell/tags/pull-target-arm-20180116' into staging
target-arm queue:
* SDHCI: cleanups and minor bug fixes
* target/arm: minor refactor preparatory to fp16 support
* omap_ssd, ssi-sd, pl181, milkymist-memcard: reset the SD
card on controller reset (fixes migration failures)
* target/arm: Handle page table walk load failures correctly
* hw/arm/virt: Add virt-2.12 machine type
* get_phys_addr_pmsav7: Support AP=0b111 for v7M
* hw/intc/armv7m: Support byte and halfword accesses to CFSR
# gpg: Signature made Tue 16 Jan 2018 13:33:31 GMT
# gpg: using RSA key 0x3C2525ED14360CDE
# gpg: Good signature from "Peter Maydell <peter.maydell@linaro.org>"
# gpg: aka "Peter Maydell <pmaydell@gmail.com>"
# gpg: aka "Peter Maydell <pmaydell@chiark.greenend.org.uk>"
# Primary key fingerprint: E1A5 C593 CD41 9DE2 8E83 15CF 3C25 25ED 1436 0CDE
* remotes/pmaydell/tags/pull-target-arm-20180116: (24 commits)
sdhci: add a 'dma' property to the sysbus devices
sdhci: fix the PCI device, using the PCI address space for DMA
sdhci: Implement write method of ACMD12ERRSTS register
sdhci: fix CAPAB/MAXCURR registers, both are 64bit and read-only
sdhci: rename the SDHC_CAPAB register
sdhci: move MASK_TRNMOD with other SDHC_TRN* defines in "sd-internal.h"
sdhci: convert the DPRINT() calls into trace events
sdhci: use qemu_log_mask(UNIMP) instead of fprintf()
sdhci: refactor common sysbus/pci unrealize() into sdhci_common_unrealize()
sdhci: refactor common sysbus/pci realize() into sdhci_common_realize()
sdhci: refactor common sysbus/pci class_init() into sdhci_common_class_init()
sdhci: use DEFINE_SDHCI_COMMON_PROPERTIES() for common sysbus/pci properties
sdhci: remove dead code
sdhci: clean up includes
target/arm: Add fp16 support to vfp_expand_imm
target/arm: Split out vfp_expand_imm
hw/sd/omap_mmc: Reset SD card on controller reset
hw/sd/ssi-sd: Reset SD card on controller reset
hw/sd/milkymist-memcard: Reset SD card on controller reset
hw/sd/pl181: Reset SD card on controller reset
...
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
This script allows analysis of mutex acquisition and hold times based
on a trace file. Given a trace control file of:
qemu_mutex_lock
qemu_mutex_locked
qemu_mutex_unlock
And running with:
$QEMU $QEMU_ARGS -trace events=./lock-trace
You can analyse the results with:
./scripts/analyse-locks-simpletrace.py trace-events-all ./trace-21812
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Flushing TB cache is required because TBs key in the cache may match
different code which existed in the previous state.
Signed-off-by: Pavel Dovgalyuk <pavel.dovgaluk@ispras.ru>
Signed-off-by: Maria Klimushenkova <maria.klimushenkova@ispras.ru>
Message-Id: <20180110134846.12940.99993.stgit@pasha-VirtualBox>
[Add comment suggested by Peter Maydell. - Paolo]
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Pavel Dovgalyuk <Pavel.Dovgaluk@ispras.ru>
in case of unaligned requests or on a target that does not support
block provisioning we leave iTask uninitialized and check iTask.task
for NULL later.
Fixes: e38bc23454
Signed-off-by: Peter Lieven <pl@kamp.de>
Reviewed-by: Eric Blake <eblake@redhat.com>
Message-Id: <1515425247-21730-1-git-send-email-pl@kamp.de>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
The dirty bitmaps are built from 'long's and there is fast-path code
for synchronising the case where the RAMBlock is aligned to the start
of a long boundary. Align the allocation to this boundary
to cause the fast path to be used.
Offsets before change:
11398@1515169675.018566:find_ram_offset size: 0x1e0000 @ 0x8000000
11398@1515169675.020064:find_ram_offset size: 0x20000 @ 0x81e0000
11398@1515169675.020244:find_ram_offset size: 0x20000 @ 0x8200000
11398@1515169675.024343:find_ram_offset size: 0x1000000 @ 0x8220000
11398@1515169675.025154:find_ram_offset size: 0x10000 @ 0x9220000
11398@1515169675.027682:find_ram_offset size: 0x40000 @ 0x9230000
11398@1515169675.032921:find_ram_offset size: 0x200000 @ 0x9270000
11398@1515169675.033307:find_ram_offset size: 0x1000 @ 0x9470000
11398@1515169675.033601:find_ram_offset size: 0x1000 @ 0x9471000
after change:
10923@1515169108.818245:find_ram_offset size: 0x1e0000 @ 0x8000000
10923@1515169108.819410:find_ram_offset size: 0x20000 @ 0x8200000
10923@1515169108.819587:find_ram_offset size: 0x20000 @ 0x8240000
10923@1515169108.823708:find_ram_offset size: 0x1000000 @ 0x8280000
10923@1515169108.824503:find_ram_offset size: 0x10000 @ 0x9280000
10923@1515169108.827093:find_ram_offset size: 0x40000 @ 0x92c0000
10923@1515169108.833045:find_ram_offset size: 0x200000 @ 0x9300000
10923@1515169108.833504:find_ram_offset size: 0x1000 @ 0x9500000
10923@1515169108.833787:find_ram_offset size: 0x1000 @ 0x9540000
Suggested-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Message-Id: <20180105170138.23357-3-dgilbert@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Add some comments so I can understand the various nested loops.
Add some tracing so I can see what they're doing.
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Message-Id: <20180105170138.23357-2-dgilbert@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
This code has an optimised, word aligned version, and a boring
unaligned version. My commit f70d345 fixed one alignment issue, but
there's another.
The optimised version operates on 'longs' dealing with (typically) 64
pages at a time, replacing the whole long by a 0 and counting the bits.
If the Ramblock is less than 64bits in length that long can contain bits
representing two different RAMBlocks, but the code will update the
bmap belinging to the 1st RAMBlock only while having updated the total
dirty page count for both.
This probably didn't matter prior to 6b6712ef which split the dirty
bitmap by RAMBlock, but now they're separate RAMBlocks we end up
with a count that doesn't match the state in the bitmaps.
Symptom:
Migration showing a few dirty pages left to be sent constantly
Seen on aarch64 and x86 with x86+ovmf
Signed-off-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Reported-by: Wei Huang <wei@redhat.com>
Fixes: 6b6712efcc
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Use of a loop construct for code that is not intended to repeat
does not make much idiomatic sense, except in one place: it is a
common usage in macros in order to wrap arbitrary code with
single-statement semantics. But when used in a macro, it is more
typical for the caller to supply the trailing ';' when calling
the macro.
Although qemu coding style frowns on bare:
if (cond)
statement1;
else
statement2;
where extra semicolons actually cause syntax errors, we still
want our macro styles to be easily copied to other projects.
Thus, declare it an error if we encounter any form of 'while (0)'
with a semicolon in the same line.
Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <20171201232433.25193-8-eblake@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
The point of writing a macro embedded in a 'do { ... } while (0)'
loop (particularly if the macro has multiple statements or would
otherwise end with an 'if' statement) is so that the macro can be
used as a drop-in statement with the caller supplying the
trailing ';'. Although our coding style frowns on brace-less 'if':
if (cond)
statement;
else
something else;
that is the classic case where failure to use do/while(0) wrapping
would cause the 'else' to pair with any embedded 'if' in the macro
rather than the intended outer 'if'. But conversely, if the macro
includes an embedded ';', then the same brace-less coding style
would now have two statements, making the 'else' a syntax error
rather than pairing with the outer 'if'. Thus, even though our
coding style with required braces is not impacted, ending a macro
with ';' makes our code harder to port to projects that use
brace-less styles.
The change should have no semantic impact. I was not able to
fully compile-test all of the changes (as some of them are
examples of the ugly bit-rotting debug print statements that are
completely elided by default, and I didn't want to recompile
with the necessary -D witnesses - cleaning those up is left as a
bite-sized task for another day); I did, however, audit that for
all files touched, all callers of the changed macros DID supply
a trailing ';' at the callsite, and did not appear to be used
as part of a brace-less conditional.
Found mechanically via: $ git grep -B1 'while (0);' | grep -A1 \\\\
Signed-off-by: Eric Blake <eblake@redhat.com>
Acked-by: Cornelia Huck <cohuck@redhat.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Acked-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
Message-Id: <20171201232433.25193-7-eblake@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Use of a do/while(0) loop as a way to allow break statements in
the middle of execute-once code is unusual. More typical is
the use of goto for early exits, with a label at the end of
the execute-once code, rather than nesting code in a scope;
however, the comment at the end of the existing code makes this
alternative a bit unpractical.
So, to avoid false positives from a future syntax check about
'while (false);', and to keep the loop form (in case someone
ever does add DONTWAIT support, where they can just as easily
manipulate the initial loop condition or add an if around the
final 'break'), I opted to use the form of a while(1) loop (the
break as an early exit is more idiomatic there), coupled with
a final break preserving the original comment.
Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <20171201232433.25193-6-eblake@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
The previous patch left in an extra scope layer for ease of
review; time to remove it. No semantic change.
Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <20171201232433.25193-5-eblake@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Use of a do/while(0) control flow in order to permit an early break
is an unusual paradigm, and triggers a false positive with a planned
future syntax check against 'while (0);'. Rewrite the code to use a
goto instead. This patch temporarily keeps an extra level of
indentation to highlight the change; the next patch cleans it up.
Signed-off-by: Eric Blake <eblake@redhat.com>
Message-Id: <20171201232433.25193-4-eblake@redhat.com>
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
It is more typical to provide the ';' by the caller of a macro
than to embed it in the macro itself; this is because syntax
highlight engines can get confused if a macro is called without
a semicolon before the closing '}'.
Signed-off-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Message-Id: <20171201232433.25193-3-eblake@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
For a couple of macros in pcnet.c, we have to provide a new scope
to avoid compiler warnings about declarations in the middle of a
switch statement that aren't in a sub-scope. But use of
'do { ... } while (0);' merely to provide that new scope is arcane
overkill, compared to just using '{ ... }'.
Signed-off-by: Eric Blake <eblake@redhat.com>
Reviewed-by: Thomas Huth <thuth@redhat.com>
Message-Id: <20171201232433.25193-2-eblake@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
