The PCI Resizable BAR (ReBAR) capability is currently hidden from the
VM because the protocol for interacting with the capability does not
support a mechanism for the device to reject an advertised supported
BAR size. However, when assigned to a VM, the act of resizing the
BAR requires adjustment of host resources for the device, which
absolutely can fail. Linux does not currently allow us to reserve
resources for the device independent of the current usage.
The only writable field within the ReBAR capability is the BAR Size
register. The PCIe spec indicates that when written, the device
should immediately begin to operate with the provided BAR size. The
spec however also notes that software must only write values
corresponding to supported sizes as indicated in the capability and
control registers. Writing unsupported sizes produces undefined
results. Therefore, if the hypervisor were to virtualize the
capability and control registers such that the current size is the
only indicated available size, then a write of anything other than
the current size falls into the category of undefined behavior,
where we can essentially expose the modified ReBAR capability as
read-only.
This may seem pointless, but users have reported that virtualizing
the capability in this way not only allows guest software to expose
related features as available (even if only cosmetic), but in some
scenarios can resolve guest driver issues. Additionally, no
regressions in behavior have been reported for this change.
A caveat here is that the PCIe spec requires for compatibility that
devices report support for a size in the range of 1MB to 512GB,
therefore if the current BAR size falls outside that range we revert
to hiding the capability.
Reviewed-by: Cédric Le Goater <clg@redhat.com>
Link: https://lore.kernel.org/r/20230505232308.2869912-1-alex.williamson@redhat.com
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Currently, VFIO log_sync can be issued while migration is in SETUP
state. However, doing this log_sync is at best redundant and at worst
can fail.
Redundant -- all RAM is marked dirty in migration SETUP state and is
transferred only after migration is set to ACTIVE state, so doing
log_sync during migration SETUP is pointless.
Can fail -- there is a time window, between setting migration state to
SETUP and starting dirty tracking by RAM save_live_setup handler, during
which dirty tracking is still not started. Any VFIO log_sync call that
is issued during this time window will fail. For example, this error can
be triggered by migrating a VM when a GUI is active, which constantly
calls log_sync.
Fix it by skipping VFIO log_sync while migration is in SETUP state.
Fixes: 758b96b61d ("vfio/migrate: Move switch of dirty tracking into vfio_memory_listener")
Signed-off-by: Avihai Horon <avihaih@nvidia.com>
Link: https://lore.kernel.org/r/20230403130000.6422-1-avihaih@nvidia.com
Signed-off-by: Alex Williamson <alex.williamson@redhat.com>
Hi
This is just the compression bits of the Migration PULL request for
20230428. Only change is that we don't run the compression tests by
default.
The problem already exist with compression code. The test just show
that it don't work.
- Add migration tests for (old) compress migration code (lukas)
- Make compression code independent of ram.c (lukas)
- Move compression code into ram-compress.c (lukas)
Please apply, Juan.
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Merge tag 'compression-code-pull-request' of https://gitlab.com/juan.quintela/qemu into staging
Migration PULL request (20230508 edition, take 2)
Hi
This is just the compression bits of the Migration PULL request for
20230428. Only change is that we don't run the compression tests by
default.
The problem already exist with compression code. The test just show
that it don't work.
- Add migration tests for (old) compress migration code (lukas)
- Make compression code independent of ram.c (lukas)
- Move compression code into ram-compress.c (lukas)
Please apply, Juan.
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# gpg: Signature made Mon 08 May 2023 07:51:56 PM BST
# gpg: using RSA key 1899FF8EDEBF58CCEE034B82F487EF185872D723
# gpg: Good signature from "Juan Quintela <quintela@redhat.com>" [undefined]
# gpg: aka "Juan Quintela <quintela@trasno.org>" [undefined]
# gpg: WARNING: This key is not certified with a trusted signature!
# gpg: There is no indication that the signature belongs to the owner.
# Primary key fingerprint: 1899 FF8E DEBF 58CC EE03 4B82 F487 EF18 5872 D723
* tag 'compression-code-pull-request' of https://gitlab.com/juan.quintela/qemu:
migration: Initialize and cleanup decompression in migration.c
ram-compress.c: Make target independent
ram compress: Assert that the file buffer matches the result
ram.c: Move core decompression code into its own file
ram.c: Move core compression code into its own file
ram.c: Remove last ram.c dependency from the core compress code
ram.c: Call update_compress_thread_counts from compress_send_queued_data
ram.c: Do not call save_page_header() from compress threads
ram.c: Reset result after sending queued data
ram.c: Dont change param->block in the compress thread
ram.c: Let the compress threads return a CompressResult enum
qtest/migration-test.c: Add postcopy tests with compress enabled
qtest/migration-test.c: Add tests with compress enabled
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>
This fixes compress with colo.
Signed-off-by: Lukas Straub <lukasstraub2@web.de>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
Make ram-compress.c target independent.
Signed-off-by: Lukas Straub <lukasstraub2@web.de>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
Before this series, "nothing to send" was handled by the file buffer
being empty. Now it is tracked via param->result.
Assert that the file buffer state matches the result.
Signed-off-by: Lukas Straub <lukasstraub2@web.de>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
No functional changes intended.
Signed-off-by: Lukas Straub <lukasstraub2@web.de>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
Make compression interfaces take send_queued_data() as an argument.
Remove save_page_use_compression() from flush_compressed_data().
This removes the last ram.c dependency from the core compress code.
Signed-off-by: Lukas Straub <lukasstraub2@web.de>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
This makes the core compress code more independend from ram.c.
Signed-off-by: Lukas Straub <lukasstraub2@web.de>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
save_page_header() accesses several global variables, so calling it
from multiple threads is pretty ugly.
Instead, call save_page_header() before writing out the compressed
data from the compress buffer to the migration stream.
This also makes the core compress code more independend from ram.c.
Signed-off-by: Lukas Straub <lukasstraub2@web.de>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
And take the param->mutex lock for the whole section to ensure
thread-safety.
Now, it is explicitly clear if there is no queued data to send.
Before, this was handled by param->file stream being empty and thus
qemu_put_qemu_file() not sending anything.
This will be used in the next commits to move save_page_header()
out of compress code.
Signed-off-by: Lukas Straub <lukasstraub2@web.de>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
Instead introduce a extra parameter to trigger the compress thread.
Now, when the compress thread is done, we know what RAMBlock and
offset it did compress.
This will be used in the next commits to move save_page_header()
out of compress code.
Signed-off-by: Lukas Straub <lukasstraub2@web.de>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
This will be used in the next commits to move save_page_header()
out of compress code.
Signed-off-by: Lukas Straub <lukasstraub2@web.de>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
Add postcopy tests with compress enabled to ensure nothing breaks
with the refactoring in the next commits.
preempt+compress is blocked, so no test needed for that case.
Signed-off-by: Lukas Straub <lukasstraub2@web.de>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
There has never been tests for migration with compress enabled.
Add suitable tests, testing with compress-wait-thread = false
too.
Signed-off-by: Lukas Straub <lukasstraub2@web.de>
Acked-by: Peter Xu <peterx@redhat.com>
Reviewed-by: Juan Quintela <quintela@redhat.com>
Signed-off-by: Juan Quintela <quintela@redhat.com>
The calling function is already working with hwaddr and uint64_t so
lets avoid bringing target_ulong in if we don't need to.
Signed-off-by: Alex Bennée <alex.bennee@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Song Gao <gaosong@loongson.cn>
Message-Id: <20230404132711.2563638-1-alex.bennee@linaro.org>
Signed-off-by: Song Gao <gaosong@loongson.cn>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Song Gao <gaosong@loongson.cn>
Message-Id: <20230504122810.4094787-45-gaosong@loongson.cn>
Introduce set_fpr() and get_fpr() and remove cpu_fpr.
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Song Gao <gaosong@loongson.cn>
Message-Id: <20230504122810.4094787-44-gaosong@loongson.cn>
This patch includes:
- VLDI.
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Song Gao <gaosong@loongson.cn>
Message-Id: <20230504122810.4094787-43-gaosong@loongson.cn>
This patch includes:
- VFCMP.cond.{S/D}.
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Song Gao <gaosong@loongson.cn>
Message-Id: <20230504122810.4094787-37-gaosong@loongson.cn>
This patch includes:
- VFRSTP[I].{B/H}.
Acked-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Song Gao <gaosong@loongson.cn>
Message-Id: <20230504122810.4094787-33-gaosong@loongson.cn>
This patch includes:
- VPCNT.{B/H/W/D}.
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Song Gao <gaosong@loongson.cn>
Message-Id: <20230504122810.4094787-31-gaosong@loongson.cn>
This patch includes:
- VSIGNCOV.{B/H/W/D}.
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Song Gao <gaosong@loongson.cn>
Message-Id: <20230504122810.4094787-20-gaosong@loongson.cn>
This patch includes:
- VSAT.{B/H/W/D}[U].
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Signed-off-by: Song Gao <gaosong@loongson.cn>
Message-Id: <20230504122810.4094787-18-gaosong@loongson.cn>
Alex Williamson