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BAYES_HAM(-3.00)[100.00%]; NEURAL_HAM_LONG(-1.00)[-1.000]; R_DKIM_ALLOW(-0.20)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; MX_GOOD(-0.01)[]; FUZZY_RATELIMITED(0.00)[rspamd.com]; RCVD_VIA_SMTP_AUTH(0.00)[]; MIME_TRACE(0.00)[0:+]; TO_DN_SOME(0.00)[]; ARC_NA(0.00)[]; MISSING_XM_UA(0.00)[]; RCVD_TLS_ALL(0.00)[]; RCPT_COUNT_THREE(0.00)[4]; FROM_EQ_ENVFROM(0.00)[]; FROM_HAS_DN(0.00)[]; MID_RHS_MATCH_FROM(0.00)[]; RCVD_COUNT_TWO(0.00)[2]; TO_MATCH_ENVRCPT_ALL(0.00)[]; DBL_BLOCKED_OPENRESOLVER(0.00)[imap1.dmz-prg2.suse.org:helo,imap1.dmz-prg2.suse.org:rdns]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; DKIM_TRACE(0.00)[suse.de:+] X-Rspamd-Queue-Id: 3E0175BCC5 X-Rspamd-Action: no action X-Rspamd-Server: rspamd2.dmz-prg2.suse.org Received-SPF: pass client-ip=195.135.223.131; envelope-from=farosas@suse.de; helo=smtp-out2.suse.de X-Spam_score_int: -43 X-Spam_score: -4.4 X-Spam_bar: ---- X-Spam_report: (-4.4 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_MED=-2.3, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: qemu development List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Peter Xu writes: > On Mon, Feb 02, 2026 at 07:40:52PM -0300, Fabiano Rosas wrote: >> Hi, just a few more patches until options.c is fully using QAPI_CLONE >> instead of open-coding options handling, we're almost there. > > While I'm reading your series, I found one thing that migration might be > racy against for a while, and this series should enlarge that window of > this issue: I don't think it's safe to free elements in MigrationParameters > in the main thread, even if we hold BQL. Because migration thread can > access parameters anytime without BQL... logically it can read any > parameter, then if it's not a scalar we need some luck not crashing. > Good point, I had thought of it and convinced myself it was ok somehow. I'll take another look. > IMHO we may need to move faster on the "whitelist that can be dynamically > set during migration" plan on migration parameters and capabilities. > Or we make set-parameters always work on top of temporary MigrationParameter objects and switch the pointer atomically. Might be a good idea regardless. > I don't think any cap (after converted to parameters) should be on this > whitelist... for parameters, I'm trying to be conservative but I believe > the list should look like this: > > CPU throttle knobs: > > throttle-trigger-threshold > cpu-throttle-increment > cpu-throttle-tailslow > max-cpu-throttle > x-vcpu-dirty-limit-period > vcpu-dirty-limit > > Bandwith knobs: > > max-bandwidth > avail-switchover-bandwidth > downtime-limit > max-postcopy-bandwidth > > COLO knob: > > x-checkpoint-delay > > That really should be all parameters we allow to change.. Luckily all of > them are scalars, so it's fine to keep the current migrate_params_free() > and logic to "free then update". > > I wonder if we should even consider having this whitelist alongside with > your this series if we want to be extra safe, but I'll let you decide.. I'm > also OK we do it later, but maybe we don't want it to be too late either. Yeah.. I'll see what I can do. Thanks for the reviews this far!