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charset=utf-8 Content-Transfer-Encoding: quoted-printable X-Spamd-Result: default: False [-4.51 / 50.00]; BAYES_HAM(-3.00)[99.98%]; 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)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; ARC_NA(0.00)[]; MISSING_XM_UA(0.00)[]; MIME_TRACE(0.00)[0:+]; FUZZY_RATELIMITED(0.00)[rspamd.com]; SPAMHAUS_XBL(0.00)[2a07:de40:b281:104:10:150:64:97:from]; TO_DN_SOME(0.00)[]; RCVD_TLS_ALL(0.00)[]; RCPT_COUNT_SEVEN(0.00)[7]; RBL_SPAMHAUS_BLOCKED_OPENRESOLVER(0.00)[2a07:de40:b281:104:10:150:64:97:from]; RCVD_COUNT_TWO(0.00)[2]; FROM_EQ_ENVFROM(0.00)[]; FROM_HAS_DN(0.00)[]; RECEIVED_SPAMHAUS_BLOCKED_OPENRESOLVER(0.00)[2a07:de40:b281:106:10:150:64:167:received]; DBL_BLOCKED_OPENRESOLVER(0.00)[suse.de:mid,suse.de:dkim,suse.de:email,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]; TO_MATCH_ENVRCPT_ALL(0.00)[]; MID_RHS_MATCH_FROM(0.00)[]; DKIM_TRACE(0.00)[suse.de:+] X-Rspamd-Queue-Id: 2314021205 X-Rspamd-Server: rspamd2.dmz-prg2.suse.org X-Rspamd-Action: no action Received-SPF: pass client-ip=2a07:de40:b251:101:10:150:64:1; envelope-from=farosas@suse.de; helo=smtp-out1.suse.de X-Spam_score_int: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 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, 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: 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 Daniel P. Berrang=C3=A9 writes: > When TLS 1.3 is negotiated on a TLS session, GNUTLS will perform > automatic rekeying of the session after 16 million records. This > is done for all algorithms except CHACHA20_POLY1305 which does > not require rekeying. > > Unfortunately the rekeying breaks GNUTLS' promise that it is safe > to use a gnutls_session_t object concurrently from multiple threads > if they are exclusively calling gnutls_record_send/recv. > > This patch implements a workaround for QEMU that adds a mutex lock > around any gnutls_record_send/recv call to serialize execution > within GNUTLS code. When GNUTLS calls into the push/pull functions > we can release the lock so the OS level I/O calls can at least > have some parallelism. > > The big downside of this is that the actual encryption/decryption > code is fully serialized, which will halve performance of that > cipher operations if two threads are contending. > > The workaround is not enabled by default, since most use of GNUTLS > in QEMU does not tickle the problem, only non-multifd migration > with a return path open is affected. Fortunately the migration > code also won't trigger the halving of performance, since only > the outbound channel diretion needs to sustain high data rates, > the inbound direction is low volume. > > Signed-off-by: Daniel P. Berrang=C3=A9 Reviewed-by: Fabiano Rosas