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dkim=pass header.d=suse.de header.s=susede2_ed25519 header.b=FASXHoFA DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1752243073; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=ZLVxbUl1QbCpvaOs+8U0flUWK625i092YCFo0WiecoQ=; b=LzQwW1q1pscp5Ja61+ZMgIzV8aoSTo+oVnjkYi+MEx0xH236M9EaCBnfYQTgHk3BBg11wK bZ6RR+6TVrHAUrgDVw3nBoinZWzyMC+4UvNafjRElqBsX6YX5VX+3vxoaTjGzXfqMUoTx8 wdLZLiiWI9ErtG5UYxNm0dGQT+yV+6o= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1752243073; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=ZLVxbUl1QbCpvaOs+8U0flUWK625i092YCFo0WiecoQ=; b=FASXHoFAE2p9UyIYcaBQuEEOc90erJ+G8G2ZV5cqewLNcyMjkVxLhLBVwj71nz5VXWVWyU HO35yFm4/mNAYCCQ== From: Fabiano Rosas To: qemu-devel@nongnu.org Cc: Peter Xu Subject: [PULL 20/26] migration/postcopy: Initialize blocktime context only until listen Date: Fri, 11 Jul 2025 11:10:25 -0300 Message-Id: <20250711141031.423-21-farosas@suse.de> X-Mailer: git-send-email 2.35.3 In-Reply-To: <20250711141031.423-1-farosas@suse.de> References: <20250711141031.423-1-farosas@suse.de> MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable X-Spamd-Result: default: False [-3.01 / 50.00]; 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envelope-from=qemu-devel-bounces+importer=patchew.org@nongnu.org; helo=lists.gnu.org; Received-SPF: pass client-ip=2a07:de40:b251:101:10:150:64:2; 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, 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+importer=patchew.org@nongnu.org Sender: qemu-devel-bounces+importer=patchew.org@nongnu.org X-ZohoMail-DKIM: pass (identity @suse.de) X-ZM-MESSAGEID: 1752243762518116600 Content-Type: text/plain; charset="utf-8" From: Peter Xu Before this patch, the blocktime context can be created very early, because postcopy_ram_supported_by_host() <- migrate_caps_check() can happen during migration object init. The trick here is the blocktime context needs system vCPU information, which seems to be possible to change after that point. I didn't verify it, but it doesn't sound right. Now move it out and initialize the context only when postcopy listen starts. That is already during a migration so it should be guaranteed the vCPU topology can never change on both sides. While at it, assert that the ctx isn't created instead this time; the old "if" trick isn't needed when we're sure it will only happen once now. Reviewed-by: Fabiano Rosas Link: https://lore.kernel.org/r/20250613141217.474825-10-peterx@redhat.com Signed-off-by: Peter Xu Signed-off-by: Fabiano Rosas --- migration/postcopy-ram.c | 15 ++++++++++----- 1 file changed, 10 insertions(+), 5 deletions(-) diff --git a/migration/postcopy-ram.c b/migration/postcopy-ram.c index fe940f89b9..dd3615663f 100644 --- a/migration/postcopy-ram.c +++ b/migration/postcopy-ram.c @@ -325,13 +325,13 @@ static bool ufd_check_and_apply(int ufd, MigrationInc= omingState *mis, } =20 #ifdef UFFD_FEATURE_THREAD_ID + /* + * Postcopy blocktime conditionally needs THREAD_ID feature (introduced + * to Linux in 2017). Always try to enable it when QEMU is compiled + * with such environment. + */ if (UFFD_FEATURE_THREAD_ID & supported_features) { asked_features |=3D UFFD_FEATURE_THREAD_ID; - if (migrate_postcopy_blocktime()) { - if (!mis->blocktime_ctx) { - mis->blocktime_ctx =3D blocktime_context_new(); - } - } } #endif =20 @@ -1239,6 +1239,11 @@ int postcopy_ram_incoming_setup(MigrationIncomingSta= te *mis) return -1; } =20 + if (migrate_postcopy_blocktime()) { + assert(mis->blocktime_ctx =3D=3D NULL); + mis->blocktime_ctx =3D blocktime_context_new(); + } + /* Now an eventfd we use to tell the fault-thread to quit */ mis->userfault_event_fd =3D eventfd(0, EFD_CLOEXEC); if (mis->userfault_event_fd =3D=3D -1) { --=20 2.35.3