From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9A7364279E3 for ; Mon, 29 Jun 2026 14:49:23 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782744566; cv=none; b=GO5vj8nu5AJzr/6fMd+YOBN0TjqcjjAHB/MbYvsOI4QD8tzt+y1j1xDAcdQ95+Lt8ahQSEs3z+TbXTfgdDwsWzydoD9Sv7cJKqWy+QAZHZsgp4Pk9eN2atsP1pQLOydXAKaXUcmpbF8Lg9oC/CL0yFJsf6WwlciYiy59RHvIB9c= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782744566; c=relaxed/simple; bh=WRvszeiPBO/Fb5FiI/vE/FGwK3nriHHDLWyvTKu4jxY=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=bjjPNnwhDmNympchN74D57SlKtwRA8k506i4c1SOB8CRg4SbW/viYEGLZBVOHkco+bqMnS3dhuevSdFMGiHAsdGu3IVnaerGHLa7vNqrjpbiYcI2dV8NzzvlNYh6tWkBFB2kDPh5jrUo6zaFpAJKfwn7ROfN7KzfKqO2/nSJlZ8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=WxY9UqmJ; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=quarantine dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="WxY9UqmJ" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1782744562; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=TT8DezCMCkGl2L1G18lDfniaKuva6//NVtalZcejz24=; b=WxY9UqmJf9FHMznmko4ZcKOS1CMwI9Rb1MwFE2yxoScoTRiwNk2Qry1UbuvXZlFHjX+njw 0xhiHKoBIeP8SaeeRUmZFwQvyKlHJILJhLFuaXTdxP4LWfIOmyAObxMC7T4Xhxq+wWWKkE 76bkHLiA59Vqt+mSOXpTkZO6a8Euj3Q= Received: from mx-prod-mc-05.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-501-m58T3XVhPY6ALAcZ2BpU0w-1; Mon, 29 Jun 2026 10:49:16 -0400 X-MC-Unique: m58T3XVhPY6ALAcZ2BpU0w-1 X-Mimecast-MFC-AGG-ID: m58T3XVhPY6ALAcZ2BpU0w_1782744555 Received: from mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.111]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id 132EB19235F6; Mon, 29 Jun 2026 14:48:50 +0000 (UTC) Received: from desnesn-thinkpadp16vgen1.rmtbr.csb (unknown [10.96.134.92]) by mx-prod-int-08.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id 6D65C18007F8; Mon, 29 Jun 2026 14:48:46 +0000 (UTC) From: Desnes Nunes To: linux-kernel@vger.kernel.org, iommu@lists.linux.dev, stable@vger.kernel.org Cc: baolu.lu@linux.intel.com, dwmw2@infradead.org, Desnes Nunes Subject: [PATCH v2] iommu/vt-d: Fix UCTP context table slot when copying root entries Date: Mon, 29 Jun 2026 11:48:37 -0300 Message-ID: <20260629144837.3244851-1-desnesn@redhat.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.111 When translation is already enabled at boot (e.g. kdump), the vt-d driver copies context tables from the previous kernel's root table. In scalable mode, buses that only populate the upper root half (UCTP, devfn >= 0x80) should be written to ctxt_tbls[tbl_idx + 1] through copy_context_table(). However, the current copy path always uses tbl[tbl_idx + 0] in this situa- tion. Since idx wraps to 0 at devfn 0x80 due to a zeroed LCTP, new_ce for LCTP will be NULL and keep pos equals to 0. Thus, UCTP entries will be co- pied into tbl[tbl_idx + 0] instead of tbl[tbl_idx + 1], and written after- wards to root_entry[bus].lo instead of .hi in copy_translation_tables(). In short, devices on bus 0x80 with devfn >= 0x80 fail DMA with fault 0x39, which will break drivers running in kernels with translation pre-enabled. This fixes NO_PASID DMAR faults for UCTP-only buses such as: DMAR: [DMA Read NO_PASID] Request device [80:14.0] fault addr 0xe81759000 [fault reason 0x39] SM: Present bit in Root Entry is clear For instance, this fault yielded to locking issues between systemd and xHCI, blocking a system's reboot after a vmcore was captured with kdump: [ 72.987601] systemd-udevd[246]: usb3: Worker [255] processing SEQNUM=2193 is taking a long time [ 132.237566] dracut-initqueue[277]: Timed out while waiting for udev queue to empty. [ 202.988014] systemd-udevd[246]: usb3: Worker [255] processing SEQNUM=2193 killed [ 202.998059] systemd-udevd[246]: usb3: Worker [255] terminated by signal 9 (KILL). ... [ 206.288378] kdump[569]: saving vmcore complete ... [ 206.821258] systemd-shutdown[1]: Rebooting. [ 246.858495] INFO: task kworker/0:1:11 blocked for more than 122 seconds. [ 246.865319] Not tainted 7.0.0-clean #1 [ 246.869663] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 246.877623] task:kworker/0:1 state:D stack:0 pid:11 tgid:11 ppid:2 task_flags:0x4208160 flags:0x00080000 [ 246.888942] Workqueue: usb_hub_wq hub_event [ 246.893202] Call Trace: [ 246.895690] [ 246.897828] __schedule+0x299/0x5c0 [ 246.901378] schedule+0x27/0x80 [ 246.904572] schedule_timeout+0xbd/0x100 [ 246.908565] __wait_for_common+0x97/0x1b0 [ 246.912644] ? __pfx_schedule_timeout+0x10/0x10 [ 246.917252] xhci_alloc_dev+0x9e/0x2b0 [ 246.921068] usb_alloc_dev+0x7a/0x3b0 [ 246.924795] hub_port_connect+0x285/0x960 [ 246.928873] hub_port_connect_change+0x94/0x290 [ 246.933482] port_event+0x4bb/0x840 [ 246.937030] hub_event+0x141/0x460 [ 246.940489] process_one_work+0x196/0x390 [ 246.944569] worker_thread+0x1af/0x320 [ 246.948383] ? __pfx_worker_thread+0x10/0x10 [ 246.952724] kthread+0xe3/0x120 [ 246.955921] ? __pfx_kthread+0x10/0x10 [ 246.959736] ret_from_fork+0x199/0x260 [ 246.963550] ? __pfx_kthread+0x10/0x10 [ 246.967362] ret_from_fork_asm+0x1a/0x30 [ 246.971355] [ 369.738508] INFO: task systemd-shutdow:1 blocked for more than 122 seconds. [ 369.745593] Not tainted 7.0.0-clean #1 [ 369.749935] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 369.757897] task:systemd-shutdow state:D stack:0 pid:1 tgid:1 ppid:0 task_flags:0x400100 flags:0x00080000 [ 369.769128] Call Trace: [ 369.771616] [ 369.773752] __schedule+0x299/0x5c0 [ 369.777299] schedule+0x27/0x80 [ 369.780493] schedule_preempt_disabled+0x15/0x30 [ 369.785188] __mutex_lock.constprop.0+0x547/0xac0 [ 369.789974] device_shutdown+0xac/0x1b0 [ 369.793877] kernel_restart+0x3a/0x70 [ 369.797603] __do_sys_reboot+0x147/0x240 [ 369.801595] do_syscall_64+0x11b/0x6a0 [ 369.805407] ? handle_mm_fault+0x110/0x350 [ 369.809574] ? do_user_addr_fault+0x206/0x680 [ 369.814006] ? irqentry_exit+0x7a/0x4d0 [ 369.817907] entry_SYSCALL_64_after_hwframe+0x76/0x7e [ 369.823046] RIP: 0033:0x7fe2958da917 [ 369.826684] RSP: 002b:00007ffc5c458618 EFLAGS: 00000206 ORIG_RAX: 00000000000000a9 [ 369.834383] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007fe2958da917 [ 369.841639] RDX: 0000000001234567 RSI: 0000000028121969 RDI: 00000000fee1dead [ 369.848893] RBP: 00007ffc5c458790 R08: 0000000000000069 R09: 00000000ffffffff [ 369.856148] R10: 0000000000000000 R11: 0000000000000206 R12: 0000000000000000 [ 369.863402] R13: 0000000000000000 R14: 00007ffc5c4588b8 R15: 0000000000000000 [ 369.870659] [ 369.872888] INFO: task systemd-shutdow:1 is blocked on a mutex likely owned by task kworker/0:1:11. Fixes: 091d42e43d21 ("iommu/vt-d: Copy translation tables from old kernel") Signed-off-by: Desnes Nunes --- V1 -> V2: Updated commit message and added xHCI stack trace as requested v1: https://lore.kernel.org/linux-iommu/ajnlKDglN6wEBBrS@google.com/T/#t drivers/iommu/intel/iommu.c | 10 ++++++---- 1 file changed, 6 insertions(+), 4 deletions(-) diff --git a/drivers/iommu/intel/iommu.c b/drivers/iommu/intel/iommu.c index 4d0e65bc131d..737936f942a0 100644 --- a/drivers/iommu/intel/iommu.c +++ b/drivers/iommu/intel/iommu.c @@ -1443,7 +1443,7 @@ static int copy_context_table(struct intel_iommu *iommu, struct context_entry **tbl, int bus, bool ext) { - int tbl_idx, pos = 0, idx, devfn, ret = 0, did; + int tbl_idx, tbl_slot = 0, idx, devfn, ret = 0, did; struct context_entry *new_ce = NULL, ce; struct context_entry *old_ce = NULL; struct root_entry re; @@ -1459,10 +1459,9 @@ static int copy_context_table(struct intel_iommu *iommu, if (idx == 0) { /* First save what we may have and clean up */ if (new_ce) { - tbl[tbl_idx] = new_ce; + tbl[tbl_idx + tbl_slot] = new_ce; __iommu_flush_cache(iommu, new_ce, VTD_PAGE_SIZE); - pos = 1; } if (old_ce) @@ -1484,6 +1483,9 @@ static int copy_context_table(struct intel_iommu *iommu, } } + /* Track if saving UCTP or LCTP entries in scalable mode */ + tbl_slot = ext && devfn >= 0x80 ? 1 : 0; + ret = -ENOMEM; old_ce = memremap(old_ce_phys, PAGE_SIZE, MEMREMAP_WB); @@ -1512,7 +1514,7 @@ static int copy_context_table(struct intel_iommu *iommu, new_ce[idx] = ce; } - tbl[tbl_idx + pos] = new_ce; + tbl[tbl_idx + tbl_slot] = new_ce; __iommu_flush_cache(iommu, new_ce, VTD_PAGE_SIZE); -- 2.54.0