From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (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 1FA3946EF8C; Tue, 21 Jul 2026 18:02:43 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784656964; cv=none; b=oVUC/guZjc/nRzWgL0Mvxz75Ue4+T1yaTv/i8KIv49b2j91imk+C0nB3a/N6bLnAk8BtRxvyuYQxnD5NShJiHELrfkeYW5o/Af7/a3JzEymfsHMAuVy+A2ltUr2RmwbUk6EjxLteemvwmWooigUC6mZAE7zIYtqxqoVtNAUqtUk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784656964; c=relaxed/simple; bh=LpwAU+STX5Pj3nZFY/khGuGKrzp78IodVBmJHP56R60=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=A0c/FDE9mjN9ELEvGwi/LCGdoftFzbPKfE8oJYz/xLJDVbCQqe+WdWSjVeIgHZKfuHpP2Wpxkfm/I3gZyDkl/UOVxtwgI5pqOCj/H7rHnUOyP/GPk3IG4VhLOxco2fcojS0qYpM5o6nQ5n+XfXiDsEt5xdU5QMn4FwGQQWXGjK8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=mjbPAO6z; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="mjbPAO6z" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 780011F000E9; Tue, 21 Jul 2026 18:02:42 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1784656963; bh=e5xoFI5nhR50IPkZ1U8HmOH0AAo6R+b36H4uscVs+yE=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=mjbPAO6z14N0uVlehgzmejtHCU7Khy4imXpA7sLzTeBZ9GNGbFPKjFqE6Uv9C/lJx nhiEyh+w3Yy0ifsF3VNDJqTxxcaYCvUT2qC4EXbWU3TbKjgRMJdp+yP6b1nt6lviAp FENv7Io2uESlQFrThPEpaLeNniktFcBIW1QX7nNo= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, "Carlos Bilbao (Lambda)" , Bjorn Helgaas , Sasha Levin Subject: [PATCH 6.18 0585/1611] PCI/ASPM: Dont reconfigure ASPM entering low-power state Date: Tue, 21 Jul 2026 17:11:41 +0200 Message-ID: <20260721152528.538750437@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260721152514.750365251@linuxfoundation.org> References: <20260721152514.750365251@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.18-stable review patch. If anyone has any objections, please let me know. ------------------ From: Carlos Bilbao [ Upstream commit c855c9921da72e535c24737c748f603a52d03f7e ] Reconfiguring ASPM when a device transitions to low-power state can enable L1.1/L1.2 substates on the PCIe link at a time when the device is sleeping and may be unable to exit them. ASPM should be reconfigured on D0 entry (resume), not on the way down. pci_set_low_power_state() calls pcie_aspm_pm_state_change() after writing D3hot to PCI_PM_CTRL. pcie_aspm_pm_state_change() resets link->aspm_capable to link->aspm_support and then calls pcie_config_aspm_path(), which can enable ASPM L1.1/L1.2 substates on the PCIe link. If the device cannot recover the link from L1.2 while in D3hot, subsequent config space reads return 0xFFFF ("device inaccessible") and pci_power_up() fails with messages like: vfio-pci 0000:5d:00.0: Unable to change power state from D3hot to D0, device inaccessible This was observed on NVIDIA H100 SXM5 GPUs bound to vfio-pci when Linux runtime PM suspends them to D3hot: the GPU becomes permanently inaccessible and disappears from the PCIe bus. The call to pcie_aspm_pm_state_change() in pci_set_low_power_state() was restored by f93e71aea6c6 ("Revert "PCI/ASPM: Remove pcie_aspm_pm_state_change()""), which reverted 08d0cc5f3426 ("PCI/ASPM: Remove pcie_aspm_pm_state_change()"). The revert was necessary because the removal broke suspend/resume on certain platforms that required ASPM to be reconfigured on D0 entry. However, the revert restored the call in both pci_set_full_power_state() (D0 entry) and pci_set_low_power_state() (low-power entry). Only the D0-entry call is needed to fix the suspend/resume regression. The low-power-entry call is harmful: reconfiguring ASPM immediately after putting a device into D3hot can enable link substates that the device or platform cannot exit while the device is sleeping. Remove the pcie_aspm_pm_state_change() call from pci_set_low_power_state(). ASPM will still be reconfigured correctly when the device returns to D0 via pci_set_full_power_state(). Fixes: f93e71aea6c6 ("Revert "PCI/ASPM: Remove pcie_aspm_pm_state_change()"") Signed-off-by: Carlos Bilbao (Lambda) Signed-off-by: Bjorn Helgaas Link: https://patch.msgid.link/20260428040104.78524-1-carlos.bilbao@kernel.org Signed-off-by: Sasha Levin --- drivers/pci/pci.c | 3 --- 1 file changed, 3 deletions(-) diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index 0b6a23405f167a..6420b371aaf07f 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -1519,9 +1519,6 @@ static int pci_set_low_power_state(struct pci_dev *dev, pci_power_t state, bool pci_power_name(dev->current_state), pci_power_name(state)); - if (dev->bus->self) - pcie_aspm_pm_state_change(dev->bus->self, locked); - return 0; } -- 2.53.0