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 36A7A572663; Wed, 9 Sep 2026 14:13:50 +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=1788963231; cv=none; b=DyvQDZuKOFjAU2WkkUw9sGgmYVvmThZ1QK5BfruKLYTKhxNBb3m3QKzV9RsWFKRH6KgSI8OFM/MLiTj0ybVlNeYb1R7xc6FRKP1yArzI7S/R9qFXE7g2q+tbYZWrHUwWWRY0cAez5AONVwkI3SWgjxgEZYrbhw3Oiuro7k2h/vY= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788963231; c=relaxed/simple; bh=XAMHINbG9pUptbsreudszIHjYF9jwGlEmmbjhppEQ8I=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=Y0DNTdsQ5cUgWevnrVmDDwXa4eh+Qg27IWinavSqTgL4lyOQn6WYwfOW/7AkD7pdNUNSfJxxcph9QWzsQo0P23vhdVz7QH/hltG8ObfIFhlKobJaewaD8qLulHlT3WJ+nwypBJVyVbwE7DFQHjzYFq1EV0ZO0n8lQOMbGNS/TWI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=1IwsKnvZ; 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="1IwsKnvZ" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 7FA661F00A3A; Wed, 9 Sep 2026 14:13:49 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1788963230; bh=VvlCPLjJf7NyIL/NnmcM28BifezN1ANT7qUPEJF4VFc=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=1IwsKnvZX6kDWuVrksO82tcBNWHSCf/yGTVI7FQnJ369PL7NWPDetDYtSx5PaGp7e 1+1ZfUlWq7yB/fdDvRHTkHtr2b1JzGUS3MpgIMvcO7U/2Yf+CU3pftxKnKtFFIlbwu LYC+2UhvcUUpErqT1Zkjc2ve8zFc3DBPm+M2vvJ0= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Niklas Schnelle , Farhan Ali , Bjorn Helgaas , Sasha Levin Subject: [PATCH 7.2 556/556] PCI: Allow per function PCI slots to fix slot reset on s390 Date: Wed, 9 Sep 2026 15:43:56 +0200 Message-ID: <20260909134249.942765595@linuxfoundation.org> X-Mailer: git-send-email 2.55.0 In-Reply-To: <20260909134230.441546314@linuxfoundation.org> References: <20260909134230.441546314@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 7.2-stable review patch. If anyone has any objections, please let me know. ------------------ From: Farhan Ali [ Upstream commit dcc5bec09e23bbc4f9de055a11fce9937244f2c8 ] On s390 systems, which use a machine level hypervisor, PCI devices are always accessed through a form of PCI pass-through which fundamentally operates on a per PCI function granularity. This is also reflected in the s390 PCI hotplug driver which creates hotplug slots for individual PCI functions. Its reset_slot() function, which is a wrapper for zpci_hot_reset_device(), thus also resets individual functions. Currently, the pci_create_slot() assigns the same pci_slot object to multifunction devices. This approach worked fine on s390 systems that only exposed virtual functions as individual PCI domains to the operating system. Since commit 44510d6fa0c0 ("s390/pci: Handling multifunctions") s390 supports exposing the topology of multifunction PCI devices by grouping them in a shared PCI domain. This creates a problem when resetting a function through the hotplug driver's slot_reset() interface. When attempting to reset a function through the hotplug driver, the shared slot assignment causes the wrong function to be reset instead of the intended one. It also leaks memory as we do create a pci_slot object for the function, but don't correctly free it in pci_slot_release(). Add a flag for struct pci_slot to allow per function PCI slots for functions managed through a hypervisor, which exposes individual PCI functions while retaining the topology. Since we can use all 8 bits for slot 'number' (for ARI devices), change slot 'number' u16 to account for special values PCI_SLOT_PLACEHOLDER and PCI_SLOT_ALL_DEVICES. Fixes: 44510d6fa0c0 ("s390/pci: Handling multifunctions") Suggested-by: Niklas Schnelle Signed-off-by: Farhan Ali Signed-off-by: Bjorn Helgaas Reviewed-by: Niklas Schnelle Cc: stable@vger.kernel.org Link: https://patch.msgid.link/20260805165518.794-3-alifm@linux.ibm.com Signed-off-by: Sasha Levin Signed-off-by: Greg Kroah-Hartman --- drivers/pci/pci.c | 5 +++-- drivers/pci/slot.c | 29 +++++++++++++++++++++++------ include/linux/pci.h | 7 ++++--- 3 files changed, 30 insertions(+), 11 deletions(-) --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -4897,8 +4897,9 @@ static int pci_reset_hotplug_slot(struct static int pci_dev_reset_slot_function(struct pci_dev *dev, bool probe) { - if (dev->multifunction || dev->subordinate || !dev->slot || - dev->dev_flags & PCI_DEV_FLAGS_NO_BUS_RESET) + if (dev->subordinate || !dev->slot || + dev->dev_flags & PCI_DEV_FLAGS_NO_BUS_RESET || + (dev->multifunction && !dev->slot->per_func_slot)) return -ENOTTY; return pci_reset_hotplug_slot(dev->slot->hotplug, probe); --- a/drivers/pci/slot.c +++ b/drivers/pci/slot.c @@ -72,6 +72,23 @@ static ssize_t cur_speed_read_file(struc return bus_speed_read(slot->bus->cur_bus_speed, buf); } +static bool pci_dev_matches_slot(struct pci_dev *dev, struct pci_slot *slot) +{ + if (slot->per_func_slot) + return dev->devfn == slot->number; + + return slot->number == PCI_SLOT_ALL_DEVICES || + PCI_SLOT(dev->devfn) == slot->number; +} + +static bool pci_slot_enabled_per_func(void) +{ + if (IS_ENABLED(CONFIG_S390)) + return true; + + return false; +} + static void pci_slot_release(struct kobject *kobj) { struct pci_dev *dev; @@ -82,8 +99,7 @@ static void pci_slot_release(struct kobj down_read(&pci_bus_sem); list_for_each_entry(dev, &slot->bus->devices, bus_list) - if (slot->number == PCI_SLOT_ALL_DEVICES || - PCI_SLOT(dev->devfn) == slot->number) + if (pci_dev_matches_slot(dev, slot)) dev->slot = NULL; up_read(&pci_bus_sem); @@ -187,8 +203,7 @@ void pci_dev_assign_slot(struct pci_dev mutex_lock(&pci_slot_mutex); list_for_each_entry(slot, &dev->bus->slots, list) - if (slot->number == PCI_SLOT_ALL_DEVICES || - PCI_SLOT(dev->devfn) == slot->number) + if (pci_dev_matches_slot(dev, slot)) dev->slot = slot; mutex_unlock(&pci_slot_mutex); } @@ -299,6 +314,9 @@ placeholder: slot->bus = pci_bus_get(parent); slot->number = slot_nr; + if (pci_slot_enabled_per_func()) + slot->per_func_slot = 1; + slot->kobj.kset = pci_slots_kset; slot_name = make_slot_name(name); @@ -319,8 +337,7 @@ placeholder: down_read(&pci_bus_sem); list_for_each_entry(dev, &parent->devices, bus_list) - if (slot_nr == PCI_SLOT_ALL_DEVICES || - PCI_SLOT(dev->devfn) == slot_nr) + if (pci_dev_matches_slot(dev, slot)) dev->slot = slot; up_read(&pci_bus_sem); --- a/include/linux/pci.h +++ b/include/linux/pci.h @@ -79,17 +79,18 @@ * and, if ARI Forwarding is enabled, functions may appear to be on multiple * devices. */ -#define PCI_SLOT_ALL_DEVICES 0xfe +#define PCI_SLOT_ALL_DEVICES 0xfeff /* Used to identify a slot as a placeholder */ -#define PCI_SLOT_PLACEHOLDER 0xff +#define PCI_SLOT_PLACEHOLDER 0xffff /* pci_slot represents a physical slot */ struct pci_slot { struct pci_bus *bus; /* Bus this slot is on */ struct list_head list; /* Node in list of slots */ struct hotplug_slot *hotplug; /* Hotplug info (move here) */ - unsigned char number; /* Device nr, or PCI_SLOT_ALL_DEVICES */ + u16 number; /* Device nr, or PCI_SLOT_ALL_DEVICES */ + unsigned int per_func_slot:1; /* Allow per function slot */ struct kobject kobj; };