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 CF0DE5803B0 for ; Wed, 9 Sep 2026 14:30:55 +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=1788964257; cv=none; b=LgtWsS0t/d2hUJHwmMFKCi5Rs7KqIEz5CPHIkZqcUu3z7Nn5wBI8UThGp1mDTO1pqZZFL08mty52pEtES4KNOLc3Q++Em8ji01reK7ekWKbgwelwR4m71T8Ngm5HRdSWF3DlYfZ/qsLSF9sze25pWQUvjIcWPfnlulFwznCO+Vc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788964257; c=relaxed/simple; bh=W8U6fqv317nGiSS5PM3W0y+Hm1X9fNbYfI0iVppd+FQ=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=lSRYJE3Lwb6bjqQZMnTwEMVIXK8LsWUJeVoR0p3F1dhcVBMjptkuaDnrfYlsVEW74+2AsW1S8/7fUmeYqlrqjZTv7AZVygkaFTt8a3jc7VnMb7mYMS7nNNtn2+zu/hRvl8cA9x+EmsLb86ZzmvW9iFREtOhPPGlNE+QS+p/wp10= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=et8br5uY; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="et8br5uY" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 2E1F61F00A3E; Wed, 9 Sep 2026 14:30:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1788964255; bh=EMQSpk1ncnJzIbUw5V4dzkIs0WfFs7U4XnyFk+SdNLM=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=et8br5uYhWamnBCKg/apWK8naLO0x7OPu3YkbqG5h+bjEiF4jCZ+d3lStq08Z3XsE z6jILL5JsETFR/HsTaKctYKmUK7y5pFIiqseBOwxiyKj1rzWL63xDLdQTVdxPvPfqt qkMpweM6I2kIcIgeDM7wFhaqJabsm30bLCSvxdbf1if/y/ube93qmSVAHBo6XnIWHL pUB1uHPXBGrdru4nG90A82jdX+7qxizbE2XftAbAnDmnemkpotzSOpi7UehsNuy5td WUTwwYzxL5BII1Vs4xv3JrDKw6z/3oJfuItlE52hdMBLyTzu6aaxCNVT5N5iRaD+5g 79crTN1bA1VPw== From: Sasha Levin To: stable@vger.kernel.org Cc: Farhan Ali , Niklas Schnelle , Bjorn Helgaas , Sasha Levin Subject: [PATCH 6.1.y 2/2] PCI: Allow per function PCI slots to fix slot reset on s390 Date: Wed, 9 Sep 2026 10:30:52 -0400 Message-ID: <20260909143052.2492494-2-sashal@kernel.org> X-Mailer: git-send-email 2.53.0 In-Reply-To: <20260909143052.2492494-1-sashal@kernel.org> References: <2026090356-exchange-blinking-b06e@gregkh> <20260909143052.2492494-1-sashal@kernel.org> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 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 --- drivers/pci/pci.c | 5 +++-- drivers/pci/slot.c | 29 +++++++++++++++++++++++------ include/linux/pci.h | 7 ++++--- 3 files changed, 30 insertions(+), 11 deletions(-) diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c index c87a5e9f75684..1b07332885db2 100644 --- a/drivers/pci/pci.c +++ b/drivers/pci/pci.c @@ -5099,8 +5099,9 @@ static int pci_reset_hotplug_slot(struct hotplug_slot *hotplug, bool probe) 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); diff --git a/drivers/pci/slot.c b/drivers/pci/slot.c index 82a37a4973f9a..c2ef32f6f6cbc 100644 --- a/drivers/pci/slot.c +++ b/drivers/pci/slot.c @@ -73,6 +73,23 @@ static ssize_t cur_speed_read_file(struct pci_slot *slot, char *buf) 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; @@ -83,8 +100,7 @@ static void pci_slot_release(struct kobject *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); @@ -177,8 +193,7 @@ void pci_dev_assign_slot(struct pci_dev *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); } @@ -288,6 +303,9 @@ struct pci_slot *pci_create_slot(struct pci_bus *parent, int slot_nr, 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); @@ -310,8 +328,7 @@ struct pci_slot *pci_create_slot(struct pci_bus *parent, int slot_nr, 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); diff --git a/include/linux/pci.h b/include/linux/pci.h index 8babaffbe8b11..0c7446bc02b55 100644 --- a/include/linux/pci.h +++ b/include/linux/pci.h @@ -77,17 +77,18 @@ * 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; }; -- 2.53.0