linux-kernel - [tip: irq/msi] PCI/MSI: Decouple MSI[-X] disable from pcim

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Date:   Thu, 16 Dec 2021 21:41:07 -0000
From:   "tip-bot2 for Thomas Gleixner" <tip-bot2@...utronix.de>
To:     linux-tip-commits@...r.kernel.org
Cc:     Nishanth Menon <nm@...com>, Thomas Gleixner <tglx@...utronix.de>,
        Michael Kelley <mikelley@...rosoft.com>,
        "Greg Kroah-Hartman" <gregkh@...uxfoundation.org>, x86@...nel.org,
        linux-kernel@...r.kernel.org
Subject: [tip: irq/msi] PCI/MSI: Decouple MSI[-X] disable from pcim_release()

The following commit has been merged into the irq/msi branch of tip:

Commit-ID:     3f35d2cf9fbc656db82579d849cc69c373b1ad0d
Gitweb:        https://git.kernel.org/tip/3f35d2cf9fbc656db82579d849cc69c373b1ad0d
Author:        Thomas Gleixner <tglx@...utronix.de>
AuthorDate:    Wed, 15 Dec 2021 18:16:44 +01:00
Committer:     Thomas Gleixner <tglx@...utronix.de>
CommitterDate: Thu, 16 Dec 2021 22:16:38 +01:00

PCI/MSI: Decouple MSI[-X] disable from pcim_release()

The MSI core will introduce runtime allocation of MSI related data. This
data will be devres managed and has to be set up before enabling
PCI/MSI[-X]. This would introduce an ordering issue vs. pcim_release().

The setup order is:

   pcim_enable_device()
	devres_alloc(pcim_release...);
	...
	pci_irq_alloc()
	  msi_setup_device_data()
	     devres_alloc(msi_device_data_release, ...)

and once the device is released these release functions are invoked in the
opposite order:

    msi_device_data_release()
    ...
    pcim_release()
       pci_disable_msi[x]()

which is obviously wrong, because pci_disable_msi[x]() requires the MSI
data to be available to tear down the MSI[-X] interrupts.

Remove the MSI[-X] teardown from pcim_release() and add an explicit action
to be installed on the attempt of enabling PCI/MSI[-X].

This allows the MSI core data allocation to be ordered correctly in a
subsequent step.

Reported-by: Nishanth Menon <nm@...com>
Signed-off-by: Thomas Gleixner <tglx@...utronix.de>
Tested-by: Michael Kelley <mikelley@...rosoft.com>
Tested-by: Nishanth Menon <nm@...com>
Reviewed-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
Link: https://lore.kernel.org/r/87tuf9rdoj.ffs@tglx

---
 drivers/pci/msi/msi.c | 33 +++++++++++++++++++++++++++++++++
 drivers/pci/pci.c     |  5 -----
 include/linux/pci.h   |  3 ++-
 3 files changed, 35 insertions(+), 6 deletions(-)

diff --git a/drivers/pci/msi/msi.c b/drivers/pci/msi/msi.c
index 5af8d9b..358b63e 100644
--- a/drivers/pci/msi/msi.c
+++ b/drivers/pci/msi/msi.c
@@ -341,6 +341,31 @@ void pci_restore_msi_state(struct pci_dev *dev)
 }
 EXPORT_SYMBOL_GPL(pci_restore_msi_state);
 
+static void pcim_msi_release(void *pcidev)
+{
+	struct pci_dev *dev = pcidev;
+
+	dev->is_msi_managed = false;
+	pci_free_irq_vectors(dev);
+}
+
+/*
+ * Needs to be separate from pcim_release to prevent an ordering problem
+ * vs. msi_device_data_release() in the MSI core code.
+ */
+static int pcim_setup_msi_release(struct pci_dev *dev)
+{
+	int ret;
+
+	if (!pci_is_managed(dev) || dev->is_msi_managed)
+		return 0;
+
+	ret = devm_add_action(&dev->dev, pcim_msi_release, dev);
+	if (!ret)
+		dev->is_msi_managed = true;
+	return ret;
+}
+
 static struct msi_desc *
 msi_setup_entry(struct pci_dev *dev, int nvec, struct irq_affinity *affd)
 {
@@ -884,6 +909,10 @@ static int __pci_enable_msi_range(struct pci_dev *dev, int minvec, int maxvec,
 	if (nvec > maxvec)
 		nvec = maxvec;
 
+	rc = pcim_setup_msi_release(dev);
+	if (rc)
+		return rc;
+
 	for (;;) {
 		if (affd) {
 			nvec = irq_calc_affinity_vectors(minvec, nvec, affd);
@@ -927,6 +956,10 @@ static int __pci_enable_msix_range(struct pci_dev *dev,
 	if (WARN_ON_ONCE(dev->msix_enabled))
 		return -EINVAL;
 
+	rc = pcim_setup_msi_release(dev);
+	if (rc)
+		return rc;
+
 	for (;;) {
 		if (affd) {
 			nvec = irq_calc_affinity_vectors(minvec, nvec, affd);
diff --git a/drivers/pci/pci.c b/drivers/pci/pci.c
index 3d2fb39..f3f606c 100644
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -2024,11 +2024,6 @@ static void pcim_release(struct device *gendev, void *res)
 	struct pci_devres *this = res;
 	int i;
 
-	if (dev->msi_enabled)
-		pci_disable_msi(dev);
-	if (dev->msix_enabled)
-		pci_disable_msix(dev);
-
 	for (i = 0; i < DEVICE_COUNT_RESOURCE; i++)
 		if (this->region_mask & (1 << i))
 			pci_release_region(dev, i);
diff --git a/include/linux/pci.h b/include/linux/pci.h
index 5cc46ba..a09736d 100644
--- a/include/linux/pci.h
+++ b/include/linux/pci.h
@@ -425,7 +425,8 @@ struct pci_dev {
 	unsigned int	ats_enabled:1;		/* Address Translation Svc */
 	unsigned int	pasid_enabled:1;	/* Process Address Space ID */
 	unsigned int	pri_enabled:1;		/* Page Request Interface */
-	unsigned int	is_managed:1;
+	unsigned int	is_managed:1;		/* Managed via devres */
+	unsigned int	is_msi_managed:1;	/* MSI release via devres installed */
 	unsigned int	needs_freset:1;		/* Requires fundamental reset */
 	unsigned int	state_saved:1;
 	unsigned int	is_physfn:1;