Subject: [patch V4 09-01/35] PCI/MSI: Decouple MSI[-X] disable from pcim_release()

From: Thomas Gleixner <[email-masked]>
Date: Wed, 15 Dec 2021 18:16:44 +0100

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 <[email-masked]>
Signed-off-by: Thomas Gleixner <[email-masked]>
---
V4: New patch
---
 drivers/pci/msi/msi.c |   33 +++++++++++++++++++++++++++++++++
 drivers/pci/pci.c     |    5 -----
 include/linux/pci.h   |    3 ++-
 3 files changed, 35 insertions(+), 6 deletions(-)

--- a/drivers/pci/msi/msi.c
+++ b/drivers/pci/msi/msi.c
@@ -341,6 +341,31 @@ void pci_restore_msi_state(struct pci_de
 }
 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
 	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(struc
 	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);
--- a/drivers/pci/pci.c
+++ b/drivers/pci/pci.c
@@ -2024,11 +2024,6 @@ static void pcim_release(struct device *
 	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);
--- 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;

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