PCI/MSI: Set pci_dev::msi[x]_enabled early

There are quite some places which retrieve the first MSI descriptor to
evaluate whether the setup is for MSI or MSI-X. That's required because
pci_dev::msi[x]_enabled is only set when the setup completed successfully.

There is no real reason why msi[x]_enabled can't be set at the beginning of
the setup sequence and cleared in case of a failure.

Implement that so the MSI descriptor evaluations can be converted to simple
property queries.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Tested-by: Michael Kelley <mikelley@microsoft.com>
Tested-by: Nishanth Menon <nm@ti.com>
Reviewed-by: Jason Gunthorpe <jgg@nvidia.com>
Link: https://lore.kernel.org/r/20211210221813.250049810@linutronix.de

drivers/pci/msi/msi.c

@@ -421,11 +421,18 @@ static int msi_capability_init(struct pci_dev *dev, int nvec,
 	struct msi_desc *entry;
 	int ret;
 
-	pci_msi_set_enable(dev, 0);	/* Disable MSI during set up */
+	/*
+	 * Disable MSI during setup in the hardware, but mark it enabled
+	 * so that setup code can evaluate it.
+	 */
+	pci_msi_set_enable(dev, 0);
+	dev->msi_enabled = 1;
 
 	entry = msi_setup_entry(dev, nvec, affd);
-	if (!entry)
-		return -ENOMEM;
+	if (!entry) {
+		ret = -ENOMEM;
+		goto fail;
+	}
 
 	/* All MSIs are unmasked by default; mask them all */
 	pci_msi_mask(entry, msi_multi_mask(entry));
@@ -452,7 +459,6 @@ static int msi_capability_init(struct pci_dev *dev, int nvec,
 	/* Set MSI enabled bits	*/
 	pci_intx_for_msi(dev, 0);
 	pci_msi_set_enable(dev, 1);
-	dev->msi_enabled = 1;
 
 	pcibios_free_irq(dev);
 	dev->irq = entry->irq;
@@ -461,6 +467,8 @@ static int msi_capability_init(struct pci_dev *dev, int nvec,
 err:
 	pci_msi_unmask(entry, msi_multi_mask(entry));
 	free_msi_irqs(dev);
+fail:
+	dev->msi_enabled = 0;
 	return ret;
 }
 
@@ -589,6 +597,9 @@ static int msix_capability_init(struct pci_dev *dev, struct msix_entry *entries,
 	pci_msix_clear_and_set_ctrl(dev, 0, PCI_MSIX_FLAGS_MASKALL |
 				    PCI_MSIX_FLAGS_ENABLE);
 
+	/* Mark it enabled so setup functions can query it */
+	dev->msix_enabled = 1;
+
 	pci_read_config_word(dev, dev->msix_cap + PCI_MSIX_FLAGS, &control);
 	/* Request & Map MSI-X table region */
 	tsize = msix_table_size(control);
@@ -623,9 +634,8 @@ static int msix_capability_init(struct pci_dev *dev, struct msix_entry *entries,
 
 	dev->msi_irq_groups = groups;
 
-	/* Set MSI-X enabled bits and unmask the function */
+	/* Disable INTX */
 	pci_intx_for_msi(dev, 0);
-	dev->msix_enabled = 1;
 
 	/*
 	 * Ensure that all table entries are masked to prevent
@@ -645,6 +655,7 @@ static int msix_capability_init(struct pci_dev *dev, struct msix_entry *entries,
 	free_msi_irqs(dev);
 
 out_disable:
+	dev->msix_enabled = 0;
 	pci_msix_clear_and_set_ctrl(dev, PCI_MSIX_FLAGS_MASKALL | PCI_MSIX_FLAGS_ENABLE, 0);
 
 	return ret;