Revert "PCI/MSI: Unmap MSI-X region on error"

[ Upstream commit f64e03d ]

This reverts commit 1a8d4c6.

Commit 1a8d4c6 ("PCI/MSI: Unmap MSI-X region on error") added an
iounmap(dev->msix_base) on the error path of msix_capability_init() to
release the MSI-X region when msix_setup_interrupts() fails.

When msix_setup_interrupts() fails, the call chain is:

  msix_setup_interrupts()
    -> __msix_setup_interrupts()
         struct pci_dev *dev __free(free_msi_irqs) = __dev;
         ...
         return ret;  // __free cleanup fires on error

The __free(free_msi_irqs) cleanup calls pci_free_msi_irqs(), which
already handles the unmap:

  void pci_free_msi_irqs(struct pci_dev *dev)
  {
      pci_msi_teardown_msi_irqs(dev);
      if (dev->msix_base) {
          iounmap(dev->msix_base);   // already unmapped here
          dev->msix_base = NULL;     // and set to NULL
      }
  }

So dev->msix_base is unmapped and set to NULL before
msix_setup_interrupts() returns to msix_capability_init(). The
"goto out_unmap" introduced by commit 1a8d4c6 ("PCI/MSI: Unmap
MSI-X region on error") then calls iounmap() a second time on a NULL
pointer.

This was reproduced on Intel Emerald Rapids (192 CPUs) while
running tools/testing/selftests/kexec/test_kexec_jump.sh:

  WARNING: CPU#44 at iounmap+0x2a/0xe0
  RIP: 0010:iounmap+0x2a/0xe0
  RDI: 0000000000000000
  Call Trace:
   msix_capability_init+0x317/0x3f0
   __pci_enable_msix_range+0x21d/0x2c0
   pci_alloc_irq_vectors_affinity+0xa9/0x130
   nvme_setup_io_queues+0x2a8/0x420 [nvme]
   nvme_reset_work+0x151/0x340 [nvme]
   ...

RDI=0 confirms iounmap() is called with NULL.

Restore the original "goto out_disable" and leave the unmap to the
existing __free(free_msi_irqs) cleanup.

Fixes: 1a8d4c6 ("PCI/MSI: Unmap MSI-X region on error")
Reported-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Yuanhe Shu <xiangzao@linux.alibaba.com>
Signed-off-by: Thomas Gleixner <tglx@kernel.org>
Link: https://lore.kernel.org/all/20260610194406.GA380991@bhelgaas/
Link: https://patch.msgid.link/20260611025901.1105209-1-xiangzao@linux.alibaba.com
Closes: https://lore.kernel.org/all/4fc6208d-513b-4f41-a13a-4a0829ab50ad@roeck-us.net/
Signed-off-by: Sasha Levin <sashal@kernel.org>

Author: Yuanhe Shu

drivers/pci/msi/msi.c

@@ -737,7 +737,7 @@ static int msix_capability_init(struct pci_dev *dev, struct msix_entry *entries,
 
 	ret = msix_setup_interrupts(dev, entries, nvec, affd);
 	if (ret)
-		goto out_unmap;
+		goto out_disable;
 
 	/* Disable INTX */
 	pci_intx_for_msi(dev, 0);
@@ -756,8 +756,6 @@ static int msix_capability_init(struct pci_dev *dev, struct msix_entry *entries,
 	pcibios_free_irq(dev);
 	return 0;
 
-out_unmap:
-	iounmap(dev->msix_base);
 out_disable:
 	dev->msix_enabled = 0;
 	pci_msix_clear_and_set_ctrl(dev, PCI_MSIX_FLAGS_MASKALL | PCI_MSIX_FLAGS_ENABLE, 0);