linux-kernel - [RFC PATCH 5/7] vfio_pci_core: allow regions with no release op

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Message-ID: <20250924141018.80202-6-mngyadam@amazon.de>
Date: Wed, 24 Sep 2025 16:09:56 +0200
From: Mahmoud Adam <mngyadam@...zon.de>
To: <kvm@...r.kernel.org>
CC: <alex.williamson@...hat.com>, <jgg@...pe.ca>, <kbusch@...nel.org>,
	<benh@...nel.crashing.org>, David Woodhouse <dwmw@...zon.co.uk>,
	<pravkmr@...zon.de>, <nagy@...aternagy.com>, <linux-kernel@...r.kernel.org>
Subject: [RFC PATCH 5/7] vfio_pci_core: allow regions with no release op

Allow regions to not to have a release op. This could be helpful with
alias regions. These regions wouldn't need to implement release ops.

Signed-off-by: Mahmoud Adam <mngyadam@...zon.de>
---
With the initial implementnation purposed in this RFC, there is
nothing to release for the alias regions. I wasn't sure if we should
force regions to implement release ops, If this is the case then an
empty function might be the better solution here.
 drivers/vfio/pci/vfio_pci_core.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/drivers/vfio/pci/vfio_pci_core.c b/drivers/vfio/pci/vfio_pci_core.c
index 78e18bfd973e5..04b93bd55a5c2 100644
--- a/drivers/vfio/pci/vfio_pci_core.c
+++ b/drivers/vfio/pci/vfio_pci_core.c
@@ -605,7 +605,8 @@ void vfio_pci_core_disable(struct vfio_pci_core_device *vdev)
 	vdev->virq_disabled = false;
 
 	for (i = 0; i < vdev->num_regions; i++)
-		vdev->region[i].ops->release(vdev, &vdev->region[i]);
+		if (vdev->region[i].ops && vdev->region[i].ops->release)
+			vdev->region[i].ops->release(vdev, &vdev->region[i]);
 
 	vdev->num_regions = 0;
 	kfree(vdev->region);
-- 
2.47.3




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