[PATCH v3 3/3] vfio/pci: Enable PCI resource mmap() on s390 and remove VFIO_PCI_MMAP

From: Niklas Schnelle
Date: Wed May 29 2024 - 08:04:41 EST


With the introduction of memory I/O (MIO) instructions enbaled in commit
71ba41c9b1d9 ("s390/pci: provide support for MIO instructions") s390
gained support for direct user-space access to mapped PCI resources.
Even without those however user-space can access mapped PCI resources
via the s390 specific MMIO syscalls. Thus mmap() can and should be
supported on all s390 systems with native PCI. Since VFIO_PCI_MMAP
enablement for s390 would make it unconditionally true and thus
pointless just remove it entirely.

Link: https://lore.kernel.org/all/c5ba134a1d4f4465b5956027e6a4ea6f6beff969.camel@xxxxxxxxxxxxx/
Suggested-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
Reviewed-by: Matthew Rosato <mjrosato@xxxxxxxxxxxxx>
Reviewed-by: Jason Gunthorpe <jgg@xxxxxxxxxx>
Signed-off-by: Niklas Schnelle <schnelle@xxxxxxxxxxxxx>
---
drivers/vfio/pci/Kconfig | 4 ----
drivers/vfio/pci/vfio_pci_core.c | 3 ---
2 files changed, 7 deletions(-)

diff --git a/drivers/vfio/pci/Kconfig b/drivers/vfio/pci/Kconfig
index bf50ffa10bde..c3bcb6911c53 100644
--- a/drivers/vfio/pci/Kconfig
+++ b/drivers/vfio/pci/Kconfig
@@ -7,10 +7,6 @@ config VFIO_PCI_CORE
select VFIO_VIRQFD
select IRQ_BYPASS_MANAGER

-config VFIO_PCI_MMAP
- def_bool y if !S390
- depends on VFIO_PCI_CORE
-
config VFIO_PCI_INTX
def_bool y if !S390
depends on VFIO_PCI_CORE
diff --git a/drivers/vfio/pci/vfio_pci_core.c b/drivers/vfio/pci/vfio_pci_core.c
index 0f1ddf2d3ef2..a0e2e2a806d1 100644
--- a/drivers/vfio/pci/vfio_pci_core.c
+++ b/drivers/vfio/pci/vfio_pci_core.c
@@ -121,9 +121,6 @@ static void vfio_pci_probe_mmaps(struct vfio_pci_core_device *vdev)

res = &vdev->pdev->resource[bar];

- if (!IS_ENABLED(CONFIG_VFIO_PCI_MMAP))
- goto no_mmap;
-
if (!(res->flags & IORESOURCE_MEM))
goto no_mmap;


--
2.40.1