linux-kernel - [PATCH v2 3/3] vfio/pci: Enable PCI resource mmap() on s390 and remove VFIO_PCI

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Message-Id: <20240523-vfio_pci_mmap-v2-3-0dc6c139a4f1@linux.ibm.com>
Date: Thu, 23 May 2024 13:10:16 +0200
From: Niklas Schnelle <schnelle@...ux.ibm.com>
To: Gerald Schaefer <gerald.schaefer@...ux.ibm.com>,
        Heiko Carstens <hca@...ux.ibm.com>, Vasily Gorbik <gor@...ux.ibm.com>,
        Alexander Gordeev <agordeev@...ux.ibm.com>,
        Christian Borntraeger <borntraeger@...ux.ibm.com>,
        Sven Schnelle <svens@...ux.ibm.com>,
        Alex Williamson <alex.williamson@...hat.com>,
        Gerd Bayer <gbayer@...ux.ibm.com>,
        Matthew Rosato <mjrosato@...ux.ibm.com>,
        Jason Gunthorpe <jgg@...pe.ca>
Cc: linux-s390@...r.kernel.org, linux-kernel@...r.kernel.org,
        kvm@...r.kernel.org, Niklas Schnelle <schnelle@...ux.ibm.com>,
        Jason Gunthorpe <jgg@...pe.ca>
Subject: [PATCH v2 3/3] vfio/pci: Enable PCI resource mmap() on s390 and
 remove VFIO_PCI_MMAP

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@linux.ibm.com/
Suggested-by: Jason Gunthorpe <jgg@...dia.com>
Signed-off-by: Niklas Schnelle <schnelle@...ux.ibm.com>
---
 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 15821a2d77d2..9c88e3a6d06b 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 23961299b695..35b8e8f214af 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