[SRU][N][PATCH 2/3] vfio/pci: Support 8-byte PCI loads and stores

[Massimiliano Pellizzer]

From: Ben Segal <bpsegal at us.ibm.com>

BugLink: https://bugs.launchpad.net/bugs/2121146

Many PCI adapters can benefit or even require full 64bit read
and write access to their registers. In order to enable work on
user-space drivers for these devices add two new variations
vfio_pci_core_io{read|write}64 of the existing access methods
when the architecture supports 64-bit ioreads and iowrites.

Signed-off-by: Ben Segal <bpsegal at us.ibm.com>
Co-developed-by: Gerd Bayer <gbayer at linux.ibm.com>
Signed-off-by: Gerd Bayer <gbayer at linux.ibm.com>
Link: https://lore.kernel.org/r/20240619115847.1344875-3-gbayer@linux.ibm.com
Signed-off-by: Alex Williamson <alex.williamson at redhat.com>
(cherry picked from commit 4df13a6871d9e97aeeef72244e9a954c5cf11f54)
Signed-off-by: Massimiliano Pellizzer <massimiliano.pellizzer at canonical.com>
---
 drivers/vfio/pci/vfio_pci_rdwr.c | 16 ++++++++++++++++
 include/linux/vfio_pci_core.h    |  3 +++
 2 files changed, 19 insertions(+)

diff --git a/drivers/vfio/pci/vfio_pci_rdwr.c b/drivers/vfio/pci/vfio_pci_rdwr.c
index 7bfe3d8cdecdf..be91024a99f7b 100644
--- a/drivers/vfio/pci/vfio_pci_rdwr.c
+++ b/drivers/vfio/pci/vfio_pci_rdwr.c
@@ -90,6 +90,9 @@ EXPORT_SYMBOL_GPL(vfio_pci_core_ioread##size);
 VFIO_IOREAD(8)
 VFIO_IOREAD(16)
 VFIO_IOREAD(32)
+#ifdef ioread64
+VFIO_IOREAD(64)
+#endif
 
 #define VFIO_IORDWR(size)						\
 static int vfio_pci_iordwr##size(struct vfio_pci_core_device *vdev,\
@@ -125,6 +128,10 @@ static int vfio_pci_iordwr##size(struct vfio_pci_core_device *vdev,\
 VFIO_IORDWR(8)
 VFIO_IORDWR(16)
 VFIO_IORDWR(32)
+#if defined(ioread64) && defined(iowrite64)
+VFIO_IORDWR(64)
+#endif
+
 /*
  * Read or write from an __iomem region (MMIO or I/O port) with an excluded
  * range which is inaccessible.  The excluded range drops writes and fills
@@ -149,6 +156,15 @@ static ssize_t do_io_rw(struct vfio_pci_core_device *vdev, bool test_mem,
 		else
 			fillable = 0;
 
+#if defined(ioread64) && defined(iowrite64)
+		if (fillable >= 8 && !(off % 8)) {
+			ret = vfio_pci_iordwr64(vdev, iswrite, test_mem,
+						io, buf, off, &filled);
+			if (ret)
+				return ret;
+
+		} else
+#endif
 		if (fillable >= 4 && !(off % 4)) {
 			ret = vfio_pci_iordwr32(vdev, iswrite, test_mem,
 						io, buf, off, &filled);
diff --git a/include/linux/vfio_pci_core.h b/include/linux/vfio_pci_core.h
index 85e84b92751b6..586d0b37c6b7a 100644
--- a/include/linux/vfio_pci_core.h
+++ b/include/linux/vfio_pci_core.h
@@ -149,5 +149,8 @@ int vfio_pci_core_ioread##size(struct vfio_pci_core_device *vdev,	\
 VFIO_IOREAD_DECLATION(8)
 VFIO_IOREAD_DECLATION(16)
 VFIO_IOREAD_DECLATION(32)
+#ifdef ioread64
+VFIO_IOREAD_DECLATION(64)
+#endif
 
 #endif /* VFIO_PCI_CORE_H */
-- 
2.48.1