From: Niklas Schnelle <schnelle@linux.ibm.com>

Date: Thu, 4 Nov 2021 15:04:10 +0100

Subject: s390/pci: move pseudo-MMIO to prevent MIO overlap

Git-commit: 52d04d408185b7aa47628d2339c28ec70074e0ae

Patch-mainline: v5.16-rc4

References: bsc#1194966 LTC#196029

When running without MIO support, with pci=nomio or for devices which

are not MIO-capable the zPCI subsystem generates pseudo-MMIO addresses

to allow access to PCI BARs via MMIO based Linux APIs even though the

platform uses function handles and BAR numbers.

This is done by stashing an index into our global IOMAP array which

contains the function handle in the 16 most significant bits of the

addresses returned by ioremap() always setting the most significant bit.

On the other hand the MIO addresses assigned by the platform for use,

while requiring special instructions, allow PCI access with virtually

mapped physical addresses. Now the problem is that these MIO addresses

and our own pseudo-MMIO addresses may overlap, while functionally this

would not be a problem by itself this overlap is detected by common code

as both address types are added as resources in the iomem_resource tree.

This leads to the overlapping resource claim of either the MIO capable

or non-MIO capable devices with being rejected.

Since PCI is tightly coupled to the use of the iomem_resource tree, see

for example the code for request_mem_region(), we can't reasonably get

rid of the overlap being detected by keeping our pseudo-MMIO addresses

out of the iomem_resource tree.

Instead let's move the range used by our own pseudo-MMIO addresses by

starting at (1UL << 62) and only using addresses below (1UL << 63) thus

avoiding the range currently used for MIO addresses.

Fixes: c7ff0e918a7c ("s390/pci: deal with devices that have no support for MIO instructions")

Cc: stable@vger.kernel.org # 5.3+

Reviewed-by: Pierre Morel <pmorel@linux.ibm.com>

Signed-off-by: Niklas Schnelle <schnelle@linux.ibm.com>

Signed-off-by: Heiko Carstens <hca@linux.ibm.com>

Acked-by: Petr Tesarik <ptesarik@suse.com>

---

 arch/s390/include/asm/pci_io.h |    7 ++++---

 1 file changed, 4 insertions(+), 3 deletions(-)

--- a/arch/s390/include/asm/pci_io.h

+++ b/arch/s390/include/asm/pci_io.h

@@ -14,12 +14,13 @@

 /* I/O Map */

 #define ZPCI_IOMAP_SHIFT		48

-#define ZPCI_IOMAP_ADDR_BASE		0x8000000000000000UL

+#define ZPCI_IOMAP_ADDR_SHIFT		62

+#define ZPCI_IOMAP_ADDR_BASE		(1UL << ZPCI_IOMAP_ADDR_SHIFT)

 #define ZPCI_IOMAP_ADDR_OFF_MASK	((1UL << ZPCI_IOMAP_SHIFT) - 1)

 #define ZPCI_IOMAP_MAX_ENTRIES							\

-	((ULONG_MAX - ZPCI_IOMAP_ADDR_BASE + 1) / (1UL << ZPCI_IOMAP_SHIFT))

+	(1UL << (ZPCI_IOMAP_ADDR_SHIFT - ZPCI_IOMAP_SHIFT))

 #define ZPCI_IOMAP_ADDR_IDX_MASK						\

-	(~ZPCI_IOMAP_ADDR_OFF_MASK - ZPCI_IOMAP_ADDR_BASE)

+	((ZPCI_IOMAP_ADDR_BASE - 1) & ~ZPCI_IOMAP_ADDR_OFF_MASK)

 struct zpci_iomap_entry {

 	u32 fh;