This is a note to let you know that I've just added the patch titled
s390/pci: fix max size calculation in zpci_memcpy_toio()
to the 5.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
s390-pci-fix-max-size-calculation-in-zpci_memcpy_toi.patch
and it can be found in the queue-5.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
commit 750289f0827c8cd33fe34b7deaff74b59cdfb477
Author: Niklas Schnelle <schnelle@xxxxxxxxxxxxx>
Date: Tue Nov 28 16:22:49 2023 +0100
s390/pci: fix max size calculation in zpci_memcpy_toio()
[ Upstream commit 80df7d6af7f6d229b34cf237b2cc9024c07111cd ]
The zpci_get_max_write_size() helper is used to determine the maximum
size a PCI store or load can use at a given __iomem address.
For the PCI block store the following restrictions apply:
1. The dst + len must not cross a 4K boundary in the (pseudo-)MMIO space
2. len must not exceed ZPCI_MAX_WRITE_SIZE
3. len must be a multiple of 8 bytes
4. The src address must be double word (8 byte) aligned
5. The dst address must be double word (8 byte) aligned
Otherwise only a normal PCI store which takes its src value from
a register can be used. For these PCI store restriction 1 still applies.
Similarly 1 also applies to PCI loads.
It turns out zpci_max_write_size() instead implements stricter
conditions which prevents PCI block stores from being used where they
can and should be used. In particular instead of conditions 4 and 5 it
wrongly enforces both dst and src to be size aligned. This indirectly
covers condition 1 but also prevents many legal PCI block stores.
On top of the functional shortcomings the zpci_get_max_write_size() is
misnamed as it is used for both read and write size calculations. Rename
it to zpci_get_max_io_size() and implement the listed conditions
explicitly.
Reviewed-by: Matthew Rosato <mjrosato@xxxxxxxxxxxxx>
Fixes: cd24834130ac ("s390/pci: base support")
Signed-off-by: Niklas Schnelle <schnelle@xxxxxxxxxxxxx>
[agordeev@xxxxxxxxxxxxx replaced spaces with tabs]
Signed-off-by: Alexander Gordeev <agordeev@xxxxxxxxxxxxx>
Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx>
diff --git a/arch/s390/include/asm/pci_io.h b/arch/s390/include/asm/pci_io.h
index 287bb88f7698..2686bee800e3 100644
--- a/arch/s390/include/asm/pci_io.h
+++ b/arch/s390/include/asm/pci_io.h
@@ -11,6 +11,8 @@
/* I/O size constraints */
#define ZPCI_MAX_READ_SIZE 8
#define ZPCI_MAX_WRITE_SIZE 128
+#define ZPCI_BOUNDARY_SIZE (1 << 12)
+#define ZPCI_BOUNDARY_MASK (ZPCI_BOUNDARY_SIZE - 1)
/* I/O Map */
#define ZPCI_IOMAP_SHIFT 48
@@ -125,16 +127,18 @@ static inline int zpci_read_single(void *dst, const volatile void __iomem *src,
int zpci_write_block(volatile void __iomem *dst, const void *src,
unsigned long len);
-static inline u8 zpci_get_max_write_size(u64 src, u64 dst, int len, int max)
+static inline int zpci_get_max_io_size(u64 src, u64 dst, int len, int max)
{
- int count = len > max ? max : len, size = 1;
+ int offset = dst & ZPCI_BOUNDARY_MASK;
+ int size;
- while (!(src & 0x1) && !(dst & 0x1) && ((size << 1) <= count)) {
- dst = dst >> 1;
- src = src >> 1;
- size = size << 1;
- }
- return size;
+ size = min3(len, ZPCI_BOUNDARY_SIZE - offset, max);
+ if (IS_ALIGNED(src, 8) && IS_ALIGNED(dst, 8) && IS_ALIGNED(size, 8))
+ return size;
+
+ if (size >= 8)
+ return 8;
+ return rounddown_pow_of_two(size);
}
static inline int zpci_memcpy_fromio(void *dst,
@@ -144,9 +148,9 @@ static inline int zpci_memcpy_fromio(void *dst,
int size, rc = 0;
while (n > 0) {
- size = zpci_get_max_write_size((u64 __force) src,
- (u64) dst, n,
- ZPCI_MAX_READ_SIZE);
+ size = zpci_get_max_io_size((u64 __force) src,
+ (u64) dst, n,
+ ZPCI_MAX_READ_SIZE);
rc = zpci_read_single(dst, src, size);
if (rc)
break;
@@ -166,9 +170,9 @@ static inline int zpci_memcpy_toio(volatile void __iomem *dst,
return -EINVAL;
while (n > 0) {
- size = zpci_get_max_write_size((u64 __force) dst,
- (u64) src, n,
- ZPCI_MAX_WRITE_SIZE);
+ size = zpci_get_max_io_size((u64 __force) dst,
+ (u64) src, n,
+ ZPCI_MAX_WRITE_SIZE);
if (size > 8) /* main path */
rc = zpci_write_block(dst, src, size);
else
diff --git a/arch/s390/pci/pci_mmio.c b/arch/s390/pci/pci_mmio.c
index a4d5048b7eee..675e6cb50584 100644
--- a/arch/s390/pci/pci_mmio.c
+++ b/arch/s390/pci/pci_mmio.c
@@ -100,9 +100,9 @@ static inline int __memcpy_toio_inuser(void __iomem *dst,
old_fs = enable_sacf_uaccess();
while (n > 0) {
- size = zpci_get_max_write_size((u64 __force) dst,
- (u64 __force) src, n,
- ZPCI_MAX_WRITE_SIZE);
+ size = zpci_get_max_io_size((u64 __force) dst,
+ (u64 __force) src, n,
+ ZPCI_MAX_WRITE_SIZE);
if (size > 8) /* main path */
rc = __pcistb_mio_inuser(dst, src, size, &status);
else
@@ -250,9 +250,9 @@ static inline int __memcpy_fromio_inuser(void __user *dst,
old_fs = enable_sacf_uaccess();
while (n > 0) {
- size = zpci_get_max_write_size((u64 __force) src,
- (u64 __force) dst, n,
- ZPCI_MAX_READ_SIZE);
+ size = zpci_get_max_io_size((u64 __force) src,
+ (u64 __force) dst, n,
+ ZPCI_MAX_READ_SIZE);
rc = __pcilg_mio_inuser(dst, src, size, &status);
if (rc)
break;
