6.6-stable review patch. If anyone has any objections, please let me know.
------------------
From: Niklas Schnelle schnelle@linux.ibm.com
[ 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@linux.ibm.com Fixes: cd24834130ac ("s390/pci: base support") Signed-off-by: Niklas Schnelle schnelle@linux.ibm.com [agordeev@linux.ibm.com replaced spaces with tabs] Signed-off-by: Alexander Gordeev agordeev@linux.ibm.com Signed-off-by: Sasha Levin sashal@kernel.org --- arch/s390/include/asm/pci_io.h | 32 ++++++++++++++++++-------------- arch/s390/pci/pci_mmio.c | 12 ++++++------ 2 files changed, 24 insertions(+), 20 deletions(-)
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 588089332931..a90499c087f0 100644 --- a/arch/s390/pci/pci_mmio.c +++ b/arch/s390/pci/pci_mmio.c @@ -97,9 +97,9 @@ static inline int __memcpy_toio_inuser(void __iomem *dst, return -EINVAL;
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 @@ -242,9 +242,9 @@ static inline int __memcpy_fromio_inuser(void __user *dst, u8 status;
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;