On 02/21/23 at 01:26pm, Niklas Schnelle wrote: > On Tue, 2023-02-21 at 19:48 +0800, Baoquan He wrote: > > On 02/16/23 at 05:21pm, Niklas Schnelle wrote: > > > On Thu, 2023-02-16 at 20:34 +0800, Baoquan He wrote: > > > > By taking GENERIC_IOREMAP method, the generic generic_ioremap_prot(), > > > > generic_iounmap(), and their generic wrapper ioremap_prot(), ioremap() > > > > and iounmap() are all visible and available to arch. Arch needs to > > > > provide wrapper functions to override the generic versions if there's > > > > arch specific handling in its ioremap_prot(), ioremap() or iounmap(). > > > > This change will simplify implementation by removing duplicated codes > > > > with generic_ioremap_prot() and generic_iounmap(), and has the equivalent > > > > functioality as before. > > > > > > > > Here, add wrapper functions ioremap_prot() and iounmap() for s390's > > > > special operation when ioremap() and iounmap(). > > > > > > > > Signed-off-by: Baoquan He <bhe@xxxxxxxxxx> > > > > Cc: Niklas Schnelle <schnelle@xxxxxxxxxxxxx> > > > > Cc: Gerald Schaefer <gerald.schaefer@xxxxxxxxxxxxx> > > > > Cc: Heiko Carstens <hca@xxxxxxxxxxxxx> > > > > Cc: Vasily Gorbik <gor@xxxxxxxxxxxxx> > > > > Cc: Alexander Gordeev <agordeev@xxxxxxxxxxxxx> > > > > Cc: Christian Borntraeger <borntraeger@xxxxxxxxxxxxx> > > > > Cc: Sven Schnelle <svens@xxxxxxxxxxxxx> > > > > Cc: linux-s390@xxxxxxxxxxxxxxx > > > > --- > > > > arch/s390/Kconfig | 1 + > > > > arch/s390/include/asm/io.h | 21 ++++++++------ > > > > arch/s390/pci/pci.c | 57 +++++++------------------------------- > > > > 3 files changed, 23 insertions(+), 56 deletions(-) > > > > > > Thanks for the patch. This is a very clear improvement for us! I tested > > > this series with s390 systems with and without the PCI memory-I/O (MIO) > > > support and everything works as expected. > > > > > > One thing I did stumble upon but which is independent from this patch > > > is that I think memremap(…, MEMREMAP_WB) on system RAM outside the > > > direct map is broken for us. At least on systems without PCI memory-I/O > > > support. I think with this series it would be much easier to fix > > > though. Basically I think we would have to define arch_memremap_wb() to > > > generic_ioremap_prot(…, PAGE_KERNEL) and then have iounmap() check > > > is_ioremap_addr() to see if it is an actual mapping or an address > > > cookie. But again this is independent of this patch which doesn't > > > change the behavior in this area. > > > > OK, I can check this after this patchset done. > > Oh this wasn't meant as adding a task for you just a FYI. I'm already > experimenting with this and plan to possibly send a patch that fixes > the case of remapping system RAM once your series has landed. The thing > is that memremap() is quite tricky for us whichever way you look at > it. > > We don't have real MMIO on s390x and thus using memremap() for PCI MMIO > spaces doesn't really work as the void* returned can still only be > accessed using ioread()/iowrite() because only our special PCI access > instructions work on the pseudo-MMIO addresses (with PCI MIO) > respectively the address cookies. Obviously void* and memremap() really > isn't the right tool if you need to use ioread()/iowrite() to access it > and can't treat it as memory though. Ah, I misunderstood it. Thanks for sharing and expect to see your post.
