Re: [PATCH v3 09/11] s390: mm: Convert to GENERIC_IOREMAP

Baoquan He
2022-10-12T09:21:06Z

On 10/12/22 at 09:37am, Niklas Schnelle wrote:
> On Wed, 2022-10-12 at 13:52 +0800, Baoquan He wrote:
> > On 10/11/22 at 05:16pm, Niklas Schnelle wrote:
> > > On Sun, 2022-10-09 at 18:31 +0800, Baoquan He wrote:
> > > > By taking GENERIC_IOREMAP method, the generic ioremap_prot() and
> > > > iounmap() are visible and available to arch. Arch only needs to
> > > > provide implementation of arch_ioremap() or arch_iounmap() if there's
> > > > arch specific handling needed in its ioremap() or iounmap(). This
> > > > change will simplify implementation by removing duplicated codes with
> > > > generic ioremap() and iounmap(), and has the equivalent functioality
> > > > as before.
> > > >
> > > > For s390, add hooks arch_ioremap() and arch_iounmap() for s390's special
> > > > operation when ioremap() and iounmap(), then ioremap_[wc|wt]() are
> > > > converted to use ioremap_prot() from GENERIC_IOREMAP.
> > > >
> > > > Signed-off-by: Baoquan He <bhe@redhat.com>
> > > > Cc: Niklas Schnelle <schnelle@linux.ibm.com>
> > > > Cc: Gerald Schaefer <gerald.schaefer@linux.ibm.com>
> > > > Cc: Heiko Carstens <hca@linux.ibm.com>
> > > > Cc: Vasily Gorbik <gor@linux.ibm.com>
> > > > Cc: Alexander Gordeev <agordeev@linux.ibm.com>
> > > > Cc: Christian Borntraeger <borntraeger@linux.ibm.com>
> > > > Cc: Sven Schnelle <svens@linux.ibm.com>
> > > > Cc: linux-s390@vger.kernel.org
> > > > ---
> > > > v2->v3:
> > > > - Add code comment inside arch_ioremap() to help uderstand the
> > > > obsucre code. Christoph suggested this, Niklas provided the
> > > > paragraph of text.
> > > >
> > > > arch/s390/Kconfig | 1 +
> > > > arch/s390/include/asm/io.h | 25 +++++++++------
> > > > arch/s390/pci/pci.c | 65 ++++++++------------------------------
> > > > 3 files changed, 30 insertions(+), 61 deletions(-)
> > > >
> > > > diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
> > > > index 318fce77601d..c59e1b25f59d 100644
> > > > --- a/arch/s390/Kconfig
> > > > +++ b/arch/s390/Kconfig
> > > > @@ -135,6 +135,7 @@ config S390
> > > > select GENERIC_SMP_IDLE_THREAD
> > > > select GENERIC_TIME_VSYSCALL
> > > > select GENERIC_VDSO_TIME_NS
> > > > + select GENERIC_IOREMAP
> > >
> > > I think you should add the "if PCI" from the diff in your last mail to
> > > this patch.
> >
> > That's reasonable, will do.
> >
> > The code change in driver should be posted separately to get reviewing
> > from the relevant drvier maintainers. I may wrap it into this series in
> > next post so that people know its background.
>
> I agree about doing the driver change separately. Since the problem
> already exists one could send it separately. If you want I can take of
> that too.

Both is fine to me, since you suggested the fix.

>
> >
> > > > select HAVE_ALIGNED_STRUCT_PAGE if SLUB
> > > > select HAVE_ARCH_AUDITSYSCALL
> > > > select HAVE_ARCH_JUMP_LABEL
> > ......
> > > > diff --git a/arch/s390/pci/pci.c b/arch/s390/pci/pci.c
> > > > index 73cdc5539384..3c00dc7d79bc 100644
> > > > --- a/arch/s390/pci/pci.c
> > > > +++ b/arch/s390/pci/pci.c
> > > > @@ -244,64 +244,25 @@ void __iowrite64_copy(void __iomem *to, const void *from, size_t count)
> > > > zpci_memcpy_toio(to, from, count);
> > > > }
> > > >
> > > > -static void __iomem *__ioremap(phys_addr_t addr, size_t size, pgprot_t prot)
> > > > +void __iomem *
> > > > +arch_ioremap(phys_addr_t *paddr, size_t size, unsigned long *prot_val)
> > > > {
> > > > - unsigned long offset, vaddr;
> > > > - struct vm_struct *area;
> > > > - phys_addr_t last_addr;
> > > > -
> > > > - last_addr = addr + size - 1;
> > > > - if (!size || last_addr < addr)
> > > > - return NULL;
> > > > -
> > > > + /*
> > > > + * When PCI MIO instructions are unavailable the "physical" address
> > > > + * encodes a hint for accessing the PCI memory space it represents.
> > > > + * Just pass it unchanged such that ioread/iowrite can decode it.
> > > > + */
> > > > if (!static_branch_unlikely(&have_mio))
> > > > - return (void __iomem *) addr;
> > > > -
> > > > - offset = addr & ~PAGE_MASK;
> > > > - addr &= PAGE_MASK;
> > > > - size = PAGE_ALIGN(size + offset);
> > > > - area = get_vm_area(size, VM_IOREMAP);
> > > > - if (!area)
> > > > - return NULL;
> > > > -
> > > > - vaddr = (unsigned long) area->addr;
> > > > - if (ioremap_page_range(vaddr, vaddr + size, addr, prot)) {
> > > > - free_vm_area(area);
> > > > - return NULL;
> > > > - }
> > > > - return (void __iomem *) ((unsigned long) area->addr + offset);
> > > > + return (void __iomem *) *paddr;
> > >
> > > nit: no space after the cast
> >
> > Sorry, remember you pointed this out in v2, while I didn't get what
> > it is. Could you be more specific or give the right line of code?
> >
> > Are you suggesting below line?
> >
> > - return (void __iomem *) ((unsigned long) area->addr + offset);
> > + return (void __iomem *)*paddr;
>
> Yes, though I did just check and somehow checkpatch doesn't complain,
> maybe because of the dereference. I do think I remember it complaining
> but I guess if it doesn't you might as well keep it this way.

OK, I will keep it unless checkpatch complaim about it. Thanks.