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

Niklas Schnelle
2022-10-11T15:28:12Z

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.

> select HAVE_ALIGNED_STRUCT_PAGE if SLUB
> select HAVE_ARCH_AUDITSYSCALL
> select HAVE_ARCH_JUMP_LABEL
> diff --git a/arch/s390/include/asm/io.h b/arch/s390/include/asm/io.h
> index e3882b012bfa..db201563baa6 100644
> --- a/arch/s390/include/asm/io.h
> +++ b/arch/s390/include/asm/io.h
> @@ -22,11 +22,22 @@ void unxlate_dev_mem_ptr(phys_addr_t phys, void *addr);
>
> #define IO_SPACE_LIMIT 0
>
> -void __iomem *ioremap_prot(phys_addr_t addr, size_t size, unsigned long prot);
> -void __iomem *ioremap(phys_addr_t addr, size_t size);
> -void __iomem *ioremap_wc(phys_addr_t addr, size_t size);
> -void __iomem *ioremap_wt(phys_addr_t addr, size_t size);
> -void iounmap(volatile void __iomem *addr);
> +/*
> + * I/O memory mapping functions.
> + */
> +void __iomem *
> +arch_ioremap(phys_addr_t *paddr, size_t size, unsigned long *prot_val);
> +#define arch_ioremap arch_ioremap
> +
> +bool arch_iounmap(void __iomem *addr);
> +#define arch_iounmap arch_iounmap
> +
> +#define _PAGE_IOREMAP pgprot_val(PAGE_KERNEL)
> +
> +#define ioremap_wc(addr, size) \
> + ioremap_prot((addr), (size), pgprot_val(pgprot_writecombine(PAGE_KERNEL)))
> +#define ioremap_wt(addr, size) \
> + ioremap_prot((addr), (size), pgprot_val(pgprot_writethrough(PAGE_KERNEL)))
>
> static inline void __iomem *ioport_map(unsigned long port, unsigned int nr)
> {
> @@ -51,10 +62,6 @@ static inline void ioport_unmap(void __iomem *p)
> #define pci_iomap_wc pci_iomap_wc
> #define pci_iomap_wc_range pci_iomap_wc_range
>
> -#define ioremap ioremap
> -#define ioremap_wt ioremap_wt
> -#define ioremap_wc ioremap_wc
> -
> #define memcpy_fromio(dst, src, count) zpci_memcpy_fromio(dst, src, count)
> #define memcpy_toio(dst, src, count) zpci_memcpy_toio(dst, src, count)
> #define memset_io(dst, val, count) zpci_memset_io(dst, val, count)
> 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

> + return NULL;
> }
>
> -void __iomem *ioremap_prot(phys_addr_t addr, size_t size, unsigned long prot)
> +bool arch_iounmap(void __iomem *addr)
> {
> - return __ioremap(addr, size, __pgprot(prot));
> -}
> -EXPORT_SYMBOL(ioremap_prot);
> -
> -void __iomem *ioremap(phys_addr_t addr, size_t size)
> -{
> - return __ioremap(addr, size, PAGE_KERNEL);
> -}
> -EXPORT_SYMBOL(ioremap);
> -
> -void __iomem *ioremap_wc(phys_addr_t addr, size_t size)
> -{
> - return __ioremap(addr, size, pgprot_writecombine(PAGE_KERNEL));
> -}
> -EXPORT_SYMBOL(ioremap_wc);
> -
> -void __iomem *ioremap_wt(phys_addr_t addr, size_t size)
> -{
> - return __ioremap(addr, size, pgprot_writethrough(PAGE_KERNEL));
> -}
> -EXPORT_SYMBOL(ioremap_wt);
> -
> -void iounmap(volatile void __iomem *addr)
> -{
> - if (static_branch_likely(&have_mio))
> - vunmap((__force void *) ((unsigned long) addr & PAGE_MASK));
> + if (!static_branch_likely(&have_mio))
> + return false;
> + return true;
> }
> -EXPORT_SYMBOL(iounmap);
>
> /* Create a virtual mapping cookie for a PCI BAR */
> static void __iomem *pci_iomap_range_fh(struct pci_dev *pdev, int bar,

Gave this a round of testing on s390 with both the MIO and non-MIO
cases. I also see you addressed my previous comments and it looks good
to me. As you showed in the other mail the compile error is a pre
existing problem so shouldn't influence this change. So assuming you
add the "if PCI" and the nit above you can add my:

Tested-by: Niklas
Schnelle <schnelle@linux.ibm.com>
Reviewed-by: Niklas Schnelle
<schnelle@linux.ibm.com>