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Subject: Re: [PATCH v3 09/11] s390: mm: Convert to GENERIC_IOREMAP
From:   Niklas Schnelle <schnelle@linux.ibm.com>
To:     Baoquan He <bhe@redhat.com>, linux-kernel@vger.kernel.org
Cc:     linux-mm@kvack.org, akpm@linux-foundation.org, hch@infradead.org,
        agordeev@linux.ibm.com, wangkefeng.wang@huawei.com,
        christophe.leroy@csgroup.eu, David.Laight@ACULAB.COM,
        shorne@gmail.com, Gerald Schaefer <gerald.schaefer@linux.ibm.com>,
        Heiko Carstens <hca@linux.ibm.com>,
        Vasily Gorbik <gor@linux.ibm.com>,
        Christian Borntraeger <borntraeger@linux.ibm.com>,
        Sven Schnelle <svens@linux.ibm.com>, linux-s390@vger.kernel.org
Date:   Tue, 11 Oct 2022 17:16:54 +0200
In-Reply-To: <20221009103114.149036-10-bhe@redhat.com>
References: <20221009103114.149036-1-bhe@redhat.com>
         <20221009103114.149036-10-bhe@redhat.com>
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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>