Re: [PATCH kvm-unit-tests v2 3/8] pci-testdev: ioremap regions

[Andre Przywara <andre.przywara@arm.com>]

On Tue, 20 Apr 2021 20:59:57 +0200
Andrew Jones <drjones@redhat.com> wrote:

Hi,

> Don't assume the physical addresses used with PCI have already been
> identity mapped.
> 
> Reviewed-by: Nikos Nikoleris <nikos.nikoleris@arm.com>
> Signed-off-by: Andrew Jones <drjones@redhat.com>
> ---
>  lib/pci-host-generic.c | 5 ++---
>  lib/pci-host-generic.h | 4 ++--
>  lib/pci-testdev.c      | 4 ++++
>  3 files changed, 8 insertions(+), 5 deletions(-)
> 
> diff --git a/lib/pci-host-generic.c b/lib/pci-host-generic.c
> index 818150dc0a66..de93b8feac39 100644
> --- a/lib/pci-host-generic.c
> +++ b/lib/pci-host-generic.c
> @@ -122,7 +122,7 @@ static struct pci_host_bridge *pci_dt_probe(void)
>  		      sizeof(host->addr_space[0]) * nr_addr_spaces);
>  	assert(host != NULL);
>  
> -	host->start		= base.addr;
> +	host->start		= ioremap(base.addr, base.size);
>  	host->size		= base.size;
>  	host->bus		= bus;
>  	host->bus_max		= bus_max;
> @@ -279,8 +279,7 @@ phys_addr_t pci_host_bridge_get_paddr(u64 pci_addr)
>  
>  static void __iomem *pci_get_dev_conf(struct pci_host_bridge *host, int devfn)
>  {
> -	return (void __iomem *)(unsigned long)
> -		host->start + (devfn << PCI_ECAM_DEVFN_SHIFT);
> +	return (void __iomem *)host->start + (devfn << PCI_ECAM_DEVFN_SHIFT);

But host->start's type is now exactly "void __iomem *", so why the cast?
And are we OK with doing pointer arithmetic on a void pointer?

>  }
>  
>  u8 pci_config_readb(pcidevaddr_t dev, u8 off)
> diff --git a/lib/pci-host-generic.h b/lib/pci-host-generic.h
> index fd30e7c74ed8..0ffe6380ec8f 100644
> --- a/lib/pci-host-generic.h
> +++ b/lib/pci-host-generic.h
> @@ -18,8 +18,8 @@ struct pci_addr_space {
>  };
>  
>  struct pci_host_bridge {
> -	phys_addr_t		start;
> -	phys_addr_t		size;
> +	void __iomem		*start;
> +	size_t			size;
>  	int			bus;
>  	int			bus_max;
>  	int			nr_addr_spaces;
> diff --git a/lib/pci-testdev.c b/lib/pci-testdev.c
> index 039bb44781c1..4f2e5663b2d6 100644
> --- a/lib/pci-testdev.c
> +++ b/lib/pci-testdev.c
> @@ -185,7 +185,11 @@ int pci_testdev(void)
>  	mem = ioremap(addr, PAGE_SIZE);
>  
>  	addr = pci_bar_get_addr(&pci_dev, 1);
> +#if defined(__i386__) || defined(__x86_64__)
>  	io = (void *)(unsigned long)addr;
> +#else
> +	io = ioremap(addr, PAGE_SIZE);
> +#endif

I am bit puzzled: For anything but x86 ioremap() is implemented like the
first statement, so why do we differentiate here? Shouldn't either one
of the statements be fine, for all architectures?

Cheers,
Andre

>  
>  	nr_tests += pci_testdev_all(mem, &pci_testdev_mem_ops);
>  	nr_tests += pci_testdev_all(io, &pci_testdev_io_ops);