linux-kernel - Re: [PATCH] kvm: fix compilation on s390

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Date:   Fri, 24 May 2019 22:24:38 +0200
From:   Michal Kubecek <mkubecek@...e.cz>
To:     Paolo Bonzini <pbonzini@...hat.com>
Cc:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org
Subject: Re: [PATCH] kvm: fix compilation on s390

On Fri, May 24, 2019 at 09:25:57PM +0200, Paolo Bonzini wrote:
> s390 does not have memremap, even though in this particular case it
> would be useful.

This is not completely true: memremap() is built when HAS_IOMEM is
defined which on s390 depends on CONFIG_PCI. So for "normal" configs
HAS_IOMEM would be enabled and memremap() would be available. We only
encountered the build error with a special minimal config for zfcpdump.

> Signed-off-by: Paolo Bonzini <pbonzini@...hat.com>
> ---
>  virt/kvm/kvm_main.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
> index 1fadfb9cf36e..134ec0283a8a 100644
> --- a/virt/kvm/kvm_main.c
> +++ b/virt/kvm/kvm_main.c
> @@ -1761,8 +1761,10 @@ static int __kvm_map_gfn(struct kvm_memory_slot *slot, gfn_t gfn,
>  	if (pfn_valid(pfn)) {
>  		page = pfn_to_page(pfn);
>  		hva = kmap(page);
> +#ifdef CONFIG_HAS_IOMEM
>  	} else {
>  		hva = memremap(pfn_to_hpa(pfn), PAGE_SIZE, MEMREMAP_WB);
> +#endif
>  	}
>  
>  	if (!hva)
> -- 
> 1.8.3.1

I would have to run a test build to be sure but IMHO you will also need
to handle the memunmap() call in kvm_vcpu_unmap().

Michal Kubecek