linux-kernel - Re: [PATCH] xen,kdump: handle pv domain in paddr_vmcoreinfo

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Message-ID: <dd900133-36e8-663a-7fb9-0edec0ed29ed@oracle.com>
Date:   Thu, 30 Mar 2017 10:51:28 -0400
From:   Boris Ostrovsky <boris.ostrovsky@...cle.com>
To:     Juergen Gross <jgross@...e.com>, linux-kernel@...r.kernel.org,
        xen-devel@...ts.xenproject.org
Cc:     ptesarik@...e.com
Subject: Re: [PATCH] xen,kdump: handle pv domain in paddr_vmcoreinfo_note()

On 03/30/2017 10:18 AM, Juergen Gross wrote:
> For kdump to work correctly it needs the physical address of
> vmcoreinfo_note. When running as dom0 this means the virtual address
> has to be translated to the related machine address.
>
> paddr_vmcoreinfo_note() is meant to do the translation via __pa() only,
> but being attributed "weak" it can be replaced easily in Xen case.
>
> Signed-off-by: Juergen Gross <jgross@...e.com>
> ---
> This patch needs to be rebased on top of Vitaly's series to split
> pv- and hvm-code. I'll do this as soon as his series is in the Xen
> tree in its final form.
> ---
>  arch/x86/xen/mmu.c | 13 +++++++++++++
>  1 file changed, 13 insertions(+)
>
> diff --git a/arch/x86/xen/mmu.c b/arch/x86/xen/mmu.c
> index 37cb5aa..0e2b8d7 100644
> --- a/arch/x86/xen/mmu.c
> +++ b/arch/x86/xen/mmu.c
> @@ -49,6 +49,9 @@
>  #include <linux/memblock.h>
>  #include <linux/seq_file.h>
>  #include <linux/crash_dump.h>
> +#ifdef CONFIG_KEXEC_CORE
> +#include <linux/kexec.h>
> +#endif
>  
>  #include <trace/events/xen.h>
>  
> @@ -2903,3 +2906,13 @@ int xen_unmap_domain_gfn_range(struct vm_area_struct *vma,
>  	return -EINVAL;
>  }
>  EXPORT_SYMBOL_GPL(xen_unmap_domain_gfn_range);
> +
> +#ifdef CONFIG_KEXEC_CORE
> +phys_addr_t paddr_vmcoreinfo_note(void)
> +{
> +	if (xen_pv_domain())
> +		return virt_to_machine(&vmcoreinfo_note).maddr;
> +	else
> +		return __pa((unsigned long)(char *)&vmcoreinfo_note);

Why not __pa_symbol(), just like in the weak version?

-boris

> +}
> +#endif /* CONFIG_KEXEC_CORE */