Re: [PATCH v6 1/2] x86/kexec: Build identity mapping for EFI systab and ACPI tables

[Borislav Petkov]

On Wed, May 15, 2019 at 05:17:19AM +0000, Junichi Nomura wrote:
> Hi Kairui,
> 
> On 5/13/19 5:02 PM, Baoquan He wrote:
> > On 05/13/19 at 09:50am, Borislav Petkov wrote:
> >> On Mon, May 13, 2019 at 03:32:54PM +0800, Baoquan He wrote:
> >> So we're going to try it again this cycle and if there's no fallout, it
> >> will go upstream. If not, it will have to be fixed. The usual thing.
> >>
> >> And I don't care if Kairui's patch fixes this one problem - judging by
> >> the fragility of this whole thing, it should be hammered on one more
> >> cycle on as many boxes as possible to make sure there's no other SNAFUs.
> >>
> >> So go test it on more machines instead. I've pushed it here:
> >>
> >> https://git.kernel.org/pub/scm/linux/kernel/git/bp/bp.git/log/?h=next-merge-window
> > 
> > Pingfan has got a machine to reproduce the kexec breakage issue, and
> > applying these two patches fix it. He planned to paste the test result.
> > I will ask him to try this branch if he has time, or I can get his
> > machine to test.
> > 
> > Junichi, also have a try on Boris's branch in NEC's test environment?
> 
> while the patch set works on most of the machines I'm testing around,
> I found kexec(1) fails to load kernel on a few machines if this patch
> is applied.  Those machines don't have IORES_DESC_ACPI_TABLES region
> and have ACPI tables in IORES_DESC_ACPI_NV_STORAGE region instead.

Why? What kind of machines are those?

Why are the ACPI tables in NV storage?

Looking at crash_setup_memmap_entries(), it already maps that type so I
guess this is needed.

+ Rafael and leaving in the rest for reference.

 
> So I think map_acpi_tables() should try to map both regions.  I tried
> following change in addition and it worked.
> 
> -- 
> Jun'ichi Nomura, NEC Corporation / NEC Solution Innovators, Ltd.
> 
> 
> diff --git a/arch/x86/kernel/machine_kexec_64.c b/arch/x86/kernel/machine_kexec_64.c
> index 3c77bdf..3837c4a 100644
> --- a/arch/x86/kernel/machine_kexec_64.c
> +++ b/arch/x86/kernel/machine_kexec_64.c
> @@ -56,12 +56,22 @@ static int mem_region_callback(struct resource *res, void *arg)
>  {
>  	unsigned long flags = IORESOURCE_MEM | IORESOURCE_BUSY;
>  	struct init_pgtable_data data;
> +	int ret;
>  
>  	data.info = info;
>  	data.level4p = level4p;
>  	flags = IORESOURCE_MEM | IORESOURCE_BUSY;
> -	return walk_iomem_res_desc(IORES_DESC_ACPI_TABLES, flags, 0, -1,
> -				   &data, mem_region_callback);
> +	ret = walk_iomem_res_desc(IORES_DESC_ACPI_TABLES, flags, 0, -1,
> +				  &data, mem_region_callback);
> +	if (ret && ret != -EINVAL)
> +		return ret;
> +
> +	ret = walk_iomem_res_desc(IORES_DESC_ACPI_NV_STORAGE, flags, 0, -1,
> +				  &data, mem_region_callback);
> +	if (ret && ret != -EINVAL)
> +		return ret;
> +
> +	return 0;
>  }
>  #else
>  static int map_acpi_tables(struct x86_mapping_info *info, pgd_t *level4p) { return 0; }

-- 
Regards/Gruss,
    Boris.

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