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Date:   Tue, 18 Sep 2018 11:20:24 +0800
From:   Dave Young <dyoung@redhat.com>
To:     Lianbo Jiang <lijiang@redhat.com>
Cc:     linux-kernel@vger.kernel.org, tglx@linutronix.de, mingo@redhat.com,
        hpa@zytor.com, x86@kernel.org, akpm@linux-foundation.org
Subject: Re: [PATCH 2/2] x86/kexec_file: add reserved e820 ranges to 2nd
 kernel e820 table
Message-ID: <20180918032024.GA22528@dhcp-128-65.nay.redhat.com>
References: <20180918024837.17710-1-lijiang@redhat.com>
 <20180918024837.17710-3-lijiang@redhat.com>
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On 09/18/18 at 10:48am, Lianbo Jiang wrote:
> e820 reserved ranges is useful in kdump kernel, we have added this in
> kexec-tools code.
> 
> One reason is PCI mmconf (extended mode) requires reserved region
> otherwise it falls back to legacy mode.
> 
> When AMD SME kdump support, it needs to map dmi table area as unencrypted.
> For normal boot these ranges sit in e820 reserved ranges thus the early
> ioremap code naturally map them as unencrypted. So if we have same e820
> reserve setup in kdump kernel then it will just work like normal kernel.
> 
> Signed-off-by: Dave Young <dyoung@redhat.com>
> Signed-off-by: Lianbo Jiang <lijiang@redhat.com>
> ---
>  arch/x86/kernel/crash.c | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> diff --git a/arch/x86/kernel/crash.c b/arch/x86/kernel/crash.c
> index 3c113e6545a3..db453e9c117b 100644
> --- a/arch/x86/kernel/crash.c
> +++ b/arch/x86/kernel/crash.c
> @@ -384,6 +384,12 @@ int crash_setup_memmap_entries(struct kimage *image, struct boot_params *params)
>  	walk_iomem_res_desc(IORES_DESC_ACPI_NV_STORAGE, flags, 0, -1, &cmd,
>  			memmap_entry_callback);
>  
> +	/* Add all reserved ranges */
> +	cmd.type = E820_TYPE_RESERVED;
> +	flags = IORESOURCE_MEM;

Lianbo, rethink about this, we will miss other io resource types if only
match IORESOURCE_MEM here, can you redo the patch with just using "0"
for the passing flags?

> +	walk_iomem_res_desc(IORES_DESC_NONE, flags, 0, -1, &cmd,
> +			memmap_entry_callback);
> +
>  	/* Add crashk_low_res region */
>  	if (crashk_low_res.end) {
>  		ei.addr = crashk_low_res.start;
> -- 
> 2.17.1
>