linux-kernel - Re: [PATCH v2] x86/boot: Use efi_setup_data for searching RSDP on kexec-ed kernel

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Date:   Wed, 3 Apr 2019 15:30:23 +0800
From:   Chao Fan <fanc.fnst@...fujitsu.com>
To:     Dave Young <dyoung@...hat.com>
CC:     Junichi Nomura <j-nomura@...jp.nec.com>,
        Borislav Petkov <bp@...en8.de>,
        "bhe@...hat.com" <bhe@...hat.com>,
        "kasong@...hat.com" <kasong@...hat.com>,
        "x86@...nel.org" <x86@...nel.org>,
        "kexec@...ts.infradead.org" <kexec@...ts.infradead.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2] x86/boot: Use efi_setup_data for searching RSDP on
 kexec-ed kernel

On Wed, Apr 03, 2019 at 02:39:11PM +0800, Dave Young wrote:
>> Actually I got some different kexec test results.
>> 
>> Yesterday, with my installed kernel (based on git head several weeks
>> ago), kexec kernel panics.
>> 
>> Then I tried latest mainline with git pull, everything works, (with or
>> without the patch, and can not reproduce the bug this patch is fixing)
>> 
>> Today, test again, kexec reboot hangs (with or without your patch), but
>> kdump works always (with or without the patch)
>> 
>> It is weird to me. Probably I need find out why I can not reproduce the
>> bug this patch is addressing first.
>> 
>> earlyprintk seems not working for me anymore, it is not easy to debug on
>> laptop now.
>> 
>> But the patch itself is clear, I think it should be good.  There might be
>> other things broken.
>
>Disable your immovable mem code then everything works for me.  There
>might be something wrong in the code.  Also "nokaslr" does not help, it
>should be another problem 

If "nokaslr" doesn't help, so I think
>+      /*num_immovable_mem = count_immovable_mem_regions();*/
also doesn't help. I think the problem is from get_rsdp_addr().

You test it in your laptop, I only tested in Qemu guest.
I have no laptop avaliable, so I will look for a physical machine
to test it.

Thanks,
Chao Fan

>
>diff --git a/arch/x86/boot/compressed/kaslr.c b/arch/x86/boot/compressed/kaslr.c
>index 2e53c056ba20..e760c9159662 100644
>--- a/arch/x86/boot/compressed/kaslr.c
>+++ b/arch/x86/boot/compressed/kaslr.c
>@@ -416,7 +416,7 @@ static void mem_avoid_init(unsigned long input, unsigned long input_size,
> 	handle_mem_options();
> 
> 	/* Enumerate the immovable memory regions */
>-	num_immovable_mem = count_immovable_mem_regions();
>+	/*num_immovable_mem = count_immovable_mem_regions();*/
> 
> #ifdef CONFIG_X86_VERBOSE_BOOTUP
> 	/* Make sure video RAM can be used. */
>diff --git a/arch/x86/boot/compressed/misc.c b/arch/x86/boot/compressed/misc.c
>index c0d6c560df69..1bc6f46d3aa7 100644
>--- a/arch/x86/boot/compressed/misc.c
>+++ b/arch/x86/boot/compressed/misc.c
>@@ -352,7 +352,7 @@ asmlinkage __visible void *extract_kernel(void *rmode, memptr heap,
> 	boot_params->hdr.loadflags &= ~KASLR_FLAG;
> 
> 	/* Save RSDP address for later use. */
>-	boot_params->acpi_rsdp_addr = get_rsdp_addr();
>+/*	boot_params->acpi_rsdp_addr = get_rsdp_addr(); */
> 
> 	sanitize_boot_params(boot_params);
> 
>
>