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

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Date:   Tue, 2 Apr 2019 09:53:51 +0000
From:   Junichi Nomura <j-nomura@...jp.nec.com>
To:     Chao Fan <fanc.fnst@...fujitsu.com>
CC:     Borislav Petkov <bp@...en8.de>, "bhe@...hat.com" <bhe@...hat.com>,
        "Dave Young" <dyoung@...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 Tue, Apr 02, 2019 at 05:41:49PM +0800, Chao Fan wrote:
> [   77.989030] kexec_core: Starting new kernel
> early console in extract_kernel
> input_data: 0x000000017f6033b1
> input_len: 0x00000000008412d4
> output: 0x000000017e000000
> output_len: 0x0000000001e15844
> kernel_total_size: 0x0000000001e2c000
> trampoline_32bit: 0x000000000009d000
> booted via startup_64()
> 
> 
> Physical KASLR disabled: no suitable memory region!
> ------
> 
> I am not sure whether I have done the right test.
> This guest is booted from EFI. Here we can see the kexeced kernel
> has completed the compressed boot stage. So I think your PATCH works.

Thanks for testing.  If your test bed doesn't boot even with the patch,
you could check what was found as RSDP with a debug patch like below.

diff --git a/arch/x86/boot/compressed/misc.c b/arch/x86/boot/compressed/misc.c
--- a/arch/x86/boot/compressed/misc.c
+++ b/arch/x86/boot/compressed/misc.c
@@ -379,6 +379,7 @@ asmlinkage __visible void *extract_kernel(void *rmode, memptr heap,
 	debug_putaddr(output);
 	debug_putaddr(output_len);
 	debug_putaddr(kernel_total_size);
+	debug_putaddr(boot_params->acpi_rsdp_addr);
 
 #ifdef CONFIG_X86_64
 	/* Report address of 32-bit trampoline */