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

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Message-ID: <20190402094149.GB1555@localhost.localdomain>
Date:   Tue, 2 Apr 2019 17:41:49 +0800
From:   Chao Fan <fanc.fnst@...fujitsu.com>
To:     Junichi Nomura <j-nomura@...jp.nec.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

Hi,

I have test your PATCH in Qemu guest:
----------
Fedora 29 (Workstation Edition)
Kernel 5.1.0-rc3+ on an x86_64 (ttyS0)

localhost login: root
Password:
Last login: Tue Apr  2 05:30:33 on ttyS0
[root@...alhost ~]# cd /boot
[root@...alhost boot]# ls
config-4.18.16-300.fc29.x86_64
efi
extlinux
grub2
initramfs-0-rescue-858ff1f5d0cb453898ae6c7f77c68ba7.img
initramfs-4.18.16-300.fc29.x86_64.img
initramfs-4.18.16-300.fc29.x86_64kdump.img
initramfs-5.1.0-rc3+.img
initramfs-5.1.0-rc3+kdump.img
loader
lost+found
System.map
System.map-4.18.16-300.fc29.x86_64
System.map-5.1.0-rc3+
vmlinuz
vmlinuz-0-rescue-858ff1f5d0cb453898ae6c7f77c68ba7
vmlinuz-4.18.16-300.fc29.x86_64
vmlinuz-5.1.0-rc3+
[root@...alhost boot]# kexec -l vmlinuz-5.1.0-rc3+ --initrd=initramfs-5.1.0-rc3+.img --reuse-cmdline
[root@...alhost boot]# kexec -e
[   77.933760] Unregister pv shared memory for cpu 1
[   77.933763] Unregister pv shared memory for cpu 2
[   77.933766] Unregister pv shared memory for cpu 5
[   77.933825] Unregister pv shared memory for cpu 7
[   77.933882] Unregister pv shared memory for cpu 3
[   77.933904] Unregister pv shared memory for cpu 8
[   77.936147] Unregister pv shared memory for cpu 4
[   77.936199] Unregister pv shared memory for cpu 9
[   77.945822] Unregister pv shared memory for cpu 0
[   77.946308] Unregister pv shared memory for cpu 6
[   77.947420] sd 0:0:0:0: [sda] Synchronizing SCSI cache
[   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,
Chao Fan