Commit-ID: 980621daf368f2b9aa69c7ea01baa654edb7577b Gitweb: https://git.kernel.org/tip/980621daf368f2b9aa69c7ea01baa654edb7577b Author: Lianbo Jiang <[email protected]> AuthorDate: Tue, 23 Apr 2019 09:30:07 +0800 Committer: Borislav Petkov <[email protected]> CommitDate: Thu, 20 Jun 2019 10:05:06 +0200
x86/crash: Add e820 reserved ranges to kdump kernel's e820 table At present, when using the kexec_file_load() syscall to load the kernel image and initramfs, for example: kexec -s -p xxx the kernel does not pass the e820 reserved ranges to the second kernel, which might cause two problems: 1. MMCONFIG: A device in PCI segment 1 cannot be discovered by the kernel PCI probing without all the e820 I/O reservations being present in the e820 table. Which is the case currently, because the kdump kernel does not have those reservations because the kexec command does not pass the I/O reservation via the "memmap=xxx" command line option. Further details courtesy of Bjorn Helgaas¹: I think you should regard correct MCFG/ECAM usage in the kdump kernel as a requirement. MMCONFIG (aka ECAM) space is described in the ACPI MCFG table. If you don't have ECAM: (a) PCI devices won't work at all on non-x86 systems that use only ECAM for config access, (b) you won't be able to access devices on non-0 segments (granted, there aren't very many of these yet, but there will be more in the future), and (c) you won't be able to access extended config space (addresses 0x100-0xfff), which means none of the Extended Capabilities will be available (AER, ACS, ATS, etc). 2. The second issue is that the SME kdump kernel doesn't work without the e820 reserved ranges. When SME is active in the kdump kernel, those reserved regions are still decrypted, but because those reserved ranges are not present at all in kdump kernel's e820 table, they are accessed as encrypted. Which is obviously wrong. [1]: https://lkml.kernel.org/r/cabhmzuuscs3juzusm5y6eyjk6weo7mjj5-eakgvbw0qee%[email protected] [ bp: Heavily massage commit message. ] Suggested-by: Dave Young <[email protected]> Signed-off-by: Lianbo Jiang <[email protected]> Signed-off-by: Borislav Petkov <[email protected]> Cc: Andrew Morton <[email protected]> Cc: Andy Lutomirski <[email protected]> Cc: Baoquan He <[email protected]> Cc: Bjorn Helgaas <[email protected]> Cc: [email protected] Cc: Dave Young <[email protected]> Cc: "Gustavo A. R. Silva" <[email protected]> Cc: "H. Peter Anvin" <[email protected]> Cc: Ingo Molnar <[email protected]> Cc: [email protected] Cc: Peter Zijlstra <[email protected]> Cc: Thomas Gleixner <[email protected]> Cc: Tom Lendacky <[email protected]> Cc: x86-ml <[email protected]> Cc: Yi Wang <[email protected]> Link: https://lkml.kernel.org/r/[email protected] --- 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 576b2e1bfc12..32c956705b8e 100644 --- a/arch/x86/kernel/crash.c +++ b/arch/x86/kernel/crash.c @@ -381,6 +381,12 @@ 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 e820 reserved ranges */ + cmd.type = E820_TYPE_RESERVED; + flags = IORESOURCE_MEM; + walk_iomem_res_desc(IORES_DESC_RESERVED, flags, 0, -1, &cmd, + memmap_entry_callback); + /* Add crashk_low_res region */ if (crashk_low_res.end) { ei.addr = crashk_low_res.start;
