From 980621daf368f2b9aa69c7ea01baa654edb7577b Mon Sep 17 00:00:00 2001 From: Lianbo Jiang Date: Tue, 23 Apr 2019 09:30:07 +0800 Subject: [PATCH] x86/crash: Add e820 reserved ranges to kdump kernel's e820 table MIME-Version: 1.0 Content-Type: text/plain; charset=utf8 Content-Transfer-Encoding: 8bit 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%2B38zw@mail.gmail.com [ bp: Heavily massage commit message. ] Suggested-by: Dave Young Signed-off-by: Lianbo Jiang Signed-off-by: Borislav Petkov Cc: Andrew Morton Cc: Andy Lutomirski Cc: Baoquan He Cc: Bjorn Helgaas Cc: dave.hansen@linux.intel.com Cc: Dave Young Cc: "Gustavo A. R. Silva" Cc: "H. Peter Anvin" Cc: Ingo Molnar Cc: kexec@lists.infradead.org Cc: Peter Zijlstra Cc: Thomas Gleixner Cc: Tom Lendacky Cc: x86-ml Cc: Yi Wang Link: https://lkml.kernel.org/r/20190423013007.17838-4-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 576b2e1..32c9567 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; -- 2.7.4