This patchset did two things: a). add a new I/O resource descriptor 'IORES_DESC_RESERVED' When doing kexec_file_load, the first kernel needs to pass the e820 reserved ranges to the second kernel. But kernel can not exactly match the e820 reserved ranges when walking through the iomem resources with the descriptor 'IORES_DESC_NONE', because several e820 types( e.g. E820_TYPE_RESERVED_KERN/E820_TYPE_RAM/E820_TYPE_UNUSABLE/E820 _TYPE_RESERVED) are converted to the descriptor 'IORES_DESC_NONE'. It may pass these four types to the kdump kernel, that is not desired result. So, this patch adds a new I/O resource descriptor 'IORES_DESC_RESERVED' for the iomem resources search interfaces. It is helpful to exactly match the reserved resource ranges when walking through iomem resources. In addition, since the new descriptor 'IORES_DESC_RESERVED' is introduced, these code originally related to the descriptor 'IORES_DESC_NONE' need to be updated. Otherwise, it will be easily confused and also cause some errors. Because the 'E820_TYPE_RESERVED' type is converted to the new descriptor 'IORES_DESC_RESERVED' instead of 'IORES_DESC_NONE', it has been changed. b). add the e820 reserved ranges to kdump kernel e820 table At present, when use the kexec_file_load syscall to load the kernel image and initramfs(for example: kexec -s -p xxx), kernel does not pass the e820 reserved ranges to the second kernel, which might cause two problems: The first one is the MMCONFIG issue. The basic problem is that this device is in PCI segment 1 and the kernel PCI probing can not find it without all the e820 I/O reservations being present in the e820 table. And 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. (This problem does not show up for other vendors, as SGI is apparently the actually fails for everyone, but devices in segment 0 are then found by some legacy lookup method.) The workaround for this is to pass the I/O reserved regions to the kdump kernel. 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 albe to access devices on non-0 segments, (c) you won't be able to access extended config space( address 0x100-0xffff), which means none of the Extended Capabilities will be available(AER, ACS, ATS, etc). [Bjorn's comment] The second issue is that the SME kdump kernel doesn't work without the e820 reserved ranges. When SME is active in kdump kernel, actually, those reserved regions are still decrypted, but because those reserved ranges are not present at all in kdump kernel e820 table, those reserved regions are considered as encrypted, it goes wrong. The e820 reserved range is useful in kdump kernel, so it is necessary to pass the e820 reserved ranges to kdump kernel. Changes since v1: 1. Modified the value of flags to "0", when walking through the whole tree for e820 reserved ranges. Changes since v2: 1. Modified the value of flags to "0", when walking through the whole tree for e820 reserved ranges. 2. Modified the invalid SOB chain issue. Changes since v3: 1. Dropped [PATCH 1/3 v3] resource: fix an error which walks through iomem resources. Please refer to this commit <010a93bf97c7> "resource: Fix find_next_iomem_res() iteration issue" Changes since v4: 1. Improve the patch log, and add kernel log. Changes since v5: 1. Rewrite these patches log. Changes since v6: 1. Modify the [PATCH 1/2], and add the new I/O resource descriptor 'IORES_DESC_RESERVED' for the iomem resources search interfaces, and also updates these codes relates to 'IORES_DESC_NONE'. 2. Modify the [PATCH 2/2], and walk through io resource based on the new descriptor 'IORES_DESC_RESERVED'. 3. Update patch log. Changes since v7: 1. Improve patch log. 2. Improve this function __ioremap_check_desc_other(). 3. Modify code comment in the __ioremap_check_desc_other() Lianbo Jiang (2): resource: add the new I/O resource descriptor 'IORES_DESC_RESERVED' x86/kexec_file: add reserved e820 ranges to kdump kernel e820 table arch/ia64/kernel/efi.c | 4 ++++ arch/x86/kernel/crash.c | 6 ++++++ arch/x86/kernel/e820.c | 2 +- arch/x86/mm/ioremap.c | 13 ++++++++++++- include/linux/ioport.h | 1 + kernel/resource.c | 6 +++--- 6 files changed, 27 insertions(+), 5 deletions(-) -- 2.17.1 _______________________________________________ kexec mailing list kexec@xxxxxxxxxxxxxxxxxxx http://lists.infradead.org/mailman/listinfo/kexec
