On 12/04/19 at 11:14am, Ingo Molnar wrote: > > * Dave Young <dyoung@xxxxxxxxxx> wrote: > > > On 12/04/19 at 03:52pm, Dave Young wrote: > > > Michael Weiser reported he got below error during a kexec rebooting: > > > esrt: Unsupported ESRT version 2904149718861218184. > > > > > > The ESRT memory stays in EFI boot services data, and it was reserved > > > in kernel via efi_mem_reserve(). The initial purpose of the reservation > > > is to reuse the EFI boot services data across kexec reboot. For example > > > the BGRT image data and some ESRT memory like Michael reported. > > > > > > But although the memory is reserved it is not updated in X86 e820 table. > > > And kexec_file_load iterate system ram in io resource list to find places > > > for kernel, initramfs and other stuff. In Michael's case the kexec loaded > > > initramfs overwritten the ESRT memory and then the failure happened. > > > > s/overwritten/overwrote :) If need a repost please let me know.. > > > > > > > > Since kexec_file_load depends on the e820 to be updated, just fix this > > > by updating the reserved EFI boot services memory as reserved type in e820. > > > > > > Originally any memory descriptors with EFI_MEMORY_RUNTIME attribute are > > > bypassed in the reservation code path because they are assumed as reserved. > > > But the reservation is still needed for multiple kexec reboot. > > > And it is the only possible case we come here thus just drop the code > > > chunk then everything works without side effects. > > > > > > On my machine the ESRT memory sits in an EFI runtime data range, it does > > > not trigger the problem, but I successfully tested with BGRT instead. > > > both kexec_load and kexec_file_load work and kdump works as well. > > > > > > Signed-off-by: Dave Young <dyoung@xxxxxxxxxx> > > > So I edited this to: > > From: Dave Young <dyoung@xxxxxxxxxx> > > Michael Weiser reported he got this error during a kexec rebooting: > > esrt: Unsupported ESRT version 2904149718861218184. > > The ESRT memory stays in EFI boot services data, and it was reserved > in kernel via efi_mem_reserve(). The initial purpose of the reservation > is to reuse the EFI boot services data across kexec reboot. For example > the BGRT image data and some ESRT memory like Michael reported. > > But although the memory is reserved it is not updated in the X86 E820 table, > and kexec_file_load() iterates system RAM in the IO resource list to find places > for kernel, initramfs and other stuff. In Michael's case the kexec loaded > initramfs overwrote the ESRT memory and then the failure happened. > > Since kexec_file_load() depends on the E820 table being updated, just fix this > by updating the reserved EFI boot services memory as reserved type in E820. > > Originally any memory descriptors with EFI_MEMORY_RUNTIME attribute are > bypassed in the reservation code path because they are assumed as reserved. > > But the reservation is still needed for multiple kexec reboots, > and it is the only possible case we come here thus just drop the code > chunk, then everything works without side effects. > > On my machine the ESRT memory sits in an EFI runtime data range, it does > not trigger the problem, but I successfully tested with BGRT instead. > both kexec_load() and kexec_file_load() work and kdump works as well. > Thanks for the amending, also thank all for the review and test. Dave
