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-rw-r--r-- | doc/bmc.rst | 27 |
1 files changed, 27 insertions, 0 deletions
diff --git a/doc/bmc.rst b/doc/bmc.rst index bbb390a..46ae863 100644 --- a/doc/bmc.rst +++ b/doc/bmc.rst @@ -53,3 +53,30 @@ Real-time clock On platforms where a real-time-clock is not available, skiboot may use the IPMI SEL Time as a real-time-clock device. + +SBE validation +-------------- + +On some P8 platforms with an AMI or SMC BMC (ie. astbmc) SBE validation is done +by a tool on the BMC. This is done to inspect the SBE and detect if a malicious +host has written to the SBE, especially in multi-tenant +"Bare-Metal-As-A-Service" scenarios. + +To complicate this the SBE validation occurs at host-runtime and reads the SBE +SEEPROM over I2C using the FSI master which will conflict with anything the +host may be doing at the same time. To avoid this Skiboot will pause boot until +the validation is complete. +If SBE validation is required the BMC will communicate this to Skiboot by +setting an IPMI System Boot Option with OEM parameter 0x62. When this flag is +set Skiboot will pause and wait for the validation to complete and the flag to +be cleared. This ensures the validation completes before the execution is passed +to Petitboot and the host operating system and any conflicts could occur. During +this process Skiboot will print + SBE validation required, waiting for completion + System will be powered off if validation fails +to the console with an update every minute until complete. + +Unfortunately the validation performed by the BMC leaves the SBE in a bad +state. Once the validation is complete Skiboot will reboot to reset everything +to a good state and normal booting can resume. No such reboot is required if +the flag is not set and validation doesn't occur. |