Protection of secured boot secrets for operating system reboot

A computer system, comprising:

• one or more processors;
• system memory;
• and
• one or more computer-readable media having stored thereon computer-executable instructions that are executable by the one or more processors to cause the computer system to protect secured boot secrets while starting an operating system, the computer-executable instructions including instructions that are executable to cause the computer system to perform at least the following:
• start a first operating system in reliance on a trusted computing base (TCB), including obtaining one or more secured boot secrets from the TCB that are usable for attesting a security status of the first operating system;
• protect a portion of the system memory, including preventing access to the portion of the system memory by the first operating system;
• store the one or more secured boot secrets in the protected portion of the system memory;
• identify that a second operating system is to be started to replace the first operating system, without performing a full reboot of the computer system;
• and
• based at least on identifying that the second operating system is to be started to replace the first operating system, perform at least:
• configure one or more memory data structures in the protected portion of the system memory, including loading code of the second operating system in the protected portion of the system memory for starting the second operating system;
• unprotect the portion of the system memory, while mitigating attacks on the portion of the system memory;
• set a state of the one or more processors to initiate execution of the code of the second operating system to start the second operating system, the second operating system using the one or more secured boot secrets obtained by the first operating system from the TCB and stored in the portion of the system memory for attesting a security status of the second operating system;
• and
• re-protect the portion of the system the memory, including preventing access to the portion of the system memory by the second operating system.

A computer program product comprising one or more hardware storage devices having stored thereon computer-executable instructions that are executable by one or more processors of a computer system to cause the computer system to protect secured boot secrets while starting an operating system, the computer-executable instructions including instructions that are executable to cause the computer system to perform at least the following:

• start a first operating system in reliance on a trusted computing base (TCB), including obtaining one or more secured boot secrets from the TCB that are usable for attesting a security status of the first operating system;
• protect a portion of system memory of the computer system, including preventing access to the portion of the system memory by the first operating system;
• store the one or more secured boot secrets in the protected portion of the system memory;
• identify that a second operating system is to be started to replace the first operating system, without performing a full reboot of the computer system;
• and
• based at least on identifying that the second operating system is to be started to replace the first operating system, perform at least:
• configure one or more memory data structures in the protected portion of the system memory, including loading code of the second operating system in the protected portion of the system memory for starting the second operating system;
• unprotect the portion of the system memory, while mitigating attacks on the portion of the system memory;
• set a state of the one or more processors to initiate execution of the code of the second operating system to start the second operating system, the second operating system using the one or more secured boot secrets obtained by the first operating system from the TCB and stored in the portion of the system memory for attesting a security status of the second operating system;
• and
• re-protect the portion of the system the memory, including preventing access to the portion of the system memory by the second operating system.