System and method for BIOS and controller communication

1. An information handling system comprising:

a central processing unit coupled to a memory, wherein the memory further comprises a basic input/output system (BIOS);

a controller coupled to a nonvolatile memory;

a register coupled to the central processing unit and the controller;

wherein the controller is operable to:

store a key in the nonvolatile memory;

write the key to the register in response to a signal from the BIOS;

receive a command from the BIOS;

verify the command is from the BIOS using the key; and

execute the command if the command is from the BIOS.

2. The information handling system of claim 1 , wherein the central processing unit is operable to:

send a signal to the controller requesting a key;

read the key from the register;

generate the command using the key;

write the command to the register.

3. The information handling system of claim 2 , wherein the central processing unit is further operable to store the key in system management random access memory (SMRAM) coupled to the central processing unit.

4. The information handling system of claim 1 , wherein the controller is further operable to verify the command is from the BIOS by decrypting the command using the key.

5. The information handling system of claim 2 , wherein the central processing unit is further operable to generate the command by encrypting the command using the key.

6. The information handling system of claim 1 , wherein the controller is further operable to:

generate a new key;

save the new key to the nonvolatile memory;

using the key, encrypt the result of the command and the new key to form an encrypted result; and

write the encrypted result to the register.

7. The information handling system of claim 6 , wherein the central processing unit is further operable to:

read the encrypted result from the register;

decrypt the encrypted result using the key; and

save the new key to system management random access memory (SMRAM) coupled to the central processing unit.

8. The information handling system of claim 6 , wherein:

the controller is further operable to:

create a system management interrupt; and

read a confirmation message from the register; and

the central processing unit is further operable to:

receive the system management interrupt;

write the confirmation message to the register; and

return from the system management interrupt.

9. The system of claim 1 , wherein the controller is further operable to service non-critical commands by reading a command from the register; determining that the command is a non-critical command; and executing the command if the command is a non-critical command.

10. A method for communication between a BIOS and a controller in an information handling system comprising:

writing a key to a register in response to a signal from the BIOS, wherein the register is coupled to the controller;

receiving at the controller a command from the BIOS to the controller;

verifying at the controller that the command is from the BIOS by using the key; and

executing the command at the controller if the command is from the BIOS.

11. The method of claim 10 , further comprising:

sending a signal from the BIOS to the controller requesting a key;

reading the key from the register;

generating the command using the key; and

writing the command to the register.

12. The method of claim 11 , further comprising storing the key in system management random access memory (SMRAM) coupled to a central processing unit executing the BIOS, and storing the key in nonvolatile memory coupled to the controller.

13. The method of claim 12 , wherein verifying at the controller that the command is from the BIOS comprises decrypting the command using the key, and the method further comprises:

generating a new key at the controller; and

encrypting a result of the command and the new key with the key to form an encrypted result; and

writing the encrypted result to the register.

14. The method of claim 13 , further comprising:

reading the encrypted result from the register;

decrypting the encrypted result using the key; and

saving the new key in the SMRAM.

15. The method of claim 14 further comprising confirming the command, wherein confirming the command comprises:

creating a system management interrupt by the controller; and

writing a confirmation into the register by the BIOS.

16. A software for communicating between a BIOS and a controller in an information handling system, the software embodied in a non-transitory computer-readable medium and when executed operable to:

store a key in nonvolatile memory coupled to the controller;

write the key to a register in response to a signal from the BIOS, wherein the register is coupled to the controller and a central processing unit executing the BIOS;

receive a command from the BIOS;

using the key, verify at the controller that the command is from the BIOS; and

execute the command at the controller if the command is from the BIOS.

17. The software embodied in a non-transitory computer readable medium of claim 16 , wherein executed the software is further operable to:

send to the controller a signal requesting a key;

read the key from the register;

generate the command using the key;

write the command to the register.