RISC-V: KVM: Write hgatp register with valid mode bits

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: RISC-V: KVM: Write hgatp register with valid mode bits According to the RISC-V Privileged Architecture Spec, when MODE=Bare is selected,software must write zero to the remaining fields of hgatp. We have detected the valid mode supported by the HW before, So using a valid mode to detect how many vmid bits are supported.

References

• https://git.kernel.org/stable/c/d00b61cd37f4c183ce0edbc9f8ccf6d5430ea357
• https://git.kernel.org/stable/c/2b351e3d04be9e1533f26c3464f1e44a5beace30