KVM: nSVM: Always use NextRIP as vmcb02's NextRIP after first L2 VMRUN

Overview

In the Linux kernel, the following vulnerability has been resolved:

KVM: nSVM: Always use NextRIP as vmcb02's NextRIP after first L2 VMRUN

For guests with NRIPS disabled, L1 does not provide NextRIP when running an L2 with an injected soft interrupt, instead it advances the current RIP before running it. KVM uses the current RIP as the NextRIP in vmcb02 to emulate a CPU without NRIPS.

However, after L2 runs the first time, NextRIP will be updated by the CPU and/or KVM, and the current RIP is no longer the correct value to use in vmcb02. Hence, after save/restore, use the current RIP if and only if a nested run is pending, otherwise use NextRIP. Give soft_int_next_rip the same treatment, as it's the same logic, just for a narrower use case.

[sean: give soft_int_next_rip the same treatment]

Affected

• Linux >= cc440cdad5b7a4c1de12dace725209eb3e0cf663 < b1a45e8a59bcf1f1ec0da6d4e42190b4211c67fc
• Linux >= cc440cdad5b7a4c1de12dace725209eb3e0cf663 < f9197a9dd1408e203147326139122f9c5312ce9c
• Linux >= cc440cdad5b7a4c1de12dace725209eb3e0cf663 < 3428ed1529a1af4cce5aff6c5bd2fcc39ad726bb
• Linux >= cc440cdad5b7a4c1de12dace725209eb3e0cf663 < 69fe1411a5ce678b4da6489b5d2282b4e1d13acf
• Linux >= cc440cdad5b7a4c1de12dace725209eb3e0cf663 < 8d397582f6b5e9fbcf09781c7c934b4910e94a50
• Linux 5.8

Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.