KVM: arm64: Apply the fine-grained UNDEFs without FEAT_FGT

Overview

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

KVM: arm64: Apply the fine-grained UNDEFs without FEAT_FGT

FGUs don't actually require hardware support, so don't gate fgt trap config insertion on FGT. This is the only action required to allow FGUs always, as kvm_calculate_traps() already computes the FGU bits with or without FEAT_FGT.

This also fixes a spurious WARN when a TLBI OS is run on a guest in vEL1 without FEAT_TLBIOS on non FEAT_FGT hardware. In this configuration the course-grained HCR_EL2.TTLBOS trap reaches the handler handle_tlbi_el1(), which expects an EL1 TLBI only from vEL2. With FGUs enabled the UNDEF will be injected without needing the specific handler.

[oliver: Take Wei-Lin's suggested changelog]

Affected

• Linux >= f5a5a406b4b8bb6c1fc7a1e92a872bd86061a53f < 2f4a15c52a552c5244ec27f4ca8bda855594f918
• Linux >= f5a5a406b4b8bb6c1fc7a1e92a872bd86061a53f < 1113374a17d7f7d16b02ee0bbd9b1e7a60cbb087
• Linux >= f5a5a406b4b8bb6c1fc7a1e92a872bd86061a53f < af3300b3a6bace925a496f3520e171c07b999c72
• Linux >= f5a5a406b4b8bb6c1fc7a1e92a872bd86061a53f < 4bdd2b3a708c1feb701cb8b62feb8ad2fd77bb07
• Linux 6.9

Remediation

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