Description
In the Linux kernel, the following vulnerability has been resolved: x86/vmscape: Add conditional IBPB mitigation VMSCAPE is a vulnerability that exploits insufficient branch predictor isolation between a guest and a userspace hypervisor (like QEMU). Existing mitigations already protect kernel/KVM from a malicious guest. Userspace can additionally be protected by flushing the branch predictors after a VMexit. Since it is the userspace that consumes the poisoned branch predictors, conditionally issue an IBPB after a VMexit and before returning to userspace. Workloads that frequently switch between hypervisor and userspace will incur the most overhead from the new IBPB. This new IBPB is not integrated with the existing IBPB sites. For instance, a task can use the existing speculation control prctl() to get an IBPB at context switch time. With this implementation, the IBPB is doubled up: one at context switch and another before running userspace. The intent is to integrate and optimize these cases post-embargo. [ dhansen: elaborate on suboptimal IBPB solution ]
Product status
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (git) before ac60717f9a8d21c58617d0b34274babf24135835
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (git) before c08192b5d6730a914dee6175bc71092ee6a65f14
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (git) before d5490dfa35427a2967e00a4c7a1b95fdbc8ede34
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (git) before 2f4f2f8f860cb4c3336a7435ebe8dcfded0c9c6e
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (git) before 15006289e5c38b2a830e1fba221977a27598176c
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (git) before 893387c18612bb452336a5881da0d015a7e8f4a2
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (git) before f866eef8d1c65504d30923c3f14082ad294d0e6d
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (git) before 34e5667041050711a947e260fc9ebebe08bddee5
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (git) before d7ddc93392e4a7ffcccc86edf6ef3e64c778db52
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (git) before 459274c77b37ac63b78c928b4b4e748d1f9d05c8
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (git) before 510603f504796c3535f67f55fb0b124a303b44c8
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (git) before 9c23a90648e831d611152ac08dbcd1283d405e7f
1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (git) before 2f8f173413f1cbf52660d04df92d0069c4306d25
5.10.244 (semver)
5.15.193 (semver)
6.1.152 (semver)
6.6.106 (semver)
6.12.47 (semver)
6.16.7 (semver)
6.17 (original_commit_for_fix)
References
git.kernel.org/...c/ac60717f9a8d21c58617d0b34274babf24135835
git.kernel.org/...c/c08192b5d6730a914dee6175bc71092ee6a65f14
git.kernel.org/...c/d5490dfa35427a2967e00a4c7a1b95fdbc8ede34
git.kernel.org/...c/2f4f2f8f860cb4c3336a7435ebe8dcfded0c9c6e
git.kernel.org/...c/15006289e5c38b2a830e1fba221977a27598176c
git.kernel.org/...c/893387c18612bb452336a5881da0d015a7e8f4a2
git.kernel.org/...c/f866eef8d1c65504d30923c3f14082ad294d0e6d
git.kernel.org/...c/34e5667041050711a947e260fc9ebebe08bddee5
git.kernel.org/...c/d7ddc93392e4a7ffcccc86edf6ef3e64c778db52
git.kernel.org/...c/459274c77b37ac63b78c928b4b4e748d1f9d05c8
git.kernel.org/...c/510603f504796c3535f67f55fb0b124a303b44c8
git.kernel.org/...c/9c23a90648e831d611152ac08dbcd1283d405e7f
git.kernel.org/...c/2f8f173413f1cbf52660d04df92d0069c4306d25
