diff options
| author | Jim Mattson <jmattson@google.com> | 2025-09-30 17:14:08 -0700 |
|---|---|---|
| committer | Sean Christopherson <seanjc@google.com> | 2025-10-15 10:57:21 -0700 |
| commit | c53c632592a427bc01266a8ce7e2f17555a3c247 (patch) | |
| tree | 5f9f5f57bd376fb3d224c35e638cba9825b823e7 /arch/x86/kvm/svm/svm.c | |
| parent | 4793f990ea1523309a58d8fb5237b3a815e6f537 (diff) | |
KVM: SVM: Disallow EFER.LMSLE when not supported by hardware
Modern AMD CPUs do not support segment limit checks in 64-bit mode
(i.e. EFER.LMSLE must be zero). Do not allow a guest to set EFER.LMSLE
on a CPU that requires the bit to be zero.
For backwards compatibility, allow EFER.LMSLE to be set on CPUs that
support segment limit checks in 64-bit mode, even though KVM's
implementation of the feature is incomplete (e.g. KVM's emulator does
not enforce segment limits in 64-bit mode).
Fixes: eec4b140c924 ("KVM: SVM: Allow EFER.LMSLE to be set with nested svm")
Signed-off-by: Jim Mattson <jmattson@google.com>
Reviewed-by: Nikunj A Dadhania <nikunj@amd.com>
Reviewed-by: Yosry Ahmed <yosry.ahmed@linux.dev>
Link: https://lore.kernel.org/r/20251001001529.1119031-3-jmattson@google.com
Signed-off-by: Sean Christopherson <seanjc@google.com>
Diffstat (limited to 'arch/x86/kvm/svm/svm.c')
| -rw-r--r-- | arch/x86/kvm/svm/svm.c | 4 |
1 files changed, 3 insertions, 1 deletions
diff --git a/arch/x86/kvm/svm/svm.c b/arch/x86/kvm/svm/svm.c index 153c12dbf3eb..dadb562bd4b9 100644 --- a/arch/x86/kvm/svm/svm.c +++ b/arch/x86/kvm/svm/svm.c @@ -5320,7 +5320,9 @@ static __init int svm_hardware_setup(void) if (nested) { pr_info("Nested Virtualization enabled\n"); - kvm_enable_efer_bits(EFER_SVME | EFER_LMSLE); + kvm_enable_efer_bits(EFER_SVME); + if (!boot_cpu_has(X86_FEATURE_EFER_LMSLE_MBZ)) + kvm_enable_efer_bits(EFER_LMSLE); r = nested_svm_init_msrpm_merge_offsets(); if (r) |