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| author |   Josh Poimboeuf <jpoimboe@kernel.org> | 2022-06-14 23:16:14 +0200 |
|---|---|---|
| committer |   Borislav Petkov <bp@suse.de> | 2022-06-27 10:34:00 +0200 |
| commit | bea7e31a5caccb6fe8ed989c065072354f0ecb52 (patch) | |
| tree | 2848b252b6ac2c1afd882cf9b263b70fd740245e /arch/x86/kvm/vmx/vmx.c | |
| parent | KVM: VMX: Prevent guest RSB poisoning attacks with eIBRS (diff) | |
| download | linux-dev-bea7e31a5caccb6fe8ed989c065072354f0ecb52.tar.xz linux-dev-bea7e31a5caccb6fe8ed989c065072354f0ecb52.zip | |
KVM: VMX: Fix IBRS handling after vmexit
For legacy IBRS to work, the IBRS bit needs to be always re-written
after vmexit, even if it's already on.
Signed-off-by: Josh Poimboeuf <jpoimboe@kernel.org>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Borislav Petkov <bp@suse.de>
Diffstat (limited to '')
| -rw-r--r-- | arch/x86/kvm/vmx/vmx.c | 7 |
1 files changed, 6 insertions, 1 deletions
diff --git a/arch/x86/kvm/vmx/vmx.c b/arch/x86/kvm/vmx/vmx.c index b81000cc826a..421db354b1ab 100644 --- a/arch/x86/kvm/vmx/vmx.c +++ b/arch/x86/kvm/vmx/vmx.c @@ -6844,8 +6844,13 @@ void noinstr vmx_spec_ctrl_restore_host(struct vcpu_vmx *vmx, /* * If the guest/host SPEC_CTRL values differ, restore the host value. + * + * For legacy IBRS, the IBRS bit always needs to be written after + * transitioning from a less privileged predictor mode, regardless of + * whether the guest/host values differ. */ - if (vmx->spec_ctrl != hostval) + if (cpu_feature_enabled(X86_FEATURE_KERNEL_IBRS) || + vmx->spec_ctrl != hostval) native_wrmsrl(MSR_IA32_SPEC_CTRL, hostval); barrier_nospec(); |