diff options
| author | Josh Poimboeuf <jpoimboe@kernel.org> | 2022-06-14 23:16:15 +0200 |
|---|---|---|
| committer | Borislav Petkov <bp@suse.de> | 2022-06-27 10:34:00 +0200 |
| commit | 9756bba28470722dacb79ffce554336dd1f6a6cd (patch) | |
| tree | 2de4396bfa550c400fe8380e435fb28169733cd9 /arch/x86/kvm/vmx | |
| parent | KVM: VMX: Fix IBRS handling after vmexit (diff) | |
| download | linux-9756bba28470722dacb79ffce554336dd1f6a6cd.tar.xz linux-9756bba28470722dacb79ffce554336dd1f6a6cd.zip | |
x86/speculation: Fill RSB on vmexit for IBRS
Prevent RSB underflow/poisoning attacks with RSB. While at it, add a
bunch of comments to attempt to document the current state of tribal
knowledge about RSB attacks and what exactly is being mitigated.
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 'arch/x86/kvm/vmx')
| -rw-r--r-- | arch/x86/kvm/vmx/vmenter.S | 6 |
1 files changed, 3 insertions, 3 deletions
diff --git a/arch/x86/kvm/vmx/vmenter.S b/arch/x86/kvm/vmx/vmenter.S index 8641ea74a307..4c743fa98a1f 100644 --- a/arch/x86/kvm/vmx/vmenter.S +++ b/arch/x86/kvm/vmx/vmenter.S @@ -194,15 +194,15 @@ SYM_INNER_LABEL(vmx_vmexit, SYM_L_GLOBAL) * IMPORTANT: RSB filling and SPEC_CTRL handling must be done before * the first unbalanced RET after vmexit! * - * For retpoline, RSB filling is needed to prevent poisoned RSB entries - * and (in some cases) RSB underflow. + * For retpoline or IBRS, RSB filling is needed to prevent poisoned RSB + * entries and (in some cases) RSB underflow. * * eIBRS has its own protection against poisoned RSB, so it doesn't * need the RSB filling sequence. But it does need to be enabled * before the first unbalanced RET. */ - FILL_RETURN_BUFFER %_ASM_CX, RSB_CLEAR_LOOPS, X86_FEATURE_RETPOLINE + FILL_RETURN_BUFFER %_ASM_CX, RSB_CLEAR_LOOPS, X86_FEATURE_RSB_VMEXIT pop %_ASM_ARG2 /* @flags */ pop %_ASM_ARG1 /* @vmx */ |