Messages in this thread | | | Date | Wed, 9 Aug 2023 10:30:00 -0400 | From | Josh Poimboeuf <> | Subject | Re: [RFC][PATCH 07/17] x86/cpu/kvm: Provide UNTRAIN_RET_VM |
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On Wed, Aug 09, 2023 at 04:06:44PM +0200, Peter Zijlstra wrote: > On Wed, Aug 09, 2023 at 09:50:04AM -0400, Josh Poimboeuf wrote: > > On Wed, Aug 09, 2023 at 09:12:25AM +0200, Peter Zijlstra wrote: > > > With the difference being that UNTRAIN_RET_VM uses > > > X86_FEATURE_IBPB_ON_VMEXIT instead of X86_FEATURE_ENTRY_IBPB. > > > > > > This cures VMEXIT doing potentially unret+IBPB or double IBPB. > > > > > > Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> > > > --- > > > arch/x86/include/asm/nospec-branch.h | 11 +++++++++++ > > > arch/x86/kernel/cpu/bugs.c | 17 ++++++++++++++++- > > > arch/x86/kvm/svm/vmenter.S | 7 ++----- > > > 3 files changed, 29 insertions(+), 6 deletions(-) > > > > > > --- a/arch/x86/include/asm/nospec-branch.h > > > +++ b/arch/x86/include/asm/nospec-branch.h > > > @@ -299,6 +299,17 @@ > > > #endif > > > .endm > > > > > > +.macro UNTRAIN_RET_VM > > > +#if defined(CONFIG_CPU_UNRET_ENTRY) || defined(CONFIG_CPU_IBPB_ENTRY) || \ > > > + defined(CONFIG_CALL_DEPTH_TRACKING) || defined(CONFIG_CPU_SRSO) > > > > Maybe can be simplified? > > > > See patches 9 and 10 :-)
Can still be further simplified to CONFIG_RETHUNK?
-- Josh
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