Messages in this thread | | | Date | Thu, 28 Jul 2022 09:39:20 -0300 | From | Thadeu Lima de Souza Cascardo <> | Subject | Re: [PATCH] x86/bugs: Do not enable IBPB at firmware entry when IBPB is not available |
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On Thu, Jul 28, 2022 at 02:35:48PM +0200, Borislav Petkov wrote: > drop stable@ > > On Thu, Jul 28, 2022 at 09:26:02AM -0300, Thadeu Lima de Souza Cascardo wrote: > > Some cloud hypervisors do not provide IBPB on very recent CPU processors, > > including AMD processors affected by Retbleed. > > Which hypervisors are those? How relevant is that use case?
Azure for sure, and I guess AWS would be affected as well.
> > How do I reproduce it here? >
qemu -cpu host,ibpb=off on an affected AMD processor worked for me. With EFI, so with something like -drive if=pflash,index=0,file=OVMF_CODE_4M.fd -drive if=pflash,index=1,file=OVMF_VARS_4M.fd.
Cascardo.
> Thx. > > -- > Regards/Gruss, > Boris. > > https://people.kernel.org/tglx/notes-about-netiquette
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