Messages in this thread | | | From | Jim Mattson <> | Date | Tue, 3 Oct 2023 21:24:12 -0700 | Subject | Re: [PATCH] x86: KVM: Add feature flag for AMD's FsGsKernelGsBaseNonSerializing |
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On Tue, Oct 3, 2023 at 8:27 PM Dave Hansen <dave.hansen@intel.com> wrote: > > On 10/3/23 19:44, Jim Mattson wrote: > > I'm a little surprised at the pushback, TBH. Are you implying that > > there is some advantage to *not* passing this bit through? > > I'm not really trying to push back. I'm honestly just curious. Linux > obviously doesn't cat about the bit. So is this for some future Linux > or some other OS?
It's not for any particular guest OS. It's just for correctness of the virtual CPU. Pedantically, hardware that enumerates this bit cannot run a guest that doesn't. Pragmatically, it almost certainly doesn't matter. Getting it right is trivial and has no impact on performance or code size, so why not just do it?
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