Messages in this thread | | | Subject | Re: Flushing user entries for kernel mappings in x86 | From | Nadav Amit <> | Date | Wed, 29 Aug 2018 01:37:55 -0700 |
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at 8:45 PM, Andy Lutomirski <luto@kernel.org> wrote:
> On Tue, Aug 28, 2018 at 6:46 PM, Nadav Amit <nadav.amit@gmail.com> wrote: >> Hello Andy, >> >> Is there a reason for __flush_tlb_one_kernel() to flush the PTE not only in >> the kernel address space, but also in the user one (as part of >> __flush_tlb_one_user)? [ I obviously regard the case when PTI is on ]. > > In most cases, probably not, but it's fairly cheap, I think. And it > makes it so that we're okay if the TLB entry we're flushing is used by > the entry code.
Thanks. I assumed that’s the case. I don’t know how cheap they are (especially if INVPCID is not supported) but I guess they are not that frequent.
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