Any objections to this? If not, I will push it later today. Thanks.
On Sat, 20 May 2023 at 11:20, Ard Biesheuvel <a...@kernel.org> wrote: > > The helper that updates live page table entries writes a zero entry, > invalidates the covered address range from the TLBs, and finally writes > the actual entry. This ensures that no TLB conflicts can occur. > > Writing the final entry needs to complete before any translations can be > performed, as otherwise, the zero entry, which describes an invalid > translation, may be observed by the page table walker, resulting in a > translation fault. For this reason, the final write is followed by a DSB > barrier instruction. > > However, this barrier will not stall the pipeline, and instruction > fetches may still hit this invalid translation, as has been observed and > reported by Oliver. To ensure that the new translation is fully active > before returning from this helper, we have to insert an ISB barrier as > well. > > Cc: Liming Gao <gaolim...@byosoft.com.cn> > Cc: Leif Lindholm <quic_llind...@quicinc.com> > Cc: Michael D Kinney <michael.d.kin...@intel.com> > Reported-by: Oliver Steffen <ostef...@redhat.com> > Tested-by: Oliver Steffen <ostef...@redhat.com> > Signed-off-by: Ard Biesheuvel <a...@kernel.org> > --- > ArmPkg/Library/ArmMmuLib/AArch64/ArmMmuLibReplaceEntry.S | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/ArmPkg/Library/ArmMmuLib/AArch64/ArmMmuLibReplaceEntry.S > b/ArmPkg/Library/ArmMmuLib/AArch64/ArmMmuLibReplaceEntry.S > index 887439bc042f0f16..1f0d8057926933d7 100644 > --- a/ArmPkg/Library/ArmMmuLib/AArch64/ArmMmuLibReplaceEntry.S > +++ b/ArmPkg/Library/ArmMmuLib/AArch64/ArmMmuLibReplaceEntry.S > @@ -65,6 +65,7 @@ > // write updated entry > str x1, [x0] > dsb nshst > + isb > > .L2_\@: > .endm > -- > 2.39.2 > -=-=-=-=-=-=-=-=-=-=-=- Groups.io Links: You receive all messages sent to this group. View/Reply Online (#105105): https://edk2.groups.io/g/devel/message/105105 Mute This Topic: https://groups.io/mt/99027974/21656 Group Owner: devel+ow...@edk2.groups.io Unsubscribe: https://edk2.groups.io/g/devel/unsub [arch...@mail-archive.com] -=-=-=-=-=-=-=-=-=-=-=-
