On Wed, Mar 24, 2021 at 05:40:39PM +0000, Marc Zyngier wrote: > On Wed, 24 Mar 2021 17:19:36 +0000, > Catalin Marinas <[email protected]> wrote: > > > > On Wed, Mar 24, 2021 at 05:06:58PM +0000, Suzuki K Poulose wrote: > > > On 24/03/2021 16:30, Marc Zyngier wrote: > > > > > > > > OK, so we definitely do need these patches, don't we? Both? Just one? > > > > Please have a look at kvmarm/fixes and tell me what I must keep. > > > > > > Both of them are fixes. > > > > > > commit "KVM: arm64: Disable guest access to trace filter controls" > > > - This fixes guest fiddling with the trace filter control as described > > > above. > > > > > > commit "KVM: arm64: Hide system instruction access to Trace registers" > > > - Fixes the Hypervisor to advertise what it doesn't support. i.e > > > stop advertising trace system instruction access to a guest. > > > Otherwise a guest which trusts the ID registers > > > (ID_AA64DFR0_EL1.TRACEVER == 1) can crash while trying to access the > > > trace register as we trap the accesses (CPTR_EL2.TTA == 1). On Linux, > > > the ETM drivers need a DT explicitly advertising the support. So, > > > this is not immediately impacted. And this fix goes a long way back > > > in the history, when the CPTR_EL2.TTA was added. > > > > > > Now, the reason for asking you to hold on is the way this could create > > > conflicts in merging the rest of the series. > > > > The way we normally work around this is to either rebase your series on > > top of -rc5 when the fixes go in or, if you want an earlier -rc base, > > Marc can put them on a stable branch somewhere that you can use. > > Here's what I've done: > > - the two patches are now on a branch[1] based off -rc3 which I > officially declare stable. Feel free to rebase your series on top. > > - the KVM fixes branch now embeds this branch (yes, I've rebased it -- > we'll hopefully survive the outrage).
We don't have a choice to rebase. I will rebased CS next on [1] and apply this set on top of it. Hopefully the KVM fixes will have made it to GKH's char-misc tree by the time I send him the patches for the next merge window. Otherwise we'll have to merge patches twice as Catalin mentioned. We can deal with that if/when we get there. Thanks, Mathieu > > Thanks, > > M. > > [1] > https://git.kernel.org/pub/scm/linux/kernel/git/kvmarm/kvmarm.git/log/?h=trace-fixes-5.12 > > -- > Without deviation from the norm, progress is not possible.
