On Wed, 24 Mar 2021 17:19:36 +0000, Catalin Marinas <catalin.mari...@arm.com> 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). 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.