On Wed, 24 Mar 2021 17:19:36 +0000, Catalin Marinas catalin.marinas@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=tra...