From mboxrd@z Thu Jan 1 00:00:00 1970 From: christoffer.dall@linaro.org (Christoffer Dall) Date: Wed, 6 Dec 2017 11:53:00 +0100 Subject: [PATCH 1/3] arm64: KVM: Move CPU ID reg trap setup off the world switch path In-Reply-To: <20171205123150.GX22781@e103592.cambridge.arm.com> References: <1512141582-17474-1-git-send-email-Dave.Martin@arm.com> <1512141582-17474-2-git-send-email-Dave.Martin@arm.com> <20171205090915.GI32397@cbox> <20171205123150.GX22781@e103592.cambridge.arm.com> Message-ID: <20171206105300.GK32397@cbox> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Tue, Dec 05, 2017 at 12:31:51PM +0000, Dave Martin wrote: > On Tue, Dec 05, 2017 at 10:09:15AM +0100, Christoffer Dall wrote: > > On Fri, Dec 01, 2017 at 03:19:40PM +0000, Dave Martin wrote: > > > The HCR_EL2.TID3 flag needs to be set when trapping guest access to > > > the CPU ID registers is required. However, the decision about > > > whether to set this bit does not need to be repeated at every > > > switch to the guest. > > > > > > Instead, it's sufficient to make this decision once and record the > > > outcome. > > > > > > This patch moves the decision to vcpu_reset_hcr() and records the > > > choice made in vcpu->arch.hcr_el2. The world switch code can then > > > load this directly when switching to the guest without the need for > > > conditional logic on the critical path. > > > > > > Signed-off-by: Dave Martin > > > Suggested-by: Christoffer Dall > > > Cc: Marc Zyngier > > > > Reviewed-by: Christoffer Dall > > > > > > > > --- > > > > > > Note to maintainers: this was discussed on-list [1] prior to the merge > > > window, but this patch implementing the agreed decision hasn't been > > > posted previously. > > > > > > This should be considered a fix for v4.15. > > > > It's actually easier for me to apply this for v4.16 and base my VHE > > optimization patches on it. > > If you're happy for this optimisation to be missing for v4.15, I'm fine > with that. > > Can I leave it you to pick this up then? Yes, I applied it to our queue already. > > I'll repost the other stuff from this series separately for Will to > take care of. > Thanks, -Christoffer