From mboxrd@z Thu Jan 1 00:00:00 1970 From: marc.zyngier@arm.com (Marc Zyngier) Date: Wed, 21 Feb 2018 09:32:18 +0000 Subject: [PATCH v4 01/40] KVM: arm/arm64: Avoid vcpu_load for other vcpu ioctls than KVM_RUN In-Reply-To: <20180215210332.8648-2-christoffer.dall@linaro.org> References: <20180215210332.8648-1-christoffer.dall@linaro.org> <20180215210332.8648-2-christoffer.dall@linaro.org> Message-ID: <86inaqvgbh.wl-marc.zyngier@arm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Thu, 15 Feb 2018 21:02:53 +0000, Christoffer Dall wrote: > > Calling vcpu_load() registers preempt notifiers for this vcpu and calls > kvm_arch_vcpu_load(). The latter will soon be doing a lot of heavy > lifting on arm/arm64 and will try to do things such as enabling the > virtual timer and setting us up to handle interrupts from the timer > hardware. > > Loading state onto hardware registers and enabling hardware to signal > interrupts can be problematic when we're not actually about to run the > VCPU, because it makes it difficult to establish the right context when > handling interrupts from the timer, and it makes the register access > code difficult to reason about. > > Luckily, now when we call vcpu_load in each ioctl implementation, we can > simply remove the call from the non-KVM_RUN vcpu ioctls, and our > kvm_arch_vcpu_load() is only used for loading vcpu content to the > physical CPU when we're actually going to run the vcpu. > > Reviewed-by: Julien Grall > Signed-off-by: Christoffer Dall Reviewed-by: Marc Zyngier M. -- Jazz is not dead, it just smell funny.