On 28/08/14 18:30, Mark Rutland wrote: > On Thu, Aug 28, 2014 at 06:27:04PM +0100, Marc Zyngier wrote: >> On 28/08/14 18:03, Mark Rutland wrote: >> >>> From 67104ad5a56e4c18f9c41f06af028b7561740afd Mon Sep 17 00:00:00 2001 >>> From: Mark Rutland <mark.rutland@xxxxxxx> >>> Date: Thu, 28 Aug 2014 17:41:03 +0100 >>> Subject: [PATCH] Doc: dt: arch_timer: discourage clock-frequency use >>> >>> The ARM Generic Timer (AKA the architected timer, arm_arch_timer) >>> features a CPU register (CNTFRQ) which firmware is intended to >>> initialize, and non-secure software can read to determine the frequency >>> of the timer. On CPUs with secure state, this register cannot be written >>> from non-secure states. >>> >>> The firmware of early SoCs featuring the timer did not correctly >>> initialize CNTFRQ correctly on all CPUs, requiring the frequency to be >>> described in DT as a workaround. This workaround is not complete however >>> as CNTFRQ is exposed to all software in a privileged non-secure mode, >>> including KVM guests. The firmware and DTs for recent SoCs have followed >> >> I believe Xen is also affected by this. > > True. > > s/KVM/KVM\/Xen/, then? Yup. Or "including guests running under a hypervisor", I expect this to be such a fundamental problem that all hypervisors will trip over on that one (Jailhouse definitely does). Thanks, M. -- Jazz is not dead. It just smells funny... -- To unsubscribe from this list: send the line "unsubscribe devicetree" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
