From mboxrd@z Thu Jan 1 00:00:00 1970 From: marc.zyngier@arm.com (Marc Zyngier) Date: Fri, 19 Aug 2016 15:54:21 +0100 Subject: [PATCH 5/5] arm64: KVM: vgic-v2: Enable GICV access from HYP if access from guest is unsafe In-Reply-To: References: <1471610295-1456-1-git-send-email-marc.zyngier@arm.com> <1471610295-1456-6-git-send-email-marc.zyngier@arm.com> <57B7042D.1020702@arm.com> Message-ID: <20160819155421.44355df9@arm.com> To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Fri, 19 Aug 2016 14:31:12 +0100 Peter Maydell wrote: > On 19 August 2016 at 14:05, Marc Zyngier wrote: > > On 19/08/16 13:53, Peter Maydell wrote: > >> Is it worth specifically saying "performance will be worse", or do we > >> expect this to only happen on systems where the h/w can't permit direct > >> access (as opposed to those with bad dt info) ? > > > > We cannot distinguish between the two, unfortunately. Even worse, ACPI > > only gives us a base address, and not the size of the region. So even if > > the HW was perfectly compliant with SBSA, we have to assume the worse case. > > Right, but if we expect this is mostly going to be "you just have > to live with it on this hardware" there's less point in printing > an alarming message, whereas if there's a significant subset of > "dt is just wrong" cases then the alarm might help in getting them > fixed, maybe... That'd require some more infrastructure from the kernel's GIC driver (which now provides the various base addresses), but I guess that we can have a look as well. Thanks, M. -- Jazz is not dead. It just smells funny.