From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Jones Subject: Re: [PATCH v4 0/4] KVM: arm64: BUG FIX: Correctly handle zero register transfers Date: Mon, 7 Dec 2015 16:25:59 -0600 Message-ID: <20151207222559.GI4402@hawk.localdomain> References: <20151205003334.GB3117@hawk.localdomain> <013501d130d4$635722f0$2a0568d0$@samsung.com> <20151207215811.GH4402@hawk.localdomain> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: 'Marc Zyngier' , kvmarm@lists.cs.columbia.edu, kvm@vger.kernel.org To: Pavel Fedin Return-path: Content-Disposition: inline In-Reply-To: <20151207215811.GH4402@hawk.localdomain> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: kvmarm-bounces@lists.cs.columbia.edu Sender: kvmarm-bounces@lists.cs.columbia.edu List-Id: kvm.vger.kernel.org On Mon, Dec 07, 2015 at 03:58:11PM -0600, Andrew Jones wrote: > On Mon, Dec 07, 2015 at 12:48:12PM +0300, Pavel Fedin wrote: > > Hello! > > > > > FYI, I tried writing test cases for this issue with kvm-unit-tests. The > > > issue didn't reproduce for me. It's quite possible my test cases are > > > flawed > > > > Indeed they are, a very little thing fell through again... :) > > It's not just SP, it's SP_EL0. And you never initialize it to anything because your code always runs in kernel mode, so it's just > > zero, so you get your zero. > > But if you add a little thing in the beginning of your main(): > > > > asm volatile("msr sp_el0, %0" : : "r" (0xDEADC0DE0BADC0DE)); > > Ah! Thanks for this. The mmio test does now fail for me too. The sysreg > test still doesn't fail for me (even though I'm doing the above on the > vcpu I use for that too). Maybe there's something weird with which reg > I'm using, and whether or not my attempt to get trapping enabled on it > is working the way I expected. I'll play with it some more. > Must be the trapping thing. I switched to dbgbvr0_el1, which has trapping enabled on it until it's touched, and was able the reproduce the xzr issue it. drew