From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andrew Cooper Subject: Re: [PATCH 2/3] xen: arm: correctly handle continuations for 64-bit guests Date: Wed, 25 Mar 2015 15:41:53 +0000 Message-ID: <5512D741.7000105@citrix.com> References: <1427297660-26447-2-git-send-email-ian.campbell@citrix.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <1427297660-26447-2-git-send-email-ian.campbell@citrix.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: Ian Campbell , xen-devel@lists.xen.org Cc: julien.grall@linaro.org, tim@xen.org, stefano.stabellini@eu.citrix.com List-Id: xen-devel@lists.xenproject.org On 25/03/15 15:34, Ian Campbell wrote: > The 64-bit ABI is different to 32-bit: > > - uses x16 as the op register rather than r12. > - arguments in x0..x5 and not r0..r5. Using rN here potentially > truncates. > - return value goes in x0, not r0. > > Hypercalls can only be made directly from kernel space, so checking > the domain's size is sufficient. > > The update of regs->pc is duplicated in both halves because the 32-bit > case is going to need fixing to handle Thumb mode (next patch). > > Spotted due to spurious -EFAULT when destroying a domain, due to the > hypercall's pointer argument being truncated. I'm unclear why I am > only seeing this now. > > Signed-off-by: Ian Campbell Almost certainly 15e0aac6fe76be6a710a8e6d3da610d437903266 which changed XEN_DOMCTL_destroydomain to use continuations rather than repeated hypercalls. ~Andrew