Re: [Xen-devel] [RFC PATCH v3 10/10] arm/mem_access: Walk the guest's pt in software

2017-06-16 Thread Sergej Proskurin
Hi Tamas, [...] >> + >> +if ( ((flag & GV2M_WRITE) == GV2M_WRITE) && !(perms & GV2M_WRITE) ) > > Wouldn't it be enough to do (flag & GV2M_WRITE) without the following > comparison? Also, a comment explaining why this is an error-condition > would be nice. > Yes, you are absolutely cor

Re: [Xen-devel] [RFC PATCH v3 10/10] arm/mem_access: Walk the guest's pt in software

2017-06-15 Thread Tamas K Lengyel
On Thu, Jun 15, 2017 at 5:05 AM, Sergej Proskurin wrote: > In this commit, we make use of the gpt walk functionality introduced in > the previous commits. If mem_access is active, hardware-based gva to ipa > translation might fail, as gva_to_ipa uses the guest's translation > tables, access to whi

[Xen-devel] [RFC PATCH v3 10/10] arm/mem_access: Walk the guest's pt in software

2017-06-15 Thread Sergej Proskurin
In this commit, we make use of the gpt walk functionality introduced in the previous commits. If mem_access is active, hardware-based gva to ipa translation might fail, as gva_to_ipa uses the guest's translation tables, access to which might be restricted by the active VTTBR. To side-step potential