Hi Andrew and Stefano, Thanks for pushing things forward!
> -----Original Message----- > From: Stefano Stabellini <sstabell...@kernel.org> > Subject: Re: [PATCH 3/4] xen/arm, libxl: Revert XEN_DOMCTL_shadow_op; > use p2m mempool hypercalls > > On Wed, 16 Nov 2022, Andrew Cooper wrote: > > On 16/11/2022 01:37, Stefano Stabellini wrote: > > > On Wed, 26 Oct 2022, Andrew Cooper wrote: > > >> This reverts most of commit > cf2a68d2ffbc3ce95e01449d46180bddb10d24a0, and bits > > >> of cbea5a1149ca7fd4b7cdbfa3ec2e4f109b601ff7. > > >> > > >> First of all, with ARM borrowing x86's implementation, the logic to set > the > > >> pool size should have been common, not duplicated. Introduce > > >> libxl__domain_set_p2m_pool_size() as a shared implementation, and > use it from > > >> the ARM and x86 paths. It is left as an exercise to the reader to judge > how > > >> libxl/xl can reasonably function without the ability to query the pool > size... > > >> > > >> Remove ARM's p2m_domctl() infrastructure now the functioanlity has > been > > >> replaced with a working and unit tested interface. > > >> > > >> This is part of XSA-409 / CVE-2022-33747. > > > Genuine question: I can see this patch removes the implementation of > > > XEN_DOMCTL_SHADOW_OP_SET_ALLOCATION on ARM. It also switches > libxl (both > > > ARM and x86) to the new hypercall. > > > > > > Why keep the old hypercall (XEN_DOMCTL_shadow_op and > > > XEN_DOMCTL_SHADOW_OP_SET_ALLOCATION) implementation on x86 > (not on ARM)? > > > > > > Is that because it was only recently implemented? And not actually > > > present in any past Xen release? > > > > > > If so, please add a note about this in the commit message. Also, if that > > > is the case, I think this patch series should go in 4.17. If it is too > > > late to get it in before the release, then we should backport it to 4.17 > > > as soon as possible. That's because ideally we want to keep the > > > hypercall interface changes down to a minimum. > > > > On ARM, the hypercall has existed for a little over 4 weeks, and isn't > > in any released version of Xen (yet). > > > > On x86, the hypercall has existed for more than a decade, and has known > > out-of-tree users. It needs to be deprecated properly, which in this > > case means "phased out in the 4.18 cycle once known callers have been > > adapted to the new hypercall". > > Understoon. Then I am in favor of getting all 4 patches in 4.17, either > before the release or via backports. Sorry - today it took me a little bit longer to get the office, so hopefully I still jumped into discussion on time. About this series, I don't have strong objection to taking all 4 patches, so if this series can have proper review/agreements by this weekend, feel free to add my release-ack for the patches. However, if we cannot sort out all 4 patches, I think at least patch #4 should go into 4.17 (with a commit message adjustment). The patch #4 already has proper tags from Arm maintainer and me. Kind regards, Henry
