Messages in this thread | | | Date | Thu, 5 Nov 2020 20:48:22 +0800 | From | Shuo A Liu <> | Subject | Re: [PATCH v5 06/17] virt: acrn: Introduce VM management interfaces |
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On Thu 5.Nov'20 at 10:16:45 +0100, Greg Kroah-Hartman wrote: >On Thu, Nov 05, 2020 at 05:02:00PM +0800, Shuo A Liu wrote: >> On Thu 5.Nov'20 at 9:26:39 +0100, Greg Kroah-Hartman wrote: >> > On Thu, Nov 05, 2020 at 03:35:45PM +0800, Shuo A Liu wrote: >> > > On Thu 5.Nov'20 at 7:29:07 +0100, Greg Kroah-Hartman wrote: >> > > > On Thu, Nov 05, 2020 at 11:10:29AM +0800, Shuo A Liu wrote: >> > > > > On Wed 4.Nov'20 at 20:02:35 +0100, Greg Kroah-Hartman wrote: >> > > > > > On Mon, Oct 19, 2020 at 02:17:52PM +0800, shuo.a.liu@intel.com wrote: >> > > > > > > --- /dev/null >> > > > > > > +++ b/include/uapi/linux/acrn.h >> > > > > > > @@ -0,0 +1,56 @@ >> > > > > > > +/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */ >> > > > > > > +/* >> > > > > > > + * Userspace interface for /dev/acrn_hsm - ACRN Hypervisor Service Module >> > > > > > > + * >> > > > > > > + * This file can be used by applications that need to communicate with the HSM >> > > > > > > + * via the ioctl interface. >> > > > > > > + */ >> > > > > > > + >> > > > > > > +#ifndef _UAPI_ACRN_H >> > > > > > > +#define _UAPI_ACRN_H >> > > > > > > + >> > > > > > > +#include <linux/types.h> >> > > > > > > + >> > > > > > > +/** >> > > > > > > + * struct acrn_vm_creation - Info to create a User VM >> > > > > > > + * @vmid: User VM ID returned from the hypervisor >> > > > > > > + * @reserved0: Reserved >> > > > > > > + * @vcpu_num: Number of vCPU in the VM. Return from hypervisor. >> > > > > > > + * @reserved1: Reserved >> > > > > > > + * @uuid: UUID of the VM. Pass to hypervisor directly. >> > > > > > > + * @vm_flag: Flag of the VM creating. Pass to hypervisor directly. >> > > > > > > + * @ioreq_buf: Service VM GPA of I/O request buffer. Pass to >> > > > > > > + * hypervisor directly. >> > > > > > > + * @cpu_affinity: CPU affinity of the VM. Pass to hypervisor directly. >> > > > > > > + * @reserved2: Reserved >> > > > > > >> > > > > > Reserved and must be 0? >> > > > > >> > > > > Not a must. >> > > > >> > > > That's guaranteed to come back and bite you in the end. >> > > >> > > OK. I can fill them with zero before passing them to hypervisor. >> > > >> > > > You all have read the "how to write a good api" document, right? >> > > >> > > Is it Documentation/driver-api/ioctl.rst? Or i missed.. >> > >> > That's one good document, but no, not what I was referring to. I was >> > thinking of Documentation/process/adding-syscalls.rst, which is what you >> > are doing here implicitly with these new ioctls (every ioctl is a brand >> > new syscall.) >> >> I will read it as well. Thanks. >> >> > >> > > > > > What are they reserved for? >> > > > > > >> > > > > > Same for all of the reserved fields, why? >> > > > > >> > > > > Some reserved fields are to map layout in the hypervisor side, others >> > > > > are for future use. >> > > > >> > > > ioctls should not have these, again, please read the documentation. If >> > > > you need something new in the future, just make a new ioctl. >> > > >> > > OK. I will remove some reserved fields for scalability. >> > >> > "scalability" should have nothing to do with any of this, right? What >> > am I missing? >> >> Sorry, i meant reserved fields for future use. > >Again, this is not how you do that at all. If you need something "in >the future", create it then. What you are doing here ensures that you >will never be able to do it then either, so don't even pretend :) > >Read the syscall document for why this is the case.
Alright. I will remove that type of reserved fields. Thank you.
> >> > > Though i can >> > > keep some reserved fields for alignment (and to keep same data structure >> > > layout with the hypervisor), right? >> > > Documentation/driver-api/ioctl.rst says that explicit reserved fields >> > > could be used. >> > >> > If you need alignment, yes, that is fine, but that's not what you are >> > saying these are for. And if you need alignment, why not move things >> > around so they are properly aligned. >> > >> > And this structure has nothing to do with the hypervisor structure, >> > that's a internal-kernel structure, not a userspace-visable thing if you >> > are doing things correctly. >> >> It's the same structure with the one in hypervisor. HSM driver >> doesn't maintain the VM much, it just pass the data for VM creation from >> userspace to hypervisor. > >That sounds ripe for abuse, good luck!
The hypervisor will do the sanity check. In this case, HSM driver can be kept simple.
Thanks shuo
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