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SubjectRe: [PATCH v10 12/26] gunyah: vm_mgr: Add/remove user memory regions
On Tue, Feb 14, 2023 at 01:24:16PM -0800, Elliot Berman wrote:
>
> When launching a virtual machine, Gunyah userspace allocates memory for
> the guest and informs Gunyah about these memory regions through
> SET_USER_MEMORY_REGION ioctl.

It also frees memory, see below. Why not document that?

> + case GH_VM_SET_USER_MEM_REGION: {
> + struct gh_userspace_memory_region region;
> +
> + if (copy_from_user(&region, argp, sizeof(region)))
> + return -EFAULT;
> +
> + /* All other flag bits are reserved for future use */
> + if (region.flags & ~(GH_MEM_ALLOW_READ | GH_MEM_ALLOW_WRITE | GH_MEM_ALLOW_EXEC |
> + GH_MEM_LENT))
> + return -EINVAL;

Nice, thanks for validating that.


> +
> +

Nit, 2 blank lines are not needed :(


> + if (region.memory_size)
> + r = gh_vm_mem_alloc(ghvm, &region);
> + else
> + r = gh_vm_mem_free(ghvm, region.label);

So if you set the size to 0 it is freed? Wouldn't a separate ioctl make
more sense? Where is this logic documented to userspace?

thanks,

greg k-h

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