On 2/15/2023 10:38 PM, Greg Kroah-Hartman wrote:

On Tue, Feb 14, 2023 at 01:24:16PM -0800, Elliot Berman wrote:

quoted

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?

I can mention in commit text, too.

quoted

+	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.

quoted

+
+

Nit, 2 blank lines are not needed :(

quoted

+		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? >

We're following KVM convention here. The logic is documented in patch 17/26.

Thanks,
Elliot

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