On 7/28/21 7:52 AM, Tianyu Lan wrote:

__set_memory_enc_dec() is turning into a real mess.  SEV, TDX and now
Hyper-V are messing around in here.

It doesn't help that these additions are totally uncommented.  Even
worse is that hv_set_mem_enc() was intentionally named "enc" when it
presumably has nothing to do with encryption.

This needs to be refactored.  The current __set_memory_enc_dec() can
become __set_memory_enc_pgtable().  It gets used for the hypervisors
that get informed about "encryption" status via page tables: SEV and TDX.

Then, rename hv_set_mem_enc() to hv_set_visible_hcall().  You'll end up
with:

int __set_memory_enc_dec(unsigned long addr, int numpages, bool enc)
{
	if (hv_is_isolation_supported())
		return hv_set_visible_hcall(...);

	if (mem_encrypt_active() || ...)
		return __set_memory_enc_pgtable();

	/* Nothing to do */
	return 0;
}

That tells the story pretty effectively, in code.

+int hv_set_mem_enc(unsigned long addr, int numpages, bool enc)
+{
+	return hv_set_mem_host_visibility((void *)addr,
+			numpages * HV_HYP_PAGE_SIZE,
+			enc ? VMBUS_PAGE_NOT_VISIBLE
+			: VMBUS_PAGE_VISIBLE_READ_WRITE);
+}

I know this is off in Hyper-V code, but this just makes my eyes bleed.
I'd much rather see something which is less compact but readable.

+/* Hyper-V GPA map flags */
+#define	VMBUS_PAGE_NOT_VISIBLE		0
+#define	VMBUS_PAGE_VISIBLE_READ_ONLY	1
+#define	VMBUS_PAGE_VISIBLE_READ_WRITE	3

That looks suspiciously like an enum.