On Wed, Jul 28, 2021 at 10:52:22AM -0400, Tianyu Lan wrote:
> + if (hv_is_isolation_supported()) {
> + vmbus_connection.monitor_pages_va[0]
> + = vmbus_connection.monitor_pages[0];
> + vmbus_connection.monitor_pages[0]
> + = memremap(msg->monitor_page1, HV_HYP_PAGE_SIZE,
> + MEMREMAP_WB);
> + if (!vmbus_connection.monitor_pages[0])
> + return -ENOMEM;
> +
> + vmbus_connection.monitor_pages_va[1]
> + = vmbus_connection.monitor_pages[1];
> + vmbus_connection.monitor_pages[1]
> + = memremap(msg->monitor_page2, HV_HYP_PAGE_SIZE,
> + MEMREMAP_WB);
> + if (!vmbus_connection.monitor_pages[1]) {
> + memunmap(vmbus_connection.monitor_pages[0]);
> + return -ENOMEM;
> + }
> +
> + memset(vmbus_connection.monitor_pages[0], 0x00,
> + HV_HYP_PAGE_SIZE);
> + memset(vmbus_connection.monitor_pages[1], 0x00,
> + HV_HYP_PAGE_SIZE);
> + }
Okay, let me see if I got this right. In Hyper-V Isolation VMs, when the
guest wants to make memory shared, it does":
- Call to the Hypervisor the mark the pages shared. The
Hypervisor will do the RMP update and remap the pages at
(VTOM + pa)
- The guest maps the memory again into its page-table, so that
the entries point to the correct GPA (which is above VTOM
now).
Or in other words, Hyper-V implements a hardware-independent and
configurable c-bit position, as the VTOM value is always power-of-two
aligned. Is that correct?
This would at least explain why there is no separate
allocation/dealloction of memory for the shared range.
Thanks,
Joerg
