Protection of balloon inflated memory using temporary loan pages

A system comprising:

• a guest memory having a plurality of GPPs, wherein the plurality of GPPs includes a first group of pages and a second group of pages that includes a plurality of loan pages, wherein the plurality of loan pages has a fixed quantity;
• a host memory;
• at least one processor in communication with the guest memory and the host memory;
• and
• a VMM configured to:
• track a respective state for each respective page of the plurality of GPPs of the first group of the guest memory, wherein the respective state is one of inflated and deflated,
• track a respective status of each of the plurality of loan pages of the second group, wherein each respective loan page of the plurality of loan pages of the second group has a status of one of in-use and unused,
• determine that each respective loan page of the plurality of loan pages of the second group is in-use,
• responsive to determining that each respective loan page has an in-use status, un-assign a first loan page of the plurality of loan pages of the second group from a corresponding GPP of the plurality of GPPs of the first group,
• discard the first loan page thereby changing the first loan page from in-use to unused, and
• assign the first loan page having the unused status to a first GPP of the first group that is inflated, such that the first loan page's status updates to in-use, wherein each respective page of the plurality of GPPs of the first group having an inflated state are temporarily backed by the plurality of loan pages of the second group having the fixed quantity.

A system comprising:

• a guest memory having a plurality of GPPs, wherein the plurality of GPPs includes a first group of pages and a second group of pages that comprises at least one loan page, and wherein the at least one loan page has a fixed quantity;
• a guest operating system (“OS”);
• at least one processor in communication with the guest memory;
• and
• a hypervisor configured to:
• store a guest physical address (“GPA”) for each respective loan page of the second group having a status of in-use, wherein the GPA is mapped to a corresponding virtual address, wherein each respective loan page of the at least one loan page of the second group has a status of one of in-use and unused,
• responsive to a page fault being reported by the guest OS for a first GPP of the first group of the plurality of GPPs, determine a state of the first GPP,
• responsive to determining the state of the first GPP as deflated, place a first fresh page for the first GPP,
• responsive to determining the state of the first GPP as inflated, locate an unused loan page from the at least one loan page of the second group, and
• responsive to locating the unused loan page, associate a respective GPA with the unused loan page and place a second fresh page, wherein each respective GPP of the first group having an inflated state is temporarily backed by a respective loan page.