Direct memory access tracking for pass-through devices in virtualized environments

At least one non-transitory computer readable storage medium comprising a set of frontend driver instructions which, when executed by a computing system, cause the computing system to:

• notify a hypervisor of a map request from a guest driver of a physical device, wherein the physical device is to be passed through to and directly controlled by a virtual machine, and wherein the map request is associated with an attempt of the physical device to access a guest memory page in a virtualized execution environment, wherein to notify the hypervisor of the map request, the frontend driver instructions, when executed, cause the computing system to set a bit corresponding to a guest page frame number in a direct memory access (DMA) bitmap, and wherein the guest page frame number is associated with the guest memory page;
• determine whether the guest memory page is pinned;
• send a map hypercall to the hypervisor if the guest memory page is not pinned, and
• clear the bit in response to an unmap request from the guest driver, wherein the unmap request is associated with an attempt of the physical device to discontinue access to the guest memory page.

A performance-enhanced computing system comprising:

• a physical device, wherein the physical device is to be passed through to and directly controlled by a virtual machine;
• a processor;
• and
• a system memory comprising a set of hypervisor instructions, which when executed by the processor, cause the computing system to:
• determine that a guest memory page is pinned in a virtualized execution environment,
• determine, based on a direct memory access (DMA) bitmap, that an unmap request from a guest driver of a physical device has been issued, wherein the physical device is to be passed through to and directly controlled by a virtual machine, wherein the unmap request is associated with an attempt of the physical device to discontinue access to the guest memory page, wherein to determine that the unmap request has been issued, the hypervisor instructions, when executed, cause the computing system to determine that a bit corresponding to a guest page frame number in the DMA bitmap is not set, and wherein the guest page frame number is associated with the guest memory page, and
• unpin the guest memory page.

At least one non-transitory computer readable storage medium comprising a set of hypervisor instructions which, when executed by a computing system, cause the computing system to:

• determine that a guest memory page is pinned in a virtualized execution environment;
• determine, based on a direct memory access (DMA) bitmap, that an unmap request from a guest driver of a physical device has been issued, wherein the physical device is to be passed through to and directly controlled by a virtual machine, wherein the unmap request is associated with an attempt of the physical device to discontinue access to the guest memory page, wherein to determine that the unmap request has been issued, the hypervisor instructions, when executed, cause the computing system to determine that a bit corresponding to a guest page frame number in the DMA bitmap is not set, and wherein the guest page frame number is associated with the guest memory page;
• and
• unpin the guest memory page.