slackcoder/qemu - QEMU is a generic and open source machine & userspace emulator and virtualizer

Age	Commit message (Collapse)	Author
2023-03-01	hw/xen: Support mapping grant frames	David Woodhouse
	Signed-off-by: David Woodhouse <dwmw@amazon.co.uk> Reviewed-by: Paul Durrant <paul@xen.org>
2023-03-01	i386/xen: manage and save/restore Xen guest long_mode setting	David Woodhouse
	Xen will "latch" the guest's 32-bit or 64-bit ("long mode") setting when the guest writes the MSR to fill in the hypercall page, or when the guest sets the event channel callback in HVM_PARAM_CALLBACK_IRQ. KVM handles the former and sets the kernel's long_mode flag accordingly. The latter will be handled in userspace. Keep them in sync by noticing when a hypercall is made in a mode that doesn't match qemu's idea of the guest mode, and resyncing from the kernel. Do that same sync right before serialization too, in case the guest has set the hypercall page but hasn't yet made a system call. Signed-off-by: David Woodhouse <dwmw@amazon.co.uk> Reviewed-by: Paul Durrant <paul@xen.org>
2023-03-01	hw/xen: Add xen_overlay device for emulating shared xenheap pages	David Woodhouse
	For the shared info page and for grant tables, Xen shares its own pages from the "Xen heap" to the guest. The guest requests that a given page from a certain address space (XENMAPSPACE_shared_info, etc.) be mapped to a given GPA using the XENMEM_add_to_physmap hypercall. To support that in qemu when emulating Xen, create a memory region (migratable) and allow it to be mapped as an overlay when requested. Xen theoretically allows the same page to be mapped multiple times into the guest, but that's hard to track and reinstate over migration, so we automatically unmap any previous mapping when creating a new one. This approach has been used in production with.... a non-trivial number of guests expecting true Xen, without any problems yet being noticed. This adds just the shared info page for now. The grant tables will be a larger region, and will need to be overlaid one page at a time. I think that means I need to create separate aliases for each page of the overall grant_frames region, so that they can be mapped individually. Signed-off-by: David Woodhouse <dwmw@amazon.co.uk> Reviewed-by: Paul Durrant <paul@xen.org>