Allow guest device MMIO access from bootmem memory segments.

Recent versions of UEFI have moved local APIC timer initialization into
the early SEC phase which runs out of ROM, prior to self-relocating
into RAM. This results in a hypervisor exit.

Currently bhyve prevents instruction emulation from segments that aren't
marked as "sysmem" aka guest RAM, with the vm_gpa_hold() routine failing.
However, there is no reason for this restriction: the hypervisor already
controls whether EPT mappings are marked as executable.

Fix by dropping the redundant check of sysmem.

MFC after:	3 weeks
Differential Revision:	https://reviews.freebsd.org/D25955

This commit is contained in:

Peter Grehan

2020-08-18 07:08:17 +00:00

parent 499019fdd9

commit 46567b4f5e

1 changed files with 1 additions and 2 deletions

									
										sys/amd64/vmm/vmm.c
									
		+1
		-2
	
												View File
												
				@@ -999,8 +999,7 @@ vm_gpa_hold(struct vm *vm, int vcpuid, vm_paddr_t gpa, size_t len, int reqprot,

					count = 0;

					for (i = 0; i < VM_MAX_MEMMAPS; i++) {

						mm = &vm->mem_maps[i];

						if (sysmem_mapping(vm, mm) && gpa >= mm->gpa &&

						    gpa < mm->gpa + mm->len) {

						if (gpa >= mm->gpa && gpa < mm->gpa + mm->len) {

							count = vm_fault_quick_hold_pages(&vm->vmspace->vm_map,

							    trunc_page(gpa), PAGE_SIZE, reqprot, &m, 1);

							break;