On 01/02/19 00:28, Alexandro Sanchez Bach wrote:
(CC'd Yu Ning @ Intel's HAXM team)
Not sure, if I'm understanding the issue correctly, but isn't `HAX_VM_IOCTL_SET_RAM2` with the `HAX_RAM_INFO_ROM` flag precisely what you are looking for?
More precisely, HAX_VM_IOCTL_SET_RAM2 maps an HVA range to a GPA range, the HAX_RAM_INFO_ROM flag should allow only guest memory reads to that range [1]. When the guest attempts to write, this should trigger a VM exit that will be handled by QEMU.
The missing handling is in the hypervisor: if (ret == -EACCES) { /* * For some reason, during boot-up, Chrome OS guests make hundreds of * attempts to write to GPAs close to 4GB, which are mapped into BIOS * (read-only) and thus result in EPT violations. * TODO: Handle this case properly. */ hax_warning("%s: Unexpected EPT violation cause. Skipping instruction" " (len=%u)\n", __func__, vcpu->vmx.exit_instr_length); advance_rip(vcpu); return HAX_EXIT; }
Also, this seems to be handled here: https://github.com/qemu/qemu/blob/15bede554162dda822cd762c689edb6fa32b6e3b/t...
Right, though to be precise it should be changed to if (memory_region_is_rom(section->mr) || memory_region_is_romd(section->mr)) { flags |= HAX_RAM_INFO_ROM; } for that to work. Paolo