On 2020-12-02 12:03 a.m., David Woodhouse wrote:
On Tue, 2020-12-01 at 21:19 -0800, Ankur Arora wrote:
+ for (i = 0; i < PAGE_SIZE / sizeof(instructions); i++) {
+ *(u32 *)&instructions[1] = i;
+ if (kvm_vcpu_write_guest(vcpu,
+ page_addr + (i *
sizeof(instructions)),
+ instructions,
sizeof(instructions)))
+ return 1;
+ }
HYPERVISOR_iret isn't supported on 64bit so should be ud2 instead.
Yeah, I got part way through typing that part but concluded it probably
wasn't a fast path that absolutely needed to be emulated in the kernel.
The VMM can inject the UD# when it receives the hypercall.
That would work as well but if it's a straight ud2 on the hypercall
page, wouldn't the guest just execute it when/if it does a
HYPERVISOR_iret?
Ankur
I appreciate it *is* a guest-visible difference, if we're being really
pedantic, but I don't think we were even going to be able to 100% hide
the fact that it's not actually Xen.
