On 2/5/21 12:21 AM, Paolo Bonzini wrote:
On 05/02/21 01:20, Krish Sadhukhan wrote:
I think you can use prepare_gif_clear to set RFLAGS.TF and the
exception handler can:
1) look for VMRUN at the interrupted EIP. If it is there store the
VMRUN address and set a flag.
2) on the next #DB (flag set), store the EIP and clear the flag
The finished callback then checks that the EIP was stored and that
the two EIPs are 3 bytes apart (the length of a VMRUN).
Thanks for the suggestion. It worked fine and I have sent out v2.
However, I couldn't use the two RIPs (VMRUN and post-VMRUN) to check
the result because the post-VMRUN RIP was more than the length of the
VMRUN instruction i.e., when #DB handler got executed following guest
exit, the RIP had moved forward a few instructions from VMRUN. So, I
have used the same mechanism I used in v1, to check the results.
Where did it move to? (And could it be a KVM bug?)
It moved to the next-to-next instruction and it turned out to be a KVM
(SVM) bug. I have added a fix to v3 that I have sent out.
Paolo
