On 23/04/2019 22:59, Mathieu Tarral wrote: >>> The funny thing is that it's always at the same instruction that it fails, >>> the 106th singlestep, >>> at 0x806d32dc: >>> [0x7c90e514]> s 0x806d32dc >>> [0x806d32dc]> pd 10 >>> 0x806d32dc 890d8000feff mov dword [0xfffe0080], ecx >> This is a read of the APIC TPR, which is very commonly an operation >> accelerated by hardware (because without it, virtualising windows XP is >> exceedingly slow). >> >> What is your CPU, and how exactly are you trying to singlestep. Is it >> with MTF, or using the trap flag inside the guest? > My CPU is an Intel i7-8750H. > I'm using the libvmi API, which is enabling the MTF flag to singlestep, if i > judge by the debug logs.
Ok - that is a CoffeeLake. I've had a quick play with a simple example (XTF test and xen-access) and MTF does appear to work fine with both TPR shadowing and full APIC virtualisation. I've tried on Haswell, KabyLake and CoffeeLake. Can you describe the exact VMI configuration you've got enabled - specifically which other intercepts are active? ~Andrew _______________________________________________ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel
