On Thu, May 30, 2013 at 7:34 PM, Paolo Bonzini <pbonzini@xxxxxxxxxx> wrote: > Il 30/05/2013 17:34, Paolo Bonzini ha scritto: >> Il 30/05/2013 16:35, Paolo Bonzini ha scritto: >>> The x86-64 extended low-byte registers were fetched correctly from reg, >>> but not from mod/rm. >>> >>> This fixes another bug in the boot of RHEL5.9 64-bit, but it is still >>> not enough. >> >> Well, it is enough but it takes 2 minutes to reach the point where >> hardware virtualization is used. It is doing a lot of stuff in >> emulation mode because FS and GS have leftovers from the A20 test: >> >> FS =0000 0000000000000000 0000ffff 00009300 DPL=0 DS16 [-WA] >> GS =ffff 00000000000ffff0 0000ffff 00009300 DPL=0 DS16 [-WA] >> >> 0x00000000000113be: in $0x92,%al >> 0x00000000000113c0: or $0x2,%al >> 0x00000000000113c2: out %al,$0x92 >> 0x00000000000113c4: xor %ax,%ax >> 0x00000000000113c6: mov %ax,%fs >> 0x00000000000113c8: dec %ax >> 0x00000000000113c9: mov %ax,%gs >> 0x00000000000113cb: inc %ax >> 0x00000000000113cc: mov %ax,%fs:0x200 >> 0x00000000000113d0: cmp %gs:0x210,%ax >> 0x00000000000113d5: je 0x113cb >> >> The DPL < RPL test fails. Any ideas? Should we introduce a new >> intermediate value for emulate_invalid_guest_state (0=none, 1=some, 2=full)? > > One idea could be to replace invalid descriptors with NULL ones. Then > you can intercept this in the #GP handler and trigger emulation for that > instruction only. Won't work, vmx won't let you enter in such a configuration. Maybe you can detect the exact code sequence (%eip, some instructions, register state) and clear %fs and %gs. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
