Messages in this thread | | | Date | Wed, 28 Jul 2010 14:18:22 +0200 | From | "Roedel, Joerg" <> | Subject | Re: [PATCH 2/2] KVM: SVM: Emulate next_rip svm feature |
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On Wed, Jul 28, 2010 at 07:57:36AM -0400, Avi Kivity wrote:
> If the instruction opcode is on mmio, the processor never sees the > opcode and thus can not intercept. Or the processor may see one > instruction, which is not intercepted, but by the time the emulator > kicks in a different instruction takes its place, since another vcpu is > evilly cross-modifying the code.
Right. X-modifying code is a problem too.
> The guest (L2 in this case) is doomed since it execution cannot > continue. But L1 and L0 are fine. The problem with L2 avoiding > intercepts is that L2 can change control registers and take over L1.
Right too. We can not ignore it. The right fix is probably a check for the instruction intercepts right after the decoder has run and before the emulator ran.
Joer
-- Joerg Roedel - AMD Operating System Research Center
Advanced Micro Devices GmbH Einsteinring 24 85609 Dornach General Managers: Alberto Bozzo, Andrew Bowd Registration: Dornach, Landkr. Muenchen; Registerger. Muenchen, HRB Nr. 43632
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