Messages in this thread | | | Date | Mon, 17 Jan 2022 18:45:36 +0100 | Subject | Re: [PATCH 0/5] kvm: fix latent guest entry/exit bugs | From | Paolo Bonzini <> |
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On 1/14/22 16:19, Mark Rutland wrote: > I also think there is another issue here. When an IRQ is taken from SIE, will > user_mode(regs) always be false, or could it be true if the guest userspace is > running? If it can be true I think tha context tracking checks can complain, > and it*might* be possible to trigger a panic().
I think that it would be false, because the guest PSW is in the SIE block and switched on SIE entry and exit, but I might be incorrect.
Paolo
> In irqentry_enter(), if user_mode(regs) == true, we call > irqentry_enter_from_user_mode -> __enter_from_user_mode(). There we check that > the context is CONTEXT_USER, but IIUC that will be CONTEXT_GUEST at this point. > We also call arch_check_user_regs(), and IIUC this might permit a malicious > guest to trigger a host panic by way of debug_user_asce(), but I may have > misunderstood and that might not be possible.
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