Messages in this thread | | | Date | Tue, 18 Jan 2022 12:02:06 +0000 | From | Mark Rutland <> | Subject | Re: [PATCH 0/5] kvm: fix latent guest entry/exit bugs |
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On Mon, Jan 17, 2022 at 06:45:36PM +0100, Paolo Bonzini wrote: > 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.
Ah; that's the crux of my confusion: I had thought the guest PSW would be placed in the regular lowcore *_old_psw slots. From looking at the entry asm it looks like the host PSW (around the invocation of SIE) is stored there, since that's what the OUTSIDE + SIEEXIT handling is checking for.
Assuming that's correct, I agree this problem doesn't exist, and there's only the common RCU/tracing/lockdep management to fix.
Sorry for the noise, and thanks for the pointer!
Thanks, Mark.
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