Messages in this thread | | | Date | Tue, 18 Jan 2022 13:08:31 +0100 | Subject | Re: [PATCH 0/5] kvm: fix latent guest entry/exit bugs | From | Christian Borntraeger <> |
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Am 18.01.22 um 13:02 schrieb Mark Rutland: > 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.
Yes, Paolos observation is correct. > > 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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