Re: [PATCH 0/5] kvm: fix latent guest entry/exit bugs

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 





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.



[Index of Archives]     [KVM ARM]     [KVM ia64]     [KVM ppc]     [Virtualization Tools]     [Spice Development]     [Libvirt]     [Libvirt Users]     [Linux USB Devel]     [Linux Audio Users]     [Yosemite Questions]     [Linux Kernel]     [Linux SCSI]     [XFree86]

  Powered by Linux