On 12.02.2014 11:40, Borislav Petkov wrote: > On Wed, Feb 12, 2014 at 11:37:13AM +0100, Peter Zijlstra wrote: >>> Another reporter also saw this on an AMD and said it could not be >>> reproduced on >>> the same hardware and the same software versions when using 64bit instead >>> of 32. >>> >>> In my case on a 32bit installation I will see this on every invocation of >> >> Curious.. so its both AMD and Intel. >> >> That makes funny hardware less likely... but how can the vmexit loose an >> interrupt like this. > > Also what I'm wondering about and what's not clear from Stefan's reply > is whether this is purely a 32-bit issue, i.e. a 32-bit host running a > 64-bit qemu running a 32-bit iso or what is it? > > Or do we have reports for both 32-bit and 64-bit hosts?
Only for 32bit hosts. I have not tested a 64bit kernel plus 32bit userspace, though. But 64bit kernel and 64bit user-space seemed ok. And one detail I should add is that while the reproduction is possible in all attempts, the timing can vary. In some of the cases this was even before running a Linux kernel in the guest. Something else here I run a kernel with CONFIG_PREEMPT not set and NR_CPUS limited to 8 (for the 32bit kernel). So the default apic driver is used. Since default_send_IPI_mask_logical is only used from there, I assume the trace you got does the same. Maybe something there is wrong which would explain why we only see it on 32bit hosts. > > Thanks. >
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