On 11/22/16 14:58, Evgeny Yakovlev wrote: > Wow, that is more than i expected :) > >> I wonder if you started to see this issue very recently. > Very recently, however we use a pretty old OVMF build, circa 2015
Ugh. Please update OVMF first... A whole lot of things has changed in edk2 in this year. > >> OVMF debug log > Sorry, we hadn't had it enabled when VM crashed and these crashes are very > rare. We will try to capture it when it happens again > >> - your host CPU model, > cpu family : 6 > model : 42 > model name : Intel(R) Core(TM) i7-2600 CPU @ 3.40GHz > stepping : 7 > >> - the host kernel (KVM) version, > Our kernel is roughly based on RHEL7.2 (kernel version 3.10.0-327.36.1). We > also have some upstream KVM patches backported. > >> - the guest CPU model, > -cpu > SandyBridge,+vme,+ds,+acpi,+ss,+ht,+tm,+pbe,+dtes64,+monitor,+ds_cpl,+smx,+est,+tm2,+xtpr,+pdcm,+pcid,+osxsave,-arat,-xsaveopt,-xgetbv1,-vmx,-xsavec,hv_time,hv_relaxed,hv_vapic,hv_spinlocks=0x1fff,hv_vpindex,hv_runtime,hv_synic,hv_stimer,hv_reset,hv_crash > >> - the guest CPU topology. > 8 sockets, 1 core per socket, 1 thread per core > > Hope that helps! The fact that you are using 8 VCPUs is definitely relevant. However, I don't think it would make sense to try to analyze any errors with an OVMF / edk2 tree this old. Please try to reproduce the issue with a fresh build from master. Thanks! Laszlo > 2016-11-22 16:41 GMT+03:00 Laszlo Ersek <[email protected]>: > >> Hello Evgeny, >> >> On 11/22/16 13:57, Evgeny Yakovlev wrote: >>> We are running windows UEFI-based VMs on QEMU/KVM with OvmfPkg. >>> >>> Very rarely we are experiencing a crash when VM tries to write to RO >> memory >>> very early during UEFI boot process. >>> >>> Crash happens when VM tries to execute this code in interrupt handler: >>> https://github.com/tianocore/edk2/blob/master/UefiCpuPkg/Library/ >> CpuExceptionHandlerLib/X64/ExceptionHandlerAsm.asm#L244-L246 >>> >>> >>> fxsave [rdi], where RDI = 0xffe60 >>> >>> Which is bad - it points to ISA BIOS F-segment area. >>> >>> This memory was mapped by qemu for read only access, which is reflected >> in >>> KVM EPT: >>> 00000000000e0000-00000000000fffff (prio 1, R-): isa-bios >>> >>> This is a very early IRQ0 interrupt, presumably during early >> initialization >>> phase (Sec or Pei). >>> >>> Looks like CommonInterruptHandler does not switch to a separate stack and >>> works on interrupted context's stack, which was fairly close to 1MB >>> boundary when IRQ0 fired (RSP around 1002c0). When CommonInterruptEntry >>> reached highlighted code it subtracted 512 bytes from current RSP which >>> dropped to 0xffe60, below 1MB and into QEMU RO region. >>> >>> We were figuring out how to best fix this. Possible solutions are to >> switch >>> to a separate stack in CommonInterruptEntry, relocate early OvmfPkg stack >>> to somewhere farther away from 1MB, to run with interrupts disabled until >>> we reach a later phase or maybe something else. >>> >>> Any comments would be very appreciated! >> >> I wonder if you started to see this issue very recently. >> >> I suspect (hope!) that the symptoms you are experiencing are a >> consequence of a bug in UefiCpuPkg that I've debugged and fixed just >> today. (I hope to post the patches today.) >> >> While testing those patches on your end will of course tell us if your >> issue has the same root cause, you could gather a few more symptoms even >> before I get around posting the patches. The bug that I'm working on has >> extremely varied crash symptoms (basically the APs wander off into the >> weeds), and some of those symptoms have involved CpuExceptionHandlerLib. >> The point is, by the time we get into CpuExceptionHandlerLib, all is >> lost -- it is executing on an AP whose state is corrupt anyway. The >> fxsave symptom is a red herring, most likely. >> >> CpuExceptionHandlerLib works fine otherwise, especially when invoked >> from the BSP -- we've used the output dumped by CpuExceptionHandlerLib >> to the serial port several times to track down issues. >> >> So, my request is that you please capture the OVMF debug log (please see >> the "OvmfPkg/README" file for how). I'm curious if it crashes where and >> how I suspect it crashes. >> >> Also, it would help if you provided >> - your host CPU model, >> - the host kernel (KVM) version, >> - the guest CPU model, >> - the guest CPU topology. >> >> Thanks! >> Laszlo >> > _______________________________________________ > edk2-devel mailing list > [email protected] > https://lists.01.org/mailman/listinfo/edk2-devel > _______________________________________________ edk2-devel mailing list [email protected] https://lists.01.org/mailman/listinfo/edk2-devel
