Date: Sat, 14 Dec 2013 09:15:45 +0100 From: =?ISO-8859-1?Q?Roger_Pau_Monn=E9?= <roger.pau@citrix.com> To: Neel Natu <neelnatu@gmail.com>, John Baldwin <jhb@freebsd.org> Cc: "freebsd-virtualization@freebsd.org" <virtualization@freebsd.org> Subject: Re: Panic starting a bhyve guest after resume Message-ID: <52AC13B1.8060402@citrix.com> In-Reply-To: <CAFgRE9HWMY_uBEawSSiXgGEiqNHV-gmWeeBoi3qe50YAt48_2w@mail.gmail.com> References: <201312121511.38608.jhb@freebsd.org> <CAFgRE9Ej9O7jMBcE0oqshd_-59aPskhN81FoCsDbaEjdcxhJAA@mail.gmail.com> <201312131709.20264.jhb@freebsd.org> <CAFgRE9HWMY_uBEawSSiXgGEiqNHV-gmWeeBoi3qe50YAt48_2w@mail.gmail.com>
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On 14/12/13 03:28, Neel Natu wrote: > Hi John, > > On Fri, Dec 13, 2013 at 2:09 PM, John Baldwin <jhb@freebsd.org> wrote: >> On Thursday, December 12, 2013 4:00:08 pm Neel Natu wrote: >>> Hi John, >>> >>> On Thu, Dec 12, 2013 at 12:11 PM, John Baldwin <jhb@freebsd.org> wrote: >>>> If I suspend and resume my laptop and then try to start a guest after the >>>> resume, I get an odd panic. It generates a privileged instruction fault (in >>>> kernel mode) for 'vmclear'. I've checked CR4 and it claims that VMXE is set. >>>> I dont have any other ideas off the top of my head on what I should be poking >>>> at? It looks like we read a bunch of MSRs in vmx_init(), but we don't write >>>> to them, and all vmx_enable() does on each CPU is set VMXE in CR4 from what I >>>> can tell. >>>> >>> >>> It also does a "vmxon" on each logical cpu which may also need to be >>> done after a resume. >> >> Ah, yes it does. That was sufficient both for starting a new guest after >> resume and even doing a suspend/resume while a guest was active (and the >> guest continued to run fine). I have a hacky patch for this. One, it >> includes both a suspend and resume hook for VMM, though for my testing I only >> needed a resume hook to invoke vmxon. Second, the name of vmx_resume2() >> is a total hack (because vmx_resume() was already taken. I think for now >> if I were to commit this, I'd just add the resme hook and maybe call the >> Intel method vmx_reset() or vmx_restore()? >> >> http://people.freebsd.org/~jhb/patches/bhyve_resume.patch >> > > There seems to be a race after the APs are restarted and before > 'vmm_resume_p()' where it would be problematic to execute a VMX > instruction. > > Perhaps we should enable VMX on each cpu before they return to the > interrupted code? Can you use the hook in cpususpend_handler? It's cpu_ops.cpu_resume, and gets called on each CPU before returning from the handler.
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