Re: panic: mutex pmap not owned at ... efirt_machdep.c:255

On Wed, Aug 08, 2018 at 01:42:07AM +0300, Konstantin Belousov wrote:
| On Tue, Aug 07, 2018 at 02:49:10PM -0700, Doug Ambrisko wrote:
| > On Tue, Aug 07, 2018 at 08:29:49PM +0300, Konstantin Belousov wrote:
| > | On Tue, Aug 07, 2018 at 11:50:44AM -0500, Kyle Evans wrote:
| > | > On Tue, Aug 7, 2018 at 12:09 AM, Eitan Adler <eadler_at_freebsd.org> wrote:
| > | > > On Mon, 6 Aug 2018 at 11:27, Kyle Evans <kevans_at_freebsd.org> wrote:
| > | > >>
| > | > >> On Sun, Aug 5, 2018 at 5:43 AM, Konstantin Belousov <kostikbel_at_gmail.com> wrote:
| > | > >> > On Sat, Aug 04, 2018 at 09:46:39PM -0500, Kyle Evans wrote:
| > | > >> >>
| > | > >> >> He now gets a little further, but ends up with the same panic due to
| > | > >> >> efirtc_probe trying to get time to verify the rtc's actually
| > | > >> >> implemented. What kind of approach must we take to ensure curcpu is
| > | > >> >> synced?
| > | > >> >
| > | > >> > It does not panic for me, when I load efirt.ko from the loader prompt.
| > | > >> > Anyway, try this
| > | > >>
| > | > >> Right, I also don't get a panic on any of my machines from this.
| > | > >> Hopefully he'll have a chance to try this soon.
| > | > >
| > | > > This change has no impact: it still panics in the same way as without the patch.
| > | > >
| > | > 
| > | > That seems indicative of a bigger problem, since we use proc0
| > | > throughout all these bits so we should still be dealing with the same
| > | > pmap that got passed to pmap_pinit0 when we grab
| > | > curthread->td_proc->p_vmspace->vm_pmap.
| > | 
| > | Can you confirm that you get the early efi_enter() call from rtc code,
| > | when you preload the module or compile it into the kernel ?
| > 
| > When I ran into this, I did this change:
| > 
| > Index: dev/efidev/efirt.c
| > ===================================================================
| > --- dev/efidev/efirt.c	(revision 337264)
| > +++ dev/efidev/efirt.c	(working copy)
| > _at__at_ -257,7 +257,8 _at__at_
| >  	if (efi_runtime == NULL)
| >  		return (ENXIO);
| >  	td = curthread;
| > -	curpmap = &td->td_proc->p_vmspace->vm_pmap;
| > +//	curpmap = &td->td_proc->p_vmspace->vm_pmap;
| > +	curpmap = PCPU_GET(curpmap);
| >  	PMAP_LOCK(curpmap);
| >  	mtx_lock(&efi_lock);
| >  	fpu_kern_enter(td, NULL, FPU_KERN_NOCTX);
| > _at__at_ -272,7 +273,8 _at__at_
| >  
| >  	efi_arch_leave();
| >  
| > -	curpmap = &curproc->p_vmspace->vm_pmap;
| > +//	curpmap = &curproc->p_vmspace->vm_pmap;
| > +	curpmap = PCPU_GET(curpmap);
| >  	td = curthread;
| >  	fpu_kern_leave(td, NULL);
| >  	mtx_unlock(&efi_lock);
| > 
| > Don't know if it is right.  Some previous code used both
| > 	curpmap = PCPU_GET(curpmap);
| > and
| > 	curpmap = &td->td_proc->p_vmspace->vm_pmap;
| > recently it was changes to only use
| > 	curpmap = &td->td_proc->p_vmspace->vm_pmap;
| > 
| > Things seem to work after that.  I was able to repro. it with 
| > qemu-system-x86_64 in UEFI mode.  I think it also failed in
| > bhyve UEFI mode.
| 
| The pcpu curpmap and curproc vmspace pmap should be synced.  Esp. since
| there is code relying on this early.  I do not want to paper it over.
| 
| In fact, try this please.  Ignore my previous change.
| 
| diff --git a/sys/amd64/amd64/pmap.c b/sys/amd64/amd64/pmap.c
| index 572b2197453..4bce36cc0e5 100644
| --- a/sys/amd64/amd64/pmap.c
| +++ b/sys/amd64/amd64/pmap.c
| _at__at_ -7536,7 +7536,8 _at__at_ pmap_activate_sw(struct thread *td)
|  			PCPU_SET(kcr3, pmap->pm_cr3);
|  			PCPU_SET(ucr3, pmap->pm_ucr3);
|  		}
| -	}
| +	} else
| +		PCPU_SET(curpmap, pmap);
|  	if (pmap->pm_ucr3 != PMAP_NO_CR3) {
|  		rsp0 = ((vm_offset_t)PCPU_PTR(pti_stack) +
|  		    PC_PTI_STACK_SZ * sizeof(uint64_t)) & ~0xful;

That works for qemu and bhyve booting in UEFI PXE mode.  I backed
out my other change and synced to head.

Thanks,

Doug A.