Messages in this thread | | | Date | 9 Feb 2007 14:57:39 +0100 | Date | Fri, 9 Feb 2007 14:57:39 +0100 | From | Andi Kleen <> | Subject | Re: [PATCH 6/10] lguest code: the little linux hypervisor. |
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On Fri, Feb 09, 2007 at 11:39:31PM +1100, Rusty Russell wrote: > On Fri, 2007-02-09 at 11:09 +0100, Andi Kleen wrote: > > > +# This links the hypervisor in the right place and turns it into a C array. > > > +$(obj)/hypervisor-raw: $(obj)/hypervisor.o > > > + @$(LD) -static -Tdata=`printf %#x $$(($(HYPE_ADDR)))` -Ttext=`printf %#x $$(($(HYPE_ADDR)+$(HYPE_DATA_SIZE)))` -o $@ $< && $(OBJCOPY) -O binary $@ > > > +$(obj)/hypervisor-blob.c: $(obj)/hypervisor-raw > > > + @od -tx1 -An -v $< | sed -e 's/^ /0x/' -e 's/$$/,/' -e 's/ /,0x/g' > $@ > > > > an .S file with .incbin is more efficient and simpler > > (note it has to be an separate .S file, otherwise icecream/distcc break) > > > > It won't allow to show off any sed skills, but I guess we can live with that ;-) > > Good idea, except I currently use sizeof(hypervisor_blob): I'd have to > extract the size separately and hand it in the CFLAGS 8(
hypervisor_start: .incbin "hypervisor" hypervisor_end:
... extern char hypervisor_start[], hypervisor_end[];
size = hypervisor_end - hypervisor_start;
> > > +static int cpu_had_pge; > > > +static struct { > > > + unsigned long offset; > > > + unsigned short segment; > > > +} lguest_entry; > > > +struct page *hype_pages; /* Contiguous pages. */ > > > > Statics? looks funky. Why only a single hypervisor_vma? > > We only have one switcher: it contains an array of "struct > lguest_state"; one for each guest. (This is host code we're looking at > here).
This means it is not SMP safe?
> No, the guest should not be able to evoke a printk from the host kernel.
This means nobody will know why it failed.
> > > + else if (i < FIRST_EXTERNAL_VECTOR || i == SYSCALL_VECTOR) > > > + setup_idt(lg, i, &d); > > > + /* A virtual interrupt */ > > > + else if (i < FIRST_EXTERNAL_VECTOR + LGUEST_IRQS) > > > + copy_trap(lg, &lg->interrupt[i-FIRST_EXTERNAL_VECTOR], &d);\ > > > > switch is not cool enough anymore? > > It would have to be a switch then gunk at the bottom, because those last > two tests don't switch-ify. IIRC I changed back from a switch because > of that.
gcc has a handy extension for this:
case 0...FIRST_EXTERNAL_VECTOR-1: case SYSCALL_VECTOR: case FIRST_EXTERNAL_VECTOR...FIRST_EXTERNAL_VECTOR+LGUEST_IRQS:
Re: the loops; e.g. we used to have possible loop cases when a page fault does read instructions and then causes another page fault etc.etc. I haven't seen any immediate danger of this, but it might be worth double checking.
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