diff options
Diffstat (limited to 'drivers/lguest/x86')
| -rw-r--r-- | drivers/lguest/x86/core.c | 36 |
1 files changed, 36 insertions, 0 deletions
diff --git a/drivers/lguest/x86/core.c b/drivers/lguest/x86/core.c index 2ef64a2734d..84c09082f27 100644 --- a/drivers/lguest/x86/core.c +++ b/drivers/lguest/x86/core.c @@ -535,3 +535,39 @@ int lguest_arch_init_hypercalls(struct lguest *lg) /* Now we've examined the hypercall code; our Guest can make requests. There * is one other way we can do things for the Guest, as we see in * emulate_insn(). :*/ + +/*L:030 lguest_arch_setup_regs() + * + * Most of the Guest's registers are left alone: we used get_zeroed_page() to + * allocate the structure, so they will be 0. */ +void lguest_arch_setup_regs(struct lguest *lg, unsigned long start) +{ + struct lguest_regs *regs = lg->regs; + + /* There are four "segment" registers which the Guest needs to boot: + * The "code segment" register (cs) refers to the kernel code segment + * __KERNEL_CS, and the "data", "extra" and "stack" segment registers + * refer to the kernel data segment __KERNEL_DS. + * + * The privilege level is packed into the lower bits. The Guest runs + * at privilege level 1 (GUEST_PL).*/ + regs->ds = regs->es = regs->ss = __KERNEL_DS|GUEST_PL; + regs->cs = __KERNEL_CS|GUEST_PL; + + /* The "eflags" register contains miscellaneous flags. Bit 1 (0x002) + * is supposed to always be "1". Bit 9 (0x200) controls whether + * interrupts are enabled. We always leave interrupts enabled while + * running the Guest. */ + regs->eflags = 0x202; + + /* The "Extended Instruction Pointer" register says where the Guest is + * running. */ + regs->eip = start; + + /* %esi points to our boot information, at physical address 0, so don't + * touch it. */ + /* There are a couple of GDT entries the Guest expects when first + * booting. */ + + setup_guest_gdt(lg); +} |