diff options
Diffstat (limited to 'drivers/lguest/x86')
| -rw-r--r-- | drivers/lguest/x86/core.c | 33 | ||||
| -rw-r--r-- | drivers/lguest/x86/switcher_32.S | 8 |
2 files changed, 25 insertions, 16 deletions
diff --git a/drivers/lguest/x86/core.c b/drivers/lguest/x86/core.c index 635187812d52..5126d5d9ea0e 100644 --- a/drivers/lguest/x86/core.c +++ b/drivers/lguest/x86/core.c @@ -17,6 +17,13 @@ * along with this program; if not, write to the Free Software * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. */ +/*P:450 This file contains the x86-specific lguest code. It used to be all + * mixed in with drivers/lguest/core.c but several foolhardy code slashers + * wrestled most of the dependencies out to here in preparation for porting + * lguest to other architectures (see what I mean by foolhardy?). + * + * This also contains a couple of non-obvious setup and teardown pieces which + * were implemented after days of debugging pain. :*/ #include <linux/kernel.h> #include <linux/start_kernel.h> #include <linux/string.h> @@ -157,6 +164,8 @@ static void run_guest_once(struct lg_cpu *cpu, struct lguest_pages *pages) * also simplify copy_in_guest_info(). Note that we'd still need to restore * things when we exit to Launcher userspace, but that's fairly easy. * + * We could also try using this hooks for PGE, but that might be too expensive. + * * The hooks were designed for KVM, but we can also put them to good use. :*/ /*H:040 This is the i386-specific code to setup and run the Guest. Interrupts @@ -182,7 +191,7 @@ void lguest_arch_run_guest(struct lg_cpu *cpu) * was doing. */ run_guest_once(cpu, lguest_pages(raw_smp_processor_id())); - /* Note that the "regs" pointer contains two extra entries which are + /* Note that the "regs" structure contains two extra entries which are * not really registers: a trap number which says what interrupt or * trap made the switcher code come back, and an error code which some * traps set. */ @@ -293,11 +302,10 @@ void lguest_arch_handle_trap(struct lg_cpu *cpu) break; case 14: /* We've intercepted a Page Fault. */ /* The Guest accessed a virtual address that wasn't mapped. - * This happens a lot: we don't actually set up most of the - * page tables for the Guest at all when we start: as it runs - * it asks for more and more, and we set them up as - * required. In this case, we don't even tell the Guest that - * the fault happened. + * This happens a lot: we don't actually set up most of the page + * tables for the Guest at all when we start: as it runs it asks + * for more and more, and we set them up as required. In this + * case, we don't even tell the Guest that the fault happened. * * The errcode tells whether this was a read or a write, and * whether kernel or userspace code. */ @@ -342,7 +350,7 @@ void lguest_arch_handle_trap(struct lg_cpu *cpu) if (!deliver_trap(cpu, cpu->regs->trapnum)) /* If the Guest doesn't have a handler (either it hasn't * registered any yet, or it's one of the faults we don't let - * it handle), it dies with a cryptic error message. */ + * it handle), it dies with this cryptic error message. */ kill_guest(cpu, "unhandled trap %li at %#lx (%#lx)", cpu->regs->trapnum, cpu->regs->eip, cpu->regs->trapnum == 14 ? cpu->arch.last_pagefault @@ -375,8 +383,8 @@ void __init lguest_arch_host_init(void) * The only exception is the interrupt handlers in switcher.S: their * addresses are placed in a table (default_idt_entries), so we need to * update the table with the new addresses. switcher_offset() is a - * convenience function which returns the distance between the builtin - * switcher code and the high-mapped copy we just made. */ + * convenience function which returns the distance between the + * compiled-in switcher code and the high-mapped copy we just made. */ for (i = 0; i < IDT_ENTRIES; i++) default_idt_entries[i] += switcher_offset(); @@ -416,7 +424,7 @@ void __init lguest_arch_host_init(void) state->guest_gdt_desc.address = (long)&state->guest_gdt; /* We know where we want the stack to be when the Guest enters - * the switcher: in pages->regs. The stack grows upwards, so + * the Switcher: in pages->regs. The stack grows upwards, so * we start it at the end of that structure. */ state->guest_tss.sp0 = (long)(&pages->regs + 1); /* And this is the GDT entry to use for the stack: we keep a @@ -513,8 +521,8 @@ int lguest_arch_init_hypercalls(struct lg_cpu *cpu) { u32 tsc_speed; - /* The pointer to the Guest's "struct lguest_data" is the only - * argument. We check that address now. */ + /* The pointer to the Guest's "struct lguest_data" is the only argument. + * We check that address now. */ if (!lguest_address_ok(cpu->lg, cpu->hcall->arg1, sizeof(*cpu->lg->lguest_data))) return -EFAULT; @@ -546,6 +554,7 @@ int lguest_arch_init_hypercalls(struct lg_cpu *cpu) return 0; } +/*:*/ /*L:030 lguest_arch_setup_regs() * diff --git a/drivers/lguest/x86/switcher_32.S b/drivers/lguest/x86/switcher_32.S index 0af8baaa0d4a..3fc15318a80f 100644 --- a/drivers/lguest/x86/switcher_32.S +++ b/drivers/lguest/x86/switcher_32.S @@ -1,6 +1,6 @@ -/*P:900 This is the Switcher: code which sits at 0xFFC00000 to do the low-level - * Guest<->Host switch. It is as simple as it can be made, but it's naturally - * very specific to x86. +/*P:900 This is the Switcher: code which sits at 0xFFC00000 astride both the + * Host and Guest to do the low-level Guest<->Host switch. It is as simple as + * it can be made, but it's naturally very specific to x86. * * You have now completed Preparation. If this has whet your appetite; if you * are feeling invigorated and refreshed then the next, more challenging stage @@ -189,7 +189,7 @@ ENTRY(switch_to_guest) // Interrupts are turned back on: we are Guest. iret -// We treat two paths to switch back to the Host +// We tread two paths to switch back to the Host // Yet both must save Guest state and restore Host // So we put the routine in a macro. #define SWITCH_TO_HOST \ |