diff options
Diffstat (limited to 'drivers/lguest/x86/core.c')
-rw-r--r-- | drivers/lguest/x86/core.c | 62 |
1 files changed, 61 insertions, 1 deletions
diff --git a/drivers/lguest/x86/core.c b/drivers/lguest/x86/core.c index 0cc251c..2ef64a2 100644 --- a/drivers/lguest/x86/core.c +++ b/drivers/lguest/x86/core.c @@ -323,7 +323,9 @@ void lguest_arch_handle_trap(struct lguest *lg) cond_resched(); return; case LGUEST_TRAP_ENTRY: - lg->hcall = lg->regs; + /* Our 'struct hcall_args' maps directly over our regs: we set + * up the pointer now to indicate a hypercall is pending. */ + lg->hcall = (struct hcall_args *)lg->regs; return; } @@ -475,3 +477,61 @@ void __exit lguest_arch_host_fini(void) } unlock_cpu_hotplug(); } + + +/*H:122 The i386-specific hypercalls simply farm out to the right functions. */ +int lguest_arch_do_hcall(struct lguest *lg, struct hcall_args *args) +{ + switch (args->arg0) { + case LHCALL_LOAD_GDT: + load_guest_gdt(lg, args->arg1, args->arg2); + break; + case LHCALL_LOAD_IDT_ENTRY: + load_guest_idt_entry(lg, args->arg1, args->arg2, args->arg3); + break; + case LHCALL_LOAD_TLS: + guest_load_tls(lg, args->arg1); + break; + default: + /* Bad Guest. Bad! */ + return -EIO; + } + return 0; +} + +/*H:126 i386-specific hypercall initialization: */ +int lguest_arch_init_hypercalls(struct lguest *lg) +{ + u32 tsc_speed; + + /* The pointer to the Guest's "struct lguest_data" is the only + * argument. We check that address now. */ + if (!lguest_address_ok(lg, lg->hcall->arg1, sizeof(*lg->lguest_data))) + return -EFAULT; + + /* Having checked it, we simply set lg->lguest_data to point straight + * into the Launcher's memory at the right place and then use + * copy_to_user/from_user from now on, instead of lgread/write. I put + * this in to show that I'm not immune to writing stupid + * optimizations. */ + lg->lguest_data = lg->mem_base + lg->hcall->arg1; + + /* We insist that the Time Stamp Counter exist and doesn't change with + * cpu frequency. Some devious chip manufacturers decided that TSC + * changes could be handled in software. I decided that time going + * backwards might be good for benchmarks, but it's bad for users. + * + * We also insist that the TSC be stable: the kernel detects unreliable + * TSCs for its own purposes, and we use that here. */ + if (boot_cpu_has(X86_FEATURE_CONSTANT_TSC) && !check_tsc_unstable()) + tsc_speed = tsc_khz; + else + tsc_speed = 0; + if (put_user(tsc_speed, &lg->lguest_data->tsc_khz)) + return -EFAULT; + + return 0; +} +/* 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(). :*/ |