| /*P:500 Just as userspace programs request kernel operations through a system |
| * call, the Guest requests Host operations through a "hypercall". You might |
| * notice this nomenclature doesn't really follow any logic, but the name has |
| * been around for long enough that we're stuck with it. As you'd expect, this |
| * code is basically a one big switch statement. :*/ |
| |
| /* Copyright (C) 2006 Rusty Russell IBM Corporation |
| |
| This program is free software; you can redistribute it and/or modify |
| it under the terms of the GNU General Public License as published by |
| the Free Software Foundation; either version 2 of the License, or |
| (at your option) any later version. |
| |
| This program is distributed in the hope that it will be useful, |
| but WITHOUT ANY WARRANTY; without even the implied warranty of |
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
| GNU General Public License for more details. |
| |
| You should have received a copy of the GNU General Public License |
| along with this program; if not, write to the Free Software |
| Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA |
| */ |
| #include <linux/uaccess.h> |
| #include <linux/syscalls.h> |
| #include <linux/mm.h> |
| #include <linux/ktime.h> |
| #include <asm/page.h> |
| #include <asm/pgtable.h> |
| #include "lg.h" |
| |
| /*H:120 This is the core hypercall routine: where the Guest gets what it wants. |
| * Or gets killed. Or, in the case of LHCALL_SHUTDOWN, both. */ |
| static void do_hcall(struct lg_cpu *cpu, struct hcall_args *args) |
| { |
| switch (args->arg0) { |
| case LHCALL_FLUSH_ASYNC: |
| /* This call does nothing, except by breaking out of the Guest |
| * it makes us process all the asynchronous hypercalls. */ |
| break; |
| case LHCALL_SEND_INTERRUPTS: |
| /* This call does nothing too, but by breaking out of the Guest |
| * it makes us process any pending interrupts. */ |
| break; |
| case LHCALL_LGUEST_INIT: |
| /* You can't get here unless you're already initialized. Don't |
| * do that. */ |
| kill_guest(cpu, "already have lguest_data"); |
| break; |
| case LHCALL_SHUTDOWN: { |
| /* Shutdown is such a trivial hypercall that we do it in four |
| * lines right here. */ |
| char msg[128]; |
| /* If the lgread fails, it will call kill_guest() itself; the |
| * kill_guest() with the message will be ignored. */ |
| __lgread(cpu, msg, args->arg1, sizeof(msg)); |
| msg[sizeof(msg)-1] = '\0'; |
| kill_guest(cpu, "CRASH: %s", msg); |
| if (args->arg2 == LGUEST_SHUTDOWN_RESTART) |
| cpu->lg->dead = ERR_PTR(-ERESTART); |
| break; |
| } |
| case LHCALL_FLUSH_TLB: |
| /* FLUSH_TLB comes in two flavors, depending on the |
| * argument: */ |
| if (args->arg1) |
| guest_pagetable_clear_all(cpu); |
| else |
| guest_pagetable_flush_user(cpu); |
| break; |
| |
| /* All these calls simply pass the arguments through to the right |
| * routines. */ |
| case LHCALL_NEW_PGTABLE: |
| guest_new_pagetable(cpu, args->arg1); |
| break; |
| case LHCALL_SET_STACK: |
| guest_set_stack(cpu, args->arg1, args->arg2, args->arg3); |
| break; |
| case LHCALL_SET_PTE: |
| guest_set_pte(cpu, args->arg1, args->arg2, __pte(args->arg3)); |
| break; |
| case LHCALL_SET_PGD: |
| guest_set_pgd(cpu->lg, args->arg1, args->arg2); |
| break; |
| case LHCALL_SET_CLOCKEVENT: |
| guest_set_clockevent(cpu, args->arg1); |
| break; |
| case LHCALL_TS: |
| /* This sets the TS flag, as we saw used in run_guest(). */ |
| cpu->ts = args->arg1; |
| break; |
| case LHCALL_HALT: |
| /* Similarly, this sets the halted flag for run_guest(). */ |
| cpu->halted = 1; |
| break; |
| case LHCALL_NOTIFY: |
| cpu->pending_notify = args->arg1; |
| break; |
| default: |
| /* It should be an architecture-specific hypercall. */ |
| if (lguest_arch_do_hcall(cpu, args)) |
| kill_guest(cpu, "Bad hypercall %li\n", args->arg0); |
| } |
| } |
| /*:*/ |
| |
| /*H:124 Asynchronous hypercalls are easy: we just look in the array in the |
| * Guest's "struct lguest_data" to see if any new ones are marked "ready". |
| * |
| * We are careful to do these in order: obviously we respect the order the |
| * Guest put them in the ring, but we also promise the Guest that they will |
| * happen before any normal hypercall (which is why we check this before |
| * checking for a normal hcall). */ |
| static void do_async_hcalls(struct lg_cpu *cpu) |
| { |
| unsigned int i; |
| u8 st[LHCALL_RING_SIZE]; |
| |
| /* For simplicity, we copy the entire call status array in at once. */ |
| if (copy_from_user(&st, &cpu->lg->lguest_data->hcall_status, sizeof(st))) |
| return; |
| |
| /* We process "struct lguest_data"s hcalls[] ring once. */ |
| for (i = 0; i < ARRAY_SIZE(st); i++) { |
| struct hcall_args args; |
| /* We remember where we were up to from last time. This makes |
| * sure that the hypercalls are done in the order the Guest |
| * places them in the ring. */ |
| unsigned int n = cpu->next_hcall; |
| |
| /* 0xFF means there's no call here (yet). */ |
| if (st[n] == 0xFF) |
| break; |
| |
| /* OK, we have hypercall. Increment the "next_hcall" cursor, |
| * and wrap back to 0 if we reach the end. */ |
| if (++cpu->next_hcall == LHCALL_RING_SIZE) |
| cpu->next_hcall = 0; |
| |
| /* Copy the hypercall arguments into a local copy of |
| * the hcall_args struct. */ |
| if (copy_from_user(&args, &cpu->lg->lguest_data->hcalls[n], |
| sizeof(struct hcall_args))) { |
| kill_guest(cpu, "Fetching async hypercalls"); |
| break; |
| } |
| |
| /* Do the hypercall, same as a normal one. */ |
| do_hcall(cpu, &args); |
| |
| /* Mark the hypercall done. */ |
| if (put_user(0xFF, &cpu->lg->lguest_data->hcall_status[n])) { |
| kill_guest(cpu, "Writing result for async hypercall"); |
| break; |
| } |
| |
| /* Stop doing hypercalls if they want to notify the Launcher: |
| * it needs to service this first. */ |
| if (cpu->pending_notify) |
| break; |
| } |
| } |
| |
| /* Last of all, we look at what happens first of all. The very first time the |
| * Guest makes a hypercall, we end up here to set things up: */ |
| static void initialize(struct lg_cpu *cpu) |
| { |
| /* You can't do anything until you're initialized. The Guest knows the |
| * rules, so we're unforgiving here. */ |
| if (cpu->hcall->arg0 != LHCALL_LGUEST_INIT) { |
| kill_guest(cpu, "hypercall %li before INIT", cpu->hcall->arg0); |
| return; |
| } |
| |
| if (lguest_arch_init_hypercalls(cpu)) |
| kill_guest(cpu, "bad guest page %p", cpu->lg->lguest_data); |
| |
| /* The Guest tells us where we're not to deliver interrupts by putting |
| * the range of addresses into "struct lguest_data". */ |
| if (get_user(cpu->lg->noirq_start, &cpu->lg->lguest_data->noirq_start) |
| || get_user(cpu->lg->noirq_end, &cpu->lg->lguest_data->noirq_end)) |
| kill_guest(cpu, "bad guest page %p", cpu->lg->lguest_data); |
| |
| /* We write the current time into the Guest's data page once so it can |
| * set its clock. */ |
| write_timestamp(cpu); |
| |
| /* page_tables.c will also do some setup. */ |
| page_table_guest_data_init(cpu); |
| |
| /* This is the one case where the above accesses might have been the |
| * first write to a Guest page. This may have caused a copy-on-write |
| * fault, but the old page might be (read-only) in the Guest |
| * pagetable. */ |
| guest_pagetable_clear_all(cpu); |
| } |
| /*:*/ |
| |
| /*M:013 If a Guest reads from a page (so creates a mapping) that it has never |
| * written to, and then the Launcher writes to it (ie. the output of a virtual |
| * device), the Guest will still see the old page. In practice, this never |
| * happens: why would the Guest read a page which it has never written to? But |
| * a similar scenario might one day bite us, so it's worth mentioning. :*/ |
| |
| /*H:100 |
| * Hypercalls |
| * |
| * Remember from the Guest, hypercalls come in two flavors: normal and |
| * asynchronous. This file handles both of types. |
| */ |
| void do_hypercalls(struct lg_cpu *cpu) |
| { |
| /* Not initialized yet? This hypercall must do it. */ |
| if (unlikely(!cpu->lg->lguest_data)) { |
| /* Set up the "struct lguest_data" */ |
| initialize(cpu); |
| /* Hcall is done. */ |
| cpu->hcall = NULL; |
| return; |
| } |
| |
| /* The Guest has initialized. |
| * |
| * Look in the hypercall ring for the async hypercalls: */ |
| do_async_hcalls(cpu); |
| |
| /* If we stopped reading the hypercall ring because the Guest did a |
| * NOTIFY to the Launcher, we want to return now. Otherwise we do |
| * the hypercall. */ |
| if (!cpu->pending_notify) { |
| do_hcall(cpu, cpu->hcall); |
| /* Tricky point: we reset the hcall pointer to mark the |
| * hypercall as "done". We use the hcall pointer rather than |
| * the trap number to indicate a hypercall is pending. |
| * Normally it doesn't matter: the Guest will run again and |
| * update the trap number before we come back here. |
| * |
| * However, if we are signalled or the Guest sends I/O to the |
| * Launcher, the run_guest() loop will exit without running the |
| * Guest. When it comes back it would try to re-run the |
| * hypercall. Finding that bug sucked. */ |
| cpu->hcall = NULL; |
| } |
| } |
| |
| /* This routine supplies the Guest with time: it's used for wallclock time at |
| * initial boot and as a rough time source if the TSC isn't available. */ |
| void write_timestamp(struct lg_cpu *cpu) |
| { |
| struct timespec now; |
| ktime_get_real_ts(&now); |
| if (copy_to_user(&cpu->lg->lguest_data->time, |
| &now, sizeof(struct timespec))) |
| kill_guest(cpu, "Writing timestamp"); |
| } |