lguest: the host code

This is the code for the "lg.ko" module, which allows lguest guests to
be launched.

[akpm@linux-foundation.org: update for futex-new-private-futexes]
[akpm@linux-foundation.org: build fix]
[jmorris@namei.org: lguest: use hrtimers]
[akpm@linux-foundation.org: x86_64 build fix]
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Andi Kleen <ak@suse.de>
Cc: Eric Dumazet <dada1@cosmosbay.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 192 insertions, 0 deletions

diff --git a/drivers/lguest/hypercalls.c b/drivers/lguest/hypercalls.c
new file mode 100644
index 000000000000..ea52ca451f74
--- /dev/null
+++ b/drivers/lguest/hypercalls.c
@@ -0,0 +1,192 @@
+/*  Actual hypercalls, which allow guests to actually do something.
+    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 <asm/page.h>
+#include <asm/pgtable.h>
+#include <irq_vectors.h>
+#include "lg.h"
+
+static void do_hcall(struct lguest *lg, struct lguest_regs *regs)
+{
+        switch (regs->eax) {
+        case LHCALL_FLUSH_ASYNC:
+                break;
+        case LHCALL_LGUEST_INIT:
+                kill_guest(lg, "already have lguest_data");
+                break;
+        case LHCALL_CRASH: {
+                char msg[128];
+                lgread(lg, msg, regs->edx, sizeof(msg));
+                msg[sizeof(msg)-1] = '\0';
+                kill_guest(lg, "CRASH: %s", msg);
+                break;
+        }
+        case LHCALL_FLUSH_TLB:
+                if (regs->edx)
+                        guest_pagetable_clear_all(lg);
+                else
+                        guest_pagetable_flush_user(lg);
+                break;
+        case LHCALL_GET_WALLCLOCK: {
+                struct timespec ts;
+                ktime_get_real_ts(&ts);
+                regs->eax = ts.tv_sec;
+                break;
+        }
+        case LHCALL_BIND_DMA:
+                regs->eax = bind_dma(lg, regs->edx, regs->ebx,
+                                     regs->ecx >> 8, regs->ecx & 0xFF);
+                break;
+        case LHCALL_SEND_DMA:
+                send_dma(lg, regs->edx, regs->ebx);
+                break;
+        case LHCALL_LOAD_GDT:
+                load_guest_gdt(lg, regs->edx, regs->ebx);
+                break;
+        case LHCALL_LOAD_IDT_ENTRY:
+                load_guest_idt_entry(lg, regs->edx, regs->ebx, regs->ecx);
+                break;
+        case LHCALL_NEW_PGTABLE:
+                guest_new_pagetable(lg, regs->edx);
+                break;
+        case LHCALL_SET_STACK:
+                guest_set_stack(lg, regs->edx, regs->ebx, regs->ecx);
+                break;
+        case LHCALL_SET_PTE:
+                guest_set_pte(lg, regs->edx, regs->ebx, mkgpte(regs->ecx));
+                break;
+        case LHCALL_SET_PMD:
+                guest_set_pmd(lg, regs->edx, regs->ebx);
+                break;
+        case LHCALL_LOAD_TLS:
+                guest_load_tls(lg, regs->edx);
+                break;
+        case LHCALL_SET_CLOCKEVENT:
+                guest_set_clockevent(lg, regs->edx);
+                break;
+        case LHCALL_TS:
+                lg->ts = regs->edx;
+                break;
+        case LHCALL_HALT:
+                lg->halted = 1;
+                break;
+        default:
+                kill_guest(lg, "Bad hypercall %li\n", regs->eax);
+        }
+}
+
+/* We always do queued calls before actual hypercall. */
+static void do_async_hcalls(struct lguest *lg)
+{
+        unsigned int i;
+        u8 st[LHCALL_RING_SIZE];
+
+        if (copy_from_user(&st, &lg->lguest_data->hcall_status, sizeof(st)))
+                return;
+
+        for (i = 0; i < ARRAY_SIZE(st); i++) {
+                struct lguest_regs regs;
+                unsigned int n = lg->next_hcall;
+
+                if (st[n] == 0xFF)
+                        break;
+
+                if (++lg->next_hcall == LHCALL_RING_SIZE)
+                        lg->next_hcall = 0;
+
+                if (get_user(regs.eax, &lg->lguest_data->hcalls[n].eax)
+                    || get_user(regs.edx, &lg->lguest_data->hcalls[n].edx)
+                    || get_user(regs.ecx, &lg->lguest_data->hcalls[n].ecx)
+                    || get_user(regs.ebx, &lg->lguest_data->hcalls[n].ebx)) {
+                        kill_guest(lg, "Fetching async hypercalls");
+                        break;
+                }
+
+                do_hcall(lg, &regs);
+                if (put_user(0xFF, &lg->lguest_data->hcall_status[n])) {
+                        kill_guest(lg, "Writing result for async hypercall");
+                        break;
+                }
+
+                if (lg->dma_is_pending)
+                        break;
+        }
+}
+
+static void initialize(struct lguest *lg)
+{
+        u32 tsc_speed;
+
+        if (lg->regs->eax != LHCALL_LGUEST_INIT) {
+                kill_guest(lg, "hypercall %li before LGUEST_INIT",
+                           lg->regs->eax);
+                return;
+        }
+
+        /* We only tell the guest to use the TSC if it's reliable. */
+        if (boot_cpu_has(X86_FEATURE_CONSTANT_TSC) && !check_tsc_unstable())
+                tsc_speed = tsc_khz;
+        else
+                tsc_speed = 0;
+
+        lg->lguest_data = (struct lguest_data __user *)lg->regs->edx;
+        /* We check here so we can simply copy_to_user/from_user */
+        if (!lguest_address_ok(lg, lg->regs->edx, sizeof(*lg->lguest_data))) {
+                kill_guest(lg, "bad guest page %p", lg->lguest_data);
+                return;
+        }
+        if (get_user(lg->noirq_start, &lg->lguest_data->noirq_start)
+            || get_user(lg->noirq_end, &lg->lguest_data->noirq_end)
+            /* We reserve the top pgd entry. */
+            || put_user(4U*1024*1024, &lg->lguest_data->reserve_mem)
+            || put_user(tsc_speed, &lg->lguest_data->tsc_khz)
+            || put_user(lg->guestid, &lg->lguest_data->guestid))
+                kill_guest(lg, "bad guest page %p", lg->lguest_data);
+
+        /* 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 Guest might be referring to
+         * the old (read-only) page. */
+        guest_pagetable_clear_all(lg);
+}
+
+/* Even if we go out to userspace and come back, we don't want to do
+ * the hypercall again. */
+static void clear_hcall(struct lguest *lg)
+{
+        lg->regs->trapnum = 255;
+}
+
+void do_hypercalls(struct lguest *lg)
+{
+        if (unlikely(!lg->lguest_data)) {
+                if (lg->regs->trapnum == LGUEST_TRAP_ENTRY) {
+                        initialize(lg);
+                        clear_hcall(lg);
+                }
+                return;
+        }
+
+        do_async_hcalls(lg);
+        if (!lg->dma_is_pending && lg->regs->trapnum == LGUEST_TRAP_ENTRY) {
+                do_hcall(lg, lg->regs);
+                clear_hcall(lg);
+        }
+}