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authorRusty Russell <rusty@rustcorp.com.au>2009-07-30 16:03:45 -0600
committerRusty Russell <rusty@rustcorp.com.au>2009-07-30 16:03:45 +0930
commit2e04ef76916d1e29a077ea9d0f2003c8fd86724d (patch)
tree2ff8d625d6e467be9f9f1b67a3674cb6e125e970 /drivers/lguest
parente969fed542cae08cb11d666efac4f7c5d624d09f (diff)
lguest: fix comment style
I don't really notice it (except to begrudge the extra vertical space), but Ingo does. And he pointed out that one excuse of lguest is as a teaching tool, it should set a good example. Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> Cc: Ingo Molnar <mingo@redhat.com>
Diffstat (limited to 'drivers/lguest')
-rw-r--r--drivers/lguest/core.c114
-rw-r--r--drivers/lguest/hypercalls.c141
-rw-r--r--drivers/lguest/interrupts_and_traps.c288
-rw-r--r--drivers/lguest/lg.h23
-rw-r--r--drivers/lguest/lguest_device.c150
-rw-r--r--drivers/lguest/lguest_user.c137
-rw-r--r--drivers/lguest/page_tables.c427
-rw-r--r--drivers/lguest/segments.c106
-rw-r--r--drivers/lguest/x86/core.c372
-rw-r--r--drivers/lguest/x86/switcher_32.S18
10 files changed, 1168 insertions, 608 deletions
diff --git a/drivers/lguest/core.c b/drivers/lguest/core.c
index a6974e9b8eb..cd058bc903f 100644
--- a/drivers/lguest/core.c
+++ b/drivers/lguest/core.c
@@ -1,6 +1,8 @@
-/*P:400 This contains run_guest() which actually calls into the Host<->Guest
+/*P:400
+ * This contains run_guest() which actually calls into the Host<->Guest
* Switcher and analyzes the return, such as determining if the Guest wants the
- * Host to do something. This file also contains useful helper routines. :*/
+ * Host to do something. This file also contains useful helper routines.
+:*/
#include <linux/module.h>
#include <linux/stringify.h>
#include <linux/stddef.h>
@@ -24,7 +26,8 @@ static struct page **switcher_page;
/* This One Big lock protects all inter-guest data structures. */
DEFINE_MUTEX(lguest_lock);
-/*H:010 We need to set up the Switcher at a high virtual address. Remember the
+/*H:010
+ * We need to set up the Switcher at a high virtual address. Remember the
* Switcher is a few hundred bytes of assembler code which actually changes the
* CPU to run the Guest, and then changes back to the Host when a trap or
* interrupt happens.
@@ -33,7 +36,8 @@ DEFINE_MUTEX(lguest_lock);
* Host since it will be running as the switchover occurs.
*
* Trying to map memory at a particular address is an unusual thing to do, so
- * it's not a simple one-liner. */
+ * it's not a simple one-liner.
+ */
static __init int map_switcher(void)
{
int i, err;
@@ -47,8 +51,10 @@ static __init int map_switcher(void)
* easy.
*/
- /* We allocate an array of struct page pointers. map_vm_area() wants
- * this, rather than just an array of pages. */
+ /*
+ * We allocate an array of struct page pointers. map_vm_area() wants
+ * this, rather than just an array of pages.
+ */
switcher_page = kmalloc(sizeof(switcher_page[0])*TOTAL_SWITCHER_PAGES,
GFP_KERNEL);
if (!switcher_page) {
@@ -56,8 +62,10 @@ static __init int map_switcher(void)
goto out;
}
- /* Now we actually allocate the pages. The Guest will see these pages,
- * so we make sure they're zeroed. */
+ /*
+ * Now we actually allocate the pages. The Guest will see these pages,
+ * so we make sure they're zeroed.
+ */
for (i = 0; i < TOTAL_SWITCHER_PAGES; i++) {
unsigned long addr = get_zeroed_page(GFP_KERNEL);
if (!addr) {
@@ -67,19 +75,23 @@ static __init int map_switcher(void)
switcher_page[i] = virt_to_page(addr);
}
- /* First we check that the Switcher won't overlap the fixmap area at
+ /*
+ * First we check that the Switcher won't overlap the fixmap area at
* the top of memory. It's currently nowhere near, but it could have
- * very strange effects if it ever happened. */
+ * very strange effects if it ever happened.
+ */
if (SWITCHER_ADDR + (TOTAL_SWITCHER_PAGES+1)*PAGE_SIZE > FIXADDR_START){
err = -ENOMEM;
printk("lguest: mapping switcher would thwack fixmap\n");
goto free_pages;
}
- /* Now we reserve the "virtual memory area" we want: 0xFFC00000
+ /*
+ * Now we reserve the "virtual memory area" we want: 0xFFC00000
* (SWITCHER_ADDR). We might not get it in theory, but in practice
* it's worked so far. The end address needs +1 because __get_vm_area
- * allocates an extra guard page, so we need space for that. */
+ * allocates an extra guard page, so we need space for that.
+ */
switcher_vma = __get_vm_area(TOTAL_SWITCHER_PAGES * PAGE_SIZE,
VM_ALLOC, SWITCHER_ADDR, SWITCHER_ADDR
+ (TOTAL_SWITCHER_PAGES+1) * PAGE_SIZE);
@@ -89,11 +101,13 @@ static __init int map_switcher(void)
goto free_pages;
}
- /* This code actually sets up the pages we've allocated to appear at
+ /*
+ * This code actually sets up the pages we've allocated to appear at
* SWITCHER_ADDR. map_vm_area() takes the vma we allocated above, the
* kind of pages we're mapping (kernel pages), and a pointer to our
* array of struct pages. It increments that pointer, but we don't
- * care. */
+ * care.
+ */
pagep = switcher_page;
err = map_vm_area(switcher_vma, PAGE_KERNEL_EXEC, &pagep);
if (err) {
@@ -101,8 +115,10 @@ static __init int map_switcher(void)
goto free_vma;
}
- /* Now the Switcher is mapped at the right address, we can't fail!
- * Copy in the compiled-in Switcher code (from <arch>_switcher.S). */
+ /*
+ * Now the Switcher is mapped at the right address, we can't fail!
+ * Copy in the compiled-in Switcher code (from <arch>_switcher.S).
+ */
memcpy(switcher_vma->addr, start_switcher_text,
end_switcher_text - start_switcher_text);
@@ -124,8 +140,7 @@ out:
}
/*:*/
-/* Cleaning up the mapping when the module is unloaded is almost...
- * too easy. */
+/* Cleaning up the mapping when the module is unloaded is almost... too easy. */
static void unmap_switcher(void)
{
unsigned int i;
@@ -151,16 +166,19 @@ static void unmap_switcher(void)
* But we can't trust the Guest: it might be trying to access the Launcher
* code. We have to check that the range is below the pfn_limit the Launcher
* gave us. We have to make sure that addr + len doesn't give us a false
- * positive by overflowing, too. */
+ * positive by overflowing, too.
+ */
bool lguest_address_ok(const struct lguest *lg,
unsigned long addr, unsigned long len)
{
return (addr+len) / PAGE_SIZE < lg->pfn_limit && (addr+len >= addr);
}
-/* This routine copies memory from the Guest. Here we can see how useful the
+/*
+ * This routine copies memory from the Guest. Here we can see how useful the
* kill_lguest() routine we met in the Launcher can be: we return a random
- * value (all zeroes) instead of needing to return an error. */
+ * value (all zeroes) instead of needing to return an error.
+ */
void __lgread(struct lg_cpu *cpu, void *b, unsigned long addr, unsigned bytes)
{
if (!lguest_address_ok(cpu->lg, addr, bytes)
@@ -181,9 +199,11 @@ void __lgwrite(struct lg_cpu *cpu, unsigned long addr, const void *b,
}
/*:*/
-/*H:030 Let's jump straight to the the main loop which runs the Guest.
+/*H:030
+ * Let's jump straight to the the main loop which runs the Guest.
* Remember, this is called by the Launcher reading /dev/lguest, and we keep
- * going around and around until something interesting happens. */
+ * going around and around until something interesting happens.
+ */
int run_guest(struct lg_cpu *cpu, unsigned long __user *user)
{
/* We stop running once the Guest is dead. */
@@ -195,8 +215,10 @@ int run_guest(struct lg_cpu *cpu, unsigned long __user *user)
if (cpu->hcall)
do_hypercalls(cpu);
- /* It's possible the Guest did a NOTIFY hypercall to the
- * Launcher, in which case we return from the read() now. */
+ /*
+ * It's possible the Guest did a NOTIFY hypercall to the
+ * Launcher, in which case we return from the read() now.
+ */
if (cpu->pending_notify) {
if (!send_notify_to_eventfd(cpu)) {
if (put_user(cpu->pending_notify, user))
@@ -209,29 +231,39 @@ int run_guest(struct lg_cpu *cpu, unsigned long __user *user)
if (signal_pending(current))
return -ERESTARTSYS;
- /* Check if there are any interrupts which can be delivered now:
+ /*
+ * Check if there are any interrupts which can be delivered now:
* if so, this sets up the hander to be executed when we next
- * run the Guest. */
+ * run the Guest.
+ */
irq = interrupt_pending(cpu, &more);
if (irq < LGUEST_IRQS)
try_deliver_interrupt(cpu, irq, more);
- /* All long-lived kernel loops need to check with this horrible
+ /*
+ * All long-lived kernel loops need to check with this horrible
* thing called the freezer. If the Host is trying to suspend,
- * it stops us. */
+ * it stops us.
+ */
try_to_freeze();
- /* Just make absolutely sure the Guest is still alive. One of
- * those hypercalls could have been fatal, for example. */
+ /*
+ * Just make absolutely sure the Guest is still alive. One of
+ * those hypercalls could have been fatal, for example.
+ */
if (cpu->lg->dead)
break;
- /* If the Guest asked to be stopped, we sleep. The Guest's
- * clock timer will wake us. */
+ /*
+ * If the Guest asked to be stopped, we sleep. The Guest's
+ * clock timer will wake us.
+ */
if (cpu->halted) {
set_current_state(TASK_INTERRUPTIBLE);
- /* Just before we sleep, make sure no interrupt snuck in
- * which we should be doing. */
+ /*
+ * Just before we sleep, make sure no interrupt snuck in
+ * which we should be doing.
+ */
if (interrupt_pending(cpu, &more) < LGUEST_IRQS)
set_current_state(TASK_RUNNING);
else
@@ -239,8 +271,10 @@ int run_guest(struct lg_cpu *cpu, unsigned long __user *user)
continue;
}
- /* OK, now we're ready to jump into the Guest. First we put up
- * the "Do Not Disturb" sign: */
+ /*
+ * OK, now we're ready to jump into the Guest. First we put up
+ * the "Do Not Disturb" sign:
+ */
local_irq_disable();
/* Actually run the Guest until something happens. */
@@ -327,8 +361,10 @@ static void __exit fini(void)
}
/*:*/
-/* The Host side of lguest can be a module. This is a nice way for people to
- * play with it. */
+/*
+ * The Host side of lguest can be a module. This is a nice way for people to
+ * play with it.
+ */
module_init(init);
module_exit(fini);
MODULE_LICENSE("GPL");
diff --git a/drivers/lguest/hypercalls.c b/drivers/lguest/hypercalls.c
index c29ffa19cb7..787ab4bc09f 100644
--- a/drivers/lguest/hypercalls.c
+++ b/drivers/lguest/hypercalls.c
@@ -1,8 +1,10 @@
-/*P:500 Just as userspace programs request kernel operations through a system
+/*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. :*/
+ * code is basically a one big switch statement.
+:*/
/* Copyright (C) 2006 Rusty Russell IBM Corporation
@@ -28,30 +30,41 @@
#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. */
+/*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. */
+ /*
+ * 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. */
+ /*
+ * 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. */
+ /*
+ * 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. */
+ /*
+ * Shutdown is such a trivial hypercall that we do it in four
+ * lines right here.
+ *
+ * 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);
@@ -60,16 +73,17 @@ static void do_hcall(struct lg_cpu *cpu, struct hcall_args *args)
break;
}
case LHCALL_FLUSH_TLB:
- /* FLUSH_TLB comes in two flavors, depending on the
- * argument: */
+ /* 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. */
+ /*
+ * All these calls simply pass the arguments through to the right
+ * routines.
+ */
case LHCALL_NEW_PGTABLE:
guest_new_pagetable(cpu, args->arg1);
break;
@@ -112,15 +126,16 @@ static void do_hcall(struct lg_cpu *cpu, struct hcall_args *args)
kill_guest(cpu, "Bad hypercall %li\n", args->arg0);
}
}
-/*:*/
-/*H:124 Asynchronous hypercalls are easy: we just look in the array in the
+/*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). */
+ * checking for a normal hcall).
+ */
static void do_async_hcalls(struct lg_cpu *cpu)
{
unsigned int i;
@@ -133,22 +148,28 @@ static void do_async_hcalls(struct lg_cpu *cpu)
/* 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
+ /*
+ * 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. */
+ * 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. */
+ /*
+ * 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. */
+ /*
+ * 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");
@@ -164,19 +185,25 @@ static void do_async_hcalls(struct lg_cpu *cpu)
break;
}
- /* Stop doing hypercalls if they want to notify the Launcher:
- * it needs to service this first. */
+ /*
+ * 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: */
+/*
+ * 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. */
+ /*
+ * 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;
@@ -185,32 +212,40 @@ static void initialize(struct lg_cpu *cpu)
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". */
+ /*
+ * 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. */
+ /*
+ * 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
+ /*
+ * 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. */
+ * pagetable.
+ */
guest_pagetable_clear_all(cpu);
}
/*:*/
-/*M:013 If a Guest reads from a page (so creates a mapping) that it has never
+/*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. :*/
+ * a similar scenario might one day bite us, so it's worth mentioning.
+:*/
/*H:100
* Hypercalls
@@ -229,17 +264,22 @@ void do_hypercalls(struct lg_cpu *cpu)
return;
}
- /* The Guest has initialized.
+ /*
+ * The Guest has initialized.
*
- * Look in the hypercall ring for the async hypercalls: */
+ * 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
+ /*
+ * 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. */
+ * the hypercall.
+ */
if (!cpu->pending_notify) {
do_hcall(cpu, cpu->hcall);
- /* Tricky point: we reset the hcall pointer to mark the
+ /*
+ * 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
@@ -248,13 +288,16 @@ void do_hypercalls(struct lg_cpu *cpu)
* 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. */
+ * 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. */
+/*
+ * 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;
diff --git a/drivers/lguest/interrupts_and_traps.c b/drivers/lguest/interrupts_and_traps.c
index 0e9067b0d50..18648180db0 100644
--- a/drivers/lguest/interrupts_and_traps.c
+++ b/drivers/lguest/interrupts_and_traps.c
@@ -1,4 +1,5 @@
-/*P:800 Interrupts (traps) are complicated enough to earn their own file.
+/*P:800
+ * Interrupts (traps) are complicated enough to earn their own file.
* There are three classes of interrupts:
*
* 1) Real hardware interrupts which occur while we're running the Guest,
@@ -10,7 +11,8 @@
* just like real hardware would deliver them. Traps from the Guest can be set
* up to go directly back into the Guest, but sometimes the Host wants to see
* them first, so we also have a way of "reflecting" them into the Guest as if
- * they had been delivered to it directly. :*/
+ * they had been delivered to it directly.
+:*/
#include <linux/uaccess.h>
#include <linux/interrupt.h>
#include <linux/module.h>
@@ -26,8 +28,10 @@ static unsigned long idt_address(u32 lo, u32 hi)
return (lo & 0x0000FFFF) | (hi & 0xFFFF0000);
}
-/* The "type" of the interrupt handler is a 4 bit field: we only support a
- * couple of types. */
+/*
+ * The "type" of the interrupt handler is a 4 bit field: we only support a
+ * couple of types.
+ */
static int idt_type(u32 lo, u32 hi)
{
return (hi >> 8) & 0xF;
@@ -39,8 +43,10 @@ static bool idt_present(u32 lo, u32 hi)
return (hi & 0x8000);
}
-/* We need a helper to "push" a value onto the Guest's stack, since that's a
- * big part of what delivering an interrupt does. */
+/*
+ * We need a helper to "push" a value onto the Guest's stack, since that's a
+ * big part of what delivering an interrupt does.
+ */
static void push_guest_stack(struct lg_cpu *cpu, unsigned long *gstack, u32 val)
{
/* Stack grows upwards: move stack then write value. */
@@ -48,7 +54,8 @@ static void push_guest_stack(struct lg_cpu *cpu, unsigned long *gstack, u32 val)
lgwrite(cpu, *gstack, u32, val);
}
-/*H:210 The set_guest_interrupt() routine actually delivers the interrupt or
+/*H:210
+ * The set_guest_interrupt() routine actually delivers the interrupt or
* trap. The mechanics of delivering traps and interrupts to the Guest are the
* same, except some traps have an "error code" which gets pushed onto the
* stack as well: the caller tells us if this is one.
@@ -59,7 +66,8 @@ static void push_guest_stack(struct lg_cpu *cpu, unsigned long *gstack, u32 val)
*
* We set up the stack just like the CPU does for a real interrupt, so it's
* identical for the Guest (and the standard "iret" instruction will undo
- * it). */
+ * it).
+ */
static void set_guest_interrupt(struct lg_cpu *cpu, u32 lo, u32 hi,
bool has_err)
{
@@ -67,20 +75,26 @@ static void set_guest_interrupt(struct lg_cpu *cpu, u32 lo, u32 hi,
u32 eflags, ss, irq_enable;
unsigned long virtstack;
- /* There are two cases for interrupts: one where the Guest is already
+ /*
+ * There are two cases for interrupts: one where the Guest is already
* in the kernel, and a more complex one where the Guest is in
- * userspace. We check the privilege level to find out. */
+ * userspace. We check the privilege level to find out.
+ */
if ((cpu->regs->ss&0x3) != GUEST_PL) {
- /* The Guest told us their kernel stack with the SET_STACK
- * hypercall: both the virtual address and the segment */
+ /*
+ * The Guest told us their kernel stack with the SET_STACK
+ * hypercall: both the virtual address and the segment.
+ */
virtstack = cpu->esp1;
ss = cpu->ss1;
origstack = gstack = guest_pa(cpu, virtstack);
- /* We push the old stack segment and pointer onto the new
+ /*
+ * We push the old stack segment and pointer onto the new
* stack: when the Guest does an "iret" back from the interrupt
* handler the CPU will notice they're dropping privilege
- * levels and expect these here. */
+ * levels and expect these here.
+ */
push_guest_stack(cpu, &gstack, cpu->regs->ss);
push_guest_stack(cpu, &gstack, cpu->regs->esp);
} else {
@@ -91,18 +105,22 @@ static void set_guest_interrupt(struct lg_cpu *cpu, u32 lo, u32 hi,
origstack = gstack = guest_pa(cpu, virtstack);
}
- /* Remember that we never let the Guest actually disable interrupts, so
+ /*
+ * Remember that we never let the Guest actually disable interrupts, so
* the "Interrupt Flag" bit is always set. We copy that bit from the
* Guest's "irq_enabled" field into the eflags word: we saw the Guest
- * copy it back in "lguest_iret". */
+ * copy it back in "lguest_iret".
+ */
eflags = cpu->regs->eflags;
if (get_user(irq_enable, &cpu->lg->lguest_data->irq_enabled) == 0
&& !(irq_enable & X86_EFLAGS_IF))
eflags &= ~X86_EFLAGS_IF;
- /* An interrupt is expected to push three things on the stack: the old
+ /*
+ * An interrupt is expected to push three things on the stack: the old
* "eflags" word, the old code segment, and the old instruction
- * pointer. */
+ * pointer.
+ */
push_guest_stack(cpu, &gstack, eflags);
push_guest_stack(cpu, &gstack, cpu->regs->cs);
push_guest_stack(cpu, &gstack, cpu->regs->eip);
@@ -111,15 +129,19 @@ static void set_guest_interrupt(struct lg_cpu *cpu, u32 lo, u32 hi,
if (has_err)
push_guest_stack(cpu, &gstack, cpu->regs->errcode);
- /* Now we've pushed all the old state, we change the stack, the code
- * segment and the address to execute. */
+ /*
+ * Now we've pushed all the old state, we change the stack, the code
+ * segment and the address to execute.
+ */
cpu->regs->ss = ss;
cpu->regs->esp = virtstack + (gstack - origstack);
cpu->regs->cs = (__KERNEL_CS|GUEST_PL);
cpu->regs->eip = idt_address(lo, hi);
- /* There are two kinds of interrupt handlers: 0xE is an "interrupt
- * gate" which expects interrupts to be disabled on entry. */
+ /*
+ * There are two kinds of interrupt handlers: 0xE is an "interrupt
+ * gate" which expects interrupts to be disabled on entry.
+ */
if (idt_type(lo, hi) == 0xE)
if (put_user(0, &cpu->lg->lguest_data->irq_enabled))
kill_guest(cpu, "Disabling interrupts");
@@ -130,7 +152,8 @@ static void set_guest_interrupt(struct lg_cpu *cpu, u32 lo, u32 hi,
*
* interrupt_pending() returns the first pending interrupt which isn't blocked
* by the Guest. It is called before every entry to the Guest, and just before
- * we go to sleep when the Guest has halted itself. */
+ * we go to sleep when the Guest has halted itself.
+ */
unsigned int interrupt_pending(struct lg_cpu *cpu, bool *more)
{
unsigned int irq;
@@ -140,8 +163,10 @@ unsigned int interrupt_pending(struct lg_cpu *cpu, bool *more)
if (!cpu->lg->lguest_data)
return LGUEST_IRQS;
- /* Take our "irqs_pending" array and remove any interrupts the Guest
- * wants blocked: the result ends up in "blk". */
+ /*
+ * Take our "irqs_pending" array and remove any interrupts the Guest
+ * wants blocked: the result ends up in "blk".
+ */
if (copy_from_user(&blk, cpu->lg->lguest_data->blocked_interrupts,
sizeof(blk)))
return LGUEST_IRQS;
@@ -154,16 +179,20 @@ unsigned int interrupt_pending(struct lg_cpu *cpu, bool *more)
return irq;
}
-/* This actually diverts the Guest to running an interrupt handler, once an
- * interrupt has been identified by interrupt_pending(). */
+/*
+ * This actually diverts the Guest to running an interrupt handler, once an
+ * interrupt has been identified by interrupt_pending().
+ */
void try_deliver_interrupt(struct lg_cpu *cpu, unsigned int irq, bool more)
{
struct desc_struct *idt;
BUG_ON(irq >= LGUEST_IRQS);
- /* They may be in the middle of an iret, where they asked us never to
- * deliver interrupts. */
+ /*
+ * They may be in the middle of an iret, where they asked us never to
+ * deliver interrupts.
+ */
if (cpu->regs->eip >= cpu->lg->noirq_start &&
(cpu->regs->eip < cpu->lg->noirq_end))
return;
@@ -187,29 +216,37 @@ void try_deliver_interrupt(struct lg_cpu *cpu, unsigned int irq, bool more)
}
}
- /* Look at the IDT entry the Guest gave us for this interrupt. The
+ /*
+ * Look at the IDT entry the Guest gave us for this interrupt. The
* first 32 (FIRST_EXTERNAL_VECTOR) entries are for traps, so we skip
- * over them. */
+ * over them.
+ */
idt = &cpu->arch.idt[FIRST_EXTERNAL_VECTOR+irq];
/* If they don't have a handler (yet?), we just ignore it */
if (idt_present(idt->a, idt->b)) {
/* OK, mark it no longer pending and deliver it. */
clear_bit(irq, cpu->irqs_pending);
- /* set_guest_interrupt() takes the interrupt descriptor and a
+ /*
+ * set_guest_interrupt() takes the interrupt descriptor and a
* flag to say whether this interrupt pushes an error code onto
- * the stack as well: virtual interrupts never do. */
+ * the stack as well: virtual interrupts never do.
+ */
set_guest_interrupt(cpu, idt->a, idt->b, false);
}
- /* Every time we deliver an interrupt, we update the timestamp in the
+ /*
+ * Every time we deliver an interrupt, we update the timestamp in the
* Guest's lguest_data struct. It would be better for the Guest if we
* did this more often, but it can actually be quite slow: doing it
* here is a compromise which means at least it gets updated every
- * timer interrupt. */
+ * timer interrupt.
+ */
write_timestamp(cpu);
- /* If there are no other interrupts we want to deliver, clear
- * the pending flag. */
+ /*
+ * If there are no other interrupts we want to deliver, clear
+ * the pending flag.
+ */
if (!more)
put_user(0, &cpu->lg->lguest_data->irq_pending);
}
@@ -217,24 +254,29 @@ void try_deliver_interrupt(struct lg_cpu *cpu, unsigned int irq, bool more)
/* And this is the routine when we want to set an interrupt for the Guest. */
void set_interrupt(struct lg_cpu *cpu, unsigned int irq)
{
- /* Next time the Guest runs, the core code will see if it can deliver
- * this interrupt. */
+ /*
+ * Next time the Guest runs, the core code will see if it can deliver
+ * this interrupt.
+ */
set_bit(irq, cpu->irqs_pending);
- /* Make sure it sees it; it might be asleep (eg. halted), or
- * running the Guest right now, in which case kick_process()
- * will knock it out. */
+ /*
+ * Make sure it sees it; it might be asleep (eg. halted), or running
+ * the Guest right now, in which case kick_process() will knock it out.
+ */
if (!wake_up_process(cpu->tsk))
kick_process(cpu->tsk);
}
/*:*/
-/* Linux uses trap 128 for system calls. Plan9 uses 64, and Ron Minnich sent
+/*
+ * Linux uses trap 128 for system calls. Plan9 uses 64, and Ron Minnich sent
* me a patch, so we support that too. It'd be a big step for lguest if half
* the Plan 9 user base were to start using it.
*
* Actually now I think of it, it's possible that Ron *is* half the Plan 9
- * userbase. Oh well. */
+ * userbase. Oh well.
+ */
static bool could_be_syscall(unsigned int num)
{
/* Normal Linux SYSCALL_VECTOR or reserved vector? */
@@ -274,9 +316,11 @@ void free_interrupts(void)
clear_bit(syscall_vector, used_vectors);
}
-/*H:220 Now we've got the routines to deliver interrupts, delivering traps like
+/*H:220
+ * Now we've got the routines to deliver interrupts, delivering traps like
* page fault is easy. The only trick is that Intel decided that some traps
- * should have error codes: */
+ * should have error codes:
+ */
static bool has_err(unsigned int trap)
{
return (trap == 8 || (trap >= 10 && trap <= 14) || trap == 17);
@@ -285,13 +329,17 @@ static bool has_err(unsigned int trap)
/* deliver_trap() returns true if it could deliver the trap. */
bool deliver_trap(struct lg_cpu *cpu, unsigned int num)
{
- /* Trap numbers are always 8 bit, but we set an impossible trap number
- * for traps inside the Switcher, so check that here. */
+ /*
+ * Trap numbers are always 8 bit, but we set an impossible trap number
+ * for traps inside the Switcher, so check that here.
+ */
if (num >= ARRAY_SIZE(cpu->arch.idt))
return false;
- /* Early on the Guest hasn't set the IDT entries (or maybe it put a
- * bogus one in): if we fail here, the Guest will be killed. */
+ /*
+ * Early on the Guest hasn't set the IDT entries (or maybe it put a
+ * bogus one in): if we fail here, the Guest will be killed.
+ */
if (!idt_present(cpu->arch.idt[num].a, cpu->arch.idt[num].b))
return false;
set_guest_interrupt(cpu, cpu->arch.idt[num].a,
@@ -299,7 +347,8 @@ bool deliver_trap(struct lg_cpu *cpu, unsigned int num)
return true;
}
-/*H:250 Here's the hard part: returning to the Host every time a trap happens
+/*H:250
+ * Here's the hard part: returning to the Host every time a trap happens
* and then calling deliver_trap() and re-entering the Guest is slow.
* Particularly because Guest userspace system calls are traps (usually trap
* 128).
@@ -311,69 +360,87 @@ bool deliver_trap(struct lg_cpu *cpu, unsigned int num)
* the other hypervisors would beat it up at lunchtime.
*
* This routine indicates if a particular trap number could be delivered
- * directly. */
+ * directly.
+ */
static bool direct_trap(unsigned int num)
{
- /* Hardware interrupts don't go to the Guest at all (except system
- * call). */
+ /*
+ * Hardware interrupts don't go to the Guest at all (except system
+ * call).
+ */
if (num >= FIRST_EXTERNAL_VECTOR && !could_be_syscall(num))
return false;
- /* The Host needs to see page faults (for shadow paging and to save the
+ /*
+ * The Host needs to see page faults (for shadow paging and to save the
* fault address), general protection faults (in/out emulation) and
* device not available (TS handling), invalid opcode fault (kvm hcall),
- * and of course, the hypercall trap. */
+ * and of course, the hypercall trap.
+ */
return num != 14 && num != 13 && num != 7 &&
num != 6 && num != LGUEST_TRAP_ENTRY;
}
/*:*/
-/*M:005 The Guest has the ability to turn its interrupt gates into trap gates,
+/*M:005
+ * The Guest has the ability to turn its interrupt gates into trap gates,
* if it is careful. The Host will let trap gates can go directly to the
* Guest, but the Guest needs the interrupts atomically disabled for an
* interrupt gate. It can do this by pointing the trap gate at instructions
- * within noirq_start and noirq_end, where it can safely disable interrupts. */
+ * within noirq_start and noirq_end, where it can safely disable interrupts.
+ */
-/*M:006 The Guests do not use the sysenter (fast system call) instruction,
+/*M:006
+ * The Guests do not use the sysenter (fast system call) i