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Date: Fri, 6 Feb 2015 15:51:46 +1030
From: Rusty Russell <rusty@...tcorp.com.au>
To: "lkml" <linux-kernel@...r.kernel.org>
Cc: Rusty Russell <rusty@...tcorp.com.au>
Subject: [PATCH 03/29] lguest: write more information to userspace about pending traps.
This is preparation for userspace handling MMIO and ioport accesses.
Signed-off-by: Rusty Russell <rusty@...tcorp.com.au>
---
drivers/lguest/core.c | 7 ++++---
drivers/lguest/hypercalls.c | 7 ++++---
drivers/lguest/lg.h | 3 ++-
drivers/lguest/lguest_user.c | 14 +++++++++-----
include/linux/lguest_launcher.h | 13 +++++++++++++
tools/lguest/lguest.c | 16 ++++++++++------
6 files changed, 42 insertions(+), 18 deletions(-)
diff --git a/drivers/lguest/core.c b/drivers/lguest/core.c
index cdb2f9aa5860..9159dbc583f6 100644
--- a/drivers/lguest/core.c
+++ b/drivers/lguest/core.c
@@ -229,16 +229,17 @@ int run_guest(struct lg_cpu *cpu, unsigned long __user *user)
* It's possible the Guest did a NOTIFY hypercall to the
* Launcher.
*/
- if (cpu->pending_notify) {
+ if (cpu->pending.trap) {
/*
* Does it just needs to write to a registered
* eventfd (ie. the appropriate virtqueue thread)?
*/
if (!send_notify_to_eventfd(cpu)) {
/* OK, we tell the main Launcher. */
- if (put_user(cpu->pending_notify, user))
+ if (copy_to_user(user, &cpu->pending,
+ sizeof(cpu->pending)))
return -EFAULT;
- return sizeof(cpu->pending_notify);
+ return sizeof(cpu->pending);
}
}
diff --git a/drivers/lguest/hypercalls.c b/drivers/lguest/hypercalls.c
index 83511eb0923d..5dd1fb8a6610 100644
--- a/drivers/lguest/hypercalls.c
+++ b/drivers/lguest/hypercalls.c
@@ -118,7 +118,8 @@ static void do_hcall(struct lg_cpu *cpu, struct hcall_args *args)
cpu->halted = 1;
break;
case LHCALL_NOTIFY:
- cpu->pending_notify = args->arg1;
+ cpu->pending.trap = LGUEST_TRAP_ENTRY;
+ cpu->pending.addr = args->arg1;
break;
default:
/* It should be an architecture-specific hypercall. */
@@ -189,7 +190,7 @@ static void do_async_hcalls(struct lg_cpu *cpu)
* Stop doing hypercalls if they want to notify the Launcher:
* it needs to service this first.
*/
- if (cpu->pending_notify)
+ if (cpu->pending.trap)
break;
}
}
@@ -280,7 +281,7 @@ void do_hypercalls(struct lg_cpu *cpu)
* NOTIFY to the Launcher, we want to return now. Otherwise we do
* the hypercall.
*/
- if (!cpu->pending_notify) {
+ if (!cpu->pending.trap) {
do_hcall(cpu, cpu->hcall);
/*
* Tricky point: we reset the hcall pointer to mark the
diff --git a/drivers/lguest/lg.h b/drivers/lguest/lg.h
index 1c98bf74fd68..020fec5bb072 100644
--- a/drivers/lguest/lg.h
+++ b/drivers/lguest/lg.h
@@ -50,7 +50,8 @@ struct lg_cpu {
/* Bitmap of what has changed: see CHANGED_* above. */
int changed;
- unsigned long pending_notify; /* pfn from LHCALL_NOTIFY */
+ /* Pending operation. */
+ struct lguest_pending pending;
unsigned long *reg_read; /* register from LHREQ_GETREG */
diff --git a/drivers/lguest/lguest_user.c b/drivers/lguest/lguest_user.c
index 7f14c152dd23..dcf9efd94cf4 100644
--- a/drivers/lguest/lguest_user.c
+++ b/drivers/lguest/lguest_user.c
@@ -29,6 +29,10 @@ bool send_notify_to_eventfd(struct lg_cpu *cpu)
unsigned int i;
struct lg_eventfd_map *map;
+ /* We only connect LHCALL_NOTIFY to event fds, not other traps. */
+ if (cpu->pending.trap != LGUEST_TRAP_ENTRY)
+ return false;
+
/*
* This "rcu_read_lock()" helps track when someone is still looking at
* the (RCU-using) eventfds array. It's not actually a lock at all;
@@ -52,9 +56,9 @@ bool send_notify_to_eventfd(struct lg_cpu *cpu)
* we'll continue to use the old array and just won't see the new one.
*/
for (i = 0; i < map->num; i++) {
- if (map->map[i].addr == cpu->pending_notify) {
+ if (map->map[i].addr == cpu->pending.addr) {
eventfd_signal(map->map[i].event, 1);
- cpu->pending_notify = 0;
+ cpu->pending.trap = 0;
break;
}
}
@@ -62,7 +66,7 @@ bool send_notify_to_eventfd(struct lg_cpu *cpu)
rcu_read_unlock();
/* If we cleared the notification, it's because we found a match. */
- return cpu->pending_notify == 0;
+ return cpu->pending.trap == 0;
}
/*L:055
@@ -282,8 +286,8 @@ static ssize_t read(struct file *file, char __user *user, size_t size,loff_t*o)
* If we returned from read() last time because the Guest sent I/O,
* clear the flag.
*/
- if (cpu->pending_notify)
- cpu->pending_notify = 0;
+ if (cpu->pending.trap)
+ cpu->pending.trap = 0;
/* Run the Guest until something interesting happens. */
return run_guest(cpu, (unsigned long __user *)user);
diff --git a/include/linux/lguest_launcher.h b/include/linux/lguest_launcher.h
index f27cae27b0c1..c4451ebece47 100644
--- a/include/linux/lguest_launcher.h
+++ b/include/linux/lguest_launcher.h
@@ -68,6 +68,19 @@ enum lguest_req
};
/*
+ * This is what read() of the lguest fd populates. trap ==
+ * LGUEST_TRAP_ENTRY for an LHCALL_NOTIFY (addr is the
+ * argument), 14 for a page fault in the MMIO region (addr is
+ * the trap address, insn is the instruction), or 13 for a GPF
+ * (insn is the instruction).
+ */
+struct lguest_pending {
+ __u8 trap;
+ __u8 insn[7];
+ __u32 addr;
+};
+
+/*
* The alignment to use between consumer and producer parts of vring.
* x86 pagesize for historical reasons.
*/
diff --git a/tools/lguest/lguest.c b/tools/lguest/lguest.c
index 3f7f2326cd9a..0e754d04876d 100644
--- a/tools/lguest/lguest.c
+++ b/tools/lguest/lguest.c
@@ -1820,17 +1820,21 @@ static void __attribute__((noreturn)) restart_guest(void)
static void __attribute__((noreturn)) run_guest(void)
{
for (;;) {
- unsigned long notify_addr;
+ struct lguest_pending notify;
int readval;
/* We read from the /dev/lguest device to run the Guest. */
- readval = pread(lguest_fd, ¬ify_addr,
- sizeof(notify_addr), cpu_id);
+ readval = pread(lguest_fd, ¬ify, sizeof(notify), cpu_id);
/* One unsigned long means the Guest did HCALL_NOTIFY */
- if (readval == sizeof(notify_addr)) {
- verbose("Notify on address %#lx\n", notify_addr);
- handle_output(notify_addr);
+ if (readval == sizeof(notify)) {
+ if (notify.trap == 0x1F) {
+ verbose("Notify on address %#08x\n",
+ notify.addr);
+ handle_output(notify.addr);
+ } else
+ errx(1, "Unknown trap %i addr %#08x\n",
+ notify.trap, notify.addr);
/* ENOENT means the Guest died. Reading tells us why. */
} else if (errno == ENOENT) {
char reason[1024] = { 0 };
--
2.1.0
--
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