lguest: use eventfds for device notification

Currently, when a Guest wants to perform I/O it calls LHCALL_NOTIFY with
an address: the main Launcher process returns with this address, and figures
out what device to run.

A far nicer model is to let processes bind an eventfd to an address: if we
find one, we simply signal the eventfd.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
Cc: Davide Libenzi <davidel@xmailserver.org>

1 files changed, 13 insertions, 0 deletions

diff --git a/drivers/lguest/lg.h b/drivers/lguest/lg.h
index 040cb70780e7..32fefdc6ad3e 100644
--- a/drivers/lguest/lg.h
+++ b/drivers/lguest/lg.h
@@ -82,6 +82,16 @@ struct lg_cpu {
         struct lg_cpu_arch arch;
 };
 
+struct lg_eventfd {
+        unsigned long addr;
+        struct file *event;
+};
+
+struct lg_eventfd_map {
+        unsigned int num;
+        struct lg_eventfd map[];
+};
+
 /* The private info the thread maintains about the guest. */
 struct lguest
 {
@@ -102,6 +112,8 @@ struct lguest
         unsigned int stack_pages;
         u32 tsc_khz;
 
+        struct lg_eventfd_map *eventfds;
+
         /* Dead? */
         const char *dead;
 };
@@ -154,6 +166,7 @@ void setup_default_idt_entries(struct lguest_ro_state *state,
 void copy_traps(const struct lg_cpu *cpu, struct desc_struct *idt,
                 const unsigned long *def);
 void guest_set_clockevent(struct lg_cpu *cpu, unsigned long delta);
+bool send_notify_to_eventfd(struct lg_cpu *cpu);
 void init_clockdev(struct lg_cpu *cpu);
 bool check_syscall_vector(struct lguest *lg);
 int init_interrupts(void);