[PATCH 02/16] adapt lguest launcher to per-cpuness

Glauber de Oliveira Costa
2008-01-07T13:07:31Z

This patch makes uses of pread() and pwrite() in lguest launcher
to communicate the vcpu id to the lguest driver. The id is kept in
a thread variable, which means we'll span in the future, vcpus as
threads. But right now, only the infrastructure is out there.

Signed-off-by: Glauber de Oliveira Costa <gcosta@redhat.com>
---
Documentation/lguest/lguest.c | 23 ++++++++++++++++-------
1 files changed, 16 insertions(+), 7 deletions(-)

diff --git a/Documentation/lguest/lguest.c b/Documentation/lguest/lguest.c
index 9b0e322..4745f7e 100644
--- a/Documentation/lguest/lguest.c
+++ b/Documentation/lguest/lguest.c
@@ -79,6 +79,9 @@ static void *guest_base;
/* The maximum guest physical address allowed, and maximum possible. */
static unsigned long guest_limit, guest_max;

+/* a per-cpu variable indicating whose vcpu is currently running */
+static unsigned int __thread vcpu_id;
+
/* This is our list of devices. */
struct device_list
{
@@ -554,7 +557,7 @@ static void wake_parent(int pipefd, int lguest_fd)
else
FD_CLR(-fd - 1, &devices.infds);
} else /* Send LHREQ_BREAK command. */
- write(lguest_fd, args, sizeof(args));
+ pwrite(lguest_fd, args, sizeof(args), 0);
}
}

@@ -1511,7 +1514,8 @@ static void __attribute__((noreturn)) run_guest(int lguest_fd)
int readval;

/* We read from the /dev/lguest device to run the Guest. */
- readval = read(lguest_fd, &notify_addr, sizeof(notify_addr));
+ readval = pread(lguest_fd, &notify_addr,
+ sizeof(notify_addr), vcpu_id);

/* One unsigned long means the Guest did HCALL_NOTIFY */
if (readval == sizeof(notify_addr)) {
@@ -1521,17 +1525,21 @@ static void __attribute__((noreturn)) run_guest(int lguest_fd)
/* ENOENT means the Guest died. Reading tells us why. */
} else if (errno == ENOENT) {
char reason[1024] = { 0 };
- read(lguest_fd, reason, sizeof(reason)-1);
+ pread(lguest_fd, reason, sizeof(reason)-1, vcpu_id);
errx(1, "%s", reason);
/* EAGAIN means the Waker wanted us to look at some input.
* Anything else means a bug or incompatible change. */
} else if (errno != EAGAIN)
err(1, "Running guest failed");

- /* Service input, then unset the BREAK to release the Waker. */
- handle_input(lguest_fd);
- if (write(lguest_fd, args, sizeof(args)) < 0)
- err(1, "Resetting break");
+ if (!vcpu_id) {
+ /* Service input, then unset the BREAK to
+ * release the Waker. Right now, simple mecahnism
+ * to issue it all to first vcpu */
+ handle_input(lguest_fd);
+ if (pwrite(lguest_fd, args, sizeof(args), 0) < 0)
+ err(1, "Resetting break");
+ }
}
}
/*
@@ -1582,6 +1590,7 @@ int main(int argc, char *argv[])
devices.lastdev = &devices.dev;
devices.next_irq = 1;

+ vcpu_id = 0;
/* We need to know how much memory so we can set up the device
* descriptor and memory pages for the devices as we parse the command
* line. So we quickly look through the arguments to find the amount
--
1.5.0.6