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


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