From: Rusty Russell <rusty@rustcorp.com.au>
To: Gregory Haskins <gregory.haskins@gmail.com>
Cc: "Michael S. Tsirkin" <mst@redhat.com>,
Avi Kivity <avi@redhat.com>,
Gregory Haskins <ghaskins@novell.com>,
linux-kernel@vger.kernel.org, agraf@suse.de,
pmullaney@novell.com, pmorreale@novell.com,
anthony@codemonkey.ws, netdev@vger.kernel.org,
kvm@vger.kernel.org, bhutchings@solarflare.com,
andi@firstfloor.org, gregkh@suse.de, herber@gondor.apana.org.au,
chrisw@sous-sol.org, shemminger@vyatta.com
Subject: Re: [RFC PATCH v2 00/19] virtual-bus
Date: Fri, 5 Jun 2009 14:25:01 +0930 [thread overview]
Message-ID: <200906051425.02924.rusty@rustcorp.com.au> (raw)
In-Reply-To: <4A28172D.6010906@gmail.com>
On Fri, 5 Jun 2009 04:19:17 am Gregory Haskins wrote:
> Avi Kivity wrote:
> > Gregory Haskins wrote:
> > One idea is similar to signalfd() or eventfd()
>
> And thus the "kvm-eventfd" (irqfd/iosignalfd) interface project was born.
> ;)
The lguest patch queue already has such an interface :) And I have a
partially complete in-kernel virtio_pci patch with the same trick.
I switched from "kernel created eventfd" to "userspace passes in eventfd"
after a while though; it lets you connect multiple virtqueues to a single fd
if you want.
Combined with a minor change to allow any process with access to the lguest fd
to queue interrupts, this allowed lguest to move to a thread-per-virtqueue
model which was a significant speedup as well as nice code reduction.
Here's the relevant kernel patch for reading.
Thanks!
Rusty.
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>
---
drivers/lguest/Kconfig | 2 -
drivers/lguest/core.c | 8 ++--
drivers/lguest/lg.h | 9 ++++
drivers/lguest/lguest_user.c | 73 ++++++++++++++++++++++++++++++++++++++++
include/linux/lguest_launcher.h | 1
5 files changed, 89 insertions(+), 4 deletions(-)
diff --git a/drivers/lguest/Kconfig b/drivers/lguest/Kconfig
--- a/drivers/lguest/Kconfig
+++ b/drivers/lguest/Kconfig
@@ -1,6 +1,6 @@
config LGUEST
tristate "Linux hypervisor example code"
- depends on X86_32 && EXPERIMENTAL && !X86_PAE && FUTEX
+ depends on X86_32 && EXPERIMENTAL && !X86_PAE && EVENTFD
select HVC_DRIVER
---help---
This is a very simple module which allows you to run
diff --git a/drivers/lguest/core.c b/drivers/lguest/core.c
--- a/drivers/lguest/core.c
+++ b/drivers/lguest/core.c
@@ -198,9 +198,11 @@ int run_guest(struct lg_cpu *cpu, unsign
/* 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 (put_user(cpu->pending_notify, user))
- return -EFAULT;
- return sizeof(cpu->pending_notify);
+ if (!send_notify_to_eventfd(cpu)) {
+ if (put_user(cpu->pending_notify, user))
+ return -EFAULT;
+ return sizeof(cpu->pending_notify);
+ }
}
/* Check for signals */
diff --git a/drivers/lguest/lg.h b/drivers/lguest/lg.h
--- a/drivers/lguest/lg.h
+++ b/drivers/lguest/lg.h
@@ -82,6 +82,11 @@ struct lg_cpu {
struct lg_cpu_arch arch;
};
+struct lg_eventfds {
+ unsigned long addr;
+ struct file *event;
+};
+
/* The private info the thread maintains about the guest. */
struct lguest
{
@@ -102,6 +107,9 @@ struct lguest
unsigned int stack_pages;
u32 tsc_khz;
+ unsigned int num_eventfds;
+ struct lg_eventfds *eventfds;
+
/* Dead? */
const char *dead;
};
@@ -152,6 +160,7 @@ void setup_default_idt_entries(struct lg
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);
diff --git a/drivers/lguest/lguest_user.c b/drivers/lguest/lguest_user.c
--- a/drivers/lguest/lguest_user.c
+++ b/drivers/lguest/lguest_user.c
@@ -7,6 +7,8 @@
#include <linux/miscdevice.h>
#include <linux/fs.h>
#include <linux/sched.h>
+#include <linux/eventfd.h>
+#include <linux/file.h>
#include "lg.h"
/*L:055 When something happens, the Waker process needs a way to stop the
@@ -35,6 +37,70 @@ static int break_guest_out(struct lg_cpu
}
}
+bool send_notify_to_eventfd(struct lg_cpu *cpu)
+{
+ unsigned int i;
+
+ /* lg->eventfds is RCU-protected */
+ preempt_disable();
+ for (i = 0; i < cpu->lg->num_eventfds; i++) {
+ if (cpu->lg->eventfds[i].addr == cpu->pending_notify) {
+ eventfd_signal(cpu->lg->eventfds[i].event, 1);
+ cpu->pending_notify = 0;
+ break;
+ }
+ }
+ preempt_enable();
+ return cpu->pending_notify == 0;
+}
+
+static int add_eventfd(struct lguest *lg, unsigned long addr, int fd)
+{
+ struct lg_eventfds *new, *old;
+
+ if (!addr)
+ return -EINVAL;
+
+ /* Replace the old array with the new one, carefully: others can
+ * be accessing it at the same time */
+ new = kmalloc(sizeof(*new) * (lg->num_eventfds + 1), GFP_KERNEL);
+ if (!new)
+ return -ENOMEM;
+
+ memcpy(new, lg->eventfds, sizeof(*new) * lg->num_eventfds);
+ old = lg->eventfds;
+ lg->eventfds = new;
+ synchronize_rcu();
+ kfree(old);
+
+ lg->eventfds[lg->num_eventfds].addr = addr;
+ lg->eventfds[lg->num_eventfds].event = eventfd_fget(fd);
+ if (IS_ERR(lg->eventfds[lg->num_eventfds].event))
+ return PTR_ERR(lg->eventfds[lg->num_eventfds].event);
+
+ wmb();
+ lg->num_eventfds++;
+ return 0;
+}
+
+static int attach_eventfd(struct lguest *lg, const unsigned long __user *input)
+{
+ unsigned long addr, fd;
+ int err;
+
+ if (get_user(addr, input) != 0)
+ return -EFAULT;
+ input++;
+ if (get_user(fd, input) != 0)
+ return -EFAULT;
+
+ mutex_lock(&lguest_lock);
+ err = add_eventfd(lg, addr, fd);
+ mutex_unlock(&lguest_lock);
+
+ return 0;
+}
+
/*L:050 Sending an interrupt is done by writing LHREQ_IRQ and an interrupt
* number to /dev/lguest. */
static int user_send_irq(struct lg_cpu *cpu, const unsigned long __user *input)
@@ -260,6 +326,8 @@ static ssize_t write(struct file *file,
return user_send_irq(cpu, input);
case LHREQ_BREAK:
return break_guest_out(cpu, input);
+ case LHREQ_EVENTFD:
+ return attach_eventfd(lg, input);
default:
return -EINVAL;
}
@@ -297,6 +365,11 @@ static int close(struct inode *inode, st
* the Launcher's memory management structure. */
mmput(lg->cpus[i].mm);
}
+
+ /* Release any eventfds they registered. */
+ for (i = 0; i < lg->num_eventfds; i++)
+ fput(lg->eventfds[i].event);
+
/* If lg->dead doesn't contain an error code it will be NULL or a
* kmalloc()ed string, either of which is ok to hand to kfree(). */
if (!IS_ERR(lg->dead))
diff --git a/include/linux/lguest_launcher.h b/include/linux/lguest_launcher.h
--- a/include/linux/lguest_launcher.h
+++ b/include/linux/lguest_launcher.h
@@ -58,6 +58,7 @@ enum lguest_req
LHREQ_GETDMA, /* No longer used */
LHREQ_IRQ, /* + irq */
LHREQ_BREAK, /* + on/off flag (on blocks until someone does off) */
+ LHREQ_EVENTFD, /* + address, fd. */
};
/* The alignment to use between consumer and producer parts of vring.
next prev parent reply other threads:[~2009-06-05 4:55 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-04-09 16:30 [RFC PATCH v2 00/19] virtual-bus Gregory Haskins
2009-04-09 16:30 ` [RFC PATCH v2 01/19] shm-signal: shared-memory signals Gregory Haskins
2009-04-09 16:30 ` [RFC PATCH v2 02/19] vbus: add virtual-bus definitions Gregory Haskins
2009-04-09 16:30 ` [RFC PATCH v2 03/19] vbus: add connection-client helper infrastructure Gregory Haskins
2009-06-04 18:06 ` Michael S. Tsirkin
2009-06-04 18:18 ` Gregory Haskins
2009-06-04 18:24 ` Avi Kivity
2009-06-04 18:30 ` Gregory Haskins
2009-06-04 19:04 ` Avi Kivity
2009-06-04 18:23 ` Avi Kivity
2009-04-09 16:31 ` [RFC PATCH v2 04/19] vbus: add bus-registration notifiers Gregory Haskins
2009-04-09 16:31 ` [RFC PATCH v2 05/19] vbus: add a "vbus-proxy" bus model for vbus_driver objects Gregory Haskins
2009-04-09 16:31 ` [RFC PATCH v2 06/19] ioq: Add basic definitions for a shared-memory, lockless queue Gregory Haskins
2009-04-09 16:31 ` [RFC PATCH v2 07/19] ioq: add vbus helpers Gregory Haskins
2009-04-09 16:31 ` [RFC PATCH v2 08/19] venet: add the ABI definitions for an 802.x packet interface Gregory Haskins
2009-04-09 16:31 ` [RFC PATCH v2 09/19] net: Add vbus_enet driver Gregory Haskins
2009-04-09 16:37 ` Stephen Hemminger
2009-04-09 19:50 ` Greg KH
2009-04-09 16:31 ` [RFC PATCH v2 10/19] venet-tap: Adds a "venet" compatible "tap" device to VBUS Gregory Haskins
2009-04-09 16:31 ` [RFC PATCH v2 11/19] venet: add scatter-gather support Gregory Haskins
2009-04-09 16:31 ` [RFC PATCH v2 12/19] venettap: " Gregory Haskins
2009-04-09 16:31 ` [RFC PATCH v2 13/19] x86: allow the irq->vector translation to be determined outside of ioapic Gregory Haskins
2009-04-09 16:31 ` [RFC PATCH v2 14/19] kvm: add a reset capability Gregory Haskins
2009-04-11 16:56 ` Avi Kivity
2009-04-09 16:32 ` [RFC PATCH v2 15/19] kvm: add dynamic IRQ support Gregory Haskins
2009-04-11 17:01 ` Avi Kivity
2009-04-13 17:44 ` Gregory Haskins
2009-04-09 16:32 ` [RFC PATCH v2 16/19] kvm: Add VBUS support to the host Gregory Haskins
2009-04-09 16:32 ` [RFC PATCH v2 17/19] kvm: Add guest-side support for VBUS Gregory Haskins
2009-04-09 16:32 ` [RFC PATCH v2 18/19] vbus: add a userspace connector Gregory Haskins
2009-04-09 16:32 ` [RFC PATCH v2 19/19] virtio: add a vbus transport Gregory Haskins
2009-08-09 16:40 ` Anthony Liguori
2009-08-10 15:40 ` Gregory Haskins
2009-04-09 16:48 ` [RFC PATCH v2 00/19] virtual-bus Gregory Haskins
2009-04-11 16:45 ` Avi Kivity
2009-06-04 18:49 ` Gregory Haskins
2009-06-05 4:55 ` Rusty Russell [this message]
2009-06-05 5:30 ` Paul E. McKenney
2009-06-05 14:55 ` Rusty Russell
2009-06-05 16:25 ` Paul E. McKenney
2009-06-11 13:21 ` Rusty Russell
2009-06-11 15:48 ` Paul E. McKenney
2009-06-05 11:56 ` Gregory Haskins
2009-06-05 12:53 ` Avi Kivity
2009-06-05 12:54 ` Gregory Haskins
2009-06-05 14:35 ` Rusty Russell
2009-06-05 14:44 ` Gregory Haskins
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=200906051425.02924.rusty@rustcorp.com.au \
--to=rusty@rustcorp.com.au \
--cc=agraf@suse.de \
--cc=andi@firstfloor.org \
--cc=anthony@codemonkey.ws \
--cc=avi@redhat.com \
--cc=bhutchings@solarflare.com \
--cc=chrisw@sous-sol.org \
--cc=ghaskins@novell.com \
--cc=gregkh@suse.de \
--cc=gregory.haskins@gmail.com \
--cc=herber@gondor.apana.org.au \
--cc=kvm@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mst@redhat.com \
--cc=netdev@vger.kernel.org \
--cc=pmorreale@novell.com \
--cc=pmullaney@novell.com \
--cc=shemminger@vyatta.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).